  MJPEG HOWTO - An introduction to the MJPEG-tools
  Praschinger Bernhard
  v1.37

  MJPEG capture/editting/replay and MPEG encoding toolset description
  ______________________________________________________________________

  Table of Contents



  1. Introduction
  2. Unsorted list of useful Hints
  3. Recording videos
     3.1 lavrec examples
     3.2 Other recording hints
     3.3 Some information about the typical lavrec output while recording
     3.4 Notes about "interlace field order - what can go wrong and how to fix it"
        3.4.1 There are three bad things that can happen with fields
        3.4.2 How can I recognize if I have one of these Problems ?
        3.4.3 How can you fix it?
        3.4.4 Hey, what about NTSC movies ?

  4. Creating videos from other sources
     4.1 Creating videos from images
     4.2 Decoding streams with mplayer
     4.3 Decoding MPEG2 streams with mpeg2dec
     4.4 Other things to know

  5. Checking if recording was successful
  6. Edit the video
     6.1 Edit with glav
     6.2 Unify videos
     6.3 Separate sound
     6.4 Separate images
     6.5 Creating movie transitions

  7. Converting the stream to MPEG or DIVx videos
     7.1 Creating sound
     7.2 Converting video
        7.2.1 Scaling
     7.3 Putting the streams together
     7.4 Creating MPEG1 Videos
        7.4.1 MPEG1 Audio creation Example
        7.4.2 MPEG1 Video creation Example
        7.4.3 MPEG1 Multiplexing Example
     7.5 Creating MPEG2 Videos
        7.5.1 MPEG2 Audio creation Example
        7.5.2 MPEG2 Video creation Example
           7.5.2.1 Which values should be used for VBR Encoding
           7.5.2.2 Encoding destination TV (interlaced) or Monitor (progressive)
        7.5.3 MPEG2 Multiplexing Example
     7.6 Creating Video-CD's
        7.6.1 VCD Audio creation Example
        7.6.2 VCD Video creation Example
        7.6.3 VCD Multiplexing Example
        7.6.4 Creating the CD
        7.6.5 Notes
        7.6.6 Storing MPEGs
     7.7 Creating SVCD
        7.7.1 SVCD Audio creation Example
        7.7.2 SVCD Video creation Example
        7.7.3 SVCD Multiplexing Example
        7.7.4 SVCD Creating the CD
     7.8 Creating DVD's
        7.8.1 DVD Audio creation Example
        7.8.2 DVD Video creation Example
        7.8.3 DVD Mplex Example
        7.8.4 DVD creation Example
     7.9 Creating DIVX Videos
        7.9.1 lav2avi.sh

  8. Optimizing the stream
     8.1 Scaling and offset correction
     8.2 Frame rate conversion

  9. Transcoding of existing MPEG-2
     9.1 If you want to do every step on your own it will look something like this

  10. Trading Quality/Speed
     10.1 Creating streams to be played from disk using Software players

  11. SMP and distributed Encoding
  12. Interoperability


  ______________________________________________________________________


  1.  Introduction

  I wrote this things down, because I had many sheets with notes on
  them.  This should be some kind of summary of collected knowledge of
  this sheets.  Andrew Stevens helped with encoding and VCD knowledge
  and hints.

  The mjpegtools are a set of programs that can do recording, playback,
  editing and eventual MPEG compression of audio and video under Linux.

  Although primarily intended for use with capture / playback boards
  based on the Zoran ZR36067 MJPEG codec chip, the mjpegtools can easily
  be used to process and compress MJPEG video streams captured using
  xawtv using simple frame-buffer devices.

  The HOWTO for the tools intended to give an an introduction to the
  MJPEG-tools and the creation of MPEG 1/2 videos. VCD and SVCD, and the
  transcoding of existing mpeg streams.

  For more information about the programs read the corresponding man-
  page.

  Achtung es gibt auch eine deutsche Version bei:
  http://sourceforge.net/projects/mjpeg

  There is also a manpage of this text, you can read it with "man
  mjpegtools" if installed.

  The text version of this text is available via cvs, you should get it
  with a tarball or the precompiled package (RPM and deb).


  2.  Unsorted list of useful Hints

  You have to compile and install the mjpeg_play package, for this read
  the README & REQUIRED_SOFTWARE & INSTALL.  If you do not want to
  compile it, you can download the mjpeg .RPM or .DEB package at
  Sourceforge.

  There is a script in the scripts/ directory. This script is something
  that show's you a way how it can be done. It also creates (under
  certain circumstances) videos that look quite good. Better videos you
  only get by tuning the parameters yourself.

  You will usually have to load the drivers for the Buz or DC10 or LML33
  cards.So you have to run the update script providing as option the
  name of your card you have. The script is usually in /usr/src/driver-
  zoran/.  The zoran kernel driver below the kernel 2.4.4 do not work.
  You have to use the driver available from:
  http://mjpeg.sourceforge.net/driver-zoran

  The driver for the Matrox Marvel card also works, more information
  about it: http://marvel.sourceforge.net

  If you compile the tools on a P6 based computer (PPro, P-II, P-III,
  P-4, Athlon,Duron) then never try to let them run on a P5 based
  computer (Pentium, Pentium-MMX, K6, K6-x, Cyrix, Via, Winchip). You'll
  get a "illegal instruction" and the program won't work.

  If lav2yuv dumps core then one possible cause is no dv support was
  included. To enable it make sure that libdv is installed on the
  system.  This will be necessary if you are using a digital camera (or
  analog to DV converter such as the Canopus ADVC100) and converting the
  dv avi format into the MPEG format.

  Start xawtv to see if you get an picture. If you want to use HW-
  playback of the recorded streams you have to start xawtv (any TV
  application works) once to get the streams played back. You should
  also check the settings of your mixer in the sound card.

  If you compile the tools on a platform other than Linux not all tools
  will work.   Mjpegtools on a OS/X system for example will not have V4L
  (video4linux) capability.

  Never try to stop or start the TV application when lavrec runs. If you
  start or stop the TV application lavrec will stop recording, or your
  computer could get "frozen". This is a problem of v4l (video4linux).

  This problem is solved with v4l2. If you use v4l2 you can record the
  video and stop and start the tv application whenever you want.  But
  v4l2 is currently (7. Jan. 2003) only supported for the zoran based
  cards (BUZ, DC10, DC10+, LML33) if you use the CVS driver from
  mjpeg.sf.net tagged with ZORAN_VIDEODEV_2.  And this driver only works
  with the 2.4.20 kernel and the 2.5.* development kernel.

  One last thing about the data you get before we start:


  Audio: ( Samplerate * Channels * Bitsize ) / (8 * 1024)
  CD Quality:(44100 Samples/sec * 2 Chanels * 16 Bit) / (8 * 1024)=172,2 kB/sec

  The 8 * 1024 convert the value from bit/sec to kByte/sec

  Video: (width * height * framerate * quality ) / (200 * 1024)
  PAL HALF Size : (352 * 288 * 25 * 80) / (200 * 1024) = 990 kB/sec
  PAL FULL size : (720 * 576 * 25 * 80) / (200 * 1024) = 4050 kB/sec
  NTSC HALF size: (352 * 240 * 30 * 80) / (200 * 1024) = 990 kB/sec
  NTSC FULL size: (720 * 480 * 30 * 80) / (200 * 1024) = 4050 kB/sec



  The 1024 converts the Bytes to kBytes. Not every card can record the
  size mentioned. The Buz and Marvel G400 for example can only record a
  size of 720x576 when using -d 1, the DC10 records a size of 384x288
  when using -d 2.

  When you add audio and video datarate this is what your hard disk has
  to be able to write constantly streaming, else you will have lost
  frames.

  If you want to play with the --mjpeg-buffer-size. Remember the value
  should be at least big enough that one frame fits in it. The size of
  one frame is: (width * height * quality ) / (200 * 1024) = kB If the
  buffer is too small the rate calculation doesn't match any more and
  buffer overflows can happen. The maximum value is 512kB.

  How video works and the difference between the video types is
  explained here: http://www.mir.com/DMG/


  There you also find how to create MPEG Still Images for VCD/SVCD.

  A good description of DV (Digital Video) can be found here:
  http://www.iki.fi/znark/video/conversion/


  3.  Recording videos



  3.1.  lavrec examples

  Recording with lavrec look's like this:

  > lavrec -f a -i P -d 2 record.avi


        Should start recording now,

     -f a
        use AVI as output format,

     -i P
        use as input source the SVHS-In with PAL format,

     -d 2
        the size of the pictures are half size (352x288)

     record.avi
        name of the created file.

  Recording is finished by pressing Crtl-C (nowadays: Strg-C).
  Sometimes using -f A instead of -f a might be necessary

  Other example:

  > lavrec -f q -i n -d 1 -q 80 -s -l 80 -R l -U record.avi


        Should start recording now,

     -f q
        use Quicktime as output format,

     -i n
        use Composite-In with NTSC format,

     -d 1
        record pictures with full size (640x480)

     -q 80
        set the quality to 80% of the captured image

     -s use stereo mode (default mono)

     -l 80
        set the recording level to 80% of the max during recording

     -R l
        set the recording source to Line-In

     -U With this lavrec uses the read instead of mmap for recording
        this is needed if your sound card does not support the mmap for
        recording.


  Setting the mixer does not work with every sound card.  If you record
  with 2 different settings and both recordings are equally loud you
  should setup the mixer with a mixer program.  After that you should
  use the -l -1 option when you record using lavrec

  The size of the image depends on the card you use.  At full size (-d
  1) you get these image sizes: BUZ and LML33: 720x576, the DC10:
  768x576

  Other example:

  > lavrec -w -f a -i S -d 2 -l -1 record%02d.avi


        Should start recording,

     -w Waits for user confirmation to start (press enter)

     -f a
        use AVI as output format,

     -i S
        use SECAM SVHS-Input (SECAM Composite recording is also
        possible: -i s)

     -d 2
        the size of the pictures are half size

     -l -1
        do not touch the mixer settings

     record%02d.avi
        Here lavrec creates the first file named record00.avi after the
        file has reached a size of 1.6GB (after about 20 Minutes
        recording) it starts a new sequence named record01.avi and so on
        till the recording is stopped or the disk is full

  Other example:

  > lavrec -f a -i t -q 80 -d 2 -C europe-west:SE20 test.avi


        Should start recording now,

     -f a
        use AVI as output format,

     -i t
        use tuner input,

     -q 80
        set the quality to 80% of the captured image

     -d 2
        the size of the pictures are half size (352x288)

     -C choose TV channels, and the corresponding -it and -iT (video
        source: TV tuner) can currently be used on the Marvel G200/G400
        and the Matrox Millenium G200/G400 with Rainbow Runner extension
        (BTTV-Support is under construction). For more information on
        how to make the TV tuner parts of these cards work, see the
        Marvel/Linux project on: http://marvel.sourceforge.net

  Last example:


  > lavrec -f a -i p -g 352x288 -q 80 -s -l 70 -R l --software-encoding
  test03.avi

  The two new options are -g 352x288, which sets the size of the video
  to be recorded when using --software-encoding, this enables the
  software encoding of the recorded images. With this option you can
  also record from a bttv based card. The processor load is high. This
  option only works for generic video4linux cards (such as the
  brooktree-848/878 based cards), it doesn't work for zoran-based cards.



  3.2.  Other recording hints

  All lavtools accept a file description like file*.avi, so you do not
  have to name each file, but that would also be a posibillity to do.

  Note: More options are described in the man-page, but with this you
  should be able to get started.

  Here are some hints for sensible settings. Turn the quality to 80% or
  more for -d 2 capture. At full resolution as low as 40% seems to be
  visually "perfect". -d 2 is already better than VHS video (a *lot*!).
  For a Marvel you should not set the quality higher than 50 when you
  record at full size (-d 1). If you use higher settings (-q 60) it is
  more likely that you will encounter problems. Higher settings will
  result in framedrops.  If you're aiming to create VCD's then there is
  little to be gained recording at full resolution as you need to reduce
  to -d 2 resolution later anyway.

  you can record at other sizes than the obvious -d 1/2/4. You can use
  combinations where you use halve horizontal size and full vertical
  size: -d 21.  This would record for NTSC at a size of 352x480. This
  helps if you want to create SVCDs, scaling the 352 Pixles put to 480
  is not that visible for the eye as if you would use the other
  combination -d 12.  Where you have the full horzontal resolution and
  half vertical this Version will have a size of 720x288 for NTSC



  3.3.  Some information about the typical lavrec output while recording

  0.06.14:22 int: 00040 lst:0 ins:0 del:0 ae:0 td1=0.014 td2=0.029

  The first part shows the time lavrec is recording.  int: the interval
  between two frames. lst: the number of lost frames. ins and del: are
  the number of frames inserted and deleted for sync correction. ae:
  number of audio errors.  td1 and td2 are the audio/video time-
  difference.


  o   (int) frame interval should be around 33 (NTSC) or 40 (PAL/SECAM).
     If it is very different, you'll likely get a bad recording and/or
     many lost frames

  o   (lst) lost frames are bad and mean that something is not working
     very well during recording (too slow HD, too high CPU usage, ...)
     Try recording with a greater decimation and possibly a lower
     quality.

  o   (ins, del) inserted OR deleted frames of them are normal -> sync.
     If you have many lost AND inserted frames, you're asking too much
     of your machine.  Use less demanding options or try a different
     sound card.


  o   (ae) audio errors are never good. Should be 0

  o   (td1, td2) time differenceis always floating around 0, unless sync
     correction is disabled (--synchronization!=2, 2 is default).


  3.4.  Notes about "interlace field order - what can go wrong and how
  to fix it"

  Firstly, what does it mean for interlace field order to be wrong?

  The whole mjpegtools image processing chain is frame-oriented. Since
  it is video material that is captured each frame comprised a top field
  (the 0th, 2nd, 4th and so lines) and a bottom field (the 1st, 3rd, 5th
  and so on lines).


  3.4.1.  There are three bad things that can happen with fields


  1.  This is really only an issue for movies in PAL video where each
     film frame is sent as a pair of fields. These can be sent top or
     bottom field first and sadly it's not always the same, though
     bottom-first appears to be usual. If you capture with the wrong
     field order (you start capturing each frame with a bottom rather
     than a top or vice versa) the frames of the movie get split
     *between* frames in the stream. Played back on a TV where each
     field is displayed on its own this is harmless. The sequence of
     fields played back is exactly the same as the sequence of fields
     broadcast. Unfortunately, playing back on a Computer monitor where
     both fields of a frame appear at once it looks *terrible* because
     each frame is effectively mixing two moments in time 1/25sec
     apparent.

  2.  The two fields can simply be swapped somehow so that top gets
     treat as bottom and bottom treat as top. Juddering and "slicing" is
     the result. This occasionally seems to happen due to hardware
     glitches in the capture card.

  3.  Somewhere in capturing/processing the *order* in time of the two
     fields in each frame can get mislabeled somehow. This is not good
     as it means that when playback eventually takes place a field
     containing an image sampled earlier in time comes after an image
     sampled later.  Weird "juddering" effects are the results.


  3.4.2.  How can I recognize if I have one of these Problems ?


  1. This can be hard to spot. If you have mysteriously flickery
     pictures during playback try encoding a snippet with the reverse
     field-order forced (see below). If things improve drastically you
     know what the problem was and what the solution is!

  2. The two fields can simply be swapped somehow so that top gets treat
     as bottom and bottom treat as top. Juddering and "slicing" is the
     result. This occasionally seems to happen due to hardware glitches
     in the capture card.

  3. Somewhere in capturing/processing the *order* in time of the two
     fields in each frame can get mislabeled somehow. This is not good
     as it means that when playback eventually takes place a field
     containing an image sampled earlier in time comes after an image
     sampled later. Weird "juddering" effects are the result.


  If you use glav or lavplay be sure that you also use the -F/--flicker
  option. This disables some things that make the picture look better.

  If you want to look at the video you can also use yuvplay:

  > lav2yuv | ... | yuvplay

  If there is a field order problem you should see it with yuvplay.


  3.4.3.  How can you fix it?


  1. To fix this one the fields need to be "shifted" through the frames.
     Use yuvcorrect's -T BOTT_FORWARD/TOP_FORWARD to shift the way
     fields are allocated to frames. You can find out the current field
     order for an MJPEG file by looking at the first few lines of debug
     output from: > lav2yuv -v 2 the_mjpeg_file > /dev/null Or re-record
     exchanging -f a for -F A or vice-versa.

  2. This isn't too bad either. Use a tool that simply swaps the top and
     bottom fields a second time. yuvcorrect can do this use the -T
     LINE_SWITCH.

  3. Is easy to fix. Either tell a tool someplace to relabel the fields
     or simply tell the player to play back in swapped order (the latter
     can be done "indirectly" by telling mpeg2enc when encoding to
     reverse the flag (-z b|t) that tells the decoder which field order
     to use.


  In order to determine exactly what type of interlacing problem you
  have, you need to extract some frames from the recorded stream and
  take a look at them:


  > mkdir pnm
  > lav2yuv -f 40 video.avi | y4mtoppm | pnmsplit - pnm/image%d.pnm
  > rm pnm/image?.pnm
  > cd pnm
  > xv



  First we create a directory where we store the images. The lav2yuv -f
  40 writes only the first 40 frames to stdout. The mjpegtools y4mtoppm
  converts the frames to pnm images and the pnmsplit splits the picture
  into two frames in the picture to two single pictures. Then we remove
  the first 10 images because pnmsplit does not support the %0xd
  numbering. Without a leading zero in the number, the files will be
  sorted in the wrong order, leading to confusing playback.

  Use your favorite graphic program (xv for example) to view the
  pictures. As each picture only contain one field out of two they will
  appear scaled vertically. If you look at the pictures you should see
  the movie slowly advancing.

  If you have a film you should always see 2 pictures that are nearly
  the same (because the film frame is split into two field for
  broadcasting) after each other.  You can observe this easily if you
  have comb effects when you pause the film because both fields will be
  displayed at the same time. The two pictures that belong together
  should have an even number and the following odd number. So if you
  take a look on pictures: 4 and 5 are nearly identical, 5 and 6 differ
  (have movement), 6 and 7 identical, 7 and 8 differ , ....

  To fix this problem you have to use yuvcorrect's -T BOTT_FORWARD or
  TOP_FORWARD. You can also have the problem that the field order
  (top/bottom) is still wrong. You may have to use yuvcorrect a second
  time with -M LINE_SWITCH, or use the mpeg2enc -z (b|t) option.

  To see if you guessed correctly, extract the frames again, reordering
  them using yuvcorrect:

  > lav2yuv -f 40 video.avi | yuvcorrect -T OPTION | y4mtoppm | pnmsplit
  - pnm/image%d.pnm

  Where "OPTION" is what you think it will corrects the problem.  This
  is for material converted from film. Material produced directly for TV
  is addressed below.


  3.4.4.  Hey, what about NTSC movies ?

  Movies are broadcast in NTSC using "3:2" pulldown which means that
  half the capture frames contain fields from 1 movie frame and half
  fields from 2 frames. To undo this effect for efficient MPEG encoding
  you need to use yuvkineco.

  If you have an interlaced source like a TV camera you have a frame
  consists of two fields that are recorded at different points in time
  and shown after each other. Spotting the problem here is harder. You
  need to find something moving horizontally from the left to the right.
  When you extract the fields, the thing should move in small steps from
  the left to the right, not one large step forward, small step back,
  large forward, small back......  You have to use the same options
  mentioned aboth to correct the problem.

  Do not expect that the field order is always the same (top- or bottom-
  first) It may change between the channels, between the films, and it
  may even change within a film. If it changes constant you may have to
  encode with the mpeg2enc -I 1 or even -I 2.

  You can only have this problems if you record at full size !!!


  4.  Creating videos from other sources

  Here are some hints and descriptions of how to create the videos from
  other sources like images and other video types.

  You might also be interested in taking a look at the Transcoding of
  existing MPEG-2 section.



  4.1.  Creating videos from images

  You can use jpeg2yuv to create a yuv stream from separate JPEG images.
  This stream is sent to stdout, so that it can either be saved into a
  file, encoded directly to a mpeg video using mpeg2enc or used for
  anything else.

  Saving an yuv stream can be done like this:

  > jpeg2yuv -f 25 -j image%05d.jpg > result.yuv

  Creates the file result.yuv containing the yuv video data with 25 FPS.
  The -f option is used to set the frame rate. Note that image%05d.jpg
  means that the jpeg files are named image00000.jpg, image00001.jpg and
  so on. (05 means five digits, 04 means four digits, etc.)

  If you want to encode a mpeg video directly from jpeg images without
  saving a separate video file type:

  > jpeg2yuv -f 25 -j image%05d.jpg | mpeg2enc -o mpegfile.m1v

  Does the same as above but saves a mpeg video rather than a yuv video.
  See mpeg2enc section for details on how to use mpeg2enc.

  You can also use yuvscaler between jpeg2yuv and mpeg2enc. If you want
  to create a SVCD from your source images:

  > jpeg2yuv -f 25 -j image%05d.jpg | yuvscaler -O SVCD |  mpeg2enc -f 4
  -o video.m2v

  You can use the -b option to set the number of the image to start
  with. The number of images to be processed can be specified with the
  -n number. For example, if your first image is image01.jpg rather than
  image00.jpg, and you only want 60 images to be processed type:

  >jpeg2yuv -b 1 -f 25 -n 60 -j image*.jpg | yuv2lav -o
  stream_without_sound.avi

  Adding the sound to the stream then:

  > lavaddwav stream_without_sound.avi sound.wav stream_with_sound.avi

  For ppm input there is the ppmtoy4m util. There is a manpage for
  ppmtoy4m that should be consulted for additional information.

  So to create a mpeg video try this:

  >cat *.ppm | ppmtoy4m -o 75 -n 60 -F 25:1 | mpeg2enc -o output.m1v

  Cat's each *.ppm file to ppmtoy4m. There the first 75 frames
  (pictures) are ignored and next 60 are encoded by mpeg2enc to
  output.m1v. You can run it without the -o and -n option. The -F
  options sets the frame rate, default is NTSC (30000:1001), for PAL you
  have to use -F 25:1.

  Other picture formats can also be used if there is a converter to ppm.

  >ls *.tga | xargs -n1 tgatoppm | ppmtoy4m | yuvplay

  A list of filenames (ls *.tga) is given to xargs that executes the
  tgatoppm with one (-n 1) argument per call, and feeds the output into
  ppmtoy4m.  This time the video is only shown on the screen. The xargs
  is only needed if the converter (tgatoppm), can only operate on a
  single image at a time.

  If you want to use the ImageMagick 'convert' tool (a Swiss Army Knife)
  try:

  >convert *.gif ppm:- | ppmtoy4m | yuvplay

  That means take all '.jpg' images in directory, convert to PPM format,
  and pipe to stdout, then ppmtoy4m processes them ....


  4.2.  Decoding streams with mplayer

  Decoding the streams with mplayer is a nice way of bringing every
  video that mplayer can play back to something you can edit or encode
  directly to a mpeg video with the mjpegtools. This method works with
  mplayer 1.0pre2 or newer


  >mkfifo stream.yuv

  >mplayer -nosound -noframedrop -vo yuv4mpeg anyfile.mpg &

  >cat stream.yuv | yuv2lav -o mjpeg_wo.avi

  >mplayer -vo null -ao pcm -aofile anyfile.wav anyfile.mpg

  Now you have for example a mjpeg encoded AVI without sound. The sound
  will be in anyfile.wav. Now you can choose if you want to add the
  sound to the AVI with lavaddwav and edit the file and encode it.

  You can also use instead of yuv2lav, mpeg2enc or any other tool from
  the mjpeg tools so your command might also look like that:

  > cat stream.yuv | yuvdenoise | yuvscaler -o SVCD | mpeg2enc -f 4 -o
  video_svcd.m2v

  And cat the wav file into mp2enc to encode it to MP2 audio. The -vo
  yuv4mpeg option works well with other input types mentioned in the
  mplayer documentation.

  4.3.  Decoding MPEG2 streams with mpeg2dec

  You can decode mpeg2 streams with the patched mpeg2dec version which
  creates yuv streams. You can pipe that into any other mjpegtools
  program.  Or you use a mpeg2dec version directly from the libmpeg2
  project and use the output mode pgmpipe. With the pgmtoy4m program
  from the mjpegtools you can convert that pgm output back to yuv.


  If you ask yourself why there is a patched version and pgmtoy4m.  The
  answer is that the patch for yuv output was sent several times to the
  libmpeg2 developers but was never included.  Now we have two ways
  around that problem. Decoding looks like this:

  > mpeg2dec -s -o pgmpipe ANYTS.VOB | pgmtoy4m -i t -a 10:11 -r
  30000:1001 | mpeg2enc -f 8 newvideo.m2v

  You can decode the audio as described in the Transcoding of existing
  MPEG-2 Section.


  4.4.  Other things to know

  If you have Transport Streams from your DVB card, or os Satelite
  Receiver you might want to demultiplex or cut them. A nice tool for
  that is Project X available from: http://forum.lucike.info/

  You can process the streams afterwards as you would do with any mpeg
  movie or demultiplexed audio video. So the Transcoding of existing
  MPEG-2 section of this document will be of interest.

  5.  Checking if recording was successful

  You can use lavplay or glav. IMPORTANT: NEVER try to run xawtv and
  lavplay or glav with hardware playback, it will not work. For software
  playback it works fine.

  >lavplay -p S record.avi

  You should see the recorded video and hear the sound. But the decoding
  of the video is done by the CPU which will place a heavy load on the
  system.  The advantage of this method is you don't need xawtv.


  The better way:

  >lavplay -p H record.avi

  The video is decoded and played by the hardware. The system load is
  now very low. This will play it back on-screen using the hardware
  rather than software decoding.

  You might also try:

  > lavply -p C record.avi

  Which will play it back using the hardware but to the video output of
  the card.

  > glav record.avi

  Does the same as lavplay but you have an nice GUI. The options for
  glav and lavplay are nearly the same. Using no option SW playback is
  used.

  Using hardware playback a signal for the Composite and SVHS OUT is
  generated so you can view the movie on your TV.

  > lav2yuv test.eli | yuvplay

  Is a other way to get the video without sound. You can use yuvplay
  once in the encoding command. When you use yuvplay in the encoding
  command you see the changes made by filters and scaling. You can also
  use it for slow-motion debugging.

  NOTE: After loading the driver's you have to start xawtv to set up
  some things lavplay and glav do not, but they are needed for HW-
  Playback. Don't forget to close xawtv !!


  NOTE2: Do not try to send glav an lavplay into background, wont work
  correct !!!

  NOTE3: SECAM playback is now (12.3.2001) only in monochrome, but the
  recording and encoding is done right.

  NOTE4:Bad cables may reduce the quality of the image. Normally you
  can't see this but when there is text you might notice a small shadow.
  When you see this you should change the cable.

  Coming soon: There is a tool which makes recoding videos very simple:
  Linux Studio. You can download it at: http://ronald.bitfreak.net


  6.  Edit the video


  6.1.  Edit with glav

  Most tasks can be easily done by glav. Like deleting parts of the
  video, cut paste and copy parts of the videos.



                         glav button description


  The modifications should be saved because glav does not destructively
  edit the video. This means that the original video is left untouched
  and the modifications are kept in an extra "Edit List" file readable
  with a text editor. These files can be used as an input to the other
  lavtools programs such as lav2wav, lav2yuv, lavtrans.

  If you want to cut off the beginning and the end of the stream mark
  the beginning and the and, and use the "save select" button. The edit
  list file is than used as input for the lavtools. If you want to split
  a recorded video to some smaller parts simply select the parts and
  then save each part to a different listfile.

  You can see all changes to the video and sound NOW and you do not need
  to recalculate anything.

  If you want to get a "destructive" version of your edited video use:

  > lavtrans -o short_version.avi -f a editlist.eli


     -o specifies the output name

     -f a
        specifies the output format (AVI for example)

     editlist.eli
        is the list file where the modifications are described.  You
        generate the list file with the "save all" or "save select"
        buttons in glav.



  6.2.  Unify videos

  > lavtrans -o stream.qt -f q record_1.avi record_2.avi ...
  record_n.avi


     -o specifies the outputfile name

     -f q
        specifies the output format, quicktime in this case

  This is usually not needed. Keep in your mind that there is the 2GB
  file-size-limit on 32Bit systems with an older glibc.



  6.3.  Separate sound

  > lavtrans -o sound.wav -f w stream.avi

  Creates a wav file with the sound of the stream.avi Maybe needed if
  you want to remove noise or if you want to convert it to another sound
  format.

  Another way to split the sound is:

  > lav2wav editlist.eli >sound.wav



  6.4.  Separate images

  >mkdir jpg; lavtrans -o jpg/image%05d.jpg -f i stream.avi

  First create the directory "jpg". Then lavtrans will create single JPG
  images in the jpg directory from the stream.avi file. The files will
  be named: image00000.jpg, image00001.jpg ....

  The jpg images created contain the whole picture. But if you have
  recorded at full size the images are stored interlaced. Usually the
  picture viewers show only the first field in the jpg file.



  If you want to have the image in a single file you can use that
  version

  > lav2yuv -f 1 stream.avi | y4mtoppm -L >file.pnm

  If you want to split the fields into single files use that:

  >  lav2yuv -f 5 ../stream.avi | y4mtoppm | pnmsplit - image%d.pnm

  Maybe interesting if you need sample images and do not want to play
  around with grabbing a single image.



  6.5.  Creating movie transitions

  Thanks to Philipp Zabel's lavpipe, we can now make simple transitions
  between movies or combine multiple layers of movies.

  Philipp wrote this HOWTO on how to make transitions:

  Let's assume simple this scene: We have two input videos intro.avi and
  epilogue.mov and want to make intro.avi transition into epilogue.mov
  with a duration of one second (that is 25 frames for PAL or 30 frames
  for NTSC).

  Intro.avi and epiloque.mov have to be of the same format (the same
  frame rate and resolution). In this example they are both 352x288 PAL
  files. intro.avi contains 250 frames and epilogue.mov is 1000 frames
  long.

  Therefore our output file will contain:


        the first 225 frames of intro.avi

        a 25 frame transition containing the last 25 frames of intro.avi
        and the first 25 frames of epilogue.mov

        the last 975 frames of epilogue.mov

  We could get the last 25 frames of intro.avi by calling:

  >lav2yuv -o 225 -f 25 intro.avi

  -o 255, the offset, tells lav2yuv to begin with frame # 225 and
   -f 25 makes it output 25 frames from there on.

  Another possibility is:

  > lav2yuv -o -25 intro.avi

  Since negative offsets are counted from the end.


  And the first 25 frames of epilogue.mov:

  > lav2yuv -f 25 epilogue.mov

  -o defaults to an offset of zero


  But we need to combine the two streams with lavpipe. So the call would
  be:

  > lavpipe "lav2yuv -o 255 -f 25 intro.avi" "lav2yuv -f 25
  epilogue.mov"

  The output of this is a raw yuv stream that can be fed into
  transist.flt.

  transist.flt needs to be informed about the duration of the transition
  and the opacity of the second stream at the beginning and at the end
  of the transition:


     -o num
        opacity of second input at the beginning [0-255]

     -O num
        opacity of second input at the end [0-255]

     -d num
        duration of transition in frames

  An opacity of 0 means that the second stream is fully transparent
  (only stream one visible), at 255 stream two is fully opaque.

  In our case the correct call (transition from stream 1 to stream 2)
  would be:

  > transist.flt -o 0 -O 255 -d 25

  The -s and -n parameters equate to the -o and -f parameters of lav2yuv
  and are only needed if anybody wants to render only a portion of the
  transition for whatever reason. Please note that this only affects the
  weighting calculations - none of the input is really skipped.  If you
  use the skip parameter (-s 30, for example) you also need to skip the
  first 30 frames in lav2yuv (-o 30) in order to get the expected
  result. If you didn't understand this send an email to the authors or
  simply ignore -s and -n. The whole procedure will eventually be
  automated.


  Now we want to compress the yuv stream with yuv2lav:

  > yuv2lav -f a -q 80 -o transition.avi

  Reads the yuv stream from stdin and outputs an avi file (-f a) with
  compressed jpeg frames of quality 80.

  Now we have the whole command for creating a transition:

  > ypipe "lav2yuv -o 255 -f 25 intro.avi" "lav2yuv -f 25 epilogue.mov"
  | transist.flt -o 0 -O 255 -d 25 | yuv2lav -f a -q 80 -o
  transition.avi

  The resulting video can be written as a LAV Edit List, a plain text
  file containing the following lines:


       LAV Edit List
       PAL
       3
       intro.avi
       transition.avi
       epilogue.mov
       0 0 224
       1 0 24
       2 25 999



  This file can be fed into glav or lavplay, or you can pipe it into
  mpeg2enc with lav2yuv or combine the whole stuff into one single mjpeg
  file with lavtrans or lav2yuv|yuv2lav.


  7.  Converting the stream to MPEG or DIVx videos

  First there is some general description in the encoding process and
  afterwards there is a detailed description of some commonly used
  output formats.

  If you want a one command conversation to mpeg videos try lav2mpeg in
  the scripts directory

  The encoding with the lav2mpeg script looks like this for mpeg1
  output:

  >lav2mpeg -a 160 -b 2110 -d 320x240 -m mpeg1 -o output.mpg file.eli


  o  Will create a mpeg1 with videobitrate of 2110kBit/sec and
     audiobitrate of 160 kBit/sec

  o  at a resolution of 320x240

  Or for the generation of mpeg2 output:

  lav2mpeg -o mpeg2 -O output.mpg file.eli


  o  Will create a mpeg2 with default bitrate in same resolution as the
     input resolution

  Better results can be accomplished, however, by trying various options
  and find out which ones work best for you. These are discussed below.

  The creation of MPEG1 movies is explained with more examples and in
  greater detail because most of the things that can be used for MPEG1
  also work for the other output formats

  For the creation of of VCD/SVCD Stills sequences (-f 6, -f 7 in
  mpeg2enc) you should see: http://www.mir.com/DMG/ Still sequences are
  needed for the creation of menus in VCD/SVCD. The creation of menus is
  described in the doku of vcdimager.


  7.1.  Creating sound

  MPEG-1 videos need MPEG1-layer2 sound files. For MPEG-2 videos you can
  use MPEG1-Layer2 and MPEG1-Layer3 (MP3).    Layer 3 (MP3) audio is not
  an offically valid audio format but many VCD players will recognize
  it.   MP3 audio is not valid for DVDs.  You should stick to
  MPEG1-Layer2 because most of the MPEG2 players (DVD Player for example
  usually the different Winxx Versions have great problems with this
  too) are not able to play MPEG2-Video and MPEG1-Layer3 sound.


  mp2enc is a MPEG layer 2 Audio encoder. The toolame encoder is also
  able to produce an layer 2 file. You can use that one as well.
  Toolame is much faster than mp2enc but toolame does not peform
  resampling (48000 to 44100 samples/second).  Many hardware players
  will play SVCDs using 48000 rate audio.  For mp3 creation I'm be sure
  you have an encoder.

  Example:

  > lav2wav stream.avi | mp2enc -o sound.mp2

  This creates a mpeg sound file out of the stream.avi with 224kBit/sec
  bitrate.

  Example

  > cat sound.wav | mp2enc -v 2 -V -o sound.mp2

  This creates a VCD (-V bitrate=224, stereo, sampling rate:44100)
  compatible output from the wav file.

  With -v 2 mp2enc is more verbose, while encoding you see the number of
  sec of audio already encoded.

  You can test the output with:

  > plaympeg sound.mp2

  NOTE: plaympeg is a MPEG1 Player for Linux, you can use other players
  as well, for MPEG audio testing you can also use mpg123.


  7.2.  Converting video

  You can create MPEG1 and MPEG2 videos.

  Normally the first video you create is not the best. For optimal
  quality/size you need to play with the bitrate, search radius, noise
  filter .... The options of mpeg2enc are described in the manpage of
  mpeg2enc.

  Example:

  lav2yuv stream.avi stream1.avi | mpeg2enc -o video.m1v

  This creates an video file with the default constant bitrate of
  1152kBit/sec.  This is the bitrate you need if you want to create
  VCDs. You can specify more files and also use the placeholder %nd.
  Where n describes the number.

  Example:

  > lav2yuv streami%02d.avi | mpeg2enc -b 1500 -r 16 -o video.m1v


  mpeg2enc creates a video with a bitrate of 1500kBit/s uses an search
  radius of 16. That means when trying to find similar 16*16 macroblocks
  of pixels between frames the encoder looks up to 16 pixels away from
  the current position of each block. It looks twice as far when
  comparing frames 1 frame apart and so on. Reasonable values are 16 or
  24. The default is 16 so adding the option here is silly.  Lower
  values (0, 8), improve the encoding speed but you get lower quality
  (more visible artifacts) while higher values (24, 32) improve the
  quality at the cost of the speed. With the file description of
  stream%02d.avi all files are processed that match this pattern with
  00, 01....


  7.2.1.  Scaling

  Using yuvscaler one can now also scale the video before encoding it.
  This can be useful for users with a DC10 or DC10+ cards which captures
  at -d 1 768x576 or -d 2 384x288 (PAL/SECAM) or -d 1 640x480 (NTSC).

  You get a full description of all commands by reading the manpage or
  running:

  >yuvscaler -h

  Example:

  > lav2yuv stream.avi | yuvscaler -O VCD | mpeg2enc -o video.m1v

  This will scale the stream to VCD size which for PAL/SECAM is 352x288
  and for NTSC is 352x240. The scaled yuvstream is encoded to MPEG-1.

  It can also do SVCD scaling to 480x480 (NTSC) or 480x576 (PAL/SECAM):

  > lav2yuv stream.avi | yuvscaler -O SVCD -M BICUBIC | mpeg2enc -o
  video.m1v

  The mode keyword (-M) forces yuvscaler to use the higher quality
  bicubic algorithms for downscaling and not the default resample
  algorithms. Upscaling is always done using the bicubic algorithm.

  Example

  > lav2yuv stream.avi | yuvscaler -I USE_450x340+20+30 -O SIZE_320x200
  | mpeg2enc -o video.m1v

  Here we only use a part of the input and specify a nonstandard output
  resolution.

  NOTE: yuvscaler can set a active area, and set everything else to
  black using: -I ACTIVE_WidthxHeight+WidthOffset+HeightOffset

  Testing is done by:

  > plaympeg video.m1v

  NOTE:These are only examples. There are more options you can use. You
  can use most of them together to create high quality videos with the
  lowest possible bitrate.

  NOTE2:The higher you set the search radius the longer the conversion
  will take. In general the more options used the longer encoding takes.

  NOTE3:MPEG1 was not designed to be a VBR (variable bitrate stream) !!
  So if you encode with -q 15 mpeg2enc sets the maximal bitrate -b to
  1152. If you want a VBR MPEG1 you have to set -b very high (2500).

  NOTE4:Maybe you should give better names than video.mpg. A good idea
  is to use the options as part of the filename (for example:
  video_b1500_r16_41_21.m1v).  Another possibility is to call all the
  layer 2 files ".mp2" all the MPEG-1 video files ".m1v" and all MPEG-2
  video files ".m2v" Easy to see what's happening then. Reserve .mpg for
  multiplexed MPEG-1/2 streams.

  7.3.  Putting the streams together

  Example:

  > mplex sound.mp2 video.m1v -o my_video.m1v

  Puts the sound.mp2 and the video.m1v stream together to my_video.mpg

  Now you can use your preferred MPEG player and watch it. All players
  (gtv for example) based on the SMPEG library work well for MPEG-1.
  Other players (which can play MPEG-2 as well as MPEG-1 movies) are:
  xmovie, xine, and MPlayer.

  NOTE: If you have specified the -S option for mpeg2enc mplex will
  automatically split the files if there is in the output filename a %d
  (looks like: -o test%d.mpg) The files generated this way are separate
  stand-alone MPEG steams!

  NOTE2: xine might have a problem with seeking through videos.  mplayer
  has a problem with the "seek backward/forward" with variable bitrate
  streams because it goes forward in the file the amount of data for a
  constant bitrate stream. That amount might be significantly more than
  10 seconds or one minute (those are the amount mplayer seeks for each
  press of the arrow keys). So don't wonder if it seeks much more time
  forward or backward than you expect.

  Variable bit-rate multiplexing: Remember to tell mplex you're encoding
  VBR (-V option) as well as mpeg2enc (see the example scripts). It
  *could* auto-detect but it is not working yet. You should tell mplex a
  video buffer size at least as large as the one you specified to
  "mpeg2enc" Sensible numbers for MPEG-1 might be a ceiling bit-rate of
  2800Kbps, a quality ceiling (quantization floor) of 6 and a buffer
  size of 400K.

  Example:

  > mplex -V -r 1740 audio.mp2 video_vbr.m1v -o vbr_stream.mpg

  Here we multiplex a variable bitrate stream. mplex is now a single
  pass multiplexer so it can't detect the maximal bitrate and we have to
  specify it. The data rate for the output stream is: audio bitrate +
  peak videobitrate + 1-2% for mplex information. If audio (-b 224) has
  224kBit, video has 1500kBit (was encoded with -b 1500 -q 9) then we
  have 1724 * 1.01 or about 1740kBit.

  Example:

  > plaympeg my_video.mpg

  oder

  > gtv my_video.mpg

  7.4.  Creating MPEG1 Videos

  For MPEG1 you can use mpeg layer 2 Audio and mpeg1 video. A subset of
  MPEG1 movies are VCD's. You can use VBR (Variable BitRate) for the
  Video (although VCDs are almost always use CBR video) but the Audio
  has to be CBR (Constant BitRate).

  MPEG1 is recommended for picture sizes up to 352x288 for PAL and
  352x240 for NTSC for larger sizes MPEG2 is the better choice.  There
  is no exact resolution where MPEG1 is better than MPEG2.



  7.4.1.  MPEG1 Audio creation Example

  > lav2wav editlist.eli | mp2enc -o sound.mp2

  You can save some bits by telling mp2enc to use a lower bitrate (-b
  option) like 160 or 192 kBit/s

  > lav2wav editlist.eli | mp2enc -b 128 -m -o sound.mp2

  This creates a mono output with an bitrate of 128kBit/sec bitrate.
  The input this time is the editlistfile (can have any name) created
  with glav so all changes you made in glav are direct processed and
  handed over to mp2enc.  You do NOT have to create an edited stream
  with lavtrans to get it converted properly.


  7.4.2.  MPEG1 Video creation Example

  > lav2yuv editlist.eli | mpeg2enc -b 2000 -r 24 -q 6 -o video.m1v

  mpeg2enc creates an video with an bitrate of 2000kBit/s (or
  2048000Bit/s) but the -q flag activates the variable bitrate and a
  quality factor of 6. It uses a search radius of 24.


  Explanation:when mpeg2enc is invoked without the 'q' flag it creates
  "constantbit-rate" MPEG streams. Where (loosely speaking) the strength
  of compression (and hence picture quality) is adjusted to ensure that
  on average each frame of video has exactly the specified number of
  bits. Such constant bit-rate streams are needed for broadcasting and
  for low-cost hardware like DVD and VCD players which use slow fixed-
  speed player hardware.

  Obviously this is fairly inefficient as it means inactive scenes use
  up bits that could better be "spent" on rapidly changing scenes.
  Setting the 'q' flag tells mpeg2enc to generate variable bit-rate
  streams. For such streams the bit-rate specified is simply the maximum
  permissible. The 'q' parameter specifies the minimum degree of
  compression to be applied by specifying how exactly picture
  information is recorded. Typically, 'q' would be set so that quiet
  scenes would use less than the specified maximum (around 6 or 8) but
  fast moving scenes would still be bit-rate limited. For archival
  purposes setting a maximum bit-rate high enough never to be reached
  (e.g. 10Mbps) and a q of 2 or 3 are reasonable choices.

  Example:

  > lav2yuv stream.avi | yuvscaler -I ACTIVE_352x240+0+24 | mpeg2enc -b
  1152 -r 16 -4 1 -2 1 -o video.m1v

  Usually there is at the top and at the bottom a nearly black border
  and a lot of bandwidth is used for something you do not like. The
  yuvscaler -I ACTIVE option sets everything that is not in the
  described area to black, but the imagesize (352x288) is not changed.
  So you have a real black border the encoder only uses a few bits for
  encoding them. You are still compatible with the VCD's format in this
  example.  To determine the active window extract one frame to the jpeg
  format:

  > lavtrans -f i -i 100 -o frame.jpg test.avi

  Than use your favorite graphic display program to determine the active
  size.  The -4 1 and -2 1 options improves the quality about 10% but
  conversion is slower.


  At the size of 352x288 (1/2 PAL size, created when using the -d 2
  option when recording) the needed bitrate is/should be between 1000 -
  1500kBit/s. For NTSC it should be about the same, because the image is
  smaller, but there are more frames per second than in PAL.



  Anyways, the major factor is quality of the original and the degree of
  filtering. Poor quality unfiltered material typically needs a higher
  rate to avoid visible artifacts.  If you want to reduce bit-rate
  without annoying artifacts when compressing broadcast material you
  should try one (or more) of the noise filters.

  Example:

  > lav2yuv stream.avi | mpeg2enc -b 1500 -n s -g 6 -G 20 -P -o
  video.m1v

  Here the stream.avi will be encoded with:


     -b 1500
        a Bitrate of 1500kBit/sec

     -n s
        the input Video norm is forced to SECAM

     -P This ensures that 2 B frames appear between adjacent I/P frames.
        Several common MPEG-1 decoders can't handle streams that do not
        have 2 B-frames between I/P frames

     -g 6 -G 20
        the encoder can dynamically change the group-of-pictures size to
        reflect scene changes. This is done by setting a maximum GOP (-G
        flag) size larger than the minimum (-g flag).  For VCDs sensible
        values might be a minimum of 9 and a maximum of 15.  For SVCD 9
        and 15 would be good values. If you only want to play it back on
        SW player you can use other min-max values.


  Example

  > lav2yuv stream*.avi | mpeg2enc -b 1500 -r 16 -4 1 -2 1 -S 630 -B 260
  -o video_n1_1500_r16_41_21_S630_B240.m1v

  lav2yuv processes all the stream files. Then mpeg2enc is given some
  options that make the encoded stream look nicer. Using -S 630 means
  that mpeg2enc marks the stream so that mplex generates a new stream
  every 630MB. One important thing is the use of the -B option which
  specifies the non-video (audio and mplex information) bitrate. The -B
  value of 260 should be fine for audio with 224kBit and mplex
  information. For further information take a look at the encoding
  scripts in the scripts directory.


  7.4.3.  MPEG1 Multiplexing Example

  Example

   >mplex sound.mp2 video.m1v -o my_video.mpg

  Puts the sound.mp2 and the video.m1v stream together to my_video.mpg.
  It only works that easy if you have CBR (the -q option was not used
  with mpeg2enc).


  Example

  mplex -V -r 1740 audio.mp2 video_vbr.m1v -o vbr_stream.mpg

  Here we multiplex a variable bitrate stream. mplex is now a single
  pass multiplexer so it can't detect the maximal bitrate and we have to
  specify it. The data rate for the output stream is: audio bitrate +
  peak videobitrate + 1-2% for mplex information. If audio (-b 224) has
  224kBit, video has 1500kBit (was encoded with -b 1500 -q 9) then we
  have 1724 * 1.01 or about 1740kBit.


  7.5.  Creating MPEG2 Videos

  MPEG2 is recommended for sources with a greater picture than 352x240
  for NTSC and 352x288 for PAL. MPEG2 can also handle interlaced sources
  like recording from TV at full resolution.

  MPEG2 allows the usage of mpeg layer 3 (mp3) sound. So you can use
  your favorite mp3encoder for the creation of the sound.  However, MP3
  audio is not valid for DVDs.  It is best to use MP2 (Layer 2) audio.
  The audio can also be a VBR Stream.

  MPEG2 is usually a VBR Stream. MPEG2 creation with optimization
  requires a lot of CPU power.  A film with the double resolution is NOT
  4 times larger than an MPEG1 Stream. Depending on your quality
  settings it will be about 1.5 up to 3 times larger than the MPEG1
  Stream at its lower resolution.

  7.5.1.  MPEG2 Audio creation Example

  > lav2wav editlist.eli | mp2enc -o sound.mp2

  This will fit the MPEG2 quite well. You can save some bits by telling
  mp2enc to use a lower bitrate (-b option) like 160 or 192 kBit/s.  I
  hope I don't need to explain the usage of an MP3 Encoder.  But you
  should not use all the fancy options that are available.

  7.5.2.  MPEG2 Video creation Example

  > lav2yuv editlist.eli | mpeg2enc -f 3 -b 3000 -q 9 -o video.m2v

  A very simple example for MPEG2 Video.  The most important option is
  the -f 3. That tells mpeg2enc that it should create a MPEG2 stream.
  Because it is a generic MPEG2 you have to use the -b bitrate options.
  And should use the -q option because you usually want a space saving
  VBR Stream. When using VBR streams the -b option tells mpeg2enc the
  maximum bitrate that can be used. The -q option tell mpeg2enc what
  quality the streams should have.  The bitrate has an upper bound of
  the value specified by -b.

  > lav2yuv editlist.eli | mpeg2enc -f 3 -4 1 -2 1 -q7 -b 4500 -V 300 -P
  -g 6 -G 18 -I 1 -o video.m2v

  This will generate a higher quality MPEG2 stream because the -4 1 and
  -2 1 options were used.  With -b 4500 -q 7 you tell mpeg2enc the
  maximal bitrate and the quality factor.  -V is the video buffer size
  used for decoding the stream. For SW playback it can be much higher
  than the default. Dynamic GOP is set with -g and -G.  A larger GOP
  size can help reduce the bit-rate required for a given quality but
  very large sizes can introduce artifacts due to DCT/iDCT accumulated
  rounding errors.  The -P option also ensures that 2 B frames appear
  between adjacent I/P frames. The -I 1 option tells mpeg2enc that the
  source is a interlaced material like videos. There is (time consuming)
  interlaced motion compensation logic present in mpeg2enc.  Mpeg2enc
  will use that logic if the size of the frames you encode is larger
  than the VCD size for your TV Norm.

  If you denoise the images with yuvdenoise and use the deinterlacing
  (-F) option you should tell mpeg2enc that it does not need to do
  motion estimation for interlaced material. You have to use the -I 0
  option of mpeg2enc to say that the frames are already deinterlaced.
  This will save a lot of time when encoding. If you don't use -I 0 it
  will not cause problems, the encoding will just take longer.

  You can also use scaling an options that optimize (denoise) the images
  to get smaller streams.  These options are explained in detail in the
  following sections.

  7.5.2.1.  Which values should be used for VBR Encoding

  The -q option controls the minimum quantization of the output stream.
  Quantization controls the precision with which image information is
  encoded. The lower the value the better the image quality.  Values
  below 4 are extremes and should only be used if you know what you are
  doing

  Usually you have to set up a maximum bitrate with the -b option.  The
  tricky task is to set a value for the -q option and the -b option that
  produces a nice movie without using too much bandwidth and does not
  introduce too many artifacts.

  A quality factor should be chosen that way that the mplex output of
  Peak bit-rate and average bit-rate differ by about 20-25%.  If the
  difference is very small (less than < 10%) it is likely that you will
  begin to see artifacts in high motion scenes.  The most common cause
  of the average rate being too close (or equal) to the maximum rate is
  wrong value for the maximal bitrate or a quality factor that is too
  high.

  A combination that will produce more artifacts than you can count is a
  SVCD with a maximal video bitrate of 2500kBit and a qualitfactor set
  to 1 or 2.  For SVCD with a video limit of 2500kBit a quality factor
  of 7-11 fits quite good (8 is the default). If you use filter programs
  or have a very good source like digital TV, DVD like material or
  rendered pictures you can use a quality factor of 6 when creating
  SVCDs.  If your SVCD/DVD player supports higher bitrates than the
  official 2788kBit/sec for the video and audio.   When using a higher
  bitrate and quality factor action scenes will look much better but of
  course the playing time of the disc will be less.

  The same (7-11) quality factor for a full size picture and a top
  bitrate of 3500 to 4000 kBit will produce few artifacts.

  For SVCD/DVD you can expect a result like the one described if the
  maximal bitrate is not set too low:



     q <= 6 real sharp pictures, and good quality
     q <= 8 good quality
     q >= 10 average quality
     q >= 11 not that good
     q >= 13 here even still sequences might look blocky



  7.5.2.2.  Encoding destination TV (interlaced) or Monitor (progres-
  sive)

  MPEG2 supports interlaced data in addition to the progressive format.
  A MPEG2 movie can be interlaced or progressive. It depends on the
  source (film or broadcast) and on the viewing device.

  If you encode a film both fields should be the same. Deinterlace the
  stream with yuvdenoise -F, or if you have a high quality source, and
  don't need to use the denoiser, with yuvcorrect -T NOT_INTERLACED.
  Also set the mpeg2enc interlace-mode (-I) option to 0. This means that
  there is no interlacing.  We do not really need deinterlacing here
  because there is no motion between the fields of the frame. We only
  need to unite the two fields into a single progressive frame.

  This movie should play back an any device (TV or Monitor) without
  problems.

  If you have an interlaced source (broadcast) you can encode it as
  interlaced stream. Or deinterlace the stream and encode it as
  progressive stream. If you deinterlace it with yuvdenoise -F, you will
  lose details.  But if you plan to play the recorded stream on your DVD
  player and your TV it would not be wise to perform deinterlacing.  If
  you only want to play it back on the Monitor (progressive display) the
  picture looks better when playing it back if it is deinterlaced. If
  the player you use can do deinterlacing it does not matter if your
  encoded video has interlaced frames or progressive frames.

  If you plan to deinterlace the stream you can only do this with
  yuvdenoise -F, and set the mpeg2enc -I 0. If you do not want to
  deinterlace the stream you do not need to set any special option (do
  not use yuvdenoise -F and mpeg2enc -I 0)

  If you like to pause the stream and look on the still you should
  deinterlace. Because then the image is flicker free when pausing.

  If you have a film (progressive) with parts from a broadcast
  (interlaced) mixed together (like in a documentary where some parts
  from a speaker are recorded interlaced and other parts are filmed) you
  have to choose between good film sequences with average still images
  or average looking film sequences with good still images.

  For good film with average stills do not deinterlace.  For average
  film sequences with good stills then deinterlace (using -F and -I 0).

  7.5.3.  MPEG2 Multiplexing Example

  > mplex -f 3 -b 300 -r 4750 -V audio.mp3 video.mp3 -o final.mpg

  Now both streams (a mp3 audio and a mpeg2 video) are multiplex into a
  single stream (final.mpg). You have to use the -f 3 option to tell
  mplex the output format. You also have to add the -b decoder buffers
  size with the same value used when encoding the video. -r is that rate
  of video + audio +1-2% of mplex information.

  The -V option tells that your source for mplexing is a VBR stream. If
  you don't use this option mplex creates something like a CBR Stream
  with the bitrate you have told it with the -r option.  These streams
  are usually get BIG.



  7.6.  Creating Video-CD's

  VCD is a constrained version of MEPG1 streams.  VCD format was defined
  by Philips. The goal was to use a single speed CD-drive and other
  cheap hardware (not flexible) to have a cheap HW-Player.  Because of
  that there are some limitations on VCD's.  The bitrate for video is
  1152kBit and for audio layer 2 audio 224kBit stereo.  You are not
  allowed to use the -q option, dynamic GOP sizes and the video buffer
  is limited to 46kB.  The image size is limited to 352x240 for NTSC, an
  to 352x288 for PAL.

  If you have no VCD (only) player and you plan to use your DVD player
  then it is quite possible that the DVD player will be flexible enough
  to allow higher bitrates, dynamic GOP sizes, larger video buffer and
  so on

  7.6.1.  VCD Audio creation Example

  > lav2wav stream.avi | mp2enc -V -o sound.mp2

  -V force VCD compatible output (same as: -b 224 -r 44100 -s). For
  hardware players, you should stick to 44.1 224kBps Stereo layer 2
  Audio.

  7.6.2.  VCD Video creation Example

  > lav2yuv stream.avi | yuvscaler -O VCD | mpeg2enc -f 1 -r 16 -o
  video.mpg

  For a VCD compatible output the -f 1 sets all options in mpeg2enc as
  needed. It seems that many VCD players (Avex for example) are not able
  to play MPEG streams that are encoded with a search radius greater
  than 16 so do not use the -r option to override the default of 16.

  > lav2yuv streams.eli | mpeg2enc -f 1 -4 1 -2 1 -S 630 -B 260 -P -o
  video.m1v

  Using '-S 630' means that mpeg2enc marks the stream so that mplex
  generates a new stream every 630MB. One important thing is the use of
  the -B option which specifies the non-video (audio and mplex
  information) bitrate. The -B value of 260 should be fine for audio
  with 224kBit and mplex information. For further information take a
  look at the encoding scripts in the scripts directory. So the
  multiplexed streams should easily fit on a CD with 650MB.

  The default value (-B) is 700MB for the video. mpeg2enc marks
  automatically every stream at that size if the -B option is not used
  to set a different value.  If you have a CD where you can write more
  data (perhaps as much as 800MB), you have to set the -S option or
  otherwise mpeg2enc will mark the stream at 700 MB, and mplex will
  split the stream there.  Which is almost certainly not what you want.



  7.6.3.  VCD Multiplexing Example

  > mplex -f 1 sound.mp2 video.mpg -o vcd_out.mpg

  The -f 1 option turns on a lot of weird stuff that otherwise has no
  place in a respectable multiplexer!

  7.6.4.  Creating the CD

  The multiplexed streams have to be converted to an VCD compatible.
  This is done by vcdimager http://www.vcdimager.org/


  > vcdimager testvideo.mpg

  Creates a videocd.bin, the data file, and a videocd.cue which is used
  as control file for cdrdao.

  You use cdrdao to burn the image. Cdrdao is yet another fine
  Sourceforge project which is found at: http://cdrdao.sourceforge.net/

  7.6.5.  Notes

  For MPEG-1 encoding a typical (45 minute running time) show or 90 odd
  minute movie from an analog broadcast a constant bit-rate of around
  1800 kBit/sec should be ideal. The resulting files are around 700M for
  45 minutes which fits nicely as a raw XA MODE2 data track on a CD-R.
  For pure digital sources (DTV or DVD streams and similar) VCD 1152
  works fine.

  Note: If you encode VBR MPEG1 (-q) remember the Hardware was probably
  not designed to do the playback because it is not in the
  specifications. If it works be very happy. I've noticed that it helps
  when you have an MPEG1 Stream to tell vcdimager that it is an SVCD.
  vcdimager complains (but only with a warning and not a fatal error)
  but you should be able to burn it. This could convince the player to
  use different routines in its firmware and play it back correct, but
  there is no guarantee of that.

  7.6.6.  Storing MPEGs

  If you record the data as XA mode 2 tracks you can fit appreciably
  more on a CD (at the expense of error correction/detection). You can
  use vcdimager to do this and vcdxrip (part of the vcdimager package)
  to extract ("rip") the resulting files. For better Quality there are
  SVCD and XVCD and DVD.

  Currently SVCD is fully supported with a pre-set format in mplex and
  tools to create disks. MPEG streams that can be played by DVD player
  hardware and software can readily produced using mpeg2enc/mplex

  If your player doesn't support SVCD you may well find it can handle
  VCD streams that have much higher than standard bit-rates. Often as
  much as 2500kBit/sec is possible. The several brands of DVD players
  can also play wilding out of spec SVCD and VCD discs.  With higher
  bit-rates and good quality source material it is worth trying
  mpeg2enc's -h flag which produce a stream that is as sharp as the
  limits of the VCD standard permits.

  However, if your player supports it and you have the patience for the
  longer encoding times SVCD is a much better alternative. Using a more
  efficient MPEG format SVCD more than doubles VCD's resolution while
  typically producing files that are less than twice as big.

  7.7.  Creating SVCD

  Super Video CD (SVCD) is an enhancement to Video CD that was developed
  by a Chinese government-backed committee of manufacturers and
  researchers.  The final SVCD spec was announced in September 1998.  A
  good explanation of the SVCD format from Philips can be found here:
  http://licensing.philips.com/information/cd/video/documents575.html.

  Record at full TV resolution (means: -d 1 for PAL this is 720x576) The
  resolution is for NTSC is 480x480 of PAL 480x576, so you know why you
  should record at full size.

  7.7.1.  SVCD Audio creation Example

  > lav2wav stream.avi | mp2enc -V -e -o sound.mp2

  The SVCD specifications permit a much wider choice of audio rates, it
  is not necessary to use 224 kBit/sec. Any audio rate between 32 and
  384 kBit/sec is permitted. The audio may be VBR (Variable Bit Rate).
  The -e enables the CRC error protection for the audio. The CRC has to
  be enabled to be SVCD conform. But it seems that most players don't
  pay attention to the CRC information. The CRC information need 2 bytes
  per Audio frame
  The approximate frame length formula for MPEG-1 layer-II is:


  (frame length in bytes) = 144 * (byte rate) / (sample rate)



  If you have the typical VCD settings the CRC data needs about 0,27% of
  the whole data. In the worst case, where you have a MONO 32k Bitrate
  stream, the CRC data needs 1,92%.

  7.7.2.  SVCD Video creation Example

  > lav2yuv stream.avi | yuvscaler -O SVCD | mpeg2enc -f 4 -q 7 -I 1 -V
  200 -o video.m2v


     -f 4
        sets the options for mpeg2enc to SVCD

     -q 7
        tell mpeg2enc to generate a variable bitrate stream

     -I 1
        tell mpeg2enc to assume that the original signal is field
        interlaced video where the odd rows of pixels are sampled a half
        frame interval after the even ones in each frame. The -I 0
        (progressive output (no field pictures)) option will also work
        for PAL

  You can use lower bitrates, but the SVCD standard limits total bit-
  rate (audio and video) to 2788800 Bit/sec. So with 224Kbps audio and
  overhead 2550 may already be marginally too tight. Since the SVCD
  format permits any audio rate between 32 and 224 kBit/sec you can save
  a few bits/sec by using 192k audio (or for non-musical material 160k).

  SVCD supports variable bitrate (VBR), because MPEG2 is usually VBR,
  but with the top video bitrate limit of 2500kBit/sec. With the -f 4
  flag the encoder also sets dynamic GOP with a low limit of -g 6 and a
  high limit of -G 18. This saves a few bits/sec and improves the
  picture quality during scene changes.  When encoding with -f 4
  mpeg2enc ignores the video bitrate (-b) and search radius (-r)
  options. If you use -f 5 you have to specify the bitrate and other
  options to mpeg2enc.

  Another possibility for movies in PAL (European style 25 frames/50
  fields per sec) video is:

  > lav2yuv stream.avi | yuvscaler -O SVCD | mpeg2enc -f 4 -I 0 -V 300
  -o video.m2v

  Movies are shot on film at 24 frames/sec. For PAL broadcast the film
  is simply shown slightly "too fast" at 25 frame/sec (much to the pain
  of people with an absolute pitch sense of pitch). The -I 0 flag turns
  off the tedious calculations needed to compensate for field
  interlacing giving much faster encoding.

  Unfortunately, movies broadcast in NTSC (US style 30 frames/60 fields
  sec) video this will produce very poor compression. The "pulldown"
  sampling used to produce 60 fields a second from a 24 frame a second
  movie means half the frames in an NTSC *are* field interlaced.


  Don't forget the -S and -B options mentioned above. You want the
  stream to fit on a CD don't you ?

  7.7.3.  SVCD Multiplexing Example

  > mplex -f 4 -b 300 -r 2750 sound.mp2 video.m2v -o svcd_out.mpg


     -f 4
        tells mplex to mplex a SVCD

     -r 2750
        is the calculated Audio + Video Bitrate + 1-2% multiplex
        information

     -b 300
        is the buffer available on the playback device (the same value
        as used for the video encoding (mpeg2enc's -V option).

  7.7.4.  SVCD Creating the CD

  Example:

  > vcdimager -t svcd testvideo.mpg

  Creates a videocd.bin, the data file, and a videocd.cue which is used
  as control file for cdrdao.

  Use cdrdao to burn the image as mentioned earlier.

  NOTE:If you want to build "custom" VCD/SVCD you will need to use the
  mplex -f 2 and -f 5 switches.

  NOTE:The VCD and SVCD stuff may work on your HW player or not. There
  are many reports that it works quite well. Don't be worried if it does
  not work. Nor am I responsible for unusable CDs. ("coasters")

  7.8.  Creating DVD's

  Everything in this section is very new. So it can change every day.
  The limitations I mention here might not exist in the current version.

  You need obviously a DVD writer. I own a Ricoh DVD+RW that works, and
  I know of a DVD-RAM writer that is able to to burn DVD-R. That disks
  also work with a DVD-Player. Which programs you use for burning
  depends on the DVD writer drive.


  For the creation and writing of the VOB, IFO and BUP files we use
  dvdauthor. Aviable from Sourceforge (you might have guessed it)
  http://dvdauthor.sourceforge.net.

  7.8.1.  DVD Audio creation Example

  > lav2wav stream.eli | mp2enc -r 48000 -o sound.mp2


     -r 48000
        The sample rate has to be 48kHz. The mp2enc -r option forces the
        sample rate to 48kHz. If it is not a 48kHz mp2enc will resample
        the audio to get the sample rate.  If the audio is recorded at
        48kHz then no resampling is needed and toolame can be used for
        the encoding (it is much faster than mp2enc).

  7.8.2.  DVD Video creation Example

  > lav2yuv stream.eli | mpeg2enc -f 8 -o video.m2v


     -f 8
        This sets the options correctly for a MPEG-2 video that is
        compliant with the DVD standard.  The maximum bitrate is set to
        7500kBps and the video buffer size is set to 230KB. The default
        quality factor is set to 8.  mpeg2enc sets currenty no automatic
        sequence length as it does for VCD/SVCD.

  The other options to get a low bitrate and high quality stream can
  also be used to override the default settings mentioned above.  You
  can also use yuvdenoise to increase the picture quality if the input
  data is noisy (from a VHS tape for example).  A typical command will
  look like this:

  lav2yuv moby.eli | yuvdenoise -F -l 2 | mpeg2enc -f 8 -q 7 -4 1 -2 1
  -P -I 0 -N -o video_DVD.m2v

  7.8.3.  DVD Mplex Example

  > mplex -f 8 sound.mp2 video.m2v -o my_dvdlikestream.mpg



     -f 8
        Here again we specify that we want to have DVD like MPEG stream.
        mplex cannot do all the fancy things allowed for a DVD, but it
        is close enough that the HW-DVD players accept it.

     -o there we specify the output filename.

  7.8.4.  DVD creation Example

  This topic will be covered by the documentation of the dvdauthor
  program.  For questions please see dvdauthor In general it will work
  like this:

  > makedvd stream1.mpg stream2.mpg ... my_dvdlikestream.mpg

  You will get a directory with AUDIO_TS and VIDEO_TS directories.
  Burning the data from the disk to a DVD+R/+RW writer would be done
  like this:

  growisofs -Z /dev/scd2 -dvd-video mydvd/

  If you own a DVD+RW/+R drive a good place for more information is:
  DVD+RW/+R for Linux page. You also need a version of the cdrtools with
  dvd-video support.  The cdrtools 1.11a27 is known to work but newer
  versions already exist.

  For other writers the commands to write a DVD will be different. You
  can get some more information in the dvdauthor package. There is no
  guarantee that it will work at all !!!

  7.9.  Creating DIVX Videos

  7.9.1.  lav2avi.sh

  Another way of creating DIVX is the program mencoder which is from the
  mplayer project.  http://www.mplayer.hu/.  For more information about
  mencoder please read mencoder/mplayer help and documents. A first and
  a second pass give at the end of pass hints for bitrate which can be
  used for encoding to specific size (650 MB, 700 MB and 800 MB). The
  script lav2avi.sh uses this information if provided (for short streams
  it is omitted by mencoder).  Look for parameter preferedSize in the
  script. You can also specify other parameters used for encoding with
  encoderParam option in the script. For a description of the usable
  parameters take a look in the mplayer/mencoder manual.
  The outputfilename is that name of your input file (first option) but
  with the extension avi. If the size of file is less then specified by
  preferedSize it's because the source was of very high quality (no
  noise) and the specified bitrate was higher than required.  You
  usually get 700MB for 1.5 hour film at half image size with bitrate
  around 900 that means for divx good quality (assuming good quality
  source material of course).

  The script does a 3 step encoding:


  o  1st step - audio encoding

  o  2nd step - first video pass

  o  3rd step - second video pass

  The mplayer/mencoder documentation deprecates the use of the 3 pass
  encoding method (it can cause A/V sync problems) and recommends the
  use of the 2 pass method.   The mencoder/mplayer documentation is
  extensive and has many helpful hints (and a bitrate calculator in the
  TOOLS/ directory).

  For encoding use the fast ffmpeg (lavc) codec. It gives nice results
  together with high good performance. For audio encoding mp3 is used.
  For encoding of all parts it uses unix pipes. This mean that you DO
  NOT need additional space on your hard drive where all glav
  manipulations will be done. For audio encoding the script uses a FIFO
  queue.

  If you want to tweak the script for your own needs, use these hints:

  o  Output of 1st step is file called frameno.avi with encoded audio

  o  2nd step is using frameno.avi and output is text file called
     lavc_stats.txt with timing informations

  o  3rd step is using frameno.avi and lavc_stats.txt for encoding the
     stream to the output file movie2.avi

  o  If you want change only video bitrate, keep the file frameno.avi
     comment out the 1st step encoding and repeate 2nd and 3rd step.
     Dont forget to remove the line where the frameno.avi is removed.


  8.  Optimizing the stream

  Using filters helps to increase the image quality of constant bitrate
  (CBR) video streams. With VBR (variable bit rate) video the filesize
  is reduced.

  Example:

  > lav2yuv stream.avi | yuvmedianfilter | mpeg2enc -o video.m1v

  Here the yuvmedianfilter program is used to improve the image. This
  removes some of low frequence noise in the images. It also softens the
  image a little. It takes a center pointer and averages the pixels
  around it that fall within the specified threshold. It then replaces
  the center pixel with this new value.  You can also use the -r
  (radius) option for an other search radius.

  NOTE:a radius greater than the default value of 2 is horrendously
  slow!


  yuvmedianfilter has separate settings for luma and chroma. You can
  control the search radius and the trigger threshold independently.  If
  you use a threshold of 0 then filtering is disabled (-t 0 disables
  luma filtering, -T 0 disables chroma filtering).

  > lav2yuv stream.avi | yuvmedianfilter -r 3 -t 4 -T 0 | mpeg2enc -o
  video.m1v

  This example uses a search radius of 3 pixels for the luma, a
  threshold of 4 (the default is 2), and disables filtering for the
  chroma components.   Sometimes, depending on the source material,
  median filtering of the chroma can cause a slight color shift towards
  green.   Filtering on the luma component (disabling the chroma
  filtering) is the solution to that problem.

  Example:

  > lav2yuv stream.avi | yuvdenoise | mpeg2enc -o video.m1v

  Now we are using yuvdenoise to improve the image. The filter mainly
  reduces color and luminance-noise and flickering due to phase errors
  but is also effective at removing speckles.  If you want yuvdenoise to
  deinterlace the stream use the -F option.

  By default yuvdenoise denoises interlaced if the input is interlaced.
  You can of course change the denoiser threshold (-t), as well as the
  different search radius (-r). You can also set a active area where
  everything outside that area is set to real black.   Creating a black
  border can lower the bitrate of the encoded stream because pure black
  areas compress much better than noise (captures from analog sources
  such as VHS and 8mm usually have several lines at the time and bottom
  that are very noisy).

  yuvdenoise uses a different approach to filter the noise.  More
  information about how yuvdenoise works as well as descriptions of its
  options are found in the manpage.

  If you have a high quality source you can only use fast mode. In the
  fast mode yuvdenoise only uses the bitnoise reduction.  You might also
  use the mpeg2enc -h/--keep-hf option. That option tells mpeg2enc to
  keep as much high frequency information as possible.   Using -h will
  greatly increase the bitrate (filesize).  If the bitrate is too close
  to the maximum (set with -b) the encoder will have to decrease the
  quality to avoid exceeding the maximum bitrate.

  A builtin filter in mpeg2enc is the -N/--reduce-HF option.  This
  option is not really filter in the usual sense.  Rather it changes how
  exactly the high frequency information is encoded.  Often the high
  frequency is noise.  You also have high frequencies on sharp borders
  or transitions. The -N option can have values between 0.0 and 2.0
  where 0.0 does nothing (disables the high frequency quantizer boost)
  and 2.0 gives the maximum quantization boost.  The value to use
  depends on the desired output quality and filesize.  Values of -N less
  than 0.5 are very subtle while a value of 1.0 will achieve a good
  balance between bitrate reduction and output quality.   Using -N
  values above 1.5 will noticeably reduce the sharpness of the output
  picture and are normally used only for poor quality sources (VHS tapes
  for example).

  Using yuvmedianfilter's capability to only filter the chroma (-T) is
  moderately effective at reducing noise in dark scenes without
  softening the image during normal (brighter) scenes.   Median
  filtering of the luma (-t) will produce a lower bitrate but can cause
  loss of detail (softening).  Chroma only medianfiltering is less
  agressive and is a good choice to use in combination with yuvdenoise.

  Combining the filters yuvdenoise, yuvmedianfilter and the mpeg2enc -N
  option gives a very fine degree of control over the bitrate
  (filesize).  The reduction (or increase) in the bitrate depends on the
  source material and the exact encoding/filter options used.  So we can
  give no exact numbers how much each option and combination will reduce
  the filesize, only guidelines.

  Usually you should use the -N option in a range from 0.5 to 1.5.
  Below 0.5 it does not reduce the bitrate very much (but does preserve
  sharpness).  At 1.5 and higher you will notice a softening in the
  video and possibly artifacts (halo/ringing) around edges of objects
  (text/subtitles especially).  If you combine the filters you should
  use yuvdenoise and maybe afterwards yuvmedianfilter.  Maybe
  yuvmedianfilter even after scaling.  Having yuvmedianfilter in the
  chain does not reduce the bitrate that much.  Often the use of
  yuvdenoise is enough.  The yuvmedianfilter helps much if you have low
  quality sources, and not that much if you already have a rather good
  quality.  When you combine the filter and option you will very likely
  reduce the filesize to about the half of the filesize without using
  the options and programs.

  In general aggressive filtering will produce smaller files (lower
  bitrate) but reduce the quality (details) of the picture.  Less
  aggressive filtering/processing will preserve more detail but result
  in larger files.

  Example:

  > lav2yuv stream.avi | yuvkineco -F 1 | mpeg2enc -o video.m1v

  yuvkineco is used for NTSC sources. It does the conversation from
  30000.0/1001.0 (about 29.97) fps to 24000.0/1001.0 (about 23.976) fps,
  you can call it "reverse 2-3 pulldown" more info about this in the
  README.2-3pulldown. yuvkineco does only remove NTSC specific problems.

  If you want to improve the image you should also use yuvdenoise:

  > lav2yuv stream.avi | yuvkineco | yuvdenoise | mpeg2enc -o video.m1v

  Example

  > lav2yuv stream.avi | yuvycsnoise | mpeg2enc -o video.m1v

  yuvycsnoise is also used for NTSC and is specialized for NTSC Y/C
  separation noise. If video capture hardware has only a poor Y/C
  separator then at vertical stripes (especially red/blue) noises appear
  which seem checker flag and bright/dark invert per 1 frame.
  yuvycsnoise reduces noises of this type. You can also use different
  thresholds for luma/chroma and the optimizing method.  This filter is
  not needed with working with DV (Digital Video) data.

  yuvycsnoise works only correct when we have NTSC with:


  o  full height (480 lines)

  o  full motion captured (29.97 fps)

  o  captured with poor Y/C separator hardware

  For more information about the yuvkineco and yuvycsnoise read the
  README in the yuvfilters directory.

  If you want to experiment to determine the optimal settings for the
  denoiser, scaler and so on replace the mpeg2enc with yuvplay.  yuvplay
  plays back the yuv frames so you can see if the options you have
  chosen are making the thing better or worse.

  A command would look like this:

  > lav2yuv stream.eli | yuvdenoise -options | yuvscaler -options |
  yuvplay

  If you are looking for a hardware device that can make the video look
  better before you record it we currently know about two firms that
  produce such boxes.

  One produced by SIMA: http://www.simacorp.com/scc.htm, that device
  will work with NTSC.  And a one other produced by ELV (german
  distributor): http://www.elv.de there you find in the SHOP area, a
  section where you can take a look at their Video - Audio devices. Most
  of the  ELV devices work only with PAL.

  If you want to know how much each tool lowers the average bitrate.
  You can use this table to see what you can expect if you have a full
  size video and want to create a DVD with a qality factor of 5 and the
  allowed maximal bitrate of 8500kb/sec.



  o  no denoising : 8300 kb/s (mostly hitting the upper bound)

  o  yuvenoise : 7700 kb/s

  o  mpeg2enc --reduce-hf : 7400 kb/s

  o  yuvdenoise + yuvmedianfilter : 6000 kb/s

  o  yuvdenoise + mpeg2enc --reduce-hf : 4900 kb/s

  o  all of the above : 3600 kb/s

  While -N|--reduce-hf or yuvdenoise alone is only a modest improvement,
  together they reduce the bitrate substantially.  There is not really
  much visible difference between using yuvdenoise alone and yuvdenoise
  with mpeg2enc --reduce-hf. The usefull values are between 0.0 and 1.5.
  Where you can say that the higher the quality factor you want, the
  less this option improves. At a quality factor 4 you save using -N 1.0
  about 1%. If you want a quality factor of 9 and use the -N 1.0 you
  might save up to 40%. But you might save less, that depends on the
  video you encode!!!

  If you ask yourself why not alyways use all of the above filters?
  Hmmm, hard question. The image softens, and the encoding time
  increases.  Each filter needs about the same amount of time as
  mpeg2enc needs for encoding the video.

  If you have very high quality material and want to keep every detail
  you should try to use the mpeg2enc --keep-hf|-h on the other hand

  Note: The bitrate reduction you have depends on the material and on
  the noise of the images.

  A other interresting mpeg2enc option is the -E|--unit-coeff-elim
  option. This option is disabled by default. If you enable it, a
  special "unit coefficient elimination" algorithm, is applied to the
  encoded picture blocks.   Basically this proceedure forces blocks of a
  type that do not carry much information (but use many bits to encode)
  to be skipped. A negative value examines the base (DC) as well as the
  AC coefficients. A positive value means that only texture (AC)
  coefficients are examined and possibly zeroed.  The recommended values
  lies between -20 and +20. You usually can expect that you have a 5%
  decreased filesize. The amount the bitrate is reduced can vary
  considerably, the range spans from not really noticable up to 20%.

  If you think a other quantization matrice will help use the
  -K|--custom-quant-matrices option. You can try out your own
  quanitsation matrice or use another builtin than the default.  You can
  choose between kvcd, tmpgenc, hi-res, and your own. Using -K usually
  makes the file smaller except the hi-res option (that makes files
  considerably larger). Exact guidelines are hard to give, sometime a
  other quanitsation matrix saves almost nothing, and the next time up
  to 20%. More than 20% is very unlikely, 10-15% at a moderate
  qualityfactor (-q 8-10) are likely.  The higher the qualiy the less it
  saves, at a quality factor of 4-6 the reduction in bitrate may only be
  5%

  One thing to keep in mind is that the unit coefficient elimination and
  the quantization matrix option are decreasing the bitrate while
  maintaining the same visual quality.   At this point you can chose to
  use the smaller file to increase the amount of video that will fit on
  the disc media or you could chose to increase the quality even more by
  lowering the -q value by 1 and make a larger (but higher quality)
  file.

  8.1.  Scaling and offset correction

  The basic scaling is described in the Converting video section

  The scaling, takes a part of the picture, and scales it to a larger or
  smaler size. The scaling is done by yuvscaler:

  lav2yuv test.eli | yuvscaler -I USE_400x400+50+100 | yuvplay

  Here we only take part of the picture and scale it up to the size of
  the original frame.  But yuvscaler also changes the pixel aspect
  ratio.  That means when you look at the stream using yuvplay it looks
  like a square in our example.  After scaling, if the sample (pixel)
  aspect ratio were not changed, the video would not display with the
  proper aspect ratio.  Yuvscaler compensates by adjusting the sample
  aspect ratio.  If you have a interlaced video, the height and
  HeightOffset have to be a multiple by 4 if the video is interlaced.
  Else the values (width, height, widthoffset, heightoffset) have to be
  a multiple of 2.

  A problem that cannot be solved easily with scaling is when the
  picture is not centered horizontal. On one side you have no black
  pixels and on the other you have 30 for example. Scaling is here is
  the wrong solution.  y4mshift is the perfect solution because it can
  shift the image to the left or right.

  lav2yuv test.eli | y4mshift -n 20 | mpeg2enc -f 3 -b 4000 -q 10 -o
  video.m2v

  That will shift the image 20 pixels to the right. If you use a
  negative the image is shift to the left. You have to use a even
  number. The inserted pixels are set to black.

  Some might wonder why the image is not centered and there is a black
  border around the image when you view what you have recorded. The
  reason for the black border is the TV (CRT = Catode Ray Tube) and a
  really interresting storry about how the TV standart was definden. But
  tha topic is described in other books.

  The TV does not show the full picture. A part of the picture is not
  shown because the TV sets overscan (sometimes as much as 10% but more
  common today is 5%).  But when you capture the video with a card you
  see the whole image including the border that TVs lose due to
  overscanning.  A horizontal offset is usually not a problem of the
  capture card. It is a problem when the film is broadcast and not well
  synchronized with the image.  This means that the scan of the source
  not exactly synchronized with the carrier signal, you wont see that on
  TV.

  8.2.  Frame rate conversion

  Ever needed to convert the framerate from PAL to NTSC or the other
  direction around ? Or something much simpler like converting the
  framerate from 24FPS to 24000:1001 for conversation from a film frame
  rate to a valid NTSC frame rate.

  Than yuvfps is your program. It can lower the framerate by dropping
  frames, or create a higher framerate by replicating frames. If you
  have a wrong framerate in the header you can only change the header of
  the YUV stream and not modify the stream.

  Because the frames are only replicated (copied) you should denoise
  first and then change the framerate and scale at als last step. If you
  have a interlaced source you should also deinterlace before changeing
  the framerate. If you create a higher frame rate it is very likely
  that you will have weird flickers when you play it back. If you
  convert PAL to NTSC (30000:1001 FPS about 29,97 FPS) the frame rate
  will lower by about the factor 480/576 (NTSC lines / PAL lines).  If
  you lower the frame rate from PAL to NTSC (at 24000:1001) or NTSC FILM
  (24FPS) the bitrate will be about (480 Lines * 24 FPS) / (576 Lines *
  25FPS).  If you change the frame rate before denoising the yuvdenoise
  will have problems finding the noise across the frames, so the needed
  bandwith will slightly increase.

  Example

  > lav2yuv video.eli | yuvfps -r 30000:1001 | yuvscaler -O SVCD |
  mpeg2enc -f 4 -o video_ntsc_svcd.m2v

  This is a example to convert the source video to a NTSC video running
  at 30000:1001 FPS (or about 29,97FPS) at SVCD size.

  Example

  > lav2yuv video.eli | yuvdenoise -F | yuvfps -r 24000:1001 | yuvscaler
  -O SIZE_720x480 | mpeg2enc -f 3 -b 4000 -q 7 -o video_ntsc.m2v

  This example shows how you should use the tools. Denoise first and
  than change the framerate and in the last step change the image size.



  It can happen that yuvscaler or mpeg2enc do not detect the TV norm
  correct. If that happens you have to add the norm option -n n/p/s to
  the program that chooses the wrong norm.

  If you know that the header tells the wrong framerate, you can simply
  change the framerate of the yuv header this way:

  > lav2yuv video.eli | yuvfps -r 25:1 -c | mpeg2enc -f 3 -b 4000 -q 7
  -o video_pal.m2v

  You need the -c option. To tell yuvfps that it only should change the
  header of the stream. With the -r 25:1 you tell yuvfps the frame rate
  it should write into the header. In your example the PAL frame rate of
  25 FPS. You always have to use the fractional form.

  If you know that the header is wrong, and you need a different output
  bitrate you can do this in a single step:
  > lav2yuv video.eli | yuvfps -s 24:1 -r 25:1 | mpeg2enc -o video.m1v

  9.  Transcoding of existing MPEG-2

  For transcoding existing MPEG-2 streams from digital TV cards or DVD a
  lower data-rate than for broadcast will give good results.  Standard
  VCD 1152 kbps typically works just fine for MPEG1. The difference is
  in the Signal/Noise ratio of the original. The noise in the analog
  stuff makes it much harder to compress.

  One other very good guide that helps you transcoding videos can be
  found at: http://www.bunkus.org/dvdripping4linux/index.html


  You will also need to manually adjust the audio delay offset relative
  to video when multiplexing. Very often around 150ms delay seems to do
  the trick.

  You have to download the ac3dec and mpeg2dec packages. You can find
  them at mjpeg homepage ( http://sourceforge.net/projects/mjpeg ).  You
  also need sox and toolame.

  In the scripts directory there is a mpegtranscode script that does
  most of the work.

  So transcoding looks like this:

  > mjpegtranscode -V -o vcd_stream mpeg2src.mpg


     -V set's the options so that a VCD compatible stream is generated

     -o vcd_stream
        a vcd_stream.m1v (video) and vcd_stream.mp2 (audio) is created

     mpeg2src.mpg
        specifies the source stream


  The script prints also something like this:

  > SYNC 234 mSec

  You will need to adjust the audio/video startup delays when
  multiplexing to ensure audio and video are synchronized.  The exact
  delay (in milliseconds) that you need to pass to mplex to synchronize
  audio and video using the "-v"" is printed by the extract_ac3 tool
  labeled "SYNC" when run with the "s" flag. This is the value th
  mjpegtranscode script prints out after the SYNC word.

  Then you need to multiplex them like this:

  > mplex -f 1 -O 234 vcd_stream.mp2 vcd_stream.m1v -o lowrate.mpg


     -f 1
        Mux format is set to VCD

     -O 234
        Video timestamp offset in mSec, generated by the
        mjpegtranscoding script, there negative values are allowed

     vcd_stream.mp2 & vcd_stream.m1v
        generated files by the script


     lowrate.mpg
        the VCD compatible output stream

  Here we have a SVCD (MPEG-2 video) example:


  > mjpegtranscode -S -o svcd_stream mpeg2src.mpg

  You have to multiplex it with:

  > mplex -f 4 -O 234 svcd_stream.mp2 svcd_stream.m2v -o lowrate.mpg

  Problem: There is sometimes a problem with NTSC and VCD playback
  because movies may be recoded with 3:2 pulldown NTSC with 60
  fields/sec. mpeg2dec is designed for playback on computers and
  generates the original 24frames/sec bitrate. If you encode the video
  now 30frames/sec video is created. This video is now much too short
  for the encoded audio.

  The transcoding can be made to work but it must be done manually:

  > cat mpeg2src.mpg | mpeg2dec -s -o YUVs | mpeg2enc -I 0 -f 4 -q 9 -V
  230 -p -P -o svcd_stream.m2v

  The -p tells mpeg2enc to generate header flags for 3:2 pull down of
  24fps movie. It may also work if you do not add the -p flag.  You do
  not need the -p flag when transcoding to VCD format because it is not
  supported in mpeg1.

  9.1.  If you want to do every step on your own it will look something
  like this

  Extracting Audio:

  > cat test2.mpg | extract_ac3 - -s | ac3dec -o wav -p sound.wav
  2>/dev/null

  One of the first lines showed contains the label "SYNC" you have to
  use this time later when multiplexing. The 2>/dev/null redirects the
  output of ac3dec to /dev/null.  In the next step you generate the mpeg
  audio file:

  > cat sound.wav | mp2enc -V -v 2 -o audio.mp2


     -V forces VCD format, the sampling rate is converted to 44.1kHz
        from 48kHz

     -v 2
        unnecessary but if you use it mp2enc tells you how many seconds
        of the audio file are already encoded.

     -o Specifies the output file.

  cat test2.mpg | extract_ac3 - -s | ac3dec -o wav | sox -t wav
  /dev/stdin -t wav -r 44100 /dev/stdout | toolame -p 2 -b 224
  /dev/stdin audio.mp2

  One of the first lines again output contains the label "SYNC".  You
  have to use this time (referred to as "SYNC_value" below) when doing
  the multiplexing.

  For VCD creation use:

  > cat test2.mpg " mpeg2dec -s -o YUVh " mpeg2enc -s -o video_vcd.m1v

        mpeg2dec:

     -s tells mpeg2dec to use program stream demultiplexer

     -o YUVh
        the output size of the extracted frames.

  There are other output modes, try "mpeg2dec --help" but the most
  important here are:


     YUV
        is the full image size, unscaled

     YUVs
        is SVCD size, it can only scale down to 2/3 of the original size

     YUVh
        is VCD size, or about the half of the original size

  Mplex with:

  > mplex -f 1 -O SYNC_value audio.mp2 video_vcd.m1v -o vcd_stream.mpg


     -f 1
        generates an VCD stream

     -O SYNC_value
        the value mentioned above


  For SVCD creation use:

  > cat test2.mpg | mpeg2dec -s -o YUVs | mpeg2enc -f 4 -q 9 -V 230 -o
  video_svcd.mpg


     -q 9
        Quality factor for the stream (VBR stream) (default q: 12)

     -V 230
        Target video buffer size in KB

     -o Output file

  Mplex with:

  > mplex -f 4 -b 230 audio.mp2 video_svcd -o svcd_stream.mpg


     -f 4
        generate an SVCD stream

     -b 200
        Specify the video buffer size by the playback device.

  For other video output formats this might work:

  > cat test2.mpg | mpeg2dec -s -o YUV | yuvscaler -O SIZE_320x200 -O
  NOT_INTERLACED | mpeg2enc -o strange_video.m1v

  If you want to edit mpeg streams, this also works, but in a slightly
  different way. For demultiplexing you can use bbdmux, from the bbtools
  package. Splits out either video or audio very cleanly.  You can't get
  it any more from the homepage from Brent Beyler, it can still be found
  when you search for it using that keywords " bbtools linux -suse
  -blackbox". Currenty it can be found at: http://www.nop.org/inkling/


  First run:

  > bbdmux myvideo.mpg

  You should get something like this:


  Found stream id 0xE0 = Video Stream 0
  Found stream id 0xC0 = MPEG Audio Stream 0
  Found stream id 0xBE = Padding Stream



  Extract audio with:

  > bbdmux myvideo.mpg 0xC0 audio.mp1

  Convert it to wav:

  > mpg123 -w audio.wav audio.m1v

  Extract video with:

  > bbdmux myvideo.mpg 0xE0 video.m1v

  Converting video to an mjpeg avi stream:

  > cat video.m1v | mpeg2dec -o YUV | yuv2lav -f a -o test.avi

  Then adding the sound to the avi:

  > lavaddwav test.avi audio.wav final.avi

  If the source video has already the size of the target video use -o
  YUV. Using YUVh makes the video the half size!  The rest can be done
  just like editing and encoding other streams.  If you have videos with
  ac3 sound you only have to adapt the commands above.

  Extracting Audio:

  > cat test2.mpg | extract_ac3 - -s | ac3dec -o wav 2>dev/null
  >sound.wav

  Extract video:

  > cat test2.mpg | mpeg2dec -s -o YUVh | yuv2lav -f a -q 85 -o test.avi

  Adding the sound:

  > lavaddwav test.avi sound.wav fullvideo.avi

  NOTE:You need much disk space. 1GB of video has a size of about 2GB at
  SVCD format and of course disk space is needed for some temp files.
  Converting the video to mjpeg also takes some time.  On my Athlon 500
  I never get more than 6-7 Frames a second.  You loose quality each
  time you convert a stream into an other format!

  10.  Trading Quality/Speed

  If absolute quality is your objective a modest improvement can be
  achieved using the -4 and -2 flags.  These control how ruthlessly
  mpeg2enc discards bad looking matches between sections of adjacent
  frames during the early stages of the search when it is working with
  4*4 and 2*2 clusters of pixels rather than individual pixels. Setting
  -4 1 -2 1 maximizes quality. -4 4 -2 4 maximizes speed. Note that
  because the statistical criteria mpeg2enc uses for discarding bad
  looking matches are usually fairly reliable the increase/decrease in
  quality is modest (but noticeable).

  Reducing the radius of the search for matching sections of images also
  increases speed. However due to the way the search algorithm works the
  search radius is in effect rounded to the nearest multiple of 8.
  Furthermore, on modern CPU's the speed gained by reducing the radius
  below 16 is not large enough to make the marked quality reduction
  worthwhile for most applications.

  10.1.  Creating streams to be played from disk using Software players

  Usually MPEG player software is much more flexible than the hardware
  built into DVD and VCD players. This flexibility allows for
  significantly better compression to be achieved for the same quality.
  The trick is to generate video streams that use big video buffers
  (500KB or more) and variable bitrate encoding (the -f, -q flag to
  mpeg2enc). Software players will often also correctly play back the
  more efficient MPEG layer 3 (yes, "MP3" audio format.  A good MP3
  encoder like lame will produce results comparable to layer 2 at
  224Kbps at 128Kbps or 160Kbps.

  11.  SMP and distributed Encoding

  The degree to which mpeg2enc tries to split work between concurrently
  executing threads is controlled by the -M or --multi-thread [0..32]
  option. This optimizes mpeg2enc for the specified number of CPUs. By
  default (-M 1), mpeg2enc runs with just a little multi-threading:
  reading of frames happens concurrently with compression. This is done
  to allow encoding pipelines that are split across several machines
  (see below) to work efficiently without the need for special buffering
  programs.  If you are encoding on a single-CPU machine where RAM is
  tight you may find turning off multithreading altogether by setting -M
  0 works slightly more efficiently.

  For SMP machines with two ore more processors you can speed up
  mpeg2enc by setting the number of concurrently executing encoding
  threads's you wish to utilize (e.g. -M 2). Setting -M 2 or -M 3 on a
  2-way machine should allow you to speed up encoding by around 80%.
  Values above 3 are accepted but have very little effect even on 4 cpu
  systems.

  If you have a real fast SMP machine (currently 1.Aug.03) like a dual
  Athlon MP 2600 or something similar the -M 2 and the filtering might
  not keep both (or more)  CPU's busy. The use of the buffer or bfr
  program with a 10-20MB buffer helps to keep both CPUs busy.

  Obviously if your encoding pipeline contains several filtering stages
  it is likely that you can keep two or more CPU's busy simultaneously
  even without using -M. Denoising using yuvdenoise or yuvmedianfilter
  is particular demanding and uses almost as much processing power as
  MPEG encoding.

  It you more than one computer you can also split the encoding pipeline
  between computers using the standard 'rsh' or 'rcmd' remote shell
  execution commands. For example, if you have two computers:



  > rsh machine1 lav2yuv "mycapture.eli | yuvscaler -O SVCD |
  yuvdenoise" | mpeg2enc -f 4 -o mycapture.m2vi

  Here the computer where you execute the command is doing the MPEG
  encoding and "machine1" is the machine that is decoding scaling and
  denoising the captured video.

  Obviously, for this to work "machine1" has to be able to access the
  video and the computer where the command is executed has to have space
  for the encoded video. In practice, it is usually well worth setting
  up network file-storage using "NFS" or other packages if you are going
  to do stuff like this.  If you have three computers you can take this
  a stage further, one computer could do the decoding and scaling, the
  next could do denoising and the third could do MPEG encoding:

  > rsh machine1 "lav2yuv mycapture.eli | yuvscaler -O SVCD" |
  yuvdenoise | rsh machine3 mpeg2enc -f 4 -o mycapture.m2v

  NOTE:How the remote command executions are set up so that the data is
  sent direct from the machine that produces it to the machine that
  consumes it.

  In practice for this to be worthwhile the network you are using must
  be fast enough to avoid becoming a bottleneck. For Pentium-III class
  machines or above you will need a 100Mbps Ethernet.

  For really fast machines a switched 100MBps Ethernet (or better!) may
  be needed.Setting up the rshd ("Remote Shell Daemon" needed for rsh to
  do its work and configuring "rsh" is beyond the scope of this
  document, but its a standard package and should be easily installed
  and activated on any Linux or BSD distribution.

  Be aware that this is potentially a security issue so use with care on
  machines that are visible to outside networks!

  12.  Interoperability

  Quicktime files capturing using lavrec can be edited using
  Broadcast2000.  But Broadcast2000 is not available any more on
  heroinewarrior.  mjpeg AVI files captured using the streamer tool from
  the xawtv package can be edited and compressed and played back using
  software.  Hardware playback is not possible for such files due to
  limitations in the Zoran hardware currently supported. Videos recorded
  with NuppelVideo can also be processed with the mjpeg tools.


  If you have a Macintosh (MAC) and want to use the mjpeg tools look
  there: http://www.sjoki.uta.fi/~shmhav/SVCD_on_a_Macintosh.txt and
  http://homepage.mac.com/rnc/

  MPEG files produced using the tools are know to play back correctly
  on:


  o  dxr2 (hardware decoder card)

  o  xine http://xine.sourceforge.net/

  o  oms http://www.linuxvideo.org/

  o  dvdview http://rachmaninoff.informatik.uni-mannheim.de/dvdview/

  o  xmovie http://heroinewarrior.com/xmovie.php3

  o  mplayer http://mplayer.sourceforge.net/

  o  vlc http://www.videolan.org/


  o  MPEG1 only: mtv http://www.mpegtv.com/

  o  MPEG1 only: gtv http://packages.debian.org/stable/graphics/smpeg-
     gtv.html

  o  MS Media player version 6 and 7

  o  SW DVD Player

  To find out what you HW-player (most of the time DVD player) can do
  take a look at: http://www.vcdhelp.com

  It seems that the MS Media player likes MPEG-1 streams more if you
  have used -f 1 when multiplexing.

  If you have any problems or suggestions feel free to mail me (Bernhard
  Praschinger): waldviertler@users.sourceforge.net There is a lot of
  stuff added from the HINTS which Andrew Stevens (
  andrew.stevens@nexgo.de ) created. Wolfgang Goeller checked the
  document for bugs and spelling mistakes.

  And to the people who have helped me with program descriptions and
  hints, thanks



