M2VDownsizer(1)

NAME
M2VDownsizer - Re-compresses MPEG-2 video streams

SYNOPSIS
M2VDownsizer
M2VDownsizer <lowering factor> <quality 0=fast...3=high quality>
<input m2v size in bytes>

DESCRIPTION
M2VDownsizer is a tool that shrinks the size of MPEG-2 (or m2v) video streams (typically from DVD video discs) by performing a complete decompression and recompression of the MPEG-2 video streams.

Performing a complete decompression and recompression of MPEG-2 video streams will result in the best possible video quality but the operation will take substantially longer compared to transcoding the MPEG-2 video streams using M2VRequantiser.

Be forewarned! It could take many hours for M2VDownsizer to perfom the complete decompression and recompression of large MPEG-2 video streams! It is recommended that one first tries transcoding MPEG-2 streams using M2VRequantiser since transcoding is a lot faster and produces excellent results for most MPEG-2 video streams. M2VDownsizer is only intended to be used for large MPEG-2 video streams when transcoding does not produce acceptable results.

M2VDownsizer accepts the raw MPEG-2 (or m2v) video data (not VOB) from the standard input and writes the recompressed video frames to the standard output.

OPTIONS
M2VDownsizer takes three arguments and does not have any options.

The usage is:

     $ M2VDownsizer <lowering factor> <quality 0=fast...3=high quality>
<input m2v size in bytes>

The first argument is a floating point value specifying the lowering factor for re-compression. The higher the lowering factor, the higher the re-compression will be. The second argument is an integer value from 0 to 3 specifying the quality of the re-compressed MPEG-2 output video (0=lowest quality and 3=highest quality). The third argument is the size of the MPEG-2 input video in bytes. (Since the MPEG-2 video is streamed into M2VDownsizer, M2VDownsizer is unable to determine the MPEG-2 input video size by itself).

To shrink MPEG-2 video from a DVD-9 disc to fit on a DVD-5 disc, a lowering factor of 1.5 works well in most cases. Alternatively, use the following formula to more precisely calculate the lowering factor:

    lowering factor = (Total m2v video size in bytes)
                      ----------------------------------------  * 1.04
                      (4700000000 - Total audio size in bytes)

NOTES

M2VDownsizer was designed to recompress MPEG-2 (or m2v) video streams from DVD video discs. The recompression of MPEG-2 (or m2v) video streams with resolutions higher than those found on DVD video discs (i.e. resolutions greater than 720x576) may lead to undesirable and unpredictable results.

EXAMPLE
The following command would re-compress 'original.m2v', whose size is 5,974,039,472 bytes, by a lowering factor of 1.46 with the quality of 2:

    $ M2VDownsizer 1.46 2 5974039472 < original.m2v > re-compressed.m2v

It will take a long time for M2VDownsizer to completely decompress and recompress the MPEG-2 video in the above example. Time to take a long coffee break!

SEE ALSO
M2VRequantiser(1)

AUTHOR
The author is Makira. M2VDownsizer was released as open source software on the website for Metakine Inc., the developer of DVDRemaster.

This manual page was written by Robert Kennedy <amtor@hotmail.com> for the MacPorts project (but may be used by others).