.\" Originally automatically generated by txt2man and then modified by MacPorts developers
.TH M2VDownsizer 1 "September 2, 2022" "M2VDownsizer-1.1" "MPEG-2 Video Stream Re-compression"
.SH NAME
\fBM2VDownsizer\fP - Re-compresses MPEG-2 video streams
.SH SYNOPSIS
.nf
.fam C
\fBM2VDownsizer\fP

\fBM2VDownsizer\fP <lowering factor> <quality 0=fast...3=high quality>
<input m2v size in bytes>
.fam T
.fi
.SH DESCRIPTION
\fBM2VDownsizer\fP 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.
.PP
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
\fBM2VRequantiser\fP.
.PP
Be forewarned!  It could take many hours for \fBM2VDownsizer\fP 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
\fBM2VRequantiser\fP since transcoding is a lot faster and produces excellent
results for most MPEG-2 video streams.  \fBM2VDownsizer\fP is only intended to
be used for large MPEG-2 video streams when transcoding does not produce
acceptable results.
.PP
\fBM2VDownsizer\fP 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.
.SH OPTIONS
\fBM2VDownsizer\fP takes three arguments and does not have any options.
.PP
The usage is:
.PP
.nf
.fam C
.HP
     $ M2VDownsizer <lowering factor> <quality 0=fast...3=high quality>
<input m2v size in bytes>
.fam T
.fi
.PP
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 \fBM2VDownsizer\fP,
\fBM2VDownsizer\fP is unable to determine the MPEG-2 input video size by
itself).
.PP
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:
.PP
.nf
.fam C
    lowering factor = (Total m2v video size in bytes)
                      ----------------------------------------  * 1.04
                      (4700000000 - Total audio size in bytes) 
.fam T
.fi
.SH NOTES
.PP
\fBM2VDownsizer\fP 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.
.SH 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:
.PP
.nf
.fam C
    $ M2VDownsizer 1.46 2 5974039472 < original.m2v > re-compressed.m2v
.fam T
.fi
.PP
It will take a long time for \fBM2VDownsizer\fP to completely decompress and
recompress the MPEG-2 video in the above example.  Time to take a long coffee
break!
.SH SEE ALSO
\fBM2VRequantiser\fP(1)
.SH AUTHOR
The author is Makira.  \fBM2VDownsizer\fP was released as open source software
on the website for Metakine Inc., the developer of DVDRemaster.
.PP
This manual page was written by Robert Kennedy <amtor@hotmail.com> for the
MacPorts project (but may be used by others).