[MEncoder-users] Multiplexing to mpeg2

[L Lee]

On 9/22/09 3:41 AM, "Henk Schoneveld" <belcampo at zonnet.nl> wrote:

>> Thanks. I've used mplex, but it has some limitations that make it inadequate
>> for me, maybe due to the fact that it's old.
> As the dvd-standard is.


Well, yes, but I can still make standards-compliant m2v and ac3 files that
mplex won't successfully mux, apparently because their bit rates are too
high for mplex (at least that's what I've gathered after searching for
"mplex" and "will arrive too late", which appear to be the most
distinguishing excerpts from the error messages I've been seeing).

Why do I like to make DVDs? I might say that the format offers benefits
related to universal use and portability, and that I prefer to isolate the
storage and archiving system I use for video from my other digital storage
systems. I'm not sure how convincingly I can justify the choice, but until
Blu-ray is common enough for me to decide that it's time to forget about
DVD, I will probably keep making DVDs.

My problem is this. I can use MEncoder to create source files that can be
made into perfectly good DVDs using DVDAuthor. It's just that my video gets
shortened ever so slightly with respect to audio through my preferred
conversion method, so rather than compromise the visual results by using an
inferior method, I've decided to slightly change the tempo of the audio so I
can maintain sync. When I separate the source audio from the source video to
do that, so far, I've been unable to get them muxed again without
encountering errors which either halt the muxing process or introduce new
playback errors in the resulting product. This occurs whether or not I
actually make changes to either the audio file or the video file while they
exist separately. In other words, the combined process of encoding and
muxing appears to be more robust for creating the files I need than muxing
alone, except for the sync problems that arise. I don't know why that's the
case, but until I find a process that yields a satisfying result which
doesn't require my working on the files separately, I'll probably keep
looking for a more robust way to multiplex.

I did find an ffmpeg method which I consider more robust than the mplex
method because it continues without failure even if errors are encountered:

ffmpeg -y -fflags genpts -i infile.m2v -i infile.ac3 -target film-dvd
-vcodec copy -acodec copy -bufsize 3072k muxed_outfile.mpg -map 0:0 -map 1:0

Perhaps I can continue to incrementally modify my encoding process to
accommodate the limitations of ffmpeg and mplex while maintaining the level
of quality of output to which I've grown accustomed. But I would still like
to know why using the MEncoder command that I included in my previous
message in this thread results in an empty output file. Because at least one
other person (Eric Olson at http://renomath.org/ejolson/video/hi8/) appears
to have had success with the method, I wonder whether I have jumped the
track regarding muxing mpeg2 with MEncoder, or whether MEncoder has. Thanks.

Laine Lee