[MPlayer-users] mencoder, x264, vorbis, matroska - bad a/v sync problems

[matthew.garman at gmail.com]

On Fri, Feb 09, 2007 at 10:02:49AM -0600, matthew.garman at gmail.com wrote:
> I'm using a procedure similar to the one linked below to rip DVDs (I
> own the DVDs).  The intent is to use H.264 (x264) for the video,
> vorbis for the audio, and mux it into a Matroska container:
>     http://www.smorgasbord.net/howto_rip_dvds_in_mpeg_4_avc_x264_multi_audio_subtitles_matroska
> I'm having pretty bad A/V sync problems, particularly with TV
> episodes. So far I've experimented with the H264+Vorbis in the
> Matroska container with Batman Begins (the movie) and episodes of
> House, MD season 2.
> [...]
> p.s. I also posted this message to Doom9's forum:
>     http://forum.doom9.org/showthread.php?t=122018

On Doom9's Forum, it was suggested that I do a "dummy" audio encode
along with the video encoding.

So I gave that a try, and two things happened:

    - Audio/video is now in sync.  Yay!
    - Video got scaled

In addition to doing the audio encoding, I also used "-of avi"
instead of "-of rawvideo" (as suggested on the forum post).  In this
encoding, I'm not using any -vf crop or scale options; my intent is
to keep the video in its original resolution.  Anyone know why this
happened?

But, more importantly: either the -of avi or audio encoding resulted
in a perfect A/V sync in the final product (the .mkv file).  This is
what I'm having trouble understanding, how (seemingly, to my
still-learning mind) unrelated options can affect the sync.

Does anyone have a really good understanding of which options can
affect how an output file is written?  I.e., based on my experiments
thus far, there's more to getting the output right than the
"obvious" settings such as -mc, -noskip, -vf harddup, -ofps, etc.

Thanks!
Matt