[MEncoder-users] Encoding movies with DTS tracks

[RC]

On Mon, 7 Dec 2009 11:49:04 +0100
Olivier Rolland <billl at users.sourceforge.net> wrote:

> MEncoder's audio/video synchronization algorithms were designed with
> the intention of recovering files with broken sync. 

> Therefore, you may have to switch to basic A/V sync with the -mc 0
> option, or put this in your ~/.mplayer/mencoder config file, as long
> as you are only working with good sources (DVD, TV capture, high
> quality MPEG-4 rips, etc) and not broken ASF/RM/MOV files.

This is completely inaccurate.  The HTML docs do contain poor advice
here and there, I'm afraid.

> AFAICT, a DVD is a good source so I guess I can use -mc 0 to prevent
> unnecessary skipping, duplication of frames and slight A/V desync.

Generally: No.  It's not a question of "good" or "bad," but whether A/V
streams are EXACTLY the same length, and if PTS values throughout the
file are negligably small.

> Are you saying that -mc 0 should never be used ? Or that it should be
> used only if there was unnecessary skipping, duplication, ... ? Or
> that it shouldn't be used with DTS tracks ?

Close but not quite...  -mc should only be used in a few cases where you
have a significant frame dropping/corruption or A/V sync problem that
can't be corrected any other way.  And you should at least understand
what kind of problems it's likely to cause, before using it.

-mc 0 is the nuclear option, COMPLETELY disabling MPlayer's A/V sync
correction code.  The full range of non-zero values to mc (0.0001 to 10)
should be tried first if there is a frame-drop or A/V sync problem.

-- 
Ha. I'm the idiot.