[MPlayer-dev-eng] dwStart (stream delay in AVI files)

Michael Niedermayer michaelni at gmx.at
Tue Jan 31 08:59:33 CET 2006


On Mon, Jan 30, 2006 at 11:45:14PM -0800, Corey Hickey wrote:
> Oded Shimon wrote:
> >>I _think_ mplayer doesn't properly use the dwStart field in the stream
> >>header of AVI files. To reproduce, create a file with 10-second audio delay:
> >>
> >>mencoder file.avi -ovc copy -oac copy -audio-delay 10 -o delay10.avi
> >>
> >>MEncoder writes the audio delay in the dwStart field of the audio
> >>stream. You can check it with a hex editor or with 'mplayer -v delay10.avi'.
> > 
> > 
> > MEncoder supports -delay now anyway, you should use that... -audio-delay is 
> > a hack..
> Are you sure? That seems to be the intended purpose of dwStart,
> especially considering that Microsoft's player appears to use it that
> way and -audio-delay is the documented way to adjust A-V sync with
> mencoder.
> Up to this moment I was thinking of using dwStart to compensate for
> video decoding delay (with B-frames), but then I realized it could be
> detrimental to remuxing to other containers.

which? avi supports dwStart, nut can start at any timestamp too, mpeg-ps/ts
is fine too, basically a container which requires that the first packet of
every stream has the absolutly identical pts is quite limited

> Nevertheless, it still seems to me that supporting dwStart in mplayer
> would be a good thing.

yes, and yes ff* ignores it as i couldnt find a file which needed it
maybe you could make yours available?


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