[MPlayer-users] Re: dropped macroclocks and sound glitches

Tobias Diedrich ranma at tdiedrich.de
Tue Jun 8 10:58:58 CEST 2004

D Richard Felker III wrote:

> > When I view the AVI using mplayer, or transcode using
> > mencoder, I frequently see dropped macroblocks and
> > sound glitches.  They usually occur on 1GB byte
> > boundaries, although occasionally occur at points
> > where a frame or two was dropped during the initial
> > video capture.
> I would guess it's a bug in the odml code, but I don't understand
> odml...

Actually I know what probably happens, but I don't know how it could
happen except if you get memory corruption.

With OpenDML the muxer starts a new AVIX RIFF-Chunk for approx. every GB.
Because it doesn't know how long the chunk will be the size field is not
written. Instead it saves the offset to the size field in an array for
later fixup.
Now in the fixup step it probably gets the wrong offset and scribbles on
your data instead of into the size fields.  However this should not
happen because ftello is used to get the offset and that way it should
always be correct.

Tobias						PGP: http://9ac7e0bc.2ya.com
Any sufficiently advanced bug is indistinguishable from a feature.
  -- Rich Kulawiec

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