[MPlayer-users] Current CVS lavc "vcodec=mpeg4" issues

D Richard Felker III dalias at aerifal.cx
Thu Mar 3 17:52:24 CET 2005

On Thu, Mar 03, 2005 at 09:10:33PM +1030, Mark Williams (MWP) wrote:
> Greetings all,
> Has the output format of lavc mpeg4 encoding change latley?
> AVI files ive been creaaing with a CVS version of mplayer thats a few months old
> work perfectly in WinXP.
> AVI files im creating with todays CVS version will not play under WinXP...
> mplayer classic complains about missing codecs.
> Apparently its because "Fourcc: FMP4" is not supported.
> Anyone know why this is the case, and whats needed?

Before lavc used "DIVX" fourcc for its mpeg4, which was bad for
several reasons:

- DIVX is actually a trademark of the lamers who made divx, not a
  generic name.
- DIVX fourcc means Divx4, and lavc is NOT divx4-compatible unless you
  omit all the fancy options. You'd have to use DX50 instead if qpel,
  bframes, etc. are enabled..
- DIVX fourcc causes DIVX or XVID codec to be used for decoding on
  windows, which are sometimes buggy.

The decision was made to make our own fourcc, FMP4, for ffmpeg mpeg4.
In the long term this is the best solution, I think, but in the short
term it's a pain if you're trying to make files playable by windows
newbies without current ffdshow installed. Possible solutions:

- Tell the windows users to install latest ffdshow for decoding.

- Override the fourcc with -ffourcc option to mencoder. This can be
  done without reencoding just by using -ovc copy -oac copy.
  Recommended fourcc's would be XVID (probably safest), MP4S
  ("official" MS fourcc for mpeg4, but this might cause broken MS
  codec to try to decode it..?), or DX50.

Hope this helps... Someone should add this to the FAQ.


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