[Matroska-devel] Haali Mp4 FPS bug

Reuben Martin reuben.m at gmail.com
Sat Jun 13 09:53:25 CEST 2009


The Haali dshow media splitter with mp4 support seems to have a bug
when dealing with FPS. When an mp4 file with an h264 stream is played
back, it plays as fast as the computer can handle for several seconds
before slowing down to the correct frame rate.

This only appears to happen with h264 content encoded by the more
recent core versions of x264. Perhaps there was a subtle change in how
the frame rate is stored, and for all I know, the x264 encoded could
be the source of the bug. However I doubt it since remuxing the mp4
file using a separate tool doesn't fix the problem. (I'm not very well
informed about how mp4 works, so I'm not sure if the fps is stored in
the mp4 container or the h264 stream, but I'm working under the
assumption it's stored in the mp4 container) Regardless, this is not
an issue with video encoded by older x264 core versions.

When changing out the Haali mp4 splitter with another filter that
performs the same function this problem goes away. Likewise, the same
h264 stream in another container like mkv, also running through the
Haali splitter, does not have this problem. VLC, MPlayer, and other
media players that don't use dshow do not have this problem. This
happens with or without audio streams.

-Reuben



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