[Ffmpeg-devel] wrong framerate in mpeg4 file?

The Wanderer inverseparadox
Sat Sep 24 12:50:34 CEST 2005

M?ns Rullg?rd wrote:

> Rich Felker <dalias at aerifal.cx> writes:
>> Treating 1 specially is definitely wrong. 1/25 is a typical valid
>> timebase. The problem is that the codec's framerate is being used
>> at all. If the container contains a framerate/timebase, this must
>> be used.
> Why?  When the two disagree, the container is just as often the one
> that's wrong.

I have no technical knowledge in this area (which, of course, means I
probably shouldn't speak up - but then I'm me), but my guess would be:
because it's much easier to change the information (and thus fix the
problem) in the container than it is to do the same thing in the codec
(without damaging anything, i.e. without transcoding). If the two both
have values for the framerate/timebaes, and the player uses the
container's value, and it's wrong, then the problem can easily be fixed
by remuxing; on the other hand, if the player uses the codec's value and
*that* is wrong, there's probably not much you can do about it (in most
cases, anyway) without transcoding the video and thus losing quality.

       The Wanderer

Warning: Simply because I argue an issue does not mean I agree with any
side of it.

Secrecy is the beginning of tyranny.

More information about the ffmpeg-devel mailing list