[Ffmpeg-devel] [PATCH] fix frame duration computation in find_stream_infos

Fred Rothganger fred
Mon Apr 2 15:24:26 CEST 2007

Michael Niedermayer wrote:
>> We need something like "useful_frame_rate" that matches our intuitive 
>> notions of the true speed of the file.  :)
> no we dont, you want something you cant describe and cant implement
> and you reappear every few month and complain about it

It's true that I haven't kept up well with this list.  My pattern of 
reappearing is mainly due to seeing something that is particular 
interest to me (frame rate) and commenting on it.

I commented on this case because it seems evident that others besides 
myself are wrestling with the meaning of r_frame_rate, and that there 
exists an intuitive expectation that something (whether it is 
r_frame_rate or something else) give a fairly robust estimate of the 
true frame rate of a video.

> fixed rate video has per definition clean timestamps if not its not fixed
> rate
> also average fps will not make any more sense than r_frame_rate for such
> videos

If a video file starts with one screwy frame, followed by 1000 precisely 
and equally timed frames, then I would argue that it is "almost 
everywhere" fixed rate.  I also argue that it is useful to detect and 
report this.

> so you complain about your own lazyness?

Yes.  It is a confession, not a complaint.  :)

>> but it is an existence proof that average 
>> frame rate can be made useless.
> it IS useless beyond providing some statistics about the video ...

Agreed.  The point was that there are cases where average frame rate is 
useless.  However, I am much more interested in the case where there are 
a small number of screwy frames and a large number of well-timed frames.

-- Fred

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