[FFmpeg-user] Why Does ffprobe Report an Incorrect Number of Frames?

[Christian Ebert]

* Phil Rhodes on Wednesday, May 07, 2014 at 05:59:37 -0700
> I'm not that familiar with the commandline options you're
> using, but bear in mind that while AVI files do theoretically
> have a header entry containing the frame count, it can be (and
> in my experience very often is) incorrect or unset. Software
> which relies on that being correct - and as I say, I don't know
> if this does - may not be reliable.
> 
> In my experience the only way of finding out how many frames
> there really are in an AVI is to use software which actually
> goes through the file as if it were playing the movie, and
> counts frames. This may simply mean playing it, which can be
> very time-consuming. You can often get players to run at an
> unrestricted frame rate - that is, restricted only by disk and
> CPU performance. I guess it's theoretically possible to skip
> through and count "00dc" chunks without actually decoding the
> frames, and I seem to recall that mplayer or ffmpeg or
> something had an option which seemed, from its behaviour, to be
> doing that. It was some time ago. I'm not sure.

Something like this is relatively quick:

time ffprobe -select_streams v -count_frames -show_entries stream=nb_read_frames test.flv 2>/dev/null
[STREAM]
nb_read_frames=167325
[/STREAM]

real    0m47.308s
user    0m47.161s
sys     0m0.170s

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