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

[Phil Rhodes]

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.

P