I hit this once some time ago when creating an application which was intended
to assign start timecodes to recorded video files and for which we needed a
frame-accurate count. In that case the files were AVIs, which theoretically may
have a header including a frame count, but in practice we found that this was
often either missing, not set, or inaccurate in files we found in the wild, and
there are further issues specifically with AVI over a certain length. Other
file types have similar problems.
My conclusion was that the only reliable way to get a frame count is to have
something like ffmpeg go over the file frame by frame. With the command lines
suggested here (which are, if I remember correctly, close to what I used) then
it tends to be reasonably fast and, as I say, I'm not sure there's much other
option if you need a reasonable amount of reliability on arbitrary files.
If you're in a situation where all your files come from a known source and you
are confident they will always have frame count headers that will always be
accurate, great, but otherwise I'd recommend doing roughly what's been
suggested here.
P
On Tuesday, 9 March 2021, 10:54:09 GMT, Peter White
<[email protected]> wrote:
Unless it happens to be one of those special cases that don't have that
info in their metadata, like matroska:
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