[FFmpeg-user] 31bit limit of -analyzeduration and -probesize
oliver at fromme.com
Fri May 23 19:00:55 CEST 2014
Carl Eugen Hoyos wrote:
> Oliver Fromme <oliver <at> fromme.com> writes:
> > For example, there is one MPEG2 file with several subtitle
> > tracks. One of them (ID 3, i.e. PID 0x23) begins at roughly
> > 55 minutes into the movie, which is somewhere near byte offset
> > 2.5 GB in the MPEG2 file. Unfortunately I cannot specify
> > such a value for the -analyzeduration and -probesize options,
> > the maximum seems to be 2147M. But with 2147M, ffmpeg doesn't
> > find the track
> Did you confirm that the track can be found if you cut
> away the first 500M from the file?
Yes, I did a "tail -c 2G title_1.mpg > test.mpg" and then I
was able to extract the subtitle track from test.mpg (the
size of the original title_1.mpg is 4.5 GB). Although the
timestamps were all wrong, IIRC.
> I am not sure if -probesize can be extended to 64bit
> without a version bump but I first would like to be
> sure that this would solve the problem.
I see. Yes, it would certainly solve the problem. It would
be very good to remove this 31bit limit, because nowadays it
is not unusual that video files are much larger than 2 GB.
On a related note, is it really necessary that ffmpeg has to
read the whole file until the track begins? It takes a long
time. I remember that there is another tool that found all
of the subtitle tracks very quickly, even the ones that start
at several GB into the file. I think this was mediainfo, but
I'm not sure (I'll have to try again). I don't know how it
does that, though.
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