[FFmpeg-user] 31bit limit of -analyzeduration and -probesize

Oliver Fromme 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.

Best regards


More information about the ffmpeg-user mailing list