On Wed, May 09, 2018 at 02:35:00PM -0700, Aman Gupta wrote: > From: Aman Gupta <a...@tmm1.net> > > Fixes PMT parsing in some mpegts streams which contain > multiple tables within the PMT pid. Previously, the parser > assumed only one table was present in each packet, and discarded > the rest of the section data after attempting to parse the first > table. > > A similar issue was documented in the BeyondTV software[1], which > helped me diagnose the same bug in the ffmpeg mpegts demuxer. I also > tried DVBInspector, libdvbpsi's dvbinfo, and tstools' tsinfo to > help debug. The former two properly read PMTs with multiple tables, > whereas the last has the same bug as ffmpeg. > > I've created a minimal sample[2] which contains the combined PMT. > Here's what ffmpeg probe shows before and after this patch: > > Before: > > Input #0, mpegts, from 'combined-pmt-tids.ts': > Duration: 00:00:01.08, start: 4932.966167, bitrate: 741 kb/s > Program 1 > No Program > Stream #0:0[0xf9d]: Audio: ac3, 48000 Hz, mono, fltp, 96 kb/s > Stream #0:1[0xf9b]: Audio: mp3, 0 channels, fltp > Stream #0:2[0xf9c]: Unknown: none > > After: > > Input #0, mpegts, from 'combined-pmt-tids.ts': > Duration: 00:00:01.11, start: 4932.966167, bitrate: 718 kb/s > Program 1 > Stream #0:0[0xf9b]: Video: mpeg2video ([2][0][0][0] / 0x0002), > none(tv, top first), 29.97 fps, 29.97 tbr, 90k tbn, 90k tbc > Stream #0:1[0xf9c](eng): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, > 5.1(side), fltp, 384 kb/s > Stream #0:2[0xf9d](spa): Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, > mono, fltp, 96 kb/s > > With the patch, the PMT is parsed correctly so the streams are > created in the correct order, are associated with "Program 1", > and their codecs are set correctly. > > [1] http://forums.snapstream.com/vb/showpost.php?p=343816&postcount=201 > [2] https://s3.amazonaws.com/tmm1/combined-pmt-tids.ts > > Signed-off-by: Aman Gupta <a...@tmm1.net> > --- > libavformat/mpegts.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-)
probably ok. The code looks a bit convoluted, so testing with a fuzzer probably wont hurt thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB It is dangerous to be right in matters on which the established authorities are wrong. -- Voltaire
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