[Ffmpeg-devel] Bug in pts computation in compute_pkt_fields() ?

Martin Wache M.Wache
Tue Mar 20 19:18:13 CET 2007

M?ns Rullg?rd schrieb:
> Martin Wache said:
>> Wolfram Gloger schrieb:
>>> Hi,
>>>> I'm experiencing problems with the pts values of the audio packets given
>>>> by av_read_frame(). The stream I feed to ffmpeg is a DVB-T stream mpeg2
>>>> audio and video.
>>> That is probably raw mpeg-ts, right?
>> No, it is already remuxed to pes.
> Are you aware that a PES stream may only consist of one elementary stream?
> Files such as those produced by VDR are not conforming to specs.
Yes, I remember that I read it somewhere. I do send video and audio in
one stream, is it possible that this causes the problems? As I said
earlier av_read_packet() works good, so I assumed that av_read_frame()
would be able to cope with that as well.
Could you remind me what the problem with those files is?

>>> Please check that st->pts_wrap_bits is set to 60 (and not 33) if the
>>> input stream is mpeg-ts.  A long time ago I had a similar problem
>>> which was caused by the transport stream not being detected correctly.
>> Hmm, you are right, st->pts_wrap_bits is 33 and it should be 60. If I
>> manually set it to 60 it works as it should. How did you fix that problem?
> Where do you get 60 from?  All MPEG PTS/DTS values are 33 bits, nothing else.

Sorry, my mistake. I only remembered that the PTS values don't fit into
32 bits, and when I read 60 and saw that it worked with 60 I assumed
that 60 is correct.


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