[FFmpeg-devel] Bugreport: mpegts-demuxer gives wrong pts/dts with avchd files
Thu Feb 14 10:32:40 CET 2008
i just stumbled over misbehvaiour of the mpegts-demuxer of ffmpeg. I
have some avchd files here (.mts) which are just transport stream files
with 4 extra bytes before each packet. Video format is h.264 with PAFF
coding. Plays nice with some sync issues, caused by wrong timestamps.
The problem is that normally h.264 in TS has one timestamp per access
unit or per frame/field. "normally" means DVB sources. Some TV stations
code the same timestamp for both fields of a frame, others code + 1/2
But for avchd only every second field, the top field of each frame, has
a timestamp. The material has AUDs per field, the timestamps are right
before the AUDs, all ok.
However the mpegts demuxer delivers wrong values here, non-monotonous
DTS! In contrast it works ok with DVB/Paff material where each field has
As example some field sizes and pts/dts values how its stored and how
the demuxer reports it
field length pts
and what libavformat reports
field length pts dts
186221 54171 43371
40974 46971 46971
5353 50571 50571
11050 54171 54171
24266 50571 50571
17645 54171 54171
26668 64971 54171
34917 57771 57771
frame duration is 3600 (PAL)
it seems DTS is increased for every field by 3600, and sometimes reset
to values coded in the stream. Obviously it is non monotonous.
Is there any interest in this? example file?
Who maintains the mpegts demuxer?
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