[Ffmpeg-devel] Seeking with in an MPEGTS
Tue Jun 21 15:42:32 CEST 2005
Andy Parkins said:
> On Tuesday 2005 June 21 14:24, M?ns Rullg?rd wrote:
>> > I've generated an MPEG transport stream containing an MPEG4 ES using
>> > libavformat. When playing back using ffplay, it plays back perfectly
>> > until I perform a seek. After that the stream breaks up for a bit, then
>> > settles down but I start to get lots of error messages from h263.c; for
>> > example.
>> MPEG TS doesn't contain information about key frames, so when you seek you
>> are likely to end up with some P/B frames before the next I frame. Nothing
>> to be worried about. You could junk the decoder output until the next I
>> frame comes around. Look at AVFrame.key_frame.
> Thanks; but I don't think this is the case. I'm happy with the messed up
> picture, which fixes as soon as there is a key frame. However, the quoted
> error messages continue well after the next key frame has been passed.
> Something about seeking is throwing off the decoder permanently.
MPEG TS doesn't necessarily return complete frames, so after the seek you
are probably getting the end of a frame. If the decoder parses this as the
start of a frame, I can imagine those errors occurring. Apparently, this
leaves the decoder in a permanent state of confusion. Michael?
mru at inprovide.com
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