[Libav-user] muxing h264/aac stream

Anshul maheshwari er.anshul.maheshwari at gmail.com
Fri Aug 16 23:10:59 CEST 2013

On Aug 16, 2013 7:30 PM, "Nisar Ahmed" <nisar.med at gmail.com> wrote:
> I am muxing h264/aac stream to mp4 coming from an encoder and having
issues syncing audio and video streams.
> I suspect that the problem is with PTS and DTS but I am not sure what
values should i set to properly sync both streams.
> I have set the time_base of video stream's AVCodecContext to 1001/30000
and each AVPacket gets a duration of 1001
> I am recieving time stamps from the encoder with each NAL packet which is
set as PTS of the AVPacket. the sequence of PTS/DTS I set is (2002/0,
0/1001, 1001/2002, 5005/3003, 3003/4004...)
> Audio stream AVCodecContext sample rate is 48000 and PTS/DTS are simply
multiples of 1024 starting from 0 and AVPacket duration is 1024.
> The output movie 's frame rate is 20fps when it should be 29.97fps as it
is ntsc.
> Please tell me how to debug this problem and what are the guidelines of
creating pts/dts for both video and audio in my case
> _______________________________________________
> Libav-user mailing list
> Libav-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/libav-user
Hi naseer

If you are getting timestamp with encoder,  i would suggest "dont try to
manuplate that" you may set that same timestamp as presentation timestamp
(pts) if your video is realtime then try not to generate B type video frame
hence no need to set dts.
Whatever clock is set by encoder try generating the pts of audio according
to that.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20130817/3c0fb574/attachment.html>

More information about the Libav-user mailing list