Sync problem with mpeg4

sudarshan bisht bisht.sudarshan at gmail.com
Sun Apr 3 10:06:44 PDT 2011


Timestamp of each video frame should be calculated on the basis of framerate
in my_mpeg4_dec plugin and that timestamp has to be set to Gstbuffer which
has one frame of video data and then Gstbuffer should be pushed to the sink
element. You can print timestamp for each frame and check weather is it set
correctly or not.


For more information about clocks , go through the following link;
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-clocks.html



On Sat, Apr 2, 2011 at 3:22 AM, Radivoje Jovanovic <
radivojejovanovic at gmail.com> wrote:

> I have following pipeline:
> gst-launch-0.10 filesrc location=my_movie.mp4 ! qtdemux name=t ! queue  !
> my_mpeg4_dec ! my_video_sink  t. ! queue ! faad ! alsasink.
> I am using the same pipeline to play mpeg4 and h264 videos (different
> decoder for h264). H264 works just fine but mpeg4 has sync problems. The
> video is as twice as fast as it should be. If I provide sync=false into
> my_mpeg4_dec line it all works fine but I do not want to do it this way. I
> just read in the documentation that:
>
> "Sometimes it is a parser element the one that knows the time, for instance
> if a pipeline contains a
> filesrc element connected to a MPEG decoder element, the former is the one
> that knows the time of
> each sample, because the knowledge of when to play each sample is embedded
> in the MPEG format.
> In this case this element will be regarded as the source element for this
> discussion."
>
> I am not sure how does ALSA gets the time stamp when it cannot see mpeg4
> directly? Is mpeg4 supposed to update global clock upstream so ALSA can see
> it or what?
> Cheers,
> Ogi
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>
>


-- 
Regards,

Sudarshan Bisht
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