mpegtsmux with ximagesrc
t.i.m at zen.co.uk
Tue Jul 26 01:50:19 PDT 2011
On Mon, 2011-07-25 at 10:19 -0700, Cahill, Ben M wrote:
> I'm trying to capture desktop display (via H264) and system audio (via
> AAC) to send via TS->RTP->udp to another computer.
> The pipeline below works as long as something is moving within the
> desktop display. But, if display doesn't change, ximagesrc stops
> delivering frames (which saves needless thrash), and mpegtsmux output
> stops dead; mpegtsmux's collectpads won't do anything until *all* input
> pads (i.e. both audio *and* video) have data queued.
> Is this "sporadic", non-periodic video a valid usage case for TS?
> If so, any suggestions for an alternative/workaround? I've tried
> videorate in front of the H264 encoder, but that swamps the system with
> needless thrash. I'm also trying to hack mpegtsmux to allow it to
> package/forward audio frames even when video stops, but having problems
> getting things started (non-negotiated caps?? for the stream that
> starts second).
There are known issues with GstCollectPads and handling of sparse
streams, see for example , but there are probably ways this could be
hacked around until something better comes along.
Some random ideas: does ximagesrc send newsegment updates, to move time
along when it doesn't output repeat frames? (Then the muxer/collectpads
know when not to wait, but see above). Or maybe there's a way to tell
x264enc that we want a repeat frame and/or that the frame being passed
is identical to the previous frame? Then videorate could flag duplicates
it creates and x264enc could pick up on the flag.
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