[gst-devel] Gstreamer RTSP server has 2 second delay to live stream

[Wim Taymans]

On Fri, 2009-04-24 at 14:19 -0700, ScreenName01 wrote:
> Hi gstreamerians,
> 
> I'm currently using RTSP server version 0.10.1 from the link below.
> 
>   http://people.freedesktop.org/~wtay/
> 
> In addition I'm using the latest tarball releases for gstreamer, base
> plugins, bad plugins and good plugins.
> 
> I'm streaming live from a v4l2 source from a camera sensor.
> 
> The sources output goes through a hardware VPU which encodes each frame
> based on the codec-type I pass into it.  This is the line I use with the
> Gstreamer RTSP server.
> 
> "( v4l2source ! vpuencoder codec-type=h264 ! rtph264pay name=pay0 pt=96 )"
> 
> It streams fine to VLC for instance.  No luck with quicktime and smplayer on
> Windows will display the first frame and then just die.  This is not a major
> concern though I am more concerned about the delay.  Any help there is also
> great though. ;)
> 
> I tried to send the same stream above through a tcpserversink.  So something
> like:
> 
> v4l2source ! vpuencoder codec-type=h264 ! tcpserversink port=5000
> 
> and connected to it through a gstreamer client (or whatever you'd like to
> use) to see where the latency lies.  At this point I was seeing a much
> smaller delay.  Maybe 50% to 75% improvement (so 1/2 second to a second
> delay).
> 
> Which leads me to believe that it's something to either do with vlc,
> Gstreamer RTSP server or RTSP/RTP/RTP manager portion of Gstreamer
> libraries/plugins.
> 
> Anyone have any ideas where to look first or how I can more easily narrow
> down the problem.  Any help is appreciated.

The latency is usually only caused in the client (jitterbuffer mostly).
There could be latency on the server side but then it would be in the
vpuencoder element. The v4l2src has 1 frame latency, rtpbin has 0
latency.

Wim

> 
> One thing I tried is reducing all the default latencies in RTP manager. 
> That seemed to make little to no difference.
> 
> Thanks in advance!  Willing to take any advice possible.
>