Excessive latency

[David Jaggard]

Hi Tim,

I am using zerolatency and I was aware of the 200ms in the rtpbin (which is
perfectly acceptable) but not TSDemux! How do I force a lower latency on
the pipeline?

Thanks very much

On 24 February 2016 at 16:38, Tim Müller <tim at centricular.com> wrote:

> On Wed, 2016-02-24 at 16:06 +0000, David Jaggard wrote:
>
> Hi David,
>
> > The input of my stream is MPEG2 TS over RTP. The output is H264 video
> > only.
> >
> > Pipeline:
> > udpsrc->rtpbin->queue2->rtpMP2TDepay->TSDemux->(video)->queue2-
> > >DecodeBin->queue2->Deinterlace->queue2->x264Enc->queue2->h264pay-
> > >rtpbin->queue2->multiudpsink
> >
> > (I added all those queues to try and trace the bottleneck).
> >
> > The latency for the entire pipeline is set to a huge 1060ms.
> >
> > Every single queue other than the last is empty. The very last queue
> > before the sink reports about 1100ms worth of data. This means that
> > the entire pipeline is (virtually) latency free except when it
> > arrives at the sink and has to buffer in order to synchronize to the
> > clock. Why is it choosing such a high latency?
>
> Most of that (700ms) will be from tsdemux, which currently advertises
> the worst-case scenario latency.
>
> Then there's an rtpjitterbuffer in rtpbin, which by default has a
> latency of 200ms (you can configure this via the rtpbin "latency"
> property).
>
> The rest is probably from deinterlace (one frame) and x264enc (try
> x264enc tune=zerolatency if you're not using that yet).
>
> You should be able to force a lower latency on the pipeline than it
> would configure by default.
>
> You could also modify tsdemux to advertise a lower latency (most
> streams have much lower latency requirements, but we currently don't
> analyse the stream to estimate that yet, but just announce the worst
> case value).
>
> Cheers
>  -Tim
>
> --
> Tim Müller, Centricular Ltd - http://www.centricular.com
>
>
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