Unexpected latency increase on video encoder with 3-camera setup

Nicolas Dufresne nicolas at ndufresne.ca
Tue Sep 11 19:50:48 UTC 2018

Le mardi 11 septembre 2018 à 12:13 -0500, bdjukic a écrit :
> Hi there,
> We are running 3 camera GStreamer setup
> (https://www.e-consystems.com/three-synchronized-4k-cameras-for-nvidia-jetson-tx2.asp)
> on our NVIDIA Jetson TX2 with the following pipeline:
> *gst-launch-1.0 v4l2src device=/dev/video0 ! "video/x-raw,
> format=(string)UYVY, width=(int)1280, height=(int)720" ! nvvidconv
> output-buffers=50 ! omxh264enc control-rate=2 bitrate=600000 !
> 'video/x-h264, width=1280, height=720, stream-format=(string)byte-stream' !
> queue ! h264parse ! queue ! rtph264pay mtu=800 ! udpsink host=
> port=5000 sync=false

With sync=false, you'll reduce the latency, but the output will be
jittery/bursty. I would experiment the effect of going sync combined
with max-bitrate udpsink property.

> *
> The pipeline runs at *100fps*.
> After triggering all three pipelines at the same time, we can observe
> noticeable latency increase after 10 seconds period. We have managed to
> capture this strange behavior using GST Shark:
> https://1drv.ms/u/s!As2zxTr-3RwhhLFsLYWGM3dme-pdRQ . We can see that
> *omxh264enc* encoder cannot keep up with the incoming frames after 10
> seconds.
> We're confident that hardware can handle this flow, but it's rather the
> GStreamer pipeline which is not optimized. 

I've pushed this week fixes to gst-plugins-base and gst-omx to improve
omx video decoder/encoder throughput. I don't know how feasible it will
be for you to backport this into NVidia fork. This could help.


There is tones more improvement in gst-omx, but I have little fate it
will be doable to backport.

> Any ideas on how we can increase the efficiency of the hardware encoder in
> our pipeline? 
> Thanks!
> B.
> --
> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
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