Logitech C920 vidsrc syntax

Ingemar Johansson ingemar.s.johansson at ericsson.com
Sat Mar 2 12:29:28 UTC 2019

As a followup... The rate control definitely works in dynamic (run time)
mode on the C920 and it works quite well!. I hacked the gscreamtx element so
that it sets the average-bitrate and peak-bitrate properties and then it
works. One may add an adaptive setting to the min-iframe-qp to avoid that
the bitrate spikes when I-frame are generated, something that can cause the
video playout to freeze for a short while whe bandwidth is limited. Ideally
one would like periodic intra refresh capability which is available in e.g
x264enc but still I would say that the C920 can be very useful for live
streaming with low latency over e.g LTE.  The camera to eye latency is 160ms
(over local WiFi) but then I have not done much work on the pipeline on the
receiveing end and software decoding is used.

PS1 : I realized that it was possible to run the whole thing on the command
line, thus I don't need to mess with an application, the pipeline is shown

PS2 : I am a beginner here and Gstreamer definitely has a learning slope but
I must say that I like this platform more for every day. You have done a
great job!

gst-launch-1.0 rtpbin name=rtpbin ! uvch264src device=/dev/video1 name=c920
auto-start=true iframe-period=1000 min-iframe-qp=20 c920.vidsrc ! queue !
video/x-h264,width=1920,height=1080,framerate=30/1,profile=high ! rtph264pay
! gscreamtx ! rtpbin.send_rtp_sink_0 rtpbin.send_rtp_src_0 ! udpsink
host= port=5000  rtpbin.send_rtcp_src_0 ! udpsink
host= port=5001  udpsrc port=5001 ! rtpbin.recv_rtcp_sink_0

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