WebRTC generate invalid rtpmap for H264

[Peter Biro]

Hi,

Im not sure if if can run it from terminal (I dont know how to do the signalling that way) but I can setup debug logging if it that ok?

I dont set any codec preferences on the webrtc.

Strange thing this is only appears if I use H264, I just tried to run the very same pipeline with VP8 codec the SDP looks alright (but unfortunately I have to use H264 so this wont be a workaround for my use case):

v=0
o=- 711117265011778833 0 IN IP4 0.0.0.0
s=-
t=0 0
a=ice-options:trickle
a=msid-semantic:WMS webrtc_sink
m=video 9 UDP/TLS/RTP/SAVPF 96
c=IN IP4 0.0.0.0
a=setup:actpass
a=ice-ufrag:Qfsq+80LvU2YdnPZzVjuA4/UrODXoKrN
a=ice-pwd:HWOOU8kI1droNmky2tjnGekC1NquWNmH
a=sendrecv
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 nack pli
a=ssrc:2035319666 msid:user1666440897 at host-b40b4b48 webrtctransceiver0
a=ssrc:2035319666 cname:user1666440897 at host-b40b4b48
a=mid:video0
a=fingerprint:sha-256 C2:C3:5D:14:8F:06:44:8A:0E:A8:76:4B:D8:46:5D:BF:31:73:F1:CB:32:F7:8B:F8:F5:D1:D9:58:1D:3C:5D:05

Thanks,
Peter

> On 2021. Apr 9., at 19:52, Olivier Crête <olivier.crete at collabora.com> wrote:
> 
> Hi,
> 
> On Fri, 2021-04-09 at 19:22 +0200, Peter Biro wrote:
>> Hi all,
>> 
>> I found a pretty strange issue webrtcbin generates the following initial SDP offer with a negative clock rate:
>> 
>> v=0
>> o=- 5716970113760455593 0 IN IP4 0.0.0.0
>> s=-
>> t=0 0
>> a=ice-options:trickle
>> a=msid-semantic:WMS webrtc_sink
>> m=video 9 UDP/TLS/RTP/SAVPF 96
>> c=IN IP4 0.0.0.0
>> a=setup:actpass
>> a=ice-ufrag:0ybqQZNeS9CznnGxJxW/BpKyapc+CXsL
>> a=ice-pwd:ffvVDjwSJ7/+AAdh3MjUMMhz91xwZZGI
>> a=sendrecv
>> a=rtcp-mux
>> a=rtcp-rsize
>> a=rtpmap:96 H264/-1784864736
>> a=rtcp-fb:96 nack pli
>> a=mid:video0
>> a=fingerprint:sha-256 9B:11:48:BE:41:FF:CA:FE:62:B1:98:07:7B:E6:80:2A:56:9A:56:DC:A2:60:81:27:DE:EC:F5:76:C1:C4:39:51
>> 
>> Actually it is more like a random number it changes in every session setup. However as I see it should be set to 9000.
>> 
>> My pipleine is pretty simple:
>> 
>> nvarguscamerasrc sensor-id=0 sensor-mode=0 gainrange="1 16" ispdigitalgainrange="1 1"
>>     ! video/x-raw(memory:NVMM), width=(int)1920, height=(int)1080, format=(string)NV12, framerate=(fraction)30/1
>>     ! nvvidconv ! nvv4l2h264enc bitrate=8000000 control-rate=1 insert-sps-pps=true ! rtph264pay mtu=1400 
>>     ! webrtcbin name=webrtc_sink latency=0
>> 
>> And on the application side Im handling the singling. 
>> 
>> Do you have any idea how to fix this? What I am missing here?
> 
> This is definitely a bug in webrtcbin, it shouldn't be generating an SDP with an invalid clock rate.
> 
> Can you run it with "gst-launch-1.0 -v" to see wahtr caps the payloaders set on webrtcbin ?
> 
> Do you set any codec preferences on webrtcbin ?
> 
> Olivier
> 
>> 
>> Thanks,
>> Peter
>> 
>> 
>> _______________________________________________
>> gstreamer-devel mailing list
>> gstreamer-devel at lists.freedesktop.org <mailto:gstreamer-devel at lists.freedesktop.org>
>> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel <https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel>
> 
> -- 
> Olivier Crête
> olivier.crete at collabora.com <mailto:olivier.crete at collabora.com>
> 
> _______________________________________________
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