[Feature Request] API to detect if camera supports backchannel audio

[NickM-27]

As a client showing a webrtc stream I'd like to offer a microphone button only if the camera supports backchannel audio. Currently the streams info API can work for this but only if the stream that offers backchannel audio is already active.

For example, in a case where my config is

streams:
  front_cam:
    - rtsp://user:pass@address/streaming/channels/102#backchannel=0
    - isapi://user:pass@address:80/ # two-way talk

the streams info is

 "producers": [
    {
      "type": "RTSP active producer",
      "url": "rtsp://192.168.50.152/streaming/channels/102/",
      "remote_addr": "192.168.50.152:554",
      "user_agent": "go2rtc/1.8.5",
      "sdp": "v=0\r\no=- 1710317105064857 1710317105064857 IN IP4 192.168.50.152\r\ns=Media Presentation\r\ne=NONE\r\nb=AS:5100\r\nt=0 0\r\na=control:rtsp://192.168.50.152/streaming/channels/102/\r\nm=video 0 RTP/AVP 96\r\nc=IN IP4 0.0.0.0\r\nb=AS:5000\r\na=recvonly\r\na=x-dimensions:1920,536\r\na=control:rtsp://192.168.50.152/streaming/channels/102/trackID=1\r\na=rtpmap:96 H264/90000\r\na=fmtp:96 profile-level-id=420029; packetization-mode=1; sprop-parameter-sets=Z0IAM4qKUDwCK8v/gACAALZAAAD6AAAdTAE=,aM48gA==\r\nm=audio 0 RTP/AVP 0\r\nc=IN IP4 0.0.0.0\r\nb=AS:50\r\na=recvonly\r\na=control:rtsp://192.168.50.152/streaming/channels/102/trackID=2\r\na=rtpmap:0 PCMU/8000\r\na=Media_header:MEDIAINFO=494D4B48010300000400000110710110401F000000FA000000000000000000000000000000000000;\r\na=appversion:1.0\r\n",
      "medias": [
        "video, recvonly, H.264 Baseline 5.1",
        "audio, recvonly, PCMU/8000"
      ],
      "receivers": [
        "0 PCMU/8000, bytes=9692480, senders=1",
        "96 H264, bytes=368629271, senders=0"
      ],
      "recv": 381906816
    },
    {
      "url": "isapi://frigate:@[email protected]:80/"
    }
  ],

so we are not able to tell if backchannel audio is supported.

It would be very helpful if there was a separate api or perhaps a query arg on the streams api that would allow the ability to get info for all producers

[AlexxIT]

Go2rtc will run some dummy consumer for this. And run all of sources until get one with backchannel

[AlexxIT]

Check this http://192.168.1.123:1984/api/streams?src=rtsp-dahua1&video&audio&microphone
You can add codec filters to stream info query. video/audio/microphone with codec names or without.

[AlexxIT]

https://github.com/AlexxIT/go2rtc/releases/tag/v1.9.2