2-way audio with Dahua CGI HTTP interface

[felipecrs]

Hello,

I have a Dahua VTO2202F-P-S2 which unfortunately doesn't support the ONVIF Profile T (at least it didn't work in my tests).

I wonder if it's reasonable to suggest supporting additional methods for playing the audio in the camera/doorbell. For example, this doorbell exposes a small API which allows me to play audio on it:

https://s3.amazonaws.com/amcrest-files/AMCREST_CGI_SDK_API.pdf
(search for Post Audio)

I can reproduce it with something like:

curl --digest -verbose --request POST --url 'http://admin:pass@192.168.1.40/cgi-bin/audio.cgi?action=postAudio&httptype=singlepart&channel=1' --header 'Content-Type: Audio/G.711A' --data-binary '@DoorBell.wav'

So I wonder if it should be possible to pipe the audio from browser to this API in order to achieve 2-way audio.

[felipecrs]

• Refs Dahua VTO support #49 (comment)

/cc @luzik

[luzik]

Yeah, latency i low and we are ready to build video doorbell intercom. Switching audio codec is required. Please refer
blakeblackshear/frigate#2572

[AlexxIT]

Sometimes it's unnecessary to have Profile T. Camera just should response in RTSP SDP that it have separate media for back audio. You can enable rtsp trace logs for check it. Or you can see it in info link, like in this comment #49

[felipecrs]

This is what I have:

streams:
  "vto":
    - rtsp://admin:pass@192.168.1.40/cam/realmonitor?channel=1&subtype=0&unicast=true&proto=Onvif
    - ffmpeg:rtsp://admin:pass@192.168.1.40/cam/realmonitor?channel=1&subtype=0#audio=opus

[
  {
    "media:0": "video, sendonly, 96 H264/90000",
    "media:1": "audio, sendonly, 97 L16/16000",
    "media:2": "application, sendonly, 107 VND.ONVIF.METADATA/90000",
    "media:3": "audio, recvonly, 97 L16/16000",
    "receive": 213012,
    "remote_addr": "192.168.1.40:554",
    "send": 0,
    "track:0": "96 H264/90000, sinks=1",
    "type": "RTSP client producer",
    "url": "rtsp://192.168.1.40:554/cam/realmonitor?channel=1\u0026subtype=0\u0026unicast=true\u0026proto=Onvif/"
  },
  {
    "media:0": "audio, sendonly, 96 OPUS/48000/2",
    "receive": 16808,
    "remote_addr": "[::1]:43964",
    "send": 0,
    "track:0": "96 OPUS/48000/2, sinks=1",
    "type": "RTSP server producer",
    "url": "rtsp://localhost:8554/c17fa603dd6051c1a9da4cc4981af203",
    "user_agent": "Lavf59.16.100"
  },
  {
    "remote_addr": "udp4 host 192.168.1.15:56431",
    "send": 230073,
    "type": "WebRTC server consumer",
    "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36"
  }
]

But no audio is played back in the doorbell.

Switching audio codec is required. Please refer
blakeblackshear/frigate#2572

@luzik Right, I know it (since it was I that wrote it). But on my tests, it makes no difference. It does not matter which codec I select. Can you please elaborate it a little? My firmware seems to be very similar to yours.

[AlexxIT]

So you just need to change codecs. Like @luzik did.

[felipecrs]

Wow, it actually works! I just needed to select G.711 8000 instead of 16000:

[felipecrs]

Thanks a lot guys!

[felipecrs]

For completeness this is my final go2rtc configuration:

streams:
  vto:
    - rtsp://admin:pass@192.168.1.40/cam/realmonitor?channel=1&subtype=0&unicast=true&proto=Onvif

[NickM-27]

@felipecrs I am using the Amcrest AD410, my audio options are:

So far I have tried AAC and G.711A without success, but I have suspicion that my reverse proxy may not be working fully since the webrtc stream itself is also not showing

[felipecrs]

It should be G.711A with Sampling Frequency of 8000. Do you have the option of setting the sampling frequency?

I was previously trying with 16000 too, but it only works with 8000.

[felipecrs]

In the go2rtc WebUI, when you click in Info for your camera stream, it should show what's the current sampling frequency there. Feel free to share the info here.

[NickM-27]

As far as I can tell there is no option in Amcrest Surveillance Pro to adjust the sampling rate, this is my debug info:

[
  {
    "media:0": "video, sendonly, 96 H264/90000",
    "media:1": "audio, sendonly, 8 PCMA/8000",
    "media:2": "application, sendonly, 107 VND.ONVIF.METADATA/90000",
    "media:3": "audio, recvonly, 104 MPEG4-GENERIC/16000, 103 MPEG4-GENERIC/8000, 102 PCMU/16000, 0 PCMU/8000, 101 L16/16000, 97 L16/8000, 100 PCMA/16000, 8 PCMA/8000",
    "receive": 177552130,
    "remote_addr": "192.168.50.151:554",
    "send": 0,
    "track:0": "8 PCMA/8000, sinks=1",
    "type": "RTSP client producer",
    "url": "rtsp://192.168.50.151:554/cam/realmonitor?channel=1\u0026subtype=0\u0026proto=Onvif/"
  },
  {
    "media:0": "video, recvonly, 96 H264/90000",
    "media:1": "audio, recvonly, 97 PCMA/8000",
    "receive": 0,
    "remote_addr": "172.17.0.11:44376",
    "send": 177544162,
    "track:0": "97 PCMA/8000, sinks=1",
    "type": "RTSP server consumer",
    "url": "rtsp://192.168.50.106:8554/front_doorbell_cam",
    "user_agent": "Lavf59.27.100"
  }
]