(Updated) GenerateWebRtcStream returns 400, "sdp_offer contains an invalid value." when sent to Nest Camera or Nest Doorbell

Question

I've written an Android app to stream video from my nest cameras and doorbell. I have a valid access token and can retrieve a list of all my nest devices. However, when I send a GenerateWebRtcStream to any device, it returns the same 400 error.

I have verified that my offer:

1. Has a=recvonly, and that it also has H264 as an available video codec. As indicated in documentation
2. Has a data channel (as suggested by another solution to this problem).
3. Has the audio stream data before the video stream data (as suggested by a second solution to this problem).
4. [Updated] Have created the offer with a PeerConnection initialized with SdpSemantics.UNIFIED_PLAN

Additional information:

My Android app is based (almost entirely) off this very helpful blog. The app works when connecting to a non-nest camera (i.e. instance of itself on another device), so the offer and logic is valid on some level.

There appears to be very little information on what offer the Nest Camera's will accept, so I'm posting the generated offer and command I'm posting to the API in the hopes that someone has an idea on what I might need to change.

Many thanks in advance.

sdpOffer:

v=0
o=- 5150109222623794114 2 IN IP4 127.0.0.1
s=-
t=0 0
a=group:BUNDLE 0 1 2
a=msid-semantic: WMS
m=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 102 0 8 106 105 13 110 112 113 126
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:KQKv
a=ice-pwd:QvV7coYbshMtmKmkqpBno0xz
a=ice-options:trickle renomination
a=fingerprint:sha-256 C2:16:13:A3:80:1A:8E:96:21:98:4B:8C:03:26:93:DE:FA:88:C5:8B:DB:06:62:87:FF:BA:D4:0C:98:2A:3E:C9
a=setup:actpass
a=mid:0
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=recvonly
a=rtcp-mux
a=rtpmap:111 opus/48000/2
a=rtcp-fb:111 transport-cc
a=fmtp:111 minptime=10;useinbandfec=1
a=rtpmap:103 ISAC/16000
a=rtpmap:104 ISAC/32000
a=rtpmap:9 G722/8000
a=rtpmap:102 ILBC/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:106 CN/32000
a=rtpmap:105 CN/16000
a=rtpmap:13 CN/8000
a=rtpmap:110 telephone-event/48000
a=rtpmap:112 telephone-event/32000
a=rtpmap:113 telephone-event/16000
a=rtpmap:126 telephone-event/8000
m=video 9 UDP/TLS/RTP/SAVPF 96 97 98 99 125 100 101 127
c=IN IP4 0.0.0.0
a=rtcp:9 IN IP4 0.0.0.0
a=ice-ufrag:KQKv
a=ice-pwd:QvV7coYbshMtmKmkqpBno0xz
a=ice-options:trickle renomination
a=fingerprint:sha-256 C2:16:13:A3:80:1A:8E:96:21:98:4B:8C:03:26:93:DE:FA:88:C5:8B:DB:06:62:87:FF:BA:D4:0C:98:2A:3E:C9
a=setup:actpass
a=mid:1
a=extmap:14 urn:ietf:params:rtp-hdrext:toffset
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
a=extmap:13 urn:3gpp:video-orientation
a=extmap:3 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01
a=extmap:12 http://www.webrtc.org/experiments/rtp-hdrext/playout-delay
a=extmap:11 http://www.webrtc.org/experiments/rtp-hdrext/video-content-type
a=extmap:7 http://www.webrtc.org/experiments/rtp-hdrext/video-timing
a=extmap:8 http://www.webrtc.org/experiments/rtp-hdrext/color-space
a=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid
a=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id
a=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
a=recvonly
a=rtcp-mux
a=rtcp-rsize
a=rtpmap:96 VP8/90000
a=rtcp-fb:96 goog-remb
a=rtcp-fb:96 transport-cc
a=rtcp-fb:96 ccm fir
a=rtcp-fb:96 nack
a=rtcp-fb:96 nack pli
a=rtpmap:97 rtx/90000
a=fmtp:97 apt=96
a=rtpmap:98 VP9/90000
a=rtcp-fb:98 goog-remb
a=rtcp-fb:98 transport-cc
a=rtcp-fb:98 ccm fir
a=rtcp-fb:98 nack
a=rtcp-fb:98 nack pli
a=rtpmap:99 rtx/90000
a=fmtp:99 apt=98
a=rtpmap:125 H264/90000
a=rtcp-fb:125 goog-remb
a=rtcp-fb:125 transport-cc
a=rtcp-fb:125 ccm fir
a=rtcp-fb:125 nack
a=rtcp-fb:125 nack pli
a=fmtp:125 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f
a=rtpmap:100 red/90000
a=rtpmap:101 rtx/90000
a=fmtp:101 apt=100
a=rtpmap:127 ulpfec/90000
m=application 9 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 0.0.0.0
a=ice-ufrag:KQKv
a=ice-pwd:QvV7coYbshMtmKmkqpBno0xz
a=ice-options:trickle renomination
a=fingerprint:sha-256 C2:16:13:A3:80:1A:8E:96:21:98:4B:8C:03:26:93:DE:FA:88:C5:8B:DB:06:62:87:FF:BA:D4:0C:98:2A:3E:C9
a=setup:actpass
a=mid:2
a=sctp-port:5000
a=max-message-size:262144

POST Body:

{
   {
   "command":"sdm.devices.commands.CameraLiveStream.GenerateWebRtcStream",
   "params":{
      "sdpOffer":"v=0\r\no=- 5150109222623794114 2 IN IP4 127.0.0.1\r\ns=-\r\nt=0 0\r\na=group:BUNDLE 0 1 2\r\na=msid-semantic: WMS\r\nm=audio 9 UDP\/TLS\/RTP\/SAVPF 111 103 104 9 102 0 8 106 105 13 110 112 113 126\r\nc=IN IP4 0.0.0.0\r\na=rtcp:9 IN IP4 0.0.0.0\r\na=ice-ufrag:KQKv\r\na=ice-pwd:QvV7coYbshMtmKmkqpBno0xz\r\na=ice-options:trickle renomination\r\na=fingerprint:sha-256 C2:16:13:A3:80:1A:8E:96:21:98:4B:8C:03:26:93:DE:FA:88:C5:8B:DB:06:62:87:FF:BA:D4:0C:98:2A:3E:C9\r\na=setup:actpass\r\na=mid:0\r\na=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\na=extmap:2 http:\/\/www.webrtc.org\/experiments\/rtp-hdrext\/abs-send-time\r\na=extmap:3 http:\/\/www.ietf.org\/id\/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\na=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\na=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id\r\na=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id\r\na=recvonly\r\na=rtcp-mux\r\na=rtpmap:111 opus\/48000\/2\r\na=rtcp-fb:111 transport-cc\r\na=fmtp:111 minptime=10;useinbandfec=1\r\na=rtpmap:103 ISAC\/16000\r\na=rtpmap:104 ISAC\/32000\r\na=rtpmap:9 G722\/8000\r\na=rtpmap:102 ILBC\/8000\r\na=rtpmap:0 PCMU\/8000\r\na=rtpmap:8 PCMA\/8000\r\na=rtpmap:106 CN\/32000\r\na=rtpmap:105 CN\/16000\r\na=rtpmap:13 CN\/8000\r\na=rtpmap:110 telephone-event\/48000\r\na=rtpmap:112 telephone-event\/32000\r\na=rtpmap:113 telephone-event\/16000\r\na=rtpmap:126 telephone-event\/8000\r\nm=video 9 UDP\/TLS\/RTP\/SAVPF 96 97 98 99 125 100 101 127\r\nc=IN IP4 0.0.0.0\r\na=rtcp:9 IN IP4 0.0.0.0\r\na=ice-ufrag:KQKv\r\na=ice-pwd:QvV7coYbshMtmKmkqpBno0xz\r\na=ice-options:trickle renomination\r\na=fingerprint:sha-256 C2:16:13:A3:80:1A:8E:96:21:98:4B:8C:03:26:93:DE:FA:88:C5:8B:DB:06:62:87:FF:BA:D4:0C:98:2A:3E:C9\r\na=setup:actpass\r\na=mid:1\r\na=extmap:14 urn:ietf:params:rtp-hdrext:toffset\r\na=extmap:2 http:\/\/www.webrtc.org\/experiments\/rtp-hdrext\/abs-send-time\r\na=extmap:13 urn:3gpp:video-orientation\r\na=extmap:3 http:\/\/www.ietf.org\/id\/draft-holmer-rmcat-transport-wide-cc-extensions-01\r\na=extmap:12 http:\/\/www.webrtc.org\/experiments\/rtp-hdrext\/playout-delay\r\na=extmap:11 http:\/\/www.webrtc.org\/experiments\/rtp-hdrext\/video-content-type\r\na=extmap:7 http:\/\/www.webrtc.org\/experiments\/rtp-hdrext\/video-timing\r\na=extmap:8 http:\/\/www.webrtc.org\/experiments\/rtp-hdrext\/color-space\r\na=extmap:4 urn:ietf:params:rtp-hdrext:sdes:mid\r\na=extmap:5 urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id\r\na=extmap:6 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id\r\na=recvonly\r\na=rtcp-mux\r\na=rtcp-rsize\r\na=rtpmap:96 VP8\/90000\r\na=rtcp-fb:96 goog-remb\r\na=rtcp-fb:96 transport-cc\r\na=rtcp-fb:96 ccm fir\r\na=rtcp-fb:96 nack\r\na=rtcp-fb:96 nack pli\r\na=rtpmap:97 rtx\/90000\r\na=fmtp:97 apt=96\r\na=rtpmap:98 VP9\/90000\r\na=rtcp-fb:98 goog-remb\r\na=rtcp-fb:98 transport-cc\r\na=rtcp-fb:98 ccm fir\r\na=rtcp-fb:98 nack\r\na=rtcp-fb:98 nack pli\r\na=rtpmap:99 rtx\/90000\r\na=fmtp:99 apt=98\r\na=rtpmap:125 H264\/90000\r\na=rtcp-fb:125 goog-remb\r\na=rtcp-fb:125 transport-cc\r\na=rtcp-fb:125 ccm fir\r\na=rtcp-fb:125 nack\r\na=rtcp-fb:125 nack pli\r\na=fmtp:125 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f\r\na=rtpmap:100 red\/90000\r\na=rtpmap:101 rtx\/90000\r\na=fmtp:101 apt=100\r\na=rtpmap:127 ulpfec\/90000\r\nm=application 9 UDP\/DTLS\/SCTP webrtc-datachannel\r\nc=IN IP4 0.0.0.0\r\na=ice-ufrag:KQKv\r\na=ice-pwd:QvV7coYbshMtmKmkqpBno0xz\r\na=ice-options:trickle renomination\r\na=fingerprint:sha-256 C2:16:13:A3:80:1A:8E:96:21:98:4B:8C:03:26:93:DE:FA:88:C5:8B:DB:06:62:87:FF:BA:D4:0C:98:2A:3E:C9\r\na=setup:actpass\r\na=mid:2\r\na=sctp-port:5000\r\na=max-message-size:262144\r\n"
   }
}

Error Response:

{
   "error":{
      "code":400,
      "message":"sdp_offer contains an invalid value.",
      "status":"INVALID_ARGUMENT"
   }
}

Answer 1

Got the sample app at github.com/google/device-access-sample-web-app running as suggested by @BTGunner (thanks again!!!), and got to see what a successful request looks like.

The offer that I'm generating is accepted. The problem was that the documentation and implementation have deviated for GenerateWebRtcStream. The current documentation indicates that the offer description should be named offerSdp (which fails). The sample app instead uses offer_sdp and this returns a valid answer.