{
  "offer": {
    "castMode": "mirroring",
    "supportedStreams": [
      {
        "aesIvMask": "64A6AAC2821880145271BB15B0188821",
        "aesKey": "65386FD9BCC30BC7FB6A4DD1D3B0FA5E",
        "bitRate": 102000,
        "channels": 2,
        "codecName": "opus",
        "index": 0,
        "receiverRtcpEventLog": true,
        "rtpExtensions": ["adaptive_playout_delay"],
        "rtpPayloadType": 127,
        "rtpProfile": "cast",
        "sampleRate": 48000,
        "ssrc": 264890,
        "targetDelay": 400,
        "timeBase": "1/48000",
        "type": "audio_source"
      },
      {
        "aesIvMask": "64A6AAC2821880145271BB15B0188821",
        "aesKey": "65386FD9BCC30BC7FB6A4DD1D3B0FA5E",
        "codecName": "vp8",
        "index": 1,
        "maxBitRate": 5000000,
        "maxFrameRate": "30000/1000",
        "receiverRtcpEventLog": true,
        "renderMode": "video",
        "resolutions": [{"height": 1080, "width": 1920}],
        "rtpExtensions": ["adaptive_playout_delay"],
        "rtpPayloadType": 96,
        "rtpProfile": "cast",
        "ssrc": 748229,
        "targetDelay": 400,
        "timeBase": "1/90000",
        "type": "video_source"
      },
      {
        "aesIvMask": "64A6AAC2821880145271BB15B0188821",
        "aesKey": "65386FD9BCC30BC7FB6A4DD1D3B0FA5E",
        "codecName": "h264",
        "codecParameter": "avc1.4D4028",
        "index": 2,
        "maxBitRate": 4000000,
        "maxFrameRate": "25",
        "receiverRtcpEventLog": false,
        "renderMode": "video",
        "resolutions": [{"height": 720, "width": 1280}],
        "rtpExtensions": ["adaptive_playout_delay"],
        "rtpPayloadType": 97,
        "rtpProfile": "cast",
        "ssrc": 748229,
        "targetDelay": 400,
        "timeBase": "1/90000",
        "type": "video_source"
      },
      {
        "aesIvMask": "64A6AAC2821880145271BB15B0188821",
        "aesKey": "65386FD9BCC30BC7FB6A4DD1D3B0FA5E",
        "codecName": "vp9",
        "index": 2,
        "maxBitRate": 5000000,
        "maxFrameRate": "30000/1000",
        "receiverRtcpEventLog": true,
        "renderMode": "video",
        "resolutions": [{"height": 1080, "width": 1920}],
        "rtpExtensions": ["adaptive_playout_delay"],
        "rtpPayloadType": 96,
        "rtpProfile": "cast",
        "ssrc": 748230,
        "targetDelay": 400,
        "timeBase": "1/90000",
        "type": "video_source"
      },
      {
        "aesIvMask": "64A6AAC2821880145271BB15B0188821",
        "aesKey": "65386FD9BCC30BC7FB6A4DD1D3B0FA5E",
        "codecName": "av1",
        "index": 3,
        "maxBitRate": 5000000,
        "maxFrameRate": "30000/1000",
        "receiverRtcpEventLog": true,
        "renderMode": "video",
        "resolutions": [{"height": 1080, "width": 1920}],
        "rtpExtensions": ["adaptive_playout_delay"],
        "rtpPayloadType": 96,
        "rtpProfile": "cast",
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        "targetDelay": 400,
        "timeBase": "1/90000",
        "type": "video_source"
      }
    ]
  },
  "seqNum": 123,
  "type": "OFFER"
}