RTCRtpEncodingParameters-codec-opus-stereo.https.html

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This test has a WPT meta file that expects 2 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /webrtc/RTCRtpEncodingParameters-codec-opus-stereo.https.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta charset="utf-8">

<title>RTCRtpEncodingParameters codec opus stereo</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script>

'use strict';

const kNumChannelsMono = 1;

const kNumChannelsStereo = 2;

const kAudioProcessingEnabled = true;

const kAudioProcessingDisabled = false;

// In some implementations (e.g. Chrome), whether or not audio processing is

// used may affect the number of channels we get.

// To isolate this factor from the test, we constrain both channels and APM.

function getAudioConstraints(numChannels, audioProcessing) {

  return {

    channelCount: {exact: numChannels},

    autoGainControl: audioProcessing,

    echoCancellation: audioProcessing,

    noiseSuppression: audioProcessing

};

// Polls getSettings() until `channelCount` is known.

// Remote tracks don't populate their `channelCount` until media is received.

async function pollChannelCount(t, track) {

  while (true) {

    if (track.getSettings().channelCount != undefined) {

      break;

    await new Promise(r => t.step_timeout(r, 50));

  return track.getSettings().channelCount;

promise_test(async t => {

  const pc1 = new RTCPeerConnection();

  t.add_cleanup(() => pc1.close());

  const pc2 = new RTCPeerConnection();

  t.add_cleanup(() => pc2.close());

  pc1.onicecandidate = e => pc2.addIceCandidate(e.candidate);

  pc2.onicecandidate = e => pc1.addIceCandidate(e.candidate);

  // Open microphone as mono.

  const stream = await navigator.mediaDevices.getUserMedia(

      {audio: getAudioConstraints(kNumChannelsMono, kAudioProcessingEnabled)});

  const [track] = stream.getTracks();

  t.add_cleanup(() => track.stop());

  // Prerequisite of the test.

  assert_equals(track.getSettings().channelCount, 1,

                'Can open track in mono');

  // Negotiate opus.

  const transceiver = pc1.addTransceiver(track);

  transceiver.setCodecPreferences(

      RTCRtpSender.getCapabilities('audio').codecs.filter(

          codec => codec.mimeType == 'audio/opus'));

  await pc1.setLocalDescription();

  await pc2.setRemoteDescription(pc1.localDescription);

  await pc2.setLocalDescription();

  await pc1.setRemoteDescription(pc2.localDescription);

  const [receiver] = pc2.getReceivers();

  const remoteTrack = receiver.track;

  // Attaching the track to an audio element is needed for media to flow,

  // otherwise the `channelCount` is never known.

  const audio = document.createElement('audio');

  audio.srcObject = new MediaStream();

  audio.srcObject.addTrack(remoteTrack);

  // The stereo opus decoder outputs stereo regardless of the signal on the

  // wire.

  assert_equals(await pollChannelCount(t, remoteTrack), 2,

                'Remote track is stereo (despite local track being mono)');

}, 'Sending and receiving a mono track with opus (stereo decoder upmix)');

promise_test(async t => {

  const pc1 = new RTCPeerConnection();

  t.add_cleanup(() => pc1.close());

  const pc2 = new RTCPeerConnection();

  t.add_cleanup(() => pc2.close());

  pc1.onicecandidate = e => pc2.addIceCandidate(e.candidate);

  pc2.onicecandidate = e => pc1.addIceCandidate(e.candidate);

  // Open microphone as stereo.

  const stream = await navigator.mediaDevices.getUserMedia(

    {audio: getAudioConstraints(kNumChannelsStereo, kAudioProcessingDisabled)});

  const [track] = stream.getTracks();

  t.add_cleanup(() => track.stop());

  // Prerequisite of the test.

  assert_equals(track.getSettings().channelCount, 2,

                'Can open track in stereo');

  // Negotiate opus.

  const transceiver = pc1.addTransceiver(track);

  transceiver.setCodecPreferences(

      RTCRtpSender.getCapabilities('audio').codecs.filter(

          codec => codec.mimeType == 'audio/opus'));

  await pc1.setLocalDescription();

  await pc2.setRemoteDescription(pc1.localDescription);

  await pc2.setLocalDescription();

  await pc1.setRemoteDescription(pc2.localDescription);

  const [receiver] = pc2.getReceivers();

  const remoteTrack = receiver.track;

  // Attaching the track to an audio element is needed for media to flow,

  // otherwise the `channelCount` is never known.

  const audio = document.createElement('audio');

  audio.srcObject = new MediaStream();

  audio.srcObject.addTrack(remoteTrack);

  assert_equals(await pollChannelCount(t, remoteTrack), 2,

                'Remote track is also stereo');

}, 'Sending and receiving a stereo track with opus');

</script>