additional-codecs.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /webrtc/protocol/additional-codecs.html - WPT Dashboard Interop Dashboard

<!doctype html>

<meta charset=utf-8>

<title>Send additional codec supported by the other side</title>

<meta name=timeout content=long>

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

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

<script src="../RTCPeerConnection-helper.js"></script>

<script>

'use strict';

// Tests behaviour from

// https://www.rfc-editor.org/rfc/rfc8829.html#section-5.3.1

// in particular "but MAY include formats that are locally

// supported but not present in the offer"

promise_test(async t => {

  const pc1 = new RTCPeerConnection();

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

  const pc2 = new RTCPeerConnection();

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

  exchangeIceCandidates(pc1, pc2);

  const stream = await getNoiseStream({video: true});

  t.add_cleanup(() => stream.getTracks().forEach(t => t.stop()));

  pc1.addTrack(stream.getTracks()[0], stream);

  pc2.addTrack(stream.getTracks()[0], stream);

  const {codecs} = RTCRtpSender.getCapabilities('video');

  const vp8 = codecs.find(c => c.mimeType === 'video/VP8');

  const h264 = codecs.find(c => c.mimeType === 'video/H264');

  // Only offer VP8.

  pc1.getTransceivers()[0].setCodecPreferences([vp8]);

  await pc1.setLocalDescription();

  // Add H264 to the SDP.

  const sdp = pc1.localDescription.sdp.split('\n')

    .map(l => {

      if (l.startsWith('m=')) {

        return l.trim() + ' 63'; // 63 is the least-likely to be used PT.

      return l.trim();

    }).join('\r\n') +

    'a=rtpmap:63 H264/90000\r\n' +

    `a=fmtp:63 ${h264.sdpFmtpLine}\r\n`

  await pc2.setRemoteDescription({

    type: 'offer',

    sdp: sdp.replaceAll('VP8', 'no-such-codec'), // Remove VP8

});

  await pc2.setLocalDescription();

  await pc1.setRemoteDescription(pc2.localDescription);

  await listenToConnected(pc2);

  const stats = await pc1.getStats();

  const rtp = [...stats.values()].find(

    ({type, codecId}) => type === 'outbound-rtp' && codecId);

  assert_true(!!rtp, 'an outbound-rtp stat with a codec was produced');

  assert_equals(stats.get(rtp.codecId).mimeType, 'video/H264');

}, 'Listing an additional codec in the answer causes it to be sent.');

</script>