Scalable Video Codec prevent incorrect Safari usage

[opusonline]

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Browser affected

Browser name including version (e.g. Chrome 64.0.3282.119)
Tested on Safari 15.6.1 and 16.1

Description

Scalable Video Codec sample shows incorrect results on Safari browsers due to Safari's special behaviour with navigator.mediaCapabilities.encodingInfo. Safari reports supported: true and just ignoring the scalabilityMode parameter. Fortunately, Safari includes a supportedConfiguration object within the encodingInfo result, where an additional check can be performed.

if (info.supported && (!info.supportedConfiguration || info.supportedConfiguration.video.scalabilityMode === mode)) {
  // ...
}

Steps to reproduce

Open https://webrtc.github.io/samples/src/content/extensions/svc/ in Safari (>= 15.4), click "Start", allow camera access, select "video/VP8" as Codec preferences.

Expected results

If Safari really supports SVC, only L1T1, L1T2, and L1T3 should be listed. Since Safari doesn't support SVC, the list should be empty.

Actual results

Every single scalability mode is available, even though VP8 should only support L1T1, L1T2, and L1T3.