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Fix screen sharing in recent Chrome (#4241)

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* Fix screen sharing in recent Chrome

Dreadful hack to work around a bug in recent chrome/electron's
WebRTC, as explained.

I'm not sure which is the least hideous out of this (ie. repeatedly
calling setCodecPreferences and seeing if it crashes each time) or
hardcoding the bad codec and skipping it. Opinions welcome.

* Unused import

* Remove commented line
This commit is contained in:
David Baker
2024-06-13 19:44:30 +01:00
committed by GitHub
parent 661ba76763
commit 9218f6380c
1 changed files with 30 additions and 12 deletions
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42
src/webrtc/call.ts
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@@ -2381,22 +2381,40 @@ export class MatrixCall extends TypedEventEmitter<CallEvent, CallEventHandlerMap
// RTCRtpReceiver.getCapabilities and RTCRtpSender.getCapabilities don't seem to be supported on FF before v113
if (!RTCRtpReceiver.getCapabilities || !RTCRtpSender.getCapabilities) return;
const recvCodecs = RTCRtpReceiver.getCapabilities("video")!.codecs;
const sendCodecs = RTCRtpSender.getCapabilities("video")!.codecs;
const codecs = [...sendCodecs, ...recvCodecs];
for (const codec of codecs) {
if (codec.mimeType === "video/rtx") {
const rtxCodecIndex = codecs.indexOf(codec);
codecs.splice(rtxCodecIndex, 1);
}
}
const screenshareVideoTransceiver = this.transceivers.get(
getTransceiverKey(SDPStreamMetadataPurpose.Screenshare, "video"),
);
// setCodecPreferences isn't supported on FF (as of v113)
screenshareVideoTransceiver?.setCodecPreferences?.(codecs);
if (!screenshareVideoTransceiver || !screenshareVideoTransceiver.setCodecPreferences) return;
const recvCodecs = RTCRtpReceiver.getCapabilities("video")!.codecs;
const sendCodecs = RTCRtpSender.getCapabilities("video")!.codecs;
const codecs = [];
for (const codec of [...recvCodecs, ...sendCodecs]) {
if (codec.mimeType !== "video/rtx") {
codecs.push(codec);
try {
screenshareVideoTransceiver.setCodecPreferences(codecs);
} catch (e) {
// Specifically, Chrome around version 125 and Electron 30 (which is Chromium 124) return an H.264 codec in
// the sender's capabilities but throw when you try to set it. Hence... this mess.
// Specifically, that codec is:
// {
// clockRate: 90000,
// mimeType: "video/H264",
// sdpFmtpLine: "level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=640034",
// }
logger.info(
"Working around buggy WebRTC impl: claimed to support codec but threw when setting codec preferences",
codec,
e,
);
codecs.pop();
}
}
}
}
private onNegotiationNeeded = async (): Promise<void> => {