fix(voice): stop screen shares failing to reach their viewers (#2835)

2026-10-18 13:35:42 +09:00 · 2026-09-19 02:17:25 +02:00
1 parent f32356801d
commit bc47a724af
@@ -2,9 +2,18 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 import type {MediaDescription} from 'sdp-transform';
+import {parse} from 'sdp-transform';
 import {describe, expect, it} from 'vitest';
 import type {TrackBitrateInfo} from './PCTransport.ts';
-import {applyVideoStartBitrate, collectStereoMids, ensureAudioNackAndStereo, ensureOpusFmtp} from './PCTransport.ts';
+import {
+	applyVideoStartBitrate,
+	collectStereoMids,
+	ensureAudioNackAndStereo,
+	ensureOpusFmtp,
+	ensureVideoDDExtension,
+	videoSectionCanReceiveAV1,
+} from './PCTransport.ts';
+import {ddExtensionURI} from './utils.ts';

 function videoMedia(
 	trackId: string,
@@ -166,3 +175,67 @@ describe('collectStereoMids', () => {
 		expect(collectStereoMids([audioBitrateInfo(null, 'mic-track', false)], media)).toEqual([]);
 	});
 });
+
+const singlePcOffer = `v=0
+o=- 0 0 IN IP4 127.0.0.1
+s=-
+t=0 0
+a=group:BUNDLE 0 1 2
+m=video 9 UDP/TLS/RTP/SAVPF 96 45
+c=IN IP4 0.0.0.0
+a=mid:0
+a=sendonly
+a=msid:s cam
+a=rtpmap:96 VP8/90000
+a=rtpmap:45 AV1/90000
+a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
+a=extmap:11 urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id
+m=video 9 UDP/TLS/RTP/SAVPF 96 45
+c=IN IP4 0.0.0.0
+a=mid:1
+a=recvonly
+a=rtpmap:96 VP8/90000
+a=rtpmap:45 AV1/90000
+a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time
+m=video 9 UDP/TLS/RTP/SAVPF 96
+c=IN IP4 0.0.0.0
+a=mid:2
+a=recvonly
+a=rtpmap:96 VP8/90000
+a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time`;
+
+const sectionOf = (sdp: ReturnType<typeof parse>, mid: string) => sdp.media.find((media) => `${media.mid}` === mid)!;
+const ddOf = (sdp: ReturnType<typeof parse>, mid: string) =>
+	sectionOf(sdp, mid).ext?.find((ext) => ext.uri === ddExtensionURI)?.value;
+
+describe('videoSectionCanReceiveAV1', () => {
+	it('is true for a section we receive on that kept AV1, false otherwise', () => {
+		const sdp = parse(singlePcOffer);
+		expect(videoSectionCanReceiveAV1(sectionOf(sdp, '1'))).toBe(true);
+		expect(videoSectionCanReceiveAV1(sectionOf(sdp, '0'))).toBe(false);
+		expect(videoSectionCanReceiveAV1(sectionOf(sdp, '2'))).toBe(false);
+	});
+});
+
+describe('ensureVideoDDExtension', () => {
+	it('assigns an id above every extension in the bundle and reuses it', () => {
+		const sdp = parse(singlePcOffer);
+		expect(ensureVideoDDExtension(sectionOf(sdp, '1'), sdp, 0)).toBe(12);
+		expect(ddOf(sdp, '1')).toBe(12);
+		expect(ensureVideoDDExtension(sectionOf(sdp, '2'), sdp, 12)).toBe(12);
+		expect(ddOf(sdp, '2')).toBe(12);
+	});
+
+	it('adopts an id the bundle already maps the extension to', () => {
+		const sdp = parse(singlePcOffer);
+		sectionOf(sdp, '0').ext!.push({value: 13, uri: ddExtensionURI});
+		expect(ensureVideoDDExtension(sectionOf(sdp, '1'), sdp, 7)).toBe(13);
+		expect(ddOf(sdp, '1')).toBe(13);
+	});
+
+	it('leaves a section that already carries the extension alone', () => {
+		const sdp = parse(`${singlePcOffer}\na=extmap:3 ${ddExtensionURI}`);
+		expect(ensureVideoDDExtension(sectionOf(sdp, '2'), sdp, 0)).toBe(3);
+		expect(sectionOf(sdp, '2').ext).toHaveLength(2);
+	});
+});
@@ -10,7 +10,7 @@ import log, {getLogger, LoggerNames} from '../logger.ts';
 import {debounce} from './debounce.ts';
 import {NegotiationError, UnexpectedConnectionState} from './errors.ts';
 import type {LoggerOptions} from './types.ts';
-import {ddExtensionURI, isFireFox, isSafari, isSVCCodec} from './utils.ts';
+import {ddExtensionURI, isChromiumBased, isFireFox, isSafari, isSVCCodec} from './utils.ts';

 export interface TrackBitrateInfo {
 	cid?: string;
@@ -372,6 +372,9 @@ export default class PCTransport extends (EventEmitter as new () => TypedEmitter
 				if (media.type === 'audio') {
 					ensureAudioNackAndStereo(media, stereoMids, []);
 				} else if (media.type === 'video') {
+					if (isChromiumBased() && videoSectionCanReceiveAV1(media)) {
+						this.ddExtID = ensureVideoDDExtension(media, sdpParsed, this.ddExtID);
+					}
 					this.trackBitrates.some((trackbr): boolean => {
 						if (!trackbr.cid) {
 							return false;
@@ -677,6 +680,11 @@ export function ensureVideoDDExtension(
 	return id;
 }

+export function videoSectionCanReceiveAV1(media: MediaDescription): boolean {
+	if (media.direction !== 'recvonly' && media.direction !== 'sendrecv') return false;
+	return media.rtp.some((rtp) => rtp.codec.toLowerCase() === 'av1');
+}
+
 function ddExtensionIDFor(sdp: SessionDescription, cachedID: number): number | undefined {
 	const mapped = mappedExtensionID(sdp, ddExtensionURI);
 	if (mapped !== undefined) {
@@ -82,10 +82,33 @@ describe('selectPublisherCodecPreferences', () => {
 		expect(preferences).toEqual([constrainedBaselineMode1, constrainedBaselineMode0, highProfile]);
 	});

-	it('keeps non-H.264 codecs in browser capability order and appends RTX', () => {
+	it('puts the chosen codec first and keeps every other codec in browser capability order', () => {
 		const vp9 = codec('video/VP9');
 		const vp8 = codec('video/VP8');
 		const rtx = codec('video/rtx');
-		expect(selectPublisherCodecPreferences('vp9', [vp8, rtx, vp9])).toEqual([vp9, rtx]);
+		expect(selectPublisherCodecPreferences('vp9', [vp8, rtx, vp9])).toEqual([vp9, vp8, rtx]);
+	});
+
+	it('keeps the other codecs so a later publication on the same connection can negotiate them', () => {
+		const vp9 = codec('video/VP9');
+		const av1 = codec('video/AV1');
+		const h264 = codec('video/H264', 'level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f');
+		const preferences = selectPublisherCodecPreferences('vp9', [av1, h264, vp9]);
+		expect(preferences.map((entry) => entry.mimeType)).toEqual(['video/VP9', 'video/AV1', 'video/H264']);
+	});
+
+	it('ranks the H.264 profiles it leaves behind the chosen codec', () => {
+		const vp8 = codec('video/VP8');
+		const highProfile = codec('video/H264', 'level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=640033');
+		const constrainedBaseline = codec(
+			'video/H264',
+			'level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f',
+		);
+		const preferences = selectPublisherCodecPreferences('vp8', [vp8, highProfile, constrainedBaseline]);
+		expect(preferences).toEqual([vp8, constrainedBaseline, highProfile]);
+	});
+
+	it('returns nothing when the sender cannot encode the chosen codec', () => {
+		expect(selectPublisherCodecPreferences('av1', [codec('video/VP8'), codec('video/rtx')])).toEqual([]);
 	});
 });
@@ -1034,7 +1034,13 @@ export default class RTCEngine extends (EventEmitter as new () => TypedEventEmit
 		const capabilities = RTCRtpSender.getCapabilities('video');
 		if (!capabilities) return;
 		const preferences = selectPublisherCodecPreferences(codec, capabilities.codecs);
-		if (preferences.length === 0) return;
+		if (preferences.length === 0) {
+			this.log.warn('sender cannot encode the requested codec, leaving the browser order in place', {
+				...this.logContext,
+				codec,
+			});
+			return;
+		}
 		try {
 			transceiver.setCodecPreferences(preferences);
 		} catch (error) {
@@ -1828,8 +1834,12 @@ export function selectPublisherCodecPreferences(
 	const selected = codecs.filter((entry) => mimeTypes.has(entry.mimeType.toLowerCase()));
 	if (selected.length === 0) return [];
 	const preferred = codec === 'h264' ? preferHardwareH264Codecs(selected) : selected;
-	const rtx = codecs.filter((entry) => entry.mimeType.toLowerCase() === 'video/rtx');
-	return [...preferred, ...rtx];
+	const isH264 = (entry: RtpCodecCapability): boolean => entry.mimeType.toLowerCase() === 'video/h264';
+	const remaining = codecs.filter((entry) => !mimeTypes.has(entry.mimeType.toLowerCase()));
+	const rankedH264 = preferHardwareH264Codecs(remaining.filter(isH264));
+	let nextH264 = 0;
+	const rest = remaining.map((entry) => (isH264(entry) ? rankedH264[nextH264++] : entry));
+	return [...preferred, ...rest];
 }

 export type EngineEventCallbacks = {