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ref(TPC) Pass the transform object along for SDP munging.
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@jallamsetty1
jallamsetty1 committed Nov 25, 2024
1 parent 8768906 commit 07f037e
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Showing 2 changed files with 110 additions and 123 deletions.
159 changes: 97 additions & 62 deletions modules/RTC/TPCUtils.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ import { MediaDirection } from '../../service/RTC/MediaDirection';
import { MediaType } from '../../service/RTC/MediaType';
import {
SIM_LAYERS,
SSRC_GROUP_SEMANTICS,
STANDARD_CODEC_SETTINGS,
VIDEO_QUALITY_LEVELS,
VIDEO_QUALITY_SETTINGS
Expand Down Expand Up @@ -438,12 +439,11 @@ export class TPCUtils {
}

/**
* Ensures that the ssrcs associated with a FID ssrc-group appear in the correct order, i.e.,
* the primary ssrc first and the secondary rtx ssrc later. This is important for unified
* plan since we have only one FID group per media description.
* @param {Object} description the webRTC session description instance for the remote
* description.
* @private
* Ensures that the ssrcs associated with a FID ssrc-group appear in the correct order, i.e., the primary ssrc
* first and the secondary rtx ssrc later. This is important for unified plan since we have only one FID group per
* media description.
* @param {Object} description the webRTC session description instance for the remote description.
* @returns {Object} the modified webRTC session description instance.
*/
ensureCorrectOrderOfSsrcs(description) {
const parsedSdp = transform.parse(description.sdp);
Expand Down Expand Up @@ -493,14 +493,15 @@ export class TPCUtils {
if (this.pc.usesCodecSelectionAPI() && rtpSender) {
const { codecs } = rtpSender.getParameters();

return codecs[0].mimeType.split('/')[1].toLowerCase();
if (codecs?.length) {
return codecs[0].mimeType.split('/')[1].toLowerCase();
}
}

const sdp = this.pc.remoteDescription?.sdp;
const defaultCodec = CodecMimeType.VP8;

if (!sdp) {
return defaultCodec;
return CodecMimeType.VP8;
}
const parsedSdp = transform.parse(sdp);
const mLine = parsedSdp.media
Expand All @@ -512,17 +513,17 @@ export class TPCUtils {
return Object.values(CodecMimeType).find(value => value === codec.toLowerCase());
}

return defaultCodec;
return CodecMimeType.VP8;
}

/**
* Returns the codecs in the current order of preference as configured on the peerconnection.
*
* @param {RTCSessionDescription} - The local description to be used.
* @param {string} - The local SDP to be used.
* @returns {Array}
*/
getConfiguredVideoCodecs(description) {
const currentSdp = description?.sdp ?? this.pc.localDescription?.sdp;
getConfiguredVideoCodecs(sdp) {
const currentSdp = sdp ?? this.pc.localDescription?.sdp;

if (!currentSdp) {
return [];
Expand Down Expand Up @@ -574,6 +575,57 @@ export class TPCUtils {
} ];
}

/**
* Injects a 'SIM' ssrc-group line for simulcast into the given session description object to make Jicofo happy.
* This is needed only for Firefox since it does not generate it when simulcast is enabled.
*
* @param desc A session description object (with 'type' and 'sdp' fields)
* @return A session description object with its sdp field modified to contain an inject ssrc-group for simulcast.
*/
injectSsrcGroupForUnifiedSimulcast(desc) {
const sdp = transform.parse(desc.sdp);
const video = sdp.media.find(mline => mline.type === 'video');

// Check if the browser supports RTX, add only the primary ssrcs to the SIM group if that is the case.
video.ssrcGroups = video.ssrcGroups || [];
const fidGroups = video.ssrcGroups.filter(group => group.semantics === SSRC_GROUP_SEMANTICS.FID);

if (video.simulcast || video.simulcast_03) {
const ssrcs = [];

if (fidGroups && fidGroups.length) {
fidGroups.forEach(group => {
ssrcs.push(group.ssrcs.split(' ')[0]);
});
} else {
video.ssrcs.forEach(ssrc => {
if (ssrc.attribute === 'msid') {
ssrcs.push(ssrc.id);
}
});
}
if (video.ssrcGroups.find(group => group.semantics === SSRC_GROUP_SEMANTICS.SIM)) {
// Group already exists, no need to do anything
return desc;
}

// Add a SIM group for every 3 FID groups.
for (let i = 0; i < ssrcs.length; i += 3) {
const simSsrcs = ssrcs.slice(i, i + 3);

video.ssrcGroups.push({
semantics: SSRC_GROUP_SEMANTICS.SIM,
ssrcs: simSsrcs.join(' ')
});
}
}

return {
type: desc.type,
sdp: transform.write(sdp)
};
}

/**
* Takes in a *unified plan* offer and inserts the appropriate parameters for adding simulcast receive support.
* @param {Object} desc - A session description object
Expand Down Expand Up @@ -659,26 +711,22 @@ export class TPCUtils {
/**
* Munges the session description to ensure that the codec order is as per the preferred codec settings.
*
* @param {RTCSessionDescription} description - the local/remote description to be munged.
* @returns {RTCSessionDescription} - the munged local/remote description.
* @param {transform.SessionDescription} parsedSdp that needs to be munged
* @returns {transform.SessionDescription} the munged SDP.
*/
mungeCodecOrder(description) {
mungeCodecOrder(parsedSdp) {
const codecSettings = this.pc.codecSettings;

if (!codecSettings) {
return description;
return parsedSdp;
}

const mungedSdp = parsedSdp;
const { isP2P } = this.options;
const parsedSdp = transform.parse(description.sdp);
const mLines = parsedSdp.media.filter(m => m.type === codecSettings.mediaType);

if (!mLines.length) {
return description;
}
const mLines = mungedSdp.media.filter(m => m.type === codecSettings.mediaType);

for (const mLine of mLines) {
const currentCodecs = this.getConfiguredVideoCodecs(description);
const currentCodecs = this.getConfiguredVideoCodecs(transform.write(parsedSdp));

for (const codec of currentCodecs) {
if (isP2P) {
Expand Down Expand Up @@ -707,28 +755,25 @@ export class TPCUtils {
}
}

return {
type: description.type,
sdp: transform.write(parsedSdp)
};
return mungedSdp;
}

/**
* Munges the stereo flag as well as the opusMaxAverageBitrate in the SDP, based on values set through config.js,
* if present.
*
* @param {RTCSessionDescription} description that needs to be munged.
* @returns {RTCSessionDescription} the munged description.
* @param {transform.SessionDescription} parsedSdp that needs to be munged.
* @returns {transform.SessionDescription} the munged SDP.
*/
mungeOpus(description) {
mungeOpus(parsedSdp) {
const { audioQuality } = this.options;

if (!audioQuality?.enableOpusDtx && !audioQuality?.stereo && !audioQuality?.opusMaxAverageBitrate) {
return description;
return parsedSdp;
}

const parsedSdp = transform.parse(description.sdp);
const mLines = parsedSdp.media.filter(m => m.type === MediaType.AUDIO);
const mungedSdp = parsedSdp;
const mLines = mungedSdp.media.filter(m => m.type === MediaType.AUDIO);

for (const mLine of mLines) {
const { payload } = mLine.rtp.find(protocol => protocol.codec === CodecMimeType.OPUS);
Expand Down Expand Up @@ -780,30 +825,27 @@ export class TPCUtils {
fmtpOpus.config = mungedConfig.trim();
}

return {
type: description.type,
sdp: transform.write(parsedSdp)
};
return mungedSdp;
}

/**
* Munges the session description by setting the max bitrates on the video m-lines when VP9 K-SVC codec is in use.
* Munges the session SDP by setting the max bitrates on the video m-lines when VP9 K-SVC codec is in use.
*
* @param {RTCSessionDescription} description - The local/remote description that needs to be munged.
* @param {transform.SessionDescription} parsedSdp that needs to be munged.
* @param {boolean} isLocalSdp - Whether the max bitrate (via b=AS line in SDP) is set on local SDP.
* @returns {RTCSessionDescription} - The munged local/remote description.
* @returns {transform.SessionDescription} The munged SDP.
*/
setMaxBitrates(description, isLocalSdp = false) {
setMaxBitrates(parsedSdp, isLocalSdp = false) {
const pcCodecSettings = this.pc.codecSettings;

if (!pcCodecSettings) {
return description;
return parsedSdp;
}
const parsedSdp = transform.parse(description.sdp);

// Find all the m-lines associated with the local sources.
const mungedSdp = parsedSdp;
const direction = isLocalSdp ? MediaDirection.RECVONLY : MediaDirection.SENDONLY;
const mLines = parsedSdp.media.filter(m => m.type === MediaType.VIDEO && m.direction !== direction);
const mLines = mungedSdp.media.filter(m => m.type === MediaType.VIDEO && m.direction !== direction);
const currentCodec = pcCodecSettings.codecList[0];
const codecScalabilityModeSettings = this.codecSettings[currentCodec];

Expand Down Expand Up @@ -846,26 +888,22 @@ export class TPCUtils {
}
}

return {
type: description.type,
sdp: transform.write(parsedSdp)
};
return mungedSdp;
}

/**
* Checks if the AV1 Dependency descriptors are negotiated on the bridge peerconnection and removes them from the
* description when codec selected is VP8 or VP9.
* SDP when codec selected is VP8 or VP9.
*
* @param {RTCSessionDescription} description that needs to be munged.
* @returns {RTCSessionDescription} the munged description.
* @param {transform.SessionDescription} parsedSdp that needs to be munged.
* @returns {string} the munged SDP.
*/
updateAv1DdHeaders(description) {
const parsedSdp = transform.parse(description.sdp);
const mLines = parsedSdp.media.filter(m => m.type === MediaType.VIDEO);

if (!mLines.length || !browser.supportsDDExtHeaders()) {
return description;
updateAv1DdHeaders(parsedSdp) {
if (!this.supportsDDHeaderExt) {
return parsedSdp;
}
const mungedSdp = parsedSdp;
const mLines = mungedSdp.media.filter(m => m.type === MediaType.VIDEO);

mLines.forEach((mLine, idx) => {
const senderMids = Array.from(this.pc.localTrackTransceiverMids.values());
Expand Down Expand Up @@ -896,9 +934,6 @@ export class TPCUtils {
}
});

return {
type: description.type,
sdp: transform.write(parsedSdp)
};
return mungedSdp;
}
}
74 changes: 13 additions & 61 deletions modules/RTC/TraceablePeerConnection.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1187,58 +1187,6 @@ TraceablePeerConnection.prototype.getLocalSSRC = function(localTrack) {
return ssrcInfo && ssrcInfo.ssrcs[0];
};

/**
* When doing unified plan simulcast, we'll have a set of ssrcs but no ssrc-groups on Firefox. Unfortunately, Jicofo
* will complain if it sees ssrcs with matching msids but no ssrc-group, so a ssrc-group line is injected to make
* Jicofo happy.
*
* @param desc A session description object (with 'type' and 'sdp' fields)
* @return A session description object with its sdp field modified to contain an inject ssrc-group for simulcast.
*/
TraceablePeerConnection.prototype._injectSsrcGroupForUnifiedSimulcast = function(desc) {
const sdp = transform.parse(desc.sdp);
const video = sdp.media.find(mline => mline.type === 'video');

// Check if the browser supports RTX, add only the primary ssrcs to the SIM group if that is the case.
video.ssrcGroups = video.ssrcGroups || [];
const fidGroups = video.ssrcGroups.filter(group => group.semantics === SSRC_GROUP_SEMANTICS.FID);

if (video.simulcast || video.simulcast_03) {
const ssrcs = [];

if (fidGroups && fidGroups.length) {
fidGroups.forEach(group => {
ssrcs.push(group.ssrcs.split(' ')[0]);
});
} else {
video.ssrcs.forEach(ssrc => {
if (ssrc.attribute === 'msid') {
ssrcs.push(ssrc.id);
}
});
}
if (video.ssrcGroups.find(group => group.semantics === SSRC_GROUP_SEMANTICS.SIM)) {
// Group already exists, no need to do anything
return desc;
}

// Add a SIM group for every 3 FID groups.
for (let i = 0; i < ssrcs.length; i += 3) {
const simSsrcs = ssrcs.slice(i, i + 3);

video.ssrcGroups.push({
semantics: SSRC_GROUP_SEMANTICS.SIM,
ssrcs: simSsrcs.join(' ')
});
}
}

return {
type: desc.type,
sdp: transform.write(sdp)
};
};

/* eslint-disable-next-line vars-on-top */
const getters = {
signalingState() {
Expand All @@ -1261,9 +1209,8 @@ const getters = {

this.trace('getLocalDescription::preTransform', dumpSDP(desc));

// For a jvb connection, transform the SDP to Plan B first.
if (!this.isP2P) {
desc = this._injectSsrcGroupForUnifiedSimulcast(desc);
desc = this.tpcUtils.injectSsrcGroupForUnifiedSimulcast(desc);
this.trace('getLocalDescription::postTransform (inject ssrc group)', dumpSDP(desc));
}

Expand Down Expand Up @@ -1457,7 +1404,7 @@ TraceablePeerConnection.prototype._assertTrackBelongs = function(
* @returns {Array}
*/
TraceablePeerConnection.prototype.getConfiguredVideoCodecs = function(description) {
return this.tpcUtils.getConfiguredVideoCodecs(description);
return this.tpcUtils.getConfiguredVideoCodecs(description?.sdp);
};

/**
Expand Down Expand Up @@ -2001,13 +1948,18 @@ TraceablePeerConnection.prototype._setEncodings = function(localTrack) {
* @returns {RTCSessionDescription} - The munged description.
*/
TraceablePeerConnection.prototype._mungeDescription = function(description) {
let mungedDescription = description;

this.trace('RTCSessionDescription::preTransform', dumpSDP(description));
mungedDescription = this.tpcUtils.mungeOpus(description);
mungedDescription = this.tpcUtils.mungeCodecOrder(mungedDescription);
mungedDescription = this.tpcUtils.setMaxBitrates(mungedDescription, true);
mungedDescription = this.tpcUtils.updateAv1DdHeaders(mungedDescription);
let mungedSdp = transform.parse(description.sdp);

mungedSdp = this.tpcUtils.mungeOpus(mungedSdp);
mungedSdp = this.tpcUtils.mungeCodecOrder(mungedSdp);
mungedSdp = this.tpcUtils.setMaxBitrates(mungedSdp, true);
mungedSdp = this.tpcUtils.updateAv1DdHeaders(mungedSdp);
const mungedDescription = {
type: description.type,
sdp: transform.write(mungedSdp)
};

this.trace('RTCSessionDescription::postTransform', dumpSDP(mungedDescription));

return mungedDescription;
Expand Down

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