@wowzamediasystems/sdk-rts
Version:
SDK for building a realtime broadcaster using the Wowza platform.
391 lines (348 loc) • 13.8 kB
JavaScript
import { SDPInfo, MediaInfo, Direction } from 'semantic-sdp'
import Logger from '../Logger'
import UserAgent from './UserAgent'
const logger = Logger.get('SdpParser')
const firstPayloadTypeLowerRange = 35
const lastPayloadTypeLowerRange = 65
const firstPayloadTypeUpperRange = 96
const lastPayloadTypeUpperRange = 127
const payloadTypeLowerRange = Array.from({ length: (lastPayloadTypeLowerRange - firstPayloadTypeLowerRange) + 1 }, (_, i) => i + firstPayloadTypeLowerRange)
const payloadTypeUppperRange = Array.from({ length: (lastPayloadTypeUpperRange - firstPayloadTypeUpperRange) + 1 }, (_, i) => i + firstPayloadTypeUpperRange)
const firstHeaderExtensionIdLowerRange = 1
const lastHeaderExtensionIdLowerRange = 14
const firstHeaderExtensionIdUpperRange = 16
const lastHeaderExtensionIdUpperRange = 255
const headerExtensionIdLowerRange = Array.from({ length: (lastHeaderExtensionIdLowerRange - firstHeaderExtensionIdLowerRange) + 1 }, (_, i) => i + firstHeaderExtensionIdLowerRange)
const headerExtensionIdUppperRange = Array.from({ length: (lastHeaderExtensionIdUpperRange - firstHeaderExtensionIdUpperRange) + 1 }, (_, i) => i + firstHeaderExtensionIdUpperRange)
/**
* @module SdpParser
* @description Simplify SDP parser.
*/
const SdpParser = {
/**
* @function
* @name setSimulcast
* @description Parse SDP for support simulcast.
* **Only available in Google Chrome.**
* @param {String} sdp - Current SDP.
* @param {String} codec - Codec.
* @returns {String} SDP parsed with simulcast support.
* @example SdpParser.setSimulcast(sdp, 'h264')
*/
setSimulcast (sdp, codec) {
logger.info('Setting simulcast. Codec: ', codec)
const browserData = new UserAgent()
if (!browserData.isChrome()) {
logger.warn('Simulcast is only available in Google Chrome browser')
return sdp
}
if (codec !== 'h264' && codec !== 'vp8') {
logger.warn('Simulcast is only available in h264 and vp8 codecs')
return sdp
}
try {
const reg1 = /m=video.*?a=ssrc:(\d*) cname:(.+?)\r\n/s
const reg2 = /m=video.*?a=ssrc:(\d*) msid:(.+?)\r\n/s
// Get ssrc and cname and msid
const res = reg1.exec(sdp)
const ssrc = res[1]
const cname = res[2]
const msid = reg2.exec(sdp)[2]
// Add simulcasts ssrcs
const num = 2
const ssrcs = [ssrc]
for (let i = 0; i < num; ++i) {
// Create new ssrcs
const ssrc = 100 + i * 2
const rtx = ssrc + 1
// Add to ssrc list
ssrcs.push(ssrc)
// Add sdp stuff
sdp += 'a=ssrc-group:FID ' + ssrc + ' ' + rtx + '\r\n' +
'a=ssrc:' + ssrc + ' cname:' + cname + '\r\n' +
'a=ssrc:' + ssrc + ' msid:' + msid + '\r\n' +
'a=ssrc:' + rtx + ' cname:' + cname + '\r\n' +
'a=ssrc:' + rtx + ' msid:' + msid + '\r\n'
}
// Add SIM group
sdp += 'a=ssrc-group:SIM ' + ssrcs.join(' ') + '\r\n'
logger.info('Simulcast setted')
logger.debug('Simulcast SDP: ', sdp)
return sdp
} catch (e) {
logger.error('Error setting SDP for simulcast: ', e)
throw e
}
},
/**
* @function
* @name setStereo
* @description Parse SDP for support stereo.
* @param {String} sdp - Current SDP.
* @returns {String} SDP parsed with stereo support.
* @example SdpParser.setStereo(sdp)
*/
setStereo (sdp) {
logger.info('Replacing SDP response for support stereo')
sdp = sdp.replace(
/useinbandfec=1/g,
'useinbandfec=1; stereo=1'
)
logger.info('Replaced SDP response for support stereo')
logger.debug('New SDP value: ', sdp)
return sdp
},
/**
* @function
* @name setDTX
* @description Set DTX (Discontinuous Transmission) to the connection. Advanced configuration of the opus audio codec that allows for a large reduction in the audio traffic. For example, when a participant is silent, the audio packets won't be transmitted.
* @param {String} sdp - Current SDP.
* @returns {String} SDP parsed with dtx support.
* @example SdpParser.setDTX(sdp)
*/
setDTX (sdp) {
logger.info('Replacing SDP response for support dtx')
sdp = sdp.replace(
'useinbandfec=1',
'useinbandfec=1; usedtx=1'
)
logger.info('Replaced SDP response for support dtx')
logger.debug('New SDP value: ', sdp)
return sdp
},
/**
* @function
* @name setAbsoluteCaptureTime
* @description Mangle SDP for adding absolute capture time header extension.
* @param {String} sdp - Current SDP.
* @returns {String} SDP mungled with abs-capture-time header extension.
* @example SdpParser.setAbsoluteCaptureTime(sdp)
*/
setAbsoluteCaptureTime (sdp) {
const id = SdpParser.getAvailableHeaderExtensionIdRange(sdp)[0]
const header = 'a=extmap:' + id + ' http://www.webrtc.org/experiments/rtp-hdrext/abs-capture-time\r\n'
const regex = /(m=.*\r\n(?:.*\r\n)*?)(a=extmap.*\r\n)/gm
sdp = sdp.replace(regex, (match, p1, p2) => p1 + header + p2)
logger.info('Replaced SDP response for setting absolute capture time')
logger.debug('New SDP value: ', sdp)
return sdp
},
/**
* @function
* @name setDependencyDescriptor
* @description Mangle SDP for adding dependency descriptor header extension.
* @param {String} sdp - Current SDP.
* @returns {String} SDP mungled with abs-capture-time header extension.
* @example SdpParser.setAbsoluteCaptureTime(sdp)
*/
setDependencyDescriptor (sdp) {
const id = SdpParser.getAvailableHeaderExtensionIdRange(sdp)[0]
const header = 'a=extmap:' + id + ' https://aomediacodec.github.io/av1-rtp-spec/#dependency-descriptor-rtp-header-extension\r\n'
const regex = /(m=.*\r\n(?:.*\r\n)*?)(a=extmap.*\r\n)/gm
sdp = sdp.replace(regex, (match, p1, p2) => p1 + header + p2)
logger.info('Replaced SDP response for setting depency descriptor')
logger.debug('New SDP value: ', sdp)
return sdp
},
/**
* @function
* @name setVideoBitrate
* @description Parse SDP for desired bitrate.
* @param {String} sdp - Current SDP.
* @param {Number} bitrate - Bitrate value in kbps or 0 for unlimited bitrate.
* @returns {String} SDP parsed with desired bitrate.
* @example SdpParser.setVideoBitrate(sdp, 1000)
*/
setVideoBitrate (sdp, bitrate) {
if (bitrate < 1) {
logger.info('Remove bitrate restrictions')
sdp = sdp.replace(/b=AS:.*\r\n/, '').replace(/b=TIAS:.*\r\n/, '')
} else {
const offer = SDPInfo.parse(sdp)
const videoOffer = offer.getMedia('video')
logger.info('Setting video bitrate')
videoOffer.setBitrate(bitrate)
sdp = offer.toString()
}
return sdp
},
/**
* @function
* @name removeSdpLine
* @description Remove SDP line.
* @param {String} sdp - Current SDP.
* @param {String} sdpLine - SDP line to remove.
* @returns {String} SDP without the line.
* @example SdpParser.removeSdpLine(sdp, 'custom line')
*/
removeSdpLine (sdp, sdpLine) {
logger.debug('SDP before trimming: ', sdp)
sdp = sdp
.split('\n')
.filter((line) => {
return line.trim() !== sdpLine
})
.join('\n')
logger.debug('SDP trimmed result: ', sdp)
return sdp
},
/**
* @function
* @name adaptCodecName
* @description Replace codec name of a SDP.
* @param {String} sdp - Current SDP.
* @param {String} codec - Codec name to be replaced.
* @param {String} newCodecName - New codec name to replace.
* @returns {String} SDP updated with new codec name.
*/
adaptCodecName (sdp, codec, newCodecName) {
if (!sdp) {
return sdp
}
const regex = new RegExp(`${codec}`, 'i')
return sdp.replace(regex, newCodecName)
},
/**
* @function
* @name setMultiopus
* @description Parse SDP for support multiopus.
* **Only available in Google Chrome.**
* @param {String} sdp - Current SDP.
* @param {MediaStream} mediaStream - MediaStream offered in the stream.
* @returns {String} SDP parsed with multiopus support.
* @example SdpParser.setMultiopus(sdp, mediaStream)
*/
setMultiopus (sdp, mediaStream) {
const browserData = new UserAgent()
if (!browserData.isFirefox() && (!mediaStream || hasAudioMultichannel(mediaStream))) {
if (!sdp.includes('multiopus/48000/6')) {
logger.info('Setting multiopus')
// Find the audio m-line
const res = /m=audio 9 UDP\/TLS\/RTP\/SAVPF (.*)\r\n/.exec(sdp)
// Get audio line
const audio = res[0]
// Get free payload number for multiopus
const pt = SdpParser.getAvailablePayloadTypeRange(sdp)[0]
// Add multiopus
const multiopus = audio.replace('\r\n', ' ') + pt + '\r\n' +
'a=rtpmap:' + pt + ' multiopus/48000/6\r\n' +
'a=fmtp:' + pt + ' channel_mapping=0,4,1,2,3,5;coupled_streams=2;minptime=10;num_streams=4;useinbandfec=1\r\n'
// Change sdp
sdp = sdp.replace(audio, multiopus)
logger.info('Multiopus offer created')
logger.debug('SDP parsed for multioups: ', sdp)
} else {
logger.info('Multiopus already setted')
}
}
return sdp
},
/**
* @function
* @name getAvailablePayloadTypeRange
* @description Gets all available payload type IDs of the current Session Description.
* @param {String} sdp - Current SDP.
* @returns {Array<Number>} All available payload type ids.
*/
getAvailablePayloadTypeRange (sdp) {
const regex = /m=(?:.*) (?:.*) UDP\/TLS\/RTP\/SAVPF (.*)\r\n/gm
const matches = sdp.matchAll(regex)
let ptAvailable = payloadTypeUppperRange.concat(payloadTypeLowerRange)
for (const match of matches) {
const usedNumbers = match[1].split(' ').map(n => parseInt(n))
ptAvailable = ptAvailable.filter(n => !usedNumbers.includes(n))
}
return ptAvailable
},
/**
* @function
* @name getAvailableHeaderExtensionIdRange
* @description Gets all available header extension IDs of the current Session Description.
* @param {String} sdp - Current SDP.
* @returns {Array<Number>} All available header extension IDs.
*/
getAvailableHeaderExtensionIdRange (sdp) {
const regex = /a=extmap:(\d+)(?:.*)\r\n/gm
const matches = sdp.matchAll(regex)
let idAvailable = headerExtensionIdLowerRange.concat(headerExtensionIdUppperRange)
for (const match of matches) {
const usedNumbers = match[1].split(' ').map(n => parseInt(n))
idAvailable = idAvailable.filter(n => !usedNumbers.includes(n))
}
return idAvailable
},
/**
* @function
* @name renegotiate
* @description Renegotiate remote sdp based on previous description.
* This function will fill missing m-lines cloning on the remote description by cloning the codec and extensions already negotiated for that media
* @param {String} localDescription - Updated local sdp
* @param {String} remoteDescription - Previous remote sdp
*/
renegotiate (localDescription, remoteDescription) {
const offer = SDPInfo.parse(localDescription)
const answer = SDPInfo.parse(remoteDescription)
// Check all transceivers on the offer are on the answer
for (const offeredMedia of offer.getMedias()) {
// Get associated mid on the answer
let answeredMedia = answer.getMediaById(offeredMedia.getId())
// If not found in answer
if (!answeredMedia) {
// Create new one
answeredMedia = new MediaInfo(offeredMedia.getId(), offeredMedia.getType())
// Set direction
answeredMedia.setDirection(Direction.reverse(offeredMedia.getDirection()))
// Find first media line for same kind
const first = answer.getMedia(offeredMedia.getType())
// If found
if (first) {
// Copy codec info
answeredMedia.setCodecs(first.getCodecs())
// Copy extension info
for (const [id, extension] of first.getExtensions()) {
// Add it
answeredMedia.addExtension(id, extension)
}
}
// Add it to answer
answer.addMedia(answeredMedia)
}
}
return answer.toString()
},
/**
* @function
* @name updateMissingVideoExtensions
* @description Adds missing extensions of each video section in the localDescription
* @param {String} localDescription - Previous local sdp
* @param {String} remoteDescription - Remote sdp
* @returns {String} SDP updated with missing extensions.
*/
updateMissingVideoExtensions (localDescription, remoteDescription) {
const offer = SDPInfo.parse(localDescription)
const answer = SDPInfo.parse(remoteDescription)
// Get extensions of answer
const remoteVideoExtensions = answer.getMediasByType('video')[0]?.getExtensions()
if (!remoteVideoExtensions && !remoteVideoExtensions.length) {
return
}
for (const offeredMedia of offer.getMediasByType('video')) {
const offerExtensions = offeredMedia.getExtensions()
remoteVideoExtensions.forEach((val, key) => {
// If the extension is not present in offer then add it
if (!offerExtensions.get(key)) {
const id = offeredMedia.getId()
const header = 'a=extmap:' + key + ' ' + val + '\r\n'
const regex = new RegExp('(a=mid:' + id + '\r\n(?:.*\r\n)*?)', 'g')
localDescription = localDescription.replace(regex, (_, p1, p2) => p1 + header)
}
})
}
return localDescription
}
}
// Checks if mediaStream has more than 2 audio channels.
const hasAudioMultichannel = (mediaStream) => {
return mediaStream.getAudioTracks().some(value => value.getSettings().channelCount > 2)
}
export default SdpParser