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stream-controller.ts
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stream-controller.ts
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import BaseStreamController, { State } from './base-stream-controller';
import { findFragmentByPTS } from './fragment-finders';
import { FragmentState } from './fragment-tracker';
import GapController, { MAX_START_GAP_JUMP } from './gap-controller';
import TransmuxerInterface from '../demux/transmuxer-interface';
import { ErrorDetails } from '../errors';
import { Events } from '../events';
import { changeTypeSupported } from '../is-supported';
import { ElementaryStreamTypes, isMediaFragment } from '../loader/fragment';
import { PlaylistContextType, PlaylistLevelType } from '../types/loader';
import { ChunkMetadata } from '../types/transmuxer';
import { BufferHelper } from '../utils/buffer-helper';
import { pickMostCompleteCodecName } from '../utils/codecs';
import { useAlternateAudio } from '../utils/rendition-helper';
import type { FragmentTracker } from './fragment-tracker';
import type Hls from '../hls';
import type { Fragment, MediaFragment } from '../loader/fragment';
import type KeyLoader from '../loader/key-loader';
import type { LevelDetails } from '../loader/level-details';
import type { SourceBufferName } from '../types/buffer';
import type { NetworkComponentAPI } from '../types/component-api';
import type {
AudioTrackSwitchedData,
AudioTrackSwitchingData,
BufferCodecsData,
BufferCreatedData,
BufferEOSData,
BufferFlushedData,
ErrorData,
FragBufferedData,
FragLoadedData,
FragParsingMetadataData,
FragParsingUserdataData,
LevelLoadedData,
LevelLoadingData,
LevelsUpdatedData,
ManifestParsedData,
MediaAttachedData,
MediaDetachingData,
} from '../types/events';
import type { Level } from '../types/level';
import type { Track, TrackSet } from '../types/track';
import type { TransmuxerResult } from '../types/transmuxer';
import type { BufferInfo } from '../utils/buffer-helper';
const TICK_INTERVAL = 100; // how often to tick in ms
const enum AlternateAudio {
DISABLED = 0,
SWITCHING,
SWITCHED,
}
export default class StreamController
extends BaseStreamController
implements NetworkComponentAPI
{
private audioCodecSwap: boolean = false;
private gapController: GapController | null = null;
private level: number = -1;
private _forceStartLoad: boolean = false;
private _hasEnoughToStart: boolean = false;
private altAudio: AlternateAudio = AlternateAudio.DISABLED;
private audioOnly: boolean = false;
private fragPlaying: Fragment | null = null;
private fragLastKbps: number = 0;
private couldBacktrack: boolean = false;
private backtrackFragment: Fragment | null = null;
private audioCodecSwitch: boolean = false;
private videoBuffer: any | null = null;
constructor(
hls: Hls,
fragmentTracker: FragmentTracker,
keyLoader: KeyLoader,
) {
super(
hls,
fragmentTracker,
keyLoader,
'stream-controller',
PlaylistLevelType.MAIN,
);
this.registerListeners();
}
protected registerListeners() {
super.registerListeners();
const { hls } = this;
hls.on(Events.MANIFEST_PARSED, this.onManifestParsed, this);
hls.on(Events.LEVEL_LOADING, this.onLevelLoading, this);
hls.on(Events.LEVEL_LOADED, this.onLevelLoaded, this);
hls.on(
Events.FRAG_LOAD_EMERGENCY_ABORTED,
this.onFragLoadEmergencyAborted,
this,
);
hls.on(Events.AUDIO_TRACK_SWITCHING, this.onAudioTrackSwitching, this);
hls.on(Events.AUDIO_TRACK_SWITCHED, this.onAudioTrackSwitched, this);
hls.on(Events.BUFFER_CREATED, this.onBufferCreated, this);
hls.on(Events.BUFFER_FLUSHED, this.onBufferFlushed, this);
hls.on(Events.LEVELS_UPDATED, this.onLevelsUpdated, this);
hls.on(Events.FRAG_BUFFERED, this.onFragBuffered, this);
}
protected unregisterListeners() {
super.unregisterListeners();
const { hls } = this;
hls.off(Events.MANIFEST_PARSED, this.onManifestParsed, this);
hls.off(Events.LEVEL_LOADED, this.onLevelLoaded, this);
hls.off(
Events.FRAG_LOAD_EMERGENCY_ABORTED,
this.onFragLoadEmergencyAborted,
this,
);
hls.off(Events.AUDIO_TRACK_SWITCHING, this.onAudioTrackSwitching, this);
hls.off(Events.AUDIO_TRACK_SWITCHED, this.onAudioTrackSwitched, this);
hls.off(Events.BUFFER_CREATED, this.onBufferCreated, this);
hls.off(Events.BUFFER_FLUSHED, this.onBufferFlushed, this);
hls.off(Events.LEVELS_UPDATED, this.onLevelsUpdated, this);
hls.off(Events.FRAG_BUFFERED, this.onFragBuffered, this);
}
protected onHandlerDestroying() {
// @ts-ignore
this.onMediaPlaying = this.onMediaSeeked = null;
this.unregisterListeners();
super.onHandlerDestroying();
}
public startLoad(
startPosition: number,
skipSeekToStartPosition?: boolean,
): void {
if (this.levels) {
const { lastCurrentTime, hls } = this;
this.stopLoad();
this.setInterval(TICK_INTERVAL);
this.level = -1;
if (!this.startFragRequested) {
// determine load level
let startLevel = hls.startLevel;
if (startLevel === -1) {
if (hls.config.testBandwidth && this.levels.length > 1) {
// -1 : guess start Level by doing a bitrate test by loading first fragment of lowest quality level
startLevel = 0;
this.bitrateTest = true;
} else {
startLevel = hls.firstAutoLevel;
}
}
// set new level to playlist loader : this will trigger start level load
// hls.nextLoadLevel remains until it is set to a new value or until a new frag is successfully loaded
hls.nextLoadLevel = startLevel;
this.level = hls.loadLevel;
this._hasEnoughToStart = false;
}
// if startPosition undefined but lastCurrentTime set, set startPosition to last currentTime
if (
lastCurrentTime > 0 &&
startPosition === -1 &&
!skipSeekToStartPosition
) {
this.log(
`Override startPosition with lastCurrentTime @${lastCurrentTime.toFixed(
3,
)}`,
);
startPosition = lastCurrentTime;
}
this.state = State.IDLE;
this.nextLoadPosition = this.lastCurrentTime = startPosition;
this.startPosition = skipSeekToStartPosition ? -1 : startPosition;
this.tick();
} else {
this._forceStartLoad = true;
this.state = State.STOPPED;
}
}
public stopLoad() {
this._forceStartLoad = false;
super.stopLoad();
}
protected doTick() {
switch (this.state) {
case State.WAITING_LEVEL: {
const { levels, level } = this;
const currentLevel = levels?.[level];
const details = currentLevel?.details;
if (
details &&
(!details.live ||
(this.levelLastLoaded === currentLevel &&
!this.waitForLive(currentLevel)))
) {
if (this.waitForCdnTuneIn(details)) {
break;
}
this.state = State.IDLE;
break;
} else if (this.hls.nextLoadLevel !== this.level) {
this.state = State.IDLE;
break;
}
break;
}
case State.FRAG_LOADING_WAITING_RETRY:
{
const now = self.performance.now();
const retryDate = this.retryDate;
// if current time is gt than retryDate, or if media seeking let's switch to IDLE state to retry loading
if (!retryDate || now >= retryDate || this.media?.seeking) {
const { levels, level } = this;
const currentLevel = levels?.[level];
this.resetStartWhenNotLoaded(currentLevel || null);
this.state = State.IDLE;
}
}
break;
default:
break;
}
if (this.state === State.IDLE) {
this.doTickIdle();
}
this.onTickEnd();
}
protected onTickEnd() {
super.onTickEnd();
this.checkBuffer();
this.checkFragmentChanged();
}
private doTickIdle() {
const { hls, levelLastLoaded, levels, media } = this;
// if start level not parsed yet OR
// if video not attached AND start fragment already requested OR start frag prefetch not enabled
// exit loop, as we either need more info (level not parsed) or we need media to be attached to load new fragment
if (
levelLastLoaded === null ||
(!media && (this.startFragRequested || !hls.config.startFragPrefetch))
) {
return;
}
// If the "main" level is audio-only but we are loading an alternate track in the same group, do not load anything
if (this.altAudio && this.audioOnly) {
return;
}
const level = this.buffering ? hls.nextLoadLevel : hls.loadLevel;
if (!levels?.[level]) {
return;
}
const levelInfo = levels[level];
// if buffer length is less than maxBufLen try to load a new fragment
const bufferInfo = this.getMainFwdBufferInfo();
if (bufferInfo === null) {
return;
}
const lastDetails = this.getLevelDetails();
if (lastDetails && this._streamEnded(bufferInfo, lastDetails)) {
const data: BufferEOSData = {};
if (this.altAudio === AlternateAudio.SWITCHED) {
data.type = 'video';
}
this.hls.trigger(Events.BUFFER_EOS, data);
this.state = State.ENDED;
return;
}
if (!this.buffering) {
return;
}
// set next load level : this will trigger a playlist load if needed
if (hls.loadLevel !== level && hls.manualLevel === -1) {
this.log(`Adapting to level ${level} from level ${this.level}`);
}
this.level = hls.nextLoadLevel = level;
const levelDetails = levelInfo.details;
// if level info not retrieved yet, switch state and wait for level retrieval
// if live playlist, ensure that new playlist has been refreshed to avoid loading/try to load
// a useless and outdated fragment (that might even introduce load error if it is already out of the live playlist)
if (
!levelDetails ||
this.state === State.WAITING_LEVEL ||
this.waitForLive(levelInfo)
) {
this.level = level;
this.state = State.WAITING_LEVEL;
this.startFragRequested = false;
return;
}
const bufferLen = bufferInfo.len;
// compute max Buffer Length that we could get from this load level, based on level bitrate. don't buffer more than 60 MB and more than 30s
const maxBufLen = this.getMaxBufferLength(levelInfo.maxBitrate);
// Stay idle if we are still with buffer margins
if (bufferLen >= maxBufLen) {
return;
}
if (
this.backtrackFragment &&
this.backtrackFragment.start > bufferInfo.end
) {
this.backtrackFragment = null;
}
const targetBufferTime = this.backtrackFragment
? this.backtrackFragment.start
: bufferInfo.end;
let frag = this.getNextFragment(targetBufferTime, levelDetails);
// Avoid backtracking by loading an earlier segment in streams with segments that do not start with a key frame (flagged by `couldBacktrack`)
if (
this.couldBacktrack &&
!this.fragPrevious &&
frag &&
isMediaFragment(frag) &&
this.fragmentTracker.getState(frag) !== FragmentState.OK
) {
const backtrackSn = (this.backtrackFragment ?? frag).sn as number;
const fragIdx = backtrackSn - levelDetails.startSN;
const backtrackFrag = levelDetails.fragments[fragIdx - 1];
if (backtrackFrag && frag.cc === backtrackFrag.cc) {
frag = backtrackFrag;
this.fragmentTracker.removeFragment(backtrackFrag);
}
} else if (this.backtrackFragment && bufferInfo.len) {
this.backtrackFragment = null;
}
// Avoid loop loading by using nextLoadPosition set for backtracking and skipping consecutive GAP tags
if (frag && this.isLoopLoading(frag, targetBufferTime)) {
const gapStart = frag.gap;
if (!gapStart) {
// Cleanup the fragment tracker before trying to find the next unbuffered fragment
const type =
this.audioOnly && !this.altAudio
? ElementaryStreamTypes.AUDIO
: ElementaryStreamTypes.VIDEO;
const mediaBuffer =
(type === ElementaryStreamTypes.VIDEO
? this.videoBuffer
: this.mediaBuffer) || this.media;
if (mediaBuffer) {
this.afterBufferFlushed(mediaBuffer, type, PlaylistLevelType.MAIN);
}
}
frag = this.getNextFragmentLoopLoading(
frag,
levelDetails,
bufferInfo,
PlaylistLevelType.MAIN,
maxBufLen,
);
}
if (!frag) {
return;
}
if (frag.initSegment && !frag.initSegment.data && !this.bitrateTest) {
frag = frag.initSegment;
}
this.loadFragment(frag, levelInfo, targetBufferTime);
}
protected loadFragment(
frag: Fragment,
level: Level,
targetBufferTime: number,
) {
// Check if fragment is not loaded
const fragState = this.fragmentTracker.getState(frag);
if (
fragState === FragmentState.NOT_LOADED ||
fragState === FragmentState.PARTIAL
) {
if (!isMediaFragment(frag)) {
this._loadInitSegment(frag, level);
} else if (this.bitrateTest) {
this.log(
`Fragment ${frag.sn} of level ${frag.level} is being downloaded to test bitrate and will not be buffered`,
);
this._loadBitrateTestFrag(frag, level);
} else {
super.loadFragment(frag, level, targetBufferTime);
}
} else {
this.clearTrackerIfNeeded(frag);
}
}
private getBufferedFrag(position: number) {
return this.fragmentTracker.getBufferedFrag(
position,
PlaylistLevelType.MAIN,
);
}
private followingBufferedFrag(frag: Fragment | null) {
if (frag) {
// try to get range of next fragment (500ms after this range)
return this.getBufferedFrag(frag.end + 0.5);
}
return null;
}
/*
on immediate level switch :
- pause playback if playing
- cancel any pending load request
- and trigger a buffer flush
*/
public immediateLevelSwitch() {
this.abortCurrentFrag();
this.flushMainBuffer(0, Number.POSITIVE_INFINITY);
}
/**
* try to switch ASAP without breaking video playback:
* in order to ensure smooth but quick level switching,
* we need to find the next flushable buffer range
* we should take into account new segment fetch time
*/
public nextLevelSwitch() {
const { levels, media } = this;
// ensure that media is defined and that metadata are available (to retrieve currentTime)
if (media?.readyState) {
let fetchdelay;
const fragPlayingCurrent = this.getAppendedFrag(media.currentTime);
if (fragPlayingCurrent && fragPlayingCurrent.start > 1) {
// flush buffer preceding current fragment (flush until current fragment start offset)
// minus 1s to avoid video freezing, that could happen if we flush keyframe of current video ...
this.flushMainBuffer(0, fragPlayingCurrent.start - 1);
}
const levelDetails = this.getLevelDetails();
if (levelDetails?.live) {
const bufferInfo = this.getMainFwdBufferInfo();
// Do not flush in live stream with low buffer
if (!bufferInfo || bufferInfo.len < levelDetails.targetduration * 2) {
return;
}
}
if (!media.paused && levels) {
// add a safety delay of 1s
const nextLevelId = this.hls.nextLoadLevel;
const nextLevel = levels[nextLevelId];
const fragLastKbps = this.fragLastKbps;
if (fragLastKbps && this.fragCurrent) {
fetchdelay =
(this.fragCurrent.duration * nextLevel.maxBitrate) /
(1000 * fragLastKbps) +
1;
} else {
fetchdelay = 0;
}
} else {
fetchdelay = 0;
}
// this.log('fetchdelay:'+fetchdelay);
// find buffer range that will be reached once new fragment will be fetched
const bufferedFrag = this.getBufferedFrag(media.currentTime + fetchdelay);
if (bufferedFrag) {
// we can flush buffer range following this one without stalling playback
const nextBufferedFrag = this.followingBufferedFrag(bufferedFrag);
if (nextBufferedFrag) {
// if we are here, we can also cancel any loading/demuxing in progress, as they are useless
this.abortCurrentFrag();
// start flush position is in next buffered frag. Leave some padding for non-independent segments and smoother playback.
const maxStart = nextBufferedFrag.maxStartPTS
? nextBufferedFrag.maxStartPTS
: nextBufferedFrag.start;
const fragDuration = nextBufferedFrag.duration;
const startPts = Math.max(
bufferedFrag.end,
maxStart +
Math.min(
Math.max(
fragDuration - this.config.maxFragLookUpTolerance,
fragDuration * (this.couldBacktrack ? 0.5 : 0.125),
),
fragDuration * (this.couldBacktrack ? 0.75 : 0.25),
),
);
this.flushMainBuffer(startPts, Number.POSITIVE_INFINITY);
}
}
}
}
private abortCurrentFrag() {
const fragCurrent = this.fragCurrent;
this.fragCurrent = null;
this.backtrackFragment = null;
if (fragCurrent) {
fragCurrent.abortRequests();
this.fragmentTracker.removeFragment(fragCurrent);
}
switch (this.state) {
case State.KEY_LOADING:
case State.FRAG_LOADING:
case State.FRAG_LOADING_WAITING_RETRY:
case State.PARSING:
case State.PARSED:
this.state = State.IDLE;
break;
}
this.nextLoadPosition = this.getLoadPosition();
}
protected flushMainBuffer(startOffset: number, endOffset: number) {
super.flushMainBuffer(
startOffset,
endOffset,
this.altAudio === AlternateAudio.SWITCHED ? 'video' : null,
);
}
protected onMediaAttached(
event: Events.MEDIA_ATTACHED,
data: MediaAttachedData,
) {
super.onMediaAttached(event, data);
const media = data.media;
media.removeEventListener('playing', this.onMediaPlaying);
media.removeEventListener('seeked', this.onMediaSeeked);
media.addEventListener('playing', this.onMediaPlaying);
media.addEventListener('seeked', this.onMediaSeeked);
this.gapController = new GapController(
this.config,
media,
this.fragmentTracker,
this.hls,
);
}
protected onMediaDetaching(
event: Events.MEDIA_DETACHING,
data: MediaDetachingData,
) {
const { media } = this;
if (media) {
media.removeEventListener('playing', this.onMediaPlaying);
media.removeEventListener('seeked', this.onMediaSeeked);
}
this.videoBuffer = null;
this.fragPlaying = null;
if (this.gapController) {
this.gapController.destroy();
this.gapController = null;
}
super.onMediaDetaching(event, data);
const transferringMedia = !!data.transferMedia;
if (transferringMedia) {
return;
}
this._hasEnoughToStart = false;
}
private onMediaPlaying = () => {
// tick to speed up FRAG_CHANGED triggering
const gapController = this.gapController;
if (gapController) {
gapController.ended = 0;
}
this.tick();
};
private onMediaSeeked = () => {
const media = this.media;
const currentTime = media ? media.currentTime : null;
if (Number.isFinite(currentTime)) {
this.log(`Media seeked to ${(currentTime as number).toFixed(3)}`);
}
// If seeked was issued before buffer was appended do not tick immediately
const bufferInfo = this.getMainFwdBufferInfo();
if (bufferInfo === null || bufferInfo.len === 0) {
this.warn(
`Main forward buffer length on "seeked" event ${
bufferInfo ? bufferInfo.len : 'empty'
})`,
);
return;
}
// tick to speed up FRAG_CHANGED triggering
this.tick();
};
protected triggerEnded() {
const gapController = this.gapController;
if (gapController) {
if (gapController.ended) {
return;
}
gapController.ended = this.media?.currentTime || 1;
}
this.hls.trigger(Events.MEDIA_ENDED, {
stalled: false,
});
}
protected onManifestLoading() {
super.onManifestLoading();
// reset buffer on manifest loading
this.log('Trigger BUFFER_RESET');
this.hls.trigger(Events.BUFFER_RESET, undefined);
this.couldBacktrack = false;
this.fragLastKbps = 0;
this.fragPlaying = this.backtrackFragment = null;
this.altAudio = AlternateAudio.DISABLED;
this.audioOnly = false;
}
private onManifestParsed(
event: Events.MANIFEST_PARSED,
data: ManifestParsedData,
) {
// detect if we have different kind of audio codecs used amongst playlists
let aac = false;
let heaac = false;
data.levels.forEach((level) => {
const codec = level.audioCodec;
if (codec) {
aac = aac || codec.indexOf('mp4a.40.2') !== -1;
heaac = heaac || codec.indexOf('mp4a.40.5') !== -1;
}
});
this.audioCodecSwitch = aac && heaac && !changeTypeSupported();
if (this.audioCodecSwitch) {
this.log(
'Both AAC/HE-AAC audio found in levels; declaring level codec as HE-AAC',
);
}
this.levels = data.levels;
this.startFragRequested = false;
}
private onLevelLoading(event: Events.LEVEL_LOADING, data: LevelLoadingData) {
const { levels } = this;
if (!levels || this.state !== State.IDLE) {
return;
}
const level = data.levelInfo;
if (
!level.details ||
(level.details.live &&
(this.levelLastLoaded !== level || level.details.expired)) ||
this.waitForCdnTuneIn(level.details)
) {
this.state = State.WAITING_LEVEL;
}
}
private onLevelLoaded(event: Events.LEVEL_LOADED, data: LevelLoadedData) {
const { levels, startFragRequested } = this;
const newLevelId = data.level;
const newDetails = data.details;
const duration = newDetails.totalduration;
if (!levels) {
this.warn(`Levels were reset while loading level ${newLevelId}`);
return;
}
this.log(
`Level ${newLevelId} loaded [${newDetails.startSN},${newDetails.endSN}]${
newDetails.lastPartSn
? `[part-${newDetails.lastPartSn}-${newDetails.lastPartIndex}]`
: ''
}, cc [${newDetails.startCC}, ${newDetails.endCC}] duration:${duration}`,
);
const curLevel = data.levelInfo;
const fragCurrent = this.fragCurrent;
if (
fragCurrent &&
(this.state === State.FRAG_LOADING ||
this.state === State.FRAG_LOADING_WAITING_RETRY)
) {
if (fragCurrent.level !== data.level && fragCurrent.loader) {
this.abortCurrentFrag();
}
}
let sliding = 0;
if (newDetails.live || curLevel.details?.live) {
this.checkLiveUpdate(newDetails);
if (newDetails.deltaUpdateFailed) {
return;
}
sliding = this.alignPlaylists(
newDetails,
curLevel.details,
this.levelLastLoaded?.details,
);
}
// override level info
curLevel.details = newDetails;
this.levelLastLoaded = curLevel;
if (!startFragRequested) {
this.setStartPosition(newDetails, sliding);
}
this.hls.trigger(Events.LEVEL_UPDATED, {
details: newDetails,
level: newLevelId,
});
// only switch back to IDLE state if we were waiting for level to start downloading a new fragment
if (this.state === State.WAITING_LEVEL) {
if (this.waitForCdnTuneIn(newDetails)) {
// Wait for Low-Latency CDN Tune-in
return;
}
this.state = State.IDLE;
}
if (startFragRequested && newDetails.live) {
this.synchronizeToLiveEdge(newDetails);
}
// trigger handler right now
this.tick();
}
private synchronizeToLiveEdge(levelDetails: LevelDetails) {
const { config, media } = this;
if (!media) {
return;
}
const liveSyncPosition = this.hls.liveSyncPosition;
const currentTime = media.currentTime;
const start = levelDetails.fragmentStart;
const end = levelDetails.edge;
const withinSlidingWindow =
currentTime >= start - config.maxFragLookUpTolerance &&
currentTime <= end;
// Continue if we can seek forward to sync position or if current time is outside of sliding window
if (
liveSyncPosition !== null &&
media.duration > liveSyncPosition &&
(currentTime < liveSyncPosition || !withinSlidingWindow)
) {
// Continue if buffer is starving or if current time is behind max latency
const maxLatency =
config.liveMaxLatencyDuration !== undefined
? config.liveMaxLatencyDuration
: config.liveMaxLatencyDurationCount * levelDetails.targetduration;
if (
(!withinSlidingWindow && media.readyState < 4) ||
currentTime < end - maxLatency
) {
if (!this._hasEnoughToStart) {
this.nextLoadPosition = liveSyncPosition;
}
// Only seek if ready and there is not a significant forward buffer available for playback
if (media.readyState) {
this.warn(
`Playback: ${currentTime.toFixed(
3,
)} is located too far from the end of live sliding playlist: ${end}, reset currentTime to : ${liveSyncPosition.toFixed(
3,
)}`,
);
media.currentTime = liveSyncPosition;
}
}
}
}
protected _handleFragmentLoadProgress(data: FragLoadedData) {
const frag = data.frag as MediaFragment;
const { part, payload } = data;
const { levels } = this;
if (!levels) {
this.warn(
`Levels were reset while fragment load was in progress. Fragment ${frag.sn} of level ${frag.level} will not be buffered`,
);
return;
}
const currentLevel = levels[frag.level];
if (!currentLevel) {
this.warn(`Level ${frag.level} not found on progress`);
return;
}
const details = currentLevel.details;
if (!details) {
this.warn(
`Dropping fragment ${frag.sn} of level ${frag.level} after level details were reset`,
);
this.fragmentTracker.removeFragment(frag);
return;
}
const videoCodec = currentLevel.videoCodec;
// time Offset is accurate if level PTS is known, or if playlist is not sliding (not live)
const accurateTimeOffset = details.PTSKnown || !details.live;
const initSegmentData = frag.initSegment?.data;
const audioCodec = this._getAudioCodec(currentLevel);
// transmux the MPEG-TS data to ISO-BMFF segments
// this.log(`Transmuxing ${frag.sn} of [${details.startSN} ,${details.endSN}],level ${frag.level}, cc ${frag.cc}`);
const transmuxer = (this.transmuxer =
this.transmuxer ||
new TransmuxerInterface(
this.hls,
PlaylistLevelType.MAIN,
this._handleTransmuxComplete.bind(this),
this._handleTransmuxerFlush.bind(this),
));
const partIndex = part ? part.index : -1;
const partial = partIndex !== -1;
const chunkMeta = new ChunkMetadata(
frag.level,
frag.sn,
frag.stats.chunkCount,
payload.byteLength,
partIndex,
partial,
);
const initPTS = this.initPTS[frag.cc];
transmuxer.push(
payload,
initSegmentData,
audioCodec,
videoCodec,
frag,
part,
details.totalduration,
accurateTimeOffset,
chunkMeta,
initPTS,
);
}
private onAudioTrackSwitching(
event: Events.AUDIO_TRACK_SWITCHING,
data: AudioTrackSwitchingData,
) {
const hls = this.hls;
// if any URL found on new audio track, it is an alternate audio track
const fromAltAudio = this.altAudio === AlternateAudio.SWITCHED;
const altAudio = useAlternateAudio(data.url, hls);
// if we switch on main audio, ensure that main fragment scheduling is synced with media.buffered
// don't do anything if we switch to alt audio: audio stream controller is handling it.
// we will just have to change buffer scheduling on audioTrackSwitched
if (!altAudio) {
if (this.mediaBuffer !== this.media) {
this.log(
'Switching on main audio, use media.buffered to schedule main fragment loading',
);
this.mediaBuffer = this.media;
const fragCurrent = this.fragCurrent;
// we need to refill audio buffer from main: cancel any frag loading to speed up audio switch
if (fragCurrent) {
this.log('Switching to main audio track, cancel main fragment load');
fragCurrent.abortRequests();
this.fragmentTracker.removeFragment(fragCurrent);
}
// destroy transmuxer to force init segment generation (following audio switch)
this.resetTransmuxer();
// switch to IDLE state to load new fragment
this.resetLoadingState();
} else if (this.audioOnly) {
// Reset audio transmuxer so when switching back to main audio we're not still appending where we left off
this.resetTransmuxer();
}
// If switching from alt to main audio, flush all audio and trigger track switched
if (fromAltAudio) {
this.fragmentTracker.removeAllFragments();
hls.once(Events.BUFFER_FLUSHED, () => {
this.hls?.trigger(Events.AUDIO_TRACK_SWITCHED, data);
});
hls.trigger(Events.BUFFER_FLUSHING, {
startOffset: 0,
endOffset: Number.POSITIVE_INFINITY,
type: null,
});
return;
}
hls.trigger(Events.AUDIO_TRACK_SWITCHED, data);
} else {
this.altAudio = AlternateAudio.SWITCHING;
}
}
private onAudioTrackSwitched(
event: Events.AUDIO_TRACK_SWITCHED,
data: AudioTrackSwitchedData,
) {
const altAudio = useAlternateAudio(data.url, this.hls);
if (altAudio) {
const videoBuffer = this.videoBuffer;
// if we switched on alternate audio, ensure that main fragment scheduling is synced with video sourcebuffer buffered
if (videoBuffer && this.mediaBuffer !== videoBuffer) {
this.log(
'Switching on alternate audio, use video.buffered to schedule main fragment loading',
);
this.mediaBuffer = videoBuffer;
}
}
this.altAudio = altAudio
? AlternateAudio.SWITCHED
: AlternateAudio.DISABLED;
this.tick();
}
private onBufferCreated(
event: Events.BUFFER_CREATED,
data: BufferCreatedData,
) {
const tracks = data.tracks;
let mediaTrack;
let name;
let alternate = false;
for (const type in tracks) {
const track = tracks[type];
if (track.id === 'main') {
name = type;
mediaTrack = track;
// keep video source buffer reference
if (type === 'video') {
const videoTrack = tracks[type];
if (videoTrack) {
this.videoBuffer = videoTrack.buffer;
}
}
} else {
alternate = true;
}
}
if (alternate && mediaTrack) {
this.log(
`Alternate track found, use ${name}.buffered to schedule main fragment loading`,
);
this.mediaBuffer = mediaTrack.buffer;
} else {
this.mediaBuffer = this.media;
}
}
private onFragBuffered(event: Events.FRAG_BUFFERED, data: FragBufferedData) {
const { frag, part } = data;
const bufferedMainFragment = frag.type === PlaylistLevelType.MAIN;
if (bufferedMainFragment) {
if (this.fragContextChanged(frag)) {
// If a level switch was requested while a fragment was buffering, it will emit the FRAG_BUFFERED event upon completion
// Avoid setting state back to IDLE, since that will interfere with a level switch
this.warn(
`Fragment ${frag.sn}${part ? ' p: ' + part.index : ''} of level ${
frag.level
} finished buffering, but was aborted. state: ${this.state}`,
);
if (this.state === State.PARSED) {
this.state = State.IDLE;
}
return;
}
const stats = part ? part.stats : frag.stats;
this.fragLastKbps = Math.round(
(8 * stats.total) / (stats.buffering.end - stats.loading.first),
);
if (isMediaFragment(frag)) {
this.fragPrevious = frag;
}
this.fragBufferedComplete(frag, part);
}
const media = this.media;
if (!media) {
return;
}
if (!this._hasEnoughToStart && media.buffered.length) {
this._hasEnoughToStart = true;
this.seekToStartPos();
}
if (bufferedMainFragment) {
this.tick();
}
}
public get hasEnoughToStart(): boolean {
return this._hasEnoughToStart;
}