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stream-controller.js
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/*
* Stream Controller
*/
import BinarySearch from '../utils/binary-search';
import BufferHelper from '../helper/buffer-helper';
import Demuxer from '../demux/demuxer';
import Event from '../events';
import EventHandler from '../event-handler';
import * as LevelHelper from '../helper/level-helper';import TimeRanges from '../utils/timeRanges';
import {ErrorTypes, ErrorDetails} from '../errors';
import {logger} from '../utils/logger';
import { alignDiscontinuities } from '../utils/discontinuities';
const State = {
STOPPED : 'STOPPED',
IDLE : 'IDLE',
KEY_LOADING : 'KEY_LOADING',
FRAG_LOADING : 'FRAG_LOADING',
FRAG_LOADING_WAITING_RETRY : 'FRAG_LOADING_WAITING_RETRY',
WAITING_LEVEL : 'WAITING_LEVEL',
PARSING : 'PARSING',
PARSED : 'PARSED',
BUFFER_FLUSHING : 'BUFFER_FLUSHING',
ENDED : 'ENDED',
ERROR : 'ERROR'
};
class StreamController extends EventHandler {
constructor(hls) {
super(hls,
Event.MEDIA_ATTACHED,
Event.MEDIA_DETACHING,
Event.MANIFEST_LOADING,
Event.MANIFEST_PARSED,
Event.LEVEL_LOADED,
Event.KEY_LOADED,
Event.FRAG_LOADED,
Event.FRAG_LOAD_EMERGENCY_ABORTED,
Event.FRAG_PARSING_INIT_SEGMENT,
Event.FRAG_PARSING_DATA,
Event.FRAG_PARSED,
Event.ERROR,
Event.AUDIO_TRACK_SWITCHING,
Event.AUDIO_TRACK_SWITCHED,
Event.BUFFER_CREATED,
Event.BUFFER_APPENDED,
Event.BUFFER_FLUSHED);
this.config = hls.config;
this.audioCodecSwap = false;
this.ticks = 0;
this._state = State.STOPPED;
this.ontick = this.tick.bind(this);
}
destroy() {
this.stopLoad();
if (this.timer) {
clearInterval(this.timer);
this.timer = null;
}
EventHandler.prototype.destroy.call(this);
this.state = State.STOPPED;
}
startLoad(startPosition) {
if (this.levels) {
let lastCurrentTime = this.lastCurrentTime, hls = this.hls;
this.stopLoad();
if (!this.timer) {
this.timer = setInterval(this.ontick, 100);
}
this.level = -1;
this.fragLoadError = 0;
if (!this.startFragRequested) {
// determine load level
let startLevel = hls.startLevel;
if (startLevel === -1) {
// -1 : guess start Level by doing a bitrate test by loading first fragment of lowest quality level
startLevel = 0;
this.bitrateTest = true;
}
// 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
this.level = hls.nextLoadLevel = startLevel;
this.loadedmetadata = false;
}
// if startPosition undefined but lastCurrentTime set, set startPosition to last currentTime
if (lastCurrentTime > 0 && startPosition === -1) {
logger.log(`override startPosition with lastCurrentTime @${lastCurrentTime.toFixed(3)}`);
startPosition = lastCurrentTime;
}
this.state = State.IDLE;
this.nextLoadPosition = this.startPosition = this.lastCurrentTime = startPosition;
this.tick();
} else {
this.forceStartLoad = true;
this.state = State.STOPPED;
}
}
stopLoad() {
var frag = this.fragCurrent;
if (frag) {
if (frag.loader) {
frag.loader.abort();
}
this.fragCurrent = null;
}
this.fragPrevious = null;
if (this.demuxer) {
this.demuxer.destroy();
this.demuxer = null;
}
this.state = State.STOPPED;
this.forceStartLoad = false;
}
tick() {
this.ticks++;
if (this.ticks === 1) {
this.doTick();
if (this.ticks > 1) {
setTimeout(this.tick, 1);
}
this.ticks = 0;
}
}
doTick() {
switch(this.state) {
case State.ERROR:
//don't do anything in error state to avoid breaking further ...
break;
case State.BUFFER_FLUSHING:
// in buffer flushing state, reset fragLoadError counter
this.fragLoadError = 0;
break;
case State.IDLE:
this._doTickIdle();
break;
case State.WAITING_LEVEL:
var level = this.levels[this.level];
// check if playlist is already loaded
if (level && level.details) {
this.state = State.IDLE;
}
break;
case State.FRAG_LOADING_WAITING_RETRY:
var now = performance.now();
var 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 && this.media.seeking)) {
logger.log(`mediaController: retryDate reached, switch back to IDLE state`);
this.state = State.IDLE;
}
break;
case State.ERROR:
case State.STOPPED:
case State.FRAG_LOADING:
case State.PARSING:
case State.PARSED:
case State.ENDED:
break;
default:
break;
}
// check buffer
this._checkBuffer();
// check/update current fragment
this._checkFragmentChanged();
}
// Ironically the "idle" state is the on we do the most logic in it seems ....
// NOTE: Maybe we could rather schedule a check for buffer length after half of the currently
// played segment, or on pause/play/seek instead of naively checking every 100ms?
_doTickIdle() {
const hls = this.hls,
config = hls.config,
media = this.media;
// if start level not parsed yet OR
// if video not attached AND start fragment already requested OR start frag prefetch disable
// exit loop, as we either need more info (level not parsed) or we need media to be attached to load new fragment
if (this.levelLastLoaded === undefined || (
!media && (this.startFragRequested || !config.startFragPrefetch))) {
return;
}
// if we have not yet loaded any fragment, start loading from start position
let pos;
if (this.loadedmetadata) {
pos = media.currentTime;
} else {
pos = this.nextLoadPosition;
}
// determine next load level
let level = hls.nextLoadLevel,
levelInfo = this.levels[level];
if (!levelInfo) {
return;
}
let levelBitrate = levelInfo.bitrate,
maxBufLen;
// 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
if (levelBitrate) {
maxBufLen = Math.max(8 * config.maxBufferSize / levelBitrate, config.maxBufferLength);
} else {
maxBufLen = config.maxBufferLength;
}
maxBufLen = Math.min(maxBufLen, config.maxMaxBufferLength);
// determine next candidate fragment to be loaded, based on current position and end of buffer position
// ensure up to `config.maxMaxBufferLength` of buffer upfront
const bufferInfo = BufferHelper.bufferInfo(this.mediaBuffer ? this.mediaBuffer : media, pos, config.maxBufferHole),
bufferLen = bufferInfo.len;
// Stay idle if we are still with buffer margins
if (bufferLen >= maxBufLen) {
return;
}
// if buffer length is less than maxBufLen try to load a new fragment ...
logger.trace(`buffer length of ${bufferLen.toFixed(3)} is below max of ${maxBufLen.toFixed(3)}. checking for more payload ...`);
// set next load level : this will trigger a playlist load if needed
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 (typeof levelDetails === 'undefined' || levelDetails.live && this.levelLastLoaded !== level) {
this.state = State.WAITING_LEVEL;
return;
}
// we just got done loading the final fragment and there is no other buffered range after ...
// rationale is that in case there are any buffered ranges after, it means that there are unbuffered portion in between
// so we should not switch to ENDED in that case, to be able to buffer them
// dont switch to ENDED if we need to backtrack last fragment
let fragPrevious = this.fragPrevious;
if (!levelDetails.live && fragPrevious && !fragPrevious.backtracked && fragPrevious.sn === levelDetails.endSN && !bufferInfo.nextStart) {
// fragPrevious is last fragment. retrieve level duration using last frag start offset + duration
// real duration might be lower than initial duration if there are drifts between real frag duration and playlist signaling
const duration = Math.min(media.duration,fragPrevious.start + fragPrevious.duration);
// if everything (almost) til the end is buffered, let's signal eos
// we don't compare exactly media.duration === bufferInfo.end as there could be some subtle media duration difference (audio/video offsets...)
// tolerate up to one frag duration to cope with these cases.
// also cope with almost zero last frag duration (max last frag duration with 200ms) refer to https://github.com/video-dev/hls.js/pull/657
if (duration - Math.max(bufferInfo.end,fragPrevious.start) <= Math.max(0.2,fragPrevious.duration)) {
// Finalize the media stream
let data = {};
if (this.altAudio) {
data.type = 'video';
}
this.hls.trigger(Event.BUFFER_EOS,data);
this.state = State.ENDED;
return;
}
}
// if we have the levelDetails for the selected variant, lets continue enrichen our stream (load keys/fragments or trigger EOS, etc..)
this._fetchPayloadOrEos(pos, bufferInfo, levelDetails);
}
_fetchPayloadOrEos(pos, bufferInfo, levelDetails) {
const fragPrevious = this.fragPrevious,
level = this.level,
fragments = levelDetails.fragments,
fragLen = fragments.length;
// empty playlist
if (fragLen === 0) {
return;
}
// find fragment index, contiguous with end of buffer position
let start = fragments[0].start,
end = fragments[fragLen-1].start + fragments[fragLen-1].duration,
bufferEnd = bufferInfo.end,
frag;
if (levelDetails.initSegment && !levelDetails.initSegment.data) {
frag = levelDetails.initSegment;
} else {
// in case of live playlist we need to ensure that requested position is not located before playlist start
if (levelDetails.live) {
let initialLiveManifestSize = this.config.initialLiveManifestSize;
if(fragLen < initialLiveManifestSize){
logger.warn(`Can not start playback of a level, reason: not enough fragments ${fragLen} < ${initialLiveManifestSize}`);
return;
}
frag = this._ensureFragmentAtLivePoint(levelDetails, bufferEnd, start, end, fragPrevious, fragments, fragLen);
// if it explicitely returns null don't load any fragment and exit function now
if (frag === null) {
return;
}
} else {
// VoD playlist: if bufferEnd before start of playlist, load first fragment
if (bufferEnd < start) {
frag = fragments[0];
}
}
}
if (!frag) {
frag = this._findFragment(start, fragPrevious, fragLen, fragments, bufferEnd, end, levelDetails);
}
if(frag) {
this._loadFragmentOrKey(frag, level, levelDetails, pos, bufferEnd);
}
return;
}
_ensureFragmentAtLivePoint(levelDetails, bufferEnd, start, end, fragPrevious, fragments, fragLen) {
const config = this.hls.config, media = this.media;
let frag;
// check if requested position is within seekable boundaries :
//logger.log(`start/pos/bufEnd/seeking:${start.toFixed(3)}/${pos.toFixed(3)}/${bufferEnd.toFixed(3)}/${this.media.seeking}`);
let maxLatency = config.liveMaxLatencyDuration !== undefined ? config.liveMaxLatencyDuration : config.liveMaxLatencyDurationCount*levelDetails.targetduration;
if (bufferEnd < Math.max(start-config.maxFragLookUpTolerance, end - maxLatency)) {
let liveSyncPosition = this.liveSyncPosition = this.computeLivePosition(start, levelDetails);
logger.log(`buffer end: ${bufferEnd.toFixed(3)} is located too far from the end of live sliding playlist, reset currentTime to : ${liveSyncPosition.toFixed(3)}`);
bufferEnd = liveSyncPosition;
if (media && media.readyState && media.duration > liveSyncPosition) {
media.currentTime = liveSyncPosition;
}
this.nextLoadPosition = liveSyncPosition;
}
// if end of buffer greater than live edge, don't load any fragment
// this could happen if live playlist intermittently slides in the past.
// level 1 loaded [182580161,182580167]
// level 1 loaded [182580162,182580169]
// Loading 182580168 of [182580162 ,182580169],level 1 ..
// Loading 182580169 of [182580162 ,182580169],level 1 ..
// level 1 loaded [182580162,182580168] <============= here we should have bufferEnd > end. in that case break to avoid reloading 182580168
// level 1 loaded [182580164,182580171]
//
// don't return null in case media not loaded yet (readystate === 0)
if (levelDetails.PTSKnown && bufferEnd > end && media && media.readyState) {
return null;
}
if (this.startFragRequested && !levelDetails.PTSKnown) {
/* we are switching level on live playlist, but we don't have any PTS info for that quality level ...
try to load frag matching with next SN.
even if SN are not synchronized between playlists, loading this frag will help us
compute playlist sliding and find the right one after in case it was not the right consecutive one */
if (fragPrevious) {
const targetSN = fragPrevious.sn + 1;
if (targetSN >= levelDetails.startSN && targetSN <= levelDetails.endSN) {
const fragNext = fragments[targetSN - levelDetails.startSN];
if (fragPrevious.cc === fragNext.cc) {
frag = fragNext;
logger.log(`live playlist, switching playlist, load frag with next SN: ${frag.sn}`);
}
}
// next frag SN not available (or not with same continuity counter)
// look for a frag sharing the same CC
if (!frag) {
frag = BinarySearch.search(fragments, function(frag) {
return fragPrevious.cc - frag.cc;
});
if (frag) {
logger.log(`live playlist, switching playlist, load frag with same CC: ${frag.sn}`);
}
}
}
if (!frag) {
/* we have no idea about which fragment should be loaded.
so let's load mid fragment. it will help computing playlist sliding and find the right one
*/
frag = fragments[Math.min(fragLen - 1, Math.round(fragLen / 2))];
logger.log(`live playlist, switching playlist, unknown, load middle frag : ${frag.sn}`);
}
}
return frag;
}
_findFragment(start, fragPrevious, fragLen, fragments, bufferEnd, end, levelDetails) {
const config = this.hls.config;
let frag;
let foundFrag;
let maxFragLookUpTolerance = config.maxFragLookUpTolerance;
const fragNext = fragPrevious ? fragments[fragPrevious.sn - fragments[0].sn + 1] : undefined;
let fragmentWithinToleranceTest = (candidate) => {
// offset should be within fragment boundary - config.maxFragLookUpTolerance
// this is to cope with situations like
// bufferEnd = 9.991
// frag[Ø] : [0,10]
// frag[1] : [10,20]
// bufferEnd is within frag[0] range ... although what we are expecting is to return frag[1] here
// frag start frag start+duration
// |-----------------------------|
// <---> <--->
// ...--------><-----------------------------><---------....
// previous frag matching fragment next frag
// return -1 return 0 return 1
//logger.log(`level/sn/start/end/bufEnd:${level}/${candidate.sn}/${candidate.start}/${(candidate.start+candidate.duration)}/${bufferEnd}`);
// Set the lookup tolerance to be small enough to detect the current segment - ensures we don't skip over very small segments
let candidateLookupTolerance = Math.min(maxFragLookUpTolerance, candidate.duration + (candidate.deltaPTS ? candidate.deltaPTS : 0));
if (candidate.start + candidate.duration - candidateLookupTolerance <= bufferEnd) {
return 1;
} // if maxFragLookUpTolerance will have negative value then don't return -1 for first element
else if (candidate.start - candidateLookupTolerance > bufferEnd && candidate.start) {
return -1;
}
return 0;
};
if (bufferEnd < end) {
if (bufferEnd > end - maxFragLookUpTolerance) {
maxFragLookUpTolerance = 0;
}
// Prefer the next fragment if it's within tolerance
if (fragNext && !fragmentWithinToleranceTest(fragNext)) {
foundFrag = fragNext;
} else {
foundFrag = BinarySearch.search(fragments, fragmentWithinToleranceTest);
}
} else {
// reach end of playlist
foundFrag = fragments[fragLen-1];
}
if (foundFrag) {
frag = foundFrag;
const curSNIdx = frag.sn - levelDetails.startSN;
const sameLevel = fragPrevious && frag.level === fragPrevious.level;
const prevFrag = fragments[curSNIdx - 1];
const nextFrag = fragments[curSNIdx + 1];
//logger.log('find SN matching with pos:' + bufferEnd + ':' + frag.sn);
if (fragPrevious && frag.sn === fragPrevious.sn) {
if (sameLevel && !frag.backtracked) {
if (frag.sn < levelDetails.endSN) {
let deltaPTS = fragPrevious.deltaPTS;
// if there is a significant delta between audio and video, larger than max allowed hole,
// and if previous remuxed fragment did not start with a keyframe. (fragPrevious.dropped)
// let's try to load previous fragment again to get last keyframe
// then we will reload again current fragment (that way we should be able to fill the buffer hole ...)
if (deltaPTS && deltaPTS > config.maxBufferHole && fragPrevious.dropped && curSNIdx) {
frag = prevFrag;
logger.warn(`SN just loaded, with large PTS gap between audio and video, maybe frag is not starting with a keyframe ? load previous one to try to overcome this`);
// decrement previous frag load counter to avoid frag loop loading error when next fragment will get reloaded
fragPrevious.loadCounter--;
} else {
frag = nextFrag;
logger.log(`SN just loaded, load next one: ${frag.sn}`);
}
} else {
frag = null;
}
} else if (frag.backtracked) {
// Only backtrack a max of 1 consecutive fragment to prevent sliding back too far when little or no frags start with keyframes
if (nextFrag && nextFrag.backtracked) {
logger.warn(`Already backtracked from fragment ${nextFrag.sn}, will not backtrack to fragment ${frag.sn}. Loading fragment ${nextFrag.sn}`);
frag = nextFrag;
} else {
// If a fragment has dropped frames and it's in a same level/sequence, load the previous fragment to try and find the keyframe
// Reset the dropped count now since it won't be reset until we parse the fragment again, which prevents infinite backtracking on the same segment
logger.warn('Loaded fragment with dropped frames, backtracking 1 segment to find a keyframe');
frag.dropped = 0;
if (prevFrag) {
if (prevFrag.loadCounter) {
prevFrag.loadCounter--;
}
frag = prevFrag;
frag.backtracked = true;
} else if (curSNIdx) {
// can't backtrack on very first fragment
frag = null;
}
}
}
}
}
return frag;
}
_loadFragmentOrKey(frag, level, levelDetails, pos, bufferEnd) {
const hls = this.hls,
config = hls.config;
//logger.log('loading frag ' + i +',pos/bufEnd:' + pos.toFixed(3) + '/' + bufferEnd.toFixed(3));
if ((frag.decryptdata && frag.decryptdata.uri != null) && (frag.decryptdata.key == null)) {
logger.log(`Loading key for ${frag.sn} of [${levelDetails.startSN} ,${levelDetails.endSN}],level ${level}`);
this.state = State.KEY_LOADING;
hls.trigger(Event.KEY_LOADING, {frag: frag});
} else {
logger.log(`Loading ${frag.sn} of [${levelDetails.startSN} ,${levelDetails.endSN}],level ${level}, currentTime:${pos.toFixed(3)},bufferEnd:${bufferEnd.toFixed(3)}`);
// ensure that we are not reloading the same fragments in loop ...
if (this.fragLoadIdx !== undefined) {
this.fragLoadIdx++;
} else {
this.fragLoadIdx = 0;
}
if (frag.loadCounter) {
frag.loadCounter++;
let maxThreshold = config.fragLoadingLoopThreshold;
// if this frag has already been loaded 3 times, and if it has been reloaded recently
if (frag.loadCounter > maxThreshold && (Math.abs(this.fragLoadIdx - frag.loadIdx) < maxThreshold)) {
hls.trigger(Event.ERROR, {type: ErrorTypes.MEDIA_ERROR, details: ErrorDetails.FRAG_LOOP_LOADING_ERROR, fatal: false, frag: frag});
return;
}
} else {
frag.loadCounter = 1;
}
frag.loadIdx = this.fragLoadIdx;
frag.autoLevel = hls.autoLevelEnabled;
frag.bitrateTest = this.bitrateTest;
this.fragCurrent = frag;
this.startFragRequested = true;
// Don't update nextLoadPosition for fragments which are not buffered
if (!isNaN(frag.sn) && !frag.bitrateTest) {
this.nextLoadPosition = frag.start + frag.duration;
}
hls.trigger(Event.FRAG_LOADING, {frag: frag});
// lazy demuxer init, as this could take some time ... do it during frag loading
if (!this.demuxer) {
this.demuxer = new Demuxer(hls,'main');
}
this.state = State.FRAG_LOADING;
return;
}
}
set state(nextState) {
if (this.state !== nextState) {
const previousState = this.state;
this._state = nextState;
logger.log(`main stream:${previousState}->${nextState}`);
this.hls.trigger(Event.STREAM_STATE_TRANSITION, {previousState, nextState});
}
}
get state() {
return this._state;
}
getBufferedFrag(position) {
return BinarySearch.search(this._bufferedFrags, function(frag) {
if (position < frag.startPTS) {
return -1;
} else if (position > frag.endPTS) {
return 1;
}
return 0;
});
}
get currentLevel() {
let media = this.media;
if (media) {
const frag = this.getBufferedFrag(media.currentTime);
if (frag) {
return frag.level;
}
}
return -1;
}
get nextBufferedFrag() {
let media = this.media;
if (media) {
// first get end range of current fragment
return this.followingBufferedFrag(this.getBufferedFrag(media.currentTime));
} else {
return null;
}
}
followingBufferedFrag(frag) {
if (frag) {
// try to get range of next fragment (500ms after this range)
return this.getBufferedFrag(frag.endPTS + 0.5);
}
return null;
}
get nextLevel() {
const frag = this.nextBufferedFrag;
if (frag) {
return frag.level;
} else {
return -1;
}
}
_checkFragmentChanged() {
var fragPlayingCurrent, currentTime, video = this.media;
if (video && video.readyState && video.seeking === false) {
currentTime = video.currentTime;
/* if video element is in seeked state, currentTime can only increase.
(assuming that playback rate is positive ...)
As sometimes currentTime jumps back to zero after a
media decode error, check this, to avoid seeking back to
wrong position after a media decode error
*/
if(currentTime > video.playbackRate*this.lastCurrentTime) {
this.lastCurrentTime = currentTime;
}
if (BufferHelper.isBuffered(video,currentTime)) {
fragPlayingCurrent = this.getBufferedFrag(currentTime);
} else if (BufferHelper.isBuffered(video,currentTime + 0.1)) {
/* ensure that FRAG_CHANGED event is triggered at startup,
when first video frame is displayed and playback is paused.
add a tolerance of 100ms, in case current position is not buffered,
check if current pos+100ms is buffered and use that buffer range
for FRAG_CHANGED event reporting */
fragPlayingCurrent = this.getBufferedFrag(currentTime + 0.1);
}
if (fragPlayingCurrent) {
var fragPlaying = fragPlayingCurrent;
if (fragPlaying !== this.fragPlaying) {
this.hls.trigger(Event.FRAG_CHANGED, {frag: fragPlaying});
const fragPlayingLevel = fragPlaying.level;
if (!this.fragPlaying || this.fragPlaying.level !== fragPlayingLevel) {
this.hls.trigger(Event.LEVEL_SWITCHED, {level: fragPlayingLevel});
}
this.fragPlaying = fragPlaying;
}
}
}
}
/*
on immediate level switch :
- pause playback if playing
- cancel any pending load request
- and trigger a buffer flush
*/
immediateLevelSwitch() {
logger.log('immediateLevelSwitch');
if (!this.immediateSwitch) {
this.immediateSwitch = true;
let media = this.media, previouslyPaused;
if (media) {
previouslyPaused = media.paused;
media.pause();
} else {
// don't restart playback after instant level switch in case media not attached
previouslyPaused = true;
}
this.previouslyPaused = previouslyPaused;
}
var fragCurrent = this.fragCurrent;
if (fragCurrent && fragCurrent.loader) {
fragCurrent.loader.abort();
}
this.fragCurrent = null;
// increase fragment load Index to avoid frag loop loading error after buffer flush
if (this.fragLoadIdx !== undefined) {
this.fragLoadIdx += 2 * this.config.fragLoadingLoopThreshold;
}
// flush everything
this.flushMainBuffer(0,Number.POSITIVE_INFINITY);
}
/*
on immediate level switch end, after new fragment has been buffered :
- nudge video decoder by slightly adjusting video currentTime (if currentTime buffered)
- resume the playback if needed
*/
immediateLevelSwitchEnd() {
let media = this.media;
if (media && media.buffered.length) {
this.immediateSwitch = false;
if(BufferHelper.isBuffered(media,media.currentTime)) {
// only nudge if currentTime is buffered
media.currentTime -= 0.0001;
}
if (!this.previouslyPaused) {
media.play();
}
}
}
nextLevelSwitch() {
/* 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
*/
let media = this.media;
// ensure that media is defined and that metadata are available (to retrieve currentTime)
if (media && media.readyState) {
let fetchdelay, fragPlayingCurrent, nextBufferedFrag;
if (this.fragLoadIdx !== undefined) {
// increase fragment load Index to avoid frag loop loading error after buffer flush
this.fragLoadIdx += 2 * this.config.fragLoadingLoopThreshold;
}
fragPlayingCurrent = this.getBufferedFrag(media.currentTime);
if (fragPlayingCurrent && fragPlayingCurrent.startPTS > 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.startPTS - 1);
}
if (!media.paused) {
// add a safety delay of 1s
var nextLevelId = this.hls.nextLoadLevel,nextLevel = this.levels[nextLevelId], fragLastKbps = this.fragLastKbps;
if (fragLastKbps && this.fragCurrent) {
fetchdelay = this.fragCurrent.duration * nextLevel.bitrate / (1000 * fragLastKbps) + 1;
} else {
fetchdelay = 0;
}
} else {
fetchdelay = 0;
}
//logger.log('fetchdelay:'+fetchdelay);
// find buffer range that will be reached once new fragment will be fetched
nextBufferedFrag = this.getBufferedFrag(media.currentTime + fetchdelay);
if (nextBufferedFrag) {
// we can flush buffer range following this one without stalling playback
nextBufferedFrag = this.followingBufferedFrag(nextBufferedFrag);
if (nextBufferedFrag) {
// if we are here, we can also cancel any loading/demuxing in progress, as they are useless
var fragCurrent = this.fragCurrent;
if (fragCurrent && fragCurrent.loader) {
fragCurrent.loader.abort();
}
this.fragCurrent = null;
// start flush position is the start PTS of next buffered frag.
// we use frag.naxStartPTS which is max(audio startPTS, video startPTS).
// in case there is a small PTS Delta between audio and video, using maxStartPTS avoids flushing last samples from current fragment
this.flushMainBuffer(nextBufferedFrag.maxStartPTS , Number.POSITIVE_INFINITY);
}
}
}
}
flushMainBuffer(startOffset,endOffset) {
this.state = State.BUFFER_FLUSHING;
let flushScope = {startOffset: startOffset, endOffset: endOffset};
// if alternate audio tracks are used, only flush video, otherwise flush everything
if (this.altAudio) {
flushScope.type = 'video';
}
this.hls.trigger(Event.BUFFER_FLUSHING, flushScope);
}
onMediaAttached(data) {
var media = this.media = this.mediaBuffer = data.media;
this.onvseeking = this.onMediaSeeking.bind(this);
this.onvseeked = this.onMediaSeeked.bind(this);
this.onvended = this.onMediaEnded.bind(this);
media.addEventListener('seeking', this.onvseeking);
media.addEventListener('seeked', this.onvseeked);
media.addEventListener('ended', this.onvended);
let config = this.config;
if(this.levels && config.autoStartLoad) {
this.hls.startLoad(config.startPosition);
}
}
onMediaDetaching() {
var media = this.media;
if (media && media.ended) {
logger.log('MSE detaching and video ended, reset startPosition');
this.startPosition = this.lastCurrentTime = 0;
}
// reset fragment loading counter on MSE detaching to avoid reporting FRAG_LOOP_LOADING_ERROR after error recovery
var levels = this.levels;
if (levels) {
// reset fragment load counter
levels.forEach(level => {
if(level.details) {
level.details.fragments.forEach(fragment => {
fragment.loadCounter = undefined;
fragment.backtracked = undefined;
});
}
});
}
// remove video listeners
if (media) {
media.removeEventListener('seeking', this.onvseeking);
media.removeEventListener('seeked', this.onvseeked);
media.removeEventListener('ended', this.onvended);
this.onvseeking = this.onvseeked = this.onvended = null;
}
this.media = this.mediaBuffer = null;
this.loadedmetadata = false;
this.stopLoad();
}
onMediaSeeking() {
let media = this.media, currentTime = media ? media.currentTime : undefined, config = this.config;
if (!isNaN(currentTime)) {
logger.log(`media seeking to ${currentTime.toFixed(3)}`);
}
let mediaBuffer = this.mediaBuffer ? this.mediaBuffer : media;
let bufferInfo = BufferHelper.bufferInfo(mediaBuffer,currentTime,this.config.maxBufferHole);
if (this.state === State.FRAG_LOADING) {
let fragCurrent = this.fragCurrent;
// check if we are seeking to a unbuffered area AND if frag loading is in progress
if (bufferInfo.len === 0 && fragCurrent) {
let tolerance = config.maxFragLookUpTolerance,
fragStartOffset = fragCurrent.start - tolerance,
fragEndOffset = fragCurrent.start + fragCurrent.duration + tolerance;
// check if we seek position will be out of currently loaded frag range : if out cancel frag load, if in, don't do anything
if (currentTime < fragStartOffset || currentTime > fragEndOffset) {
if (fragCurrent.loader) {
logger.log('seeking outside of buffer while fragment load in progress, cancel fragment load');
fragCurrent.loader.abort();
}
this.fragCurrent = null;
this.fragPrevious = null;
// switch to IDLE state to load new fragment
this.state = State.IDLE;
} else {
logger.log('seeking outside of buffer but within currently loaded fragment range');
}
}
} else if (this.state === State.ENDED) {
// if seeking to unbuffered area, clean up fragPrevious
if (bufferInfo.len === 0) {
this.fragPrevious = 0;
}
// switch to IDLE state to check for potential new fragment
this.state = State.IDLE;
}
if (media) {
this.lastCurrentTime = currentTime;
}
// avoid reporting fragment loop loading error in case user is seeking several times on same position
if (this.state !== State.FRAG_LOADING && this.fragLoadIdx !== undefined) {
this.fragLoadIdx += 2 * config.fragLoadingLoopThreshold;
}
// in case seeking occurs although no media buffered, adjust startPosition and nextLoadPosition to seek target
if(!this.loadedmetadata) {
this.nextLoadPosition = this.startPosition = currentTime;
}
// tick to speed up processing
this.tick();
}
onMediaSeeked() {
const media = this.media, currentTime = media ? media.currentTime : undefined;
if (!isNaN(currentTime)) {
logger.log(`media seeked to ${currentTime.toFixed(3)}`);
}
// tick to speed up FRAGMENT_PLAYING triggering
this.tick();
}
onMediaEnded() {
logger.log('media ended');
// reset startPosition and lastCurrentTime to restart playback @ stream beginning
this.startPosition = this.lastCurrentTime = 0;
}
onManifestLoading() {
// reset buffer on manifest loading
logger.log('trigger BUFFER_RESET');
this.hls.trigger(Event.BUFFER_RESET);
this._bufferedFrags = [];
this.stalled = false;
this.startPosition = this.lastCurrentTime = 0;
}
onManifestParsed(data) {
var aac = false, heaac = false, codec;
data.levels.forEach(level => {
// detect if we have different kind of audio codecs used amongst playlists
codec = level.audioCodec;
if (codec) {
if (codec.indexOf('mp4a.40.2') !== -1) {
aac = true;
}
if (codec.indexOf('mp4a.40.5') !== -1) {
heaac = true;
}
}
});
this.audioCodecSwitch = (aac && heaac);
if (this.audioCodecSwitch) {
logger.log('both AAC/HE-AAC audio found in levels; declaring level codec as HE-AAC');
}
this.levels = data.levels;
this.startFragRequested = false;
let config = this.config;
if (config.autoStartLoad || this.forceStartLoad) {
this.hls.startLoad(config.startPosition);
}
}
onLevelLoaded(data) {
const newDetails = data.details;
const newLevelId = data.level;
const lastLevel = this.levels[this.levelLastLoaded];
const curLevel = this.levels[newLevelId];
const duration = newDetails.totalduration;
let sliding = 0;
logger.log(`level ${newLevelId} loaded [${newDetails.startSN},${newDetails.endSN}],duration:${duration}`);
if (newDetails.live) {
var curDetails = curLevel.details;
if (curDetails && newDetails.fragments.length > 0) {
// we already have details for that level, merge them
LevelHelper.mergeDetails(curDetails,newDetails);
sliding = newDetails.fragments[0].start;
this.liveSyncPosition = this.computeLivePosition(sliding, curDetails);
if (newDetails.PTSKnown && !isNaN(sliding)) {
logger.log(`live playlist sliding:${sliding.toFixed(3)}`);
} else {
logger.log('live playlist - outdated PTS, unknown sliding');
alignDiscontinuities(this.fragPrevious, lastLevel, newDetails);
}
} else {
logger.log('live playlist - first load, unknown sliding');
newDetails.PTSKnown = false;
alignDiscontinuities(this.fragPrevious, lastLevel, newDetails);
}
} else {
newDetails.PTSKnown = false;
}
// override level info
curLevel.details = newDetails;
this.levelLastLoaded = newLevelId;
this.hls.trigger(Event.LEVEL_UPDATED, { details: newDetails, level: newLevelId });
if (this.startFragRequested === false) {
// compute start position if set to -1. use it straight away if value is defined
if (this.startPosition === -1 || this.lastCurrentTime === -1) {
// first, check if start time offset has been set in playlist, if yes, use this value
let startTimeOffset = newDetails.startTimeOffset;
if(!isNaN(startTimeOffset)) {
if (startTimeOffset < 0) {
logger.log(`negative start time offset ${startTimeOffset}, count from end of last fragment`);
startTimeOffset = sliding + duration + startTimeOffset;
}
logger.log(`start time offset found in playlist, adjust startPosition to ${startTimeOffset}`);
this.startPosition = startTimeOffset;
} else {
// if live playlist, set start position to be fragment N-this.config.liveSyncDurationCount (usually 3)
if (newDetails.live) {
this.startPosition = this.computeLivePosition(sliding, newDetails);
logger.log(`configure startPosition to ${this.startPosition}`);
} else {
this.startPosition = 0;
}
}
this.lastCurrentTime = this.startPosition;
}
this.nextLoadPosition = this.startPosition;
}
// only switch batck to IDLE state if we were waiting for level to start downloading a new fragment
if (this.state === State.WAITING_LEVEL) {
this.state = State.IDLE;
}
//trigger handler right now
this.tick();
}
onKeyLoaded() {
if (this.state === State.KEY_LOADING) {
this.state = State.IDLE;
this.tick();
}
}
onFragLoaded(data) {
var fragCurrent = this.fragCurrent,
fragLoaded = data.frag;
if (this.state === State.FRAG_LOADING &&
fragCurrent &&
fragLoaded.type === 'main' &&
fragLoaded.level === fragCurrent.level &&
fragLoaded.sn === fragCurrent.sn) {
let stats = data.stats,
currentLevel = this.levels[fragCurrent.level],
details = currentLevel.details;
logger.log(`Loaded ${fragCurrent.sn} of [${details.startSN} ,${details.endSN}],level ${fragCurrent.level}`);
// reset frag bitrate test in any case after frag loaded event
this.bitrateTest = false;
this.stats = stats;
// if this frag was loaded to perform a bitrate test AND if hls.nextLoadLevel is greater than 0
// then this means that we should be able to load a fragment at a higher quality level
if (fragLoaded.bitrateTest === true && this.hls.nextLoadLevel) {
// switch back to IDLE state ... we just loaded a fragment to determine adequate start bitrate and initialize autoswitch algo
this.state = State.IDLE;
this.startFragRequested = false;
stats.tparsed = stats.tbuffered = performance.now();
this.hls.trigger(Event.FRAG_BUFFERED, {stats: stats, frag: fragCurrent, id : 'main'});