/**
* @license
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
goog.provide('shaka.media.StreamingEngine');
goog.require('goog.asserts');
goog.require('shaka.log');
goog.require('shaka.media.MediaSourceEngine');
goog.require('shaka.media.Playhead');
goog.require('shaka.net.Backoff');
goog.require('shaka.net.NetworkingEngine');
goog.require('shaka.util.Error');
goog.require('shaka.util.FakeEvent');
goog.require('shaka.util.Functional');
goog.require('shaka.util.IDestroyable');
goog.require('shaka.util.ManifestParserUtils');
goog.require('shaka.util.MapUtils');
goog.require('shaka.util.MimeUtils');
goog.require('shaka.util.Mp4Parser');
goog.require('shaka.util.PublicPromise');
goog.require('shaka.util.StreamUtils');
/**
* Creates a StreamingEngine.
*
* The StreamingEngine is responsible for setting up the Manifest's Streams
* (i.e., for calling each Stream's createSegmentIndex() function), for
* downloading segments, for co-ordinating audio, video, and text buffering,
* and for handling Period transitions. The StreamingEngine provides an
* interface to switch between Streams, but it does not choose which Streams to
* switch to.
*
* The StreamingEngine notifies its owner when it needs to buffer a new Period,
* so its owner can choose which Streams within that Period to initially
* buffer. Moreover, the StreamingEngine also notifies its owner when any
* Stream within the current Period may be switched to, so its owner can switch
* bitrates, resolutions, or languages.
*
* The StreamingEngine does not need to be notified about changes to the
* Manifest's SegmentIndexes; however, it does need to be notified when new
* Periods are added to the Manifest, so it can set up that Period's Streams.
*
* To start the StreamingEngine the owner must first call configure() followed
* by init(). The StreamingEngine will then call onChooseStreams(p) when it
* needs to buffer Period p; it will then switch to the Streams returned from
* that function. The StreamingEngine will call onCanSwitch() when any
* Stream within the current Period may be switched to.
*
* The owner must call seeked() each time the playhead moves to a new location
* within the presentation timeline; however, the owner may forego calling
* seeked() when the playhead moves outside the presentation timeline.
*
* @param {shaka.extern.Manifest} manifest
* @param {shaka.media.StreamingEngine.PlayerInterface} playerInterface
*
* @constructor
* @struct
* @implements {shaka.util.IDestroyable}
*/
shaka.media.StreamingEngine = function(manifest, playerInterface) {
/** @private {?shaka.media.StreamingEngine.PlayerInterface} */
this.playerInterface_ = playerInterface;
/** @private {?shaka.extern.Manifest} */
this.manifest_ = manifest;
/** @private {?shaka.extern.StreamingConfiguration} */
this.config_ = null;
/** @private {number} */
this.bufferingGoalScale_ = 1;
/** @private {Promise} */
this.setupPeriodPromise_ = Promise.resolve();
/**
* Maps a Period's index to an object that indicates that either
* 1. the Period has not been set up (undefined).
* 2. the Period is being set up ([a PublicPromise, false]).
* 3. the Period is set up (i.e., all Streams within the Period are set up)
* and can be switched to ([a PublicPromise, true]).
*
* @private {Array.<?{promise: shaka.util.PublicPromise, resolved: boolean}>}
*/
this.canSwitchPeriod_ = [];
/**
* Maps a Stream's ID to an object that indicates that either
* 1. the Stream has not been set up (undefined).
* 2. the Stream is being set up ([a Promise instance, false]).
* 3. the Stream is set up and can be switched to
* ([a Promise instance, true]).
*
* @private {Object.<number,
* ?{promise: shaka.util.PublicPromise, resolved: boolean}>}
*/
this.canSwitchStream_ = {};
/**
* Maps a content type, e.g., 'audio', 'video', or 'text', to a MediaState.
*
* @private {Object.<shaka.util.ManifestParserUtils.ContentType,
!shaka.media.StreamingEngine.MediaState_>}
*/
this.mediaStates_ = {};
/**
* Set to true once one segment of each content type has been buffered.
*
* @private {boolean}
*/
this.startupComplete_ = false;
/**
* Used for delay and backoff of failure callbacks, so that apps do not retry
* instantly.
*
* @private {shaka.net.Backoff}
*/
this.failureCallbackBackoff_ = null;
/**
* Set to true on fatal error. Interrupts fetchAndAppend_().
*
* @private {boolean}
*/
this.fatalError_ = false;
/** @private {boolean} */
this.destroyed_ = false;
/**
* Set to true when a request to unload text stream comes in. This is used
* since loading new text stream is async, the request of unloading text
* stream might come in before setting up new text stream is finished.
* @private {boolean}
*/
this.unloadingTextStream_ = false;
/** @private {number} */
this.textStreamSequenceId_ = 0;
};
/**
* @typedef {{
* variant: (?shaka.extern.Variant|undefined),
* text: ?shaka.extern.Stream
* }}
*
* @property {(?shaka.extern.Variant|undefined)} variant
* The chosen variant. May be omitted for text re-init.
* @property {?shaka.extern.Stream} text
* The chosen text stream.
*/
shaka.media.StreamingEngine.ChosenStreams;
/**
* @typedef {{
* playhead: !shaka.media.Playhead,
* mediaSourceEngine: !shaka.media.MediaSourceEngine,
* netEngine: shaka.net.NetworkingEngine,
* onChooseStreams: function(!shaka.extern.Period):
* shaka.media.StreamingEngine.ChosenStreams,
* onCanSwitch: function(),
* onError: function(!shaka.util.Error),
* onEvent: function(!Event),
* onManifestUpdate: function(),
* onSegmentAppended: function(),
* onInitialStreamsSetup: (function()|undefined),
* onStartupComplete: (function()|undefined)
* }}
*
* @property {!shaka.media.Playhead} playhead
* The Playhead. The caller retains ownership.
* @property {!shaka.media.MediaSourceEngine} mediaSourceEngine
* The MediaSourceEngine. The caller retains ownership.
* @property {shaka.net.NetworkingEngine} netEngine
* The NetworkingEngine instance to use. The caller retains ownership.
* @property {function(!shaka.extern.Period):
* shaka.media.StreamingEngine.ChosenStreams} onChooseStreams
* Called by StreamingEngine when the given Period needs to be buffered.
* StreamingEngine will switch to the variant and text stream returned from
* this function.
* The owner cannot call switch() directly until the StreamingEngine calls
* onCanSwitch().
* @property {function()} onCanSwitch
* Called by StreamingEngine when the Period is set up and switching is
* permitted.
* @property {function(!shaka.util.Error)} onError
* Called when an error occurs. If the error is recoverable (see
* {@link shaka.util.Error}) then the caller may invoke either
* StreamingEngine.switch*() or StreamingEngine.seeked() to attempt recovery.
* @property {function(!Event)} onEvent
* Called when an event occurs that should be sent to the app.
* @property {function()} onManifestUpdate
* Called when an embedded 'emsg' box should trigger a manifest update.
* @property {function()} onSegmentAppended
* Called after a segment is successfully appended to a MediaSource.
* @property {(function()|undefined)} onInitialStreamsSetup
* Optional callback which is called when the initial set of Streams have been
* setup. Intended to be used by tests.
* @property {(function()|undefined)} onStartupComplete
* Optional callback which is called when startup has completed. Intended to
* be used by tests.
*/
shaka.media.StreamingEngine.PlayerInterface;
/**
* @typedef {{
* type: shaka.util.ManifestParserUtils.ContentType,
* stream: shaka.extern.Stream,
* lastStream: ?shaka.extern.Stream,
* lastSegmentReference: shaka.media.SegmentReference,
* restoreStreamAfterTrickPlay: ?shaka.extern.Stream,
* needInitSegment: boolean,
* needPeriodIndex: number,
* endOfStream: boolean,
* performingUpdate: boolean,
* updateTimer: ?number,
* waitingToClearBuffer: boolean,
* waitingToFlushBuffer: boolean,
* clearBufferSafeMargin: number,
* clearingBuffer: boolean,
* recovering: boolean,
* hasError: boolean,
* resumeAt: number
* }}
*
* @description
* Contains the state of a logical stream, i.e., a sequence of segmented data
* for a particular content type. At any given time there is a Stream object
* associated with the state of the logical stream.
*
* @property {shaka.util.ManifestParserUtils.ContentType} type
* The stream's content type, e.g., 'audio', 'video', or 'text'.
* @property {shaka.extern.Stream} stream
* The current Stream.
* @property {?shaka.extern.Stream} lastStream
* The Stream of the last segment that was appended.
* @property {shaka.media.SegmentReference} lastSegmentReference
* The SegmentReference of the last segment that was appended.
* @property {?shaka.extern.Stream} restoreStreamAfterTrickPlay
* The Stream to restore after trick play mode is turned off.
* @property {boolean} needInitSegment
* True indicates that |stream|'s init segment must be inserted before the
* next media segment is appended.
* @property {boolean} endOfStream
* True indicates that the end of the buffer has hit the end of the
* presentation.
* @property {number} needPeriodIndex
* The index of the Period which needs to be buffered.
* @property {boolean} performingUpdate
* True indicates that an update is in progress.
* @property {?number} updateTimer
* A non-null value indicates that an update is scheduled.
* @property {boolean} waitingToClearBuffer
* True indicates that the buffer must be cleared after the current update
* finishes.
* @property {boolean} waitingToFlushBuffer
* True indicates that the buffer must be flushed after it is cleared.
* @property {number} clearBufferSafeMargin
* The amount of buffer to retain when clearing the buffer after the update.
* @property {boolean} clearingBuffer
* True indicates that the buffer is being cleared.
* @property {boolean} recovering
* True indicates that the last segment was not appended because it could not
* fit in the buffer.
* @property {boolean} hasError
* True indicates that the stream has encountered an error and has stopped
* updating.
* @property {number} resumeAt
* An override for the time to start performing updates at. If the playhead
* is behind this time, update_() will still start fetching segments from
* this time. If the playhead is ahead of the time, this field is ignored.
*/
shaka.media.StreamingEngine.MediaState_;
/**
* The fudge factor for the appendWindowStart. By adjusting the window
* backward, we avoid rounding errors that could cause us to remove the keyframe
* at the start of the Period.
*
* NOTE: This was increased as part of the solution to
* https://github.com/google/shaka-player/issues/1281
*
* @const {number}
* @private
*/
shaka.media.StreamingEngine.APPEND_WINDOW_START_FUDGE_ = 0.1;
/**
* The maximum number of segments by which a stream can get ahead of other
* streams.
*
* Introduced to keep StreamingEngine from letting one media type get too far
* ahead of another. For example, audio segments are typically much smaller
* than video segments, so in the time it takes to fetch one video segment, we
* could fetch many audio segments. This doesn't help with buffering, though,
* since the intersection of the two buffered ranges is what counts.
*
* @const {number}
* @private
*/
shaka.media.StreamingEngine.MAX_RUN_AHEAD_SEGMENTS_ = 1;
/** @override */
shaka.media.StreamingEngine.prototype.destroy = function() {
for (let type in this.mediaStates_) {
this.cancelUpdate_(this.mediaStates_[type]);
}
this.playerInterface_ = null;
this.manifest_ = null;
this.setupPeriodPromise_ = null;
this.canSwitchPeriod_ = null;
this.canSwitchStream_ = null;
this.mediaStates_ = null;
this.config_ = null;
this.destroyed_ = true;
return Promise.resolve();
};
/**
* Called by the Player to provide an updated configuration any time it changes.
* Must be called at least once before init().
*
* @param {shaka.extern.StreamingConfiguration} config
*/
shaka.media.StreamingEngine.prototype.configure = function(config) {
this.config_ = config;
// Create separate parameters for backoff during streaming failure.
/** @type {shaka.extern.RetryParameters} */
let failureRetryParams = {
// The term "attempts" includes the initial attempt, plus all retries.
// In order to see a delay, there would have to be at least 2 attempts.
maxAttempts: Math.max(config.retryParameters.maxAttempts, 2),
baseDelay: config.retryParameters.baseDelay,
backoffFactor: config.retryParameters.backoffFactor,
fuzzFactor: config.retryParameters.fuzzFactor,
timeout: 0, // irrelevant
};
// We don't want to ever run out of attempts. The application should be
// allowed to retry streaming infinitely if it wishes.
let autoReset = true;
this.failureCallbackBackoff_ =
new shaka.net.Backoff(failureRetryParams, autoReset);
};
/**
* Initializes the StreamingEngine.
*
* After this function is called the StreamingEngine will call
* onChooseStreams(p) when it needs to buffer Period p and onCanSwitch() when
* any Stream within that Period may be switched to.
*
* After the StreamingEngine calls onChooseStreams(p) for the first time, it
* will begin setting up the Streams returned from that function and
* subsequently switch to them. However, the StreamingEngine will not begin
* setting up any other Streams until at least one segment from each of the
* initial set of Streams has been buffered (this reduces startup latency).
* After the StreamingEngine completes this startup phase it will begin setting
* up each Period's Streams (while buffering in parrallel).
*
* When the StreamingEngine needs to buffer the next Period it will have
* already set up that Period's Streams. So, when the StreamingEngine calls
* onChooseStreams(p) after the first time, the StreamingEngine will
* immediately switch to the Streams returned from that function.
*
* @return {!Promise}
*/
shaka.media.StreamingEngine.prototype.init = function() {
goog.asserts.assert(this.config_,
'StreamingEngine configure() must be called before init()!');
// Determine which Period we must buffer.
let playheadTime = this.playerInterface_.playhead.getTime();
let needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
// Get the initial set of Streams.
let initialStreams = this.playerInterface_.onChooseStreams(
this.manifest_.periods[needPeriodIndex]);
if (!initialStreams.variant && !initialStreams.text) {
shaka.log.error('init: no Streams chosen');
return Promise.reject(new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INVALID_STREAMS_CHOSEN));
}
// Setup the initial set of Streams and then begin each update cycle. After
// startup completes onUpdate_() will set up the remaining Periods.
return this.initStreams_(initialStreams).then(function() {
if (this.destroyed_) {
return;
}
shaka.log.debug('init: completed initial Stream setup');
// Subtlety: onInitialStreamsSetup() may call switch() or seeked(), so we
// must schedule an update beforehand so |updateTimer| is set.
if (this.playerInterface_ && this.playerInterface_.onInitialStreamsSetup) {
shaka.log.v1('init: calling onInitialStreamsSetup()...');
this.playerInterface_.onInitialStreamsSetup();
}
}.bind(this));
};
/**
* Gets the current Period the stream is in. This Period might not be
* initialized yet if canSwitch(period) has not been called yet.
* @return {shaka.extern.Period}
*/
shaka.media.StreamingEngine.prototype.getCurrentPeriod = function() {
let playheadTime = this.playerInterface_.playhead.getTime();
let needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
return this.manifest_.periods[needPeriodIndex];
};
/**
* Gets the Period in which we are currently buffering. This might be different
* from the Period which contains the Playhead.
* @return {?shaka.extern.Period}
*/
shaka.media.StreamingEngine.prototype.getActivePeriod = function() {
goog.asserts.assert(this.mediaStates_, 'Must be initialized');
const ContentType = shaka.util.ManifestParserUtils.ContentType;
let anyMediaState = this.mediaStates_[ContentType.VIDEO] ||
this.mediaStates_[ContentType.AUDIO];
return anyMediaState ?
this.manifest_.periods[anyMediaState.needPeriodIndex] : null;
};
/**
* Get the active audio stream. Returns null if there is no audio streaming.
* @return {?shaka.extern.Stream}
*/
shaka.media.StreamingEngine.prototype.getActiveAudio = function() {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
return this.getStream_(ContentType.AUDIO);
};
/**
* Get the active video stream. Returns null if there is no video streaming.
* @return {?shaka.extern.Stream}
*/
shaka.media.StreamingEngine.prototype.getActiveVideo = function() {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
return this.getStream_(ContentType.VIDEO);
};
/**
* Get the active text stream. Returns null if there is no text streaming.
* @return {?shaka.extern.Stream}
*/
shaka.media.StreamingEngine.prototype.getActiveText = function() {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
return this.getStream_(ContentType.TEXT);
};
/**
* Get the active stream for the given type. Returns null if there is no stream
* for the given type.
* @param {shaka.util.ManifestParserUtils.ContentType} type
* @return {?shaka.extern.Stream}
* @private
*/
shaka.media.StreamingEngine.prototype.getStream_ = function(type) {
goog.asserts.assert(this.mediaStates_, 'Must be initialized');
let state = this.mediaStates_[type];
if (state) {
// Don't tell the caller about trick play streams. If we're in trick
// play, return the stream we will go back to after we exit trick play.
return state.restoreStreamAfterTrickPlay || state.stream;
} else {
return null;
}
};
/**
* Notifies StreamingEngine that a new text stream was added to the manifest.
* This initializes the given stream. This returns a Promise that resolves when
* the stream has been set up, and a media state has been created.
*
* @param {shaka.extern.Stream} stream
* @param {boolean} createMediaState
* @return {!Promise}
*/
shaka.media.StreamingEngine.prototype.loadNewTextStream = function(
stream, createMediaState) {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
// Clear MediaSource's buffered text, so that the new text stream will
// properly replace the old buffered text.
this.playerInterface_.mediaSourceEngine.clear(ContentType.TEXT);
// Since setupStreams_() is async, if the user hides/shows captions quickly,
// there would be a race condition that a new text media state is created
// but the old media state is not yet deleted.
// The Sequence Id is to avoid that risk condition.
this.textStreamSequenceId_++;
this.unloadingTextStream_ = false;
let currentSequenceId = this.textStreamSequenceId_;
let mediaSourceEngine = this.playerInterface_.mediaSourceEngine;
return mediaSourceEngine.init({text: stream}, /** forceTansmuxTS */ false)
.then(() => {
return this.setupStreams_([stream]);
}).then(() => {
if (this.destroyed_) {
return;
}
if (createMediaState &&
(this.textStreamSequenceId_ == currentSequenceId) &&
!this.mediaStates_[ContentType.TEXT] && !this.unloadingTextStream_) {
let playheadTime = this.playerInterface_.playhead.getTime();
let needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
this.mediaStates_[ContentType.TEXT] =
this.createMediaState_(stream, needPeriodIndex);
this.scheduleUpdate_(this.mediaStates_[ContentType.TEXT], 0);
}
});
};
/**
* Stop fetching text stream when the user chooses to hide the captions.
*/
shaka.media.StreamingEngine.prototype.unloadTextStream = function() {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
this.unloadingTextStream_ = true;
if (this.mediaStates_[ContentType.TEXT]) {
this.cancelUpdate_(this.mediaStates_[ContentType.TEXT]);
delete this.mediaStates_[ContentType.TEXT];
}
};
/**
* Set trick play on or off.
* If trick play is on, related trick play streams will be used when possible.
* @param {boolean} on
*/
shaka.media.StreamingEngine.prototype.setTrickPlay = function(on) {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
let mediaState = this.mediaStates_[ContentType.VIDEO];
if (!mediaState) return;
let stream = mediaState.stream;
if (!stream) return;
shaka.log.debug('setTrickPlay', on);
if (on) {
let trickModeVideo = stream.trickModeVideo;
if (!trickModeVideo) return; // Can't engage trick play.
let normalVideo = mediaState.restoreStreamAfterTrickPlay;
if (normalVideo) return; // Already in trick play.
shaka.log.debug('Engaging trick mode stream', trickModeVideo);
this.switchInternal_(trickModeVideo, false, 0);
mediaState.restoreStreamAfterTrickPlay = stream;
} else {
let normalVideo = mediaState.restoreStreamAfterTrickPlay;
if (!normalVideo) return;
shaka.log.debug('Restoring non-trick-mode stream', normalVideo);
mediaState.restoreStreamAfterTrickPlay = null;
this.switchInternal_(normalVideo, true, 0);
}
};
/**
* @param {shaka.extern.Variant} variant
* @param {boolean} clearBuffer
* @param {number} safeMargin
*/
shaka.media.StreamingEngine.prototype.switchVariant =
function(variant, clearBuffer, safeMargin) {
if (variant.video) {
this.switchInternal_(variant.video, clearBuffer, safeMargin);
}
if (variant.audio) {
this.switchInternal_(variant.audio, clearBuffer, safeMargin);
}
};
/**
* @param {shaka.extern.Stream} textStream
*/
shaka.media.StreamingEngine.prototype.switchTextStream = function(textStream) {
goog.asserts.assert(textStream && textStream.type == 'text',
'Wrong stream type passed to switchTextStream!');
this.switchInternal_(textStream, /* clearBuffer */ true, /* safeMargin */ 0);
};
/**
* Switches to the given Stream. |stream| may be from any Variant or any Period.
*
* @param {shaka.extern.Stream} stream
* @param {boolean} clearBuffer
* @param {number} safeMargin
* @private
*/
shaka.media.StreamingEngine.prototype.switchInternal_ = function(
stream, clearBuffer, safeMargin) {
const ContentType = shaka.util.ManifestParserUtils.ContentType;
let mediaState = this.mediaStates_[/** @type {!ContentType} */(stream.type)];
if (!mediaState && stream.type == ContentType.TEXT &&
this.config_.ignoreTextStreamFailures) {
this.loadNewTextStream(stream, /* createMediaState */ true);
return;
}
goog.asserts.assert(mediaState, 'switch: expected mediaState to exist');
if (!mediaState) return;
// If we are selecting a stream from a different Period, then we need to
// handle a Period transition. Simply ignore the given stream, assuming that
// Player will select the same track in onChooseStreams.
let periodIndex = this.findPeriodContainingStream_(stream);
if (clearBuffer && periodIndex != mediaState.needPeriodIndex) {
shaka.log.debug('switch: switching to stream in another Period; clearing ' +
'buffer and changing Periods');
// handlePeriodTransition_ will be called on the next update because the
// current Period won't match the playhead Period.
this.clearAllBuffers_();
return;
}
if (mediaState.restoreStreamAfterTrickPlay) {
shaka.log.debug('switch during trick play mode', stream);
// Already in trick play mode, so stick with trick mode tracks if possible.
if (stream.trickModeVideo) {
// Use the trick mode stream, but revert to the new selection later.
mediaState.restoreStreamAfterTrickPlay = stream;
stream = stream.trickModeVideo;
shaka.log.debug('switch found trick play stream', stream);
} else {
// There is no special trick mode video for this stream!
mediaState.restoreStreamAfterTrickPlay = null;
shaka.log.debug('switch found no special trick play stream');
}
}
// Ensure the Period is ready.
let canSwitchRecord = this.canSwitchPeriod_[periodIndex];
goog.asserts.assert(
canSwitchRecord && canSwitchRecord.resolved,
'switch: expected Period ' + periodIndex + ' to be ready');
if (!canSwitchRecord || !canSwitchRecord.resolved) return;
// Sanity check. If the Period is ready then the Stream should be ready too.
canSwitchRecord = this.canSwitchStream_[stream.id];
goog.asserts.assert(canSwitchRecord && canSwitchRecord.resolved,
'switch: expected Stream ' + stream.id + ' to be ready');
if (!canSwitchRecord || !canSwitchRecord.resolved) return;
if (mediaState.stream == stream) {
let streamTag = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.debug('switch: Stream ' + streamTag + ' already active');
return;
}
if (stream.type == ContentType.TEXT) {
// Mime types are allowed to change for text streams.
// Reinitialize the text parser, but only if we are going to fetch the init
// segment again.
let fullMimeType = shaka.util.MimeUtils.getFullType(
stream.mimeType, stream.codecs);
this.playerInterface_.mediaSourceEngine.reinitText(fullMimeType);
}
mediaState.stream = stream;
mediaState.needInitSegment = true;
let streamTag = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.debug('switch: switching to Stream ' + streamTag);
if (clearBuffer) {
if (mediaState.clearingBuffer) {
// We are already going to clear the buffer, but make sure it is also
// flushed.
mediaState.waitingToFlushBuffer = true;
} else if (mediaState.performingUpdate) {
// We are performing an update, so we have to wait until it's finished.
// onUpdate_() will call clearBuffer_() when the update has finished.
// We need to save the safe margin because its value will be needed when
// clearing the buffer after the update.
mediaState.waitingToClearBuffer = true;
mediaState.clearBufferSafeMargin = safeMargin;
mediaState.waitingToFlushBuffer = true;
} else {
// Cancel the update timer, if any.
this.cancelUpdate_(mediaState);
// Clear right away.
this.clearBuffer_(mediaState, /* flush */ true, safeMargin);
}
}
};
/**
* Notifies the StreamingEngine that the playhead has moved to a valid time
* within the presentation timeline.
*/
shaka.media.StreamingEngine.prototype.seeked = function() {
goog.asserts.assert(this.mediaStates_, 'Must not be destroyed');
let playheadTime = this.playerInterface_.playhead.getTime();
const smallGapLimit = this.config_.smallGapLimit;
let isAllBuffered = Object.keys(this.mediaStates_).every(function(type) {
return this.playerInterface_.mediaSourceEngine.isBuffered(
type, playheadTime, smallGapLimit);
}.bind(this));
// Only treat this as a buffered seek if every media state has a buffer. For
// example, if we have buffered text but not video, we should still clear
// every buffer so all media states need the same Period.
if (isAllBuffered) {
shaka.log.debug(
'(all): seeked: buffered seek: playheadTime=' + playheadTime);
return;
}
// This was an unbuffered seek for at least one stream, so clear all buffers.
// Don't clear only some of the buffers because we can become stalled since
// the media states are waiting for different Periods.
shaka.log.debug('(all): seeked: unbuffered seek: clearing all buffers');
this.clearAllBuffers_();
};
/**
* Clears the buffer for every stream. Unlike clearBuffer_, this will handle
* cases where a MediaState is performing an update. After this runs, every
* MediaState will have a pending update.
* @private
*/
shaka.media.StreamingEngine.prototype.clearAllBuffers_ = function() {
for (let type in this.mediaStates_) {
let mediaState = this.mediaStates_[type];
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
if (mediaState.clearingBuffer) {
// We're already clearing the buffer, so we don't need to clear the
// buffer again.
shaka.log.debug(logPrefix, 'clear: already clearing the buffer');
continue;
}
if (mediaState.waitingToClearBuffer) {
// May not be performing an update, but an update will still happen.
// See: https://github.com/google/shaka-player/issues/334
shaka.log.debug(logPrefix, 'clear: already waiting');
continue;
}
if (mediaState.performingUpdate) {
// We are performing an update, so we have to wait until it's finished.
// onUpdate_() will call clearBuffer_() when the update has finished.
shaka.log.debug(logPrefix, 'clear: currently updating');
mediaState.waitingToClearBuffer = true;
// We can set the offset to zero to remember that this was a call to
// clearAllBuffers.
mediaState.clearBufferSafeMargin = 0;
continue;
}
if (this.playerInterface_.mediaSourceEngine.bufferStart(type) == null) {
// Nothing buffered.
shaka.log.debug(logPrefix, 'clear: nothing buffered');
if (mediaState.updateTimer == null) {
// Note: an update cycle stops when we buffer to the end of the
// presentation or Period, or when we raise an error.
this.scheduleUpdate_(mediaState, 0);
}
continue;
}
// An update may be scheduled, but we can just cancel it and clear the
// buffer right away. Note: clearBuffer_() will schedule the next update.
shaka.log.debug(logPrefix, 'clear: handling right now');
this.cancelUpdate_(mediaState);
this.clearBuffer_(mediaState, /* flush */ false, 0);
}
};
/**
* Initializes the given streams and media states if required. This will
* schedule updates for the given types.
*
* @param {shaka.media.StreamingEngine.ChosenStreams} chosenStreams
* @param {number=} resumeAt
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.initStreams_ = function(
chosenStreams, resumeAt) {
goog.asserts.assert(this.config_,
'StreamingEngine configure() must be called before init()!');
// Determine which Period we must buffer.
let playheadTime = this.playerInterface_.playhead.getTime();
let needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
// Init/re-init MediaSourceEngine. Note that a re-init is only valid for text.
const ContentType = shaka.util.ManifestParserUtils.ContentType;
/** @type {!Object.<!ContentType, shaka.extern.Stream>} */
let streamsByType = {};
/** @type {!Array.<shaka.extern.Stream>} */
let streams = [];
if (chosenStreams.variant && chosenStreams.variant.audio) {
streamsByType[ContentType.AUDIO] = chosenStreams.variant.audio;
streams.push(chosenStreams.variant.audio);
}
if (chosenStreams.variant && chosenStreams.variant.video) {
streamsByType[ContentType.VIDEO] = chosenStreams.variant.video;
streams.push(chosenStreams.variant.video);
}
if (chosenStreams.text) {
streamsByType[ContentType.TEXT] = chosenStreams.text;
streams.push(chosenStreams.text);
}
// Init MediaSourceEngine.
let mediaSourceEngine = this.playerInterface_.mediaSourceEngine;
let forceTransmuxTS = this.config_.forceTransmuxTS;
return mediaSourceEngine.init(streamsByType, forceTransmuxTS).then(() => {
if (this.destroyed_) {
return;
}
this.setDuration_();
// Setup the initial set of Streams and then begin each update cycle. After
// startup completes onUpdate_() will set up the remaining Periods.
return this.setupStreams_(streams);
}).then(() => {
if (this.destroyed_) {
return;
}
for (let type in streamsByType) {
let stream = streamsByType[type];
if (!this.mediaStates_[type]) {
this.mediaStates_[type] =
this.createMediaState_(stream, needPeriodIndex, resumeAt);
this.scheduleUpdate_(this.mediaStates_[type], 0);
}
}
});
};
/**
* Creates a media state.
*
* @param {shaka.extern.Stream} stream
* @param {number} needPeriodIndex
* @param {number=} resumeAt
* @return {shaka.media.StreamingEngine.MediaState_}
* @private
*/
shaka.media.StreamingEngine.prototype.createMediaState_ = function(
stream, needPeriodIndex, resumeAt) {
return /** @type {shaka.media.StreamingEngine.MediaState_} */ ({
stream: stream,
type: stream.type,
lastStream: null,
lastSegmentReference: null,
restoreStreamAfterTrickPlay: null,
needInitSegment: true,
needPeriodIndex: needPeriodIndex,
endOfStream: false,
performingUpdate: false,
updateTimer: null,
waitingToClearBuffer: false,
clearBufferSafeMargin: 0,
waitingToFlushBuffer: false,
clearingBuffer: false,
recovering: false,
hasError: false,
resumeAt: resumeAt || 0,
});
};
/**
* Sets up the given Period if necessary. Calls onError() if an error occurs.
*
* @param {number} periodIndex The Period's index.
* @return {!Promise} A Promise which resolves when the given Period is set up.
* @private
*/
shaka.media.StreamingEngine.prototype.setupPeriod_ = function(periodIndex) {
const Functional = shaka.util.Functional;
let canSwitchRecord = this.canSwitchPeriod_[periodIndex];
if (canSwitchRecord) {
shaka.log.debug(
'(all) Period ' + periodIndex + ' is being or has been set up');
goog.asserts.assert(canSwitchRecord.promise, 'promise must not be null');
return canSwitchRecord.promise;
}
shaka.log.debug('(all) setting up Period ' + periodIndex);
canSwitchRecord = {
promise: new shaka.util.PublicPromise(),
resolved: false,
};
this.canSwitchPeriod_[periodIndex] = canSwitchRecord;
let streams = this.manifest_.periods[periodIndex].variants
.map(function(variant) {
const result = shaka.util.StreamUtils.getVariantStreams(variant);
if (variant.video && variant.video.trickModeVideo) {
result.push(variant.video.trickModeVideo);
}
return result;
})
.reduce(Functional.collapseArrays, [])
.filter(Functional.isNotDuplicate);
// Add text streams
streams.push.apply(streams, this.manifest_.periods[periodIndex].textStreams);
// Serialize Period set up.
this.setupPeriodPromise_ = this.setupPeriodPromise_.then(function() {
if (this.destroyed_) return;
return this.setupStreams_(streams);
}.bind(this)).then(function() {
if (this.destroyed_) return;
this.canSwitchPeriod_[periodIndex].promise.resolve();
this.canSwitchPeriod_[periodIndex].resolved = true;
shaka.log.v1('(all) setup Period ' + periodIndex);
}.bind(this)).catch(function(error) {
if (this.destroyed_) return;
this.canSwitchPeriod_[periodIndex].promise.catch(() => {});
this.canSwitchPeriod_[periodIndex].promise.reject();
delete this.canSwitchPeriod_[periodIndex];
shaka.log.warning('(all) failed to setup Period ' + periodIndex);
this.playerInterface_.onError(error);
// Don't stop other Periods from being set up.
}.bind(this));
return canSwitchRecord.promise;
};
/**
* Sets up the given Streams if necessary. Does NOT call onError() if an
* error occurs.
*
* @param {!Array.<!shaka.extern.Stream>} streams
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.setupStreams_ = function(streams) {
// Make sure that all the streams have unique ids.
// (Duplicate ids will cause the player to hang).
let uniqueStreamIds = streams.map(function(s) { return s.id; })
.filter(shaka.util.Functional.isNotDuplicate);
goog.asserts.assert(uniqueStreamIds.length == streams.length,
'streams should have unique ids');
// Parallelize Stream set up.
let async = [];
for (let i = 0; i < streams.length; ++i) {
let stream = streams[i];
let canSwitchRecord = this.canSwitchStream_[stream.id];
if (canSwitchRecord) {
shaka.log.debug(
'(all) Stream ' + stream.id + ' is being or has been set up');
async.push(canSwitchRecord.promise);
} else {
shaka.log.v1('(all) setting up Stream ' + stream.id);
this.canSwitchStream_[stream.id] = {
promise: new shaka.util.PublicPromise(),
resolved: false,
};
async.push(stream.createSegmentIndex());
}
}
return Promise.all(async).then(function() {
if (this.destroyed_) return;
for (let i = 0; i < streams.length; ++i) {
let stream = streams[i];
let canSwitchRecord = this.canSwitchStream_[stream.id];
if (!canSwitchRecord.resolved) {
canSwitchRecord.promise.resolve();
canSwitchRecord.resolved = true;
shaka.log.v1('(all) setup Stream ' + stream.id);
}
}
}.bind(this)).catch(function(error) {
if (this.destroyed_) return;
for (let i = 0; i < streams.length; i++) {
this.canSwitchStream_[streams[i].id].promise.catch(() => {});
this.canSwitchStream_[streams[i].id].promise.reject();
delete this.canSwitchStream_[streams[i].id];
}
return Promise.reject(error);
}.bind(this));
};
/**
* Sets the MediaSource's duration.
* @private
*/
shaka.media.StreamingEngine.prototype.setDuration_ = function() {
let duration = this.manifest_.presentationTimeline.getDuration();
if (duration < Infinity) {
this.playerInterface_.mediaSourceEngine.setDuration(duration);
} else {
// Not all platforms support infinite durations, so set a finite duration
// so we can append segments and so the user agent can seek.
this.playerInterface_.mediaSourceEngine.setDuration(Math.pow(2, 32));
}
};
/**
* Called when |mediaState|'s update timer has expired.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @private
*/
shaka.media.StreamingEngine.prototype.onUpdate_ = function(mediaState) {
const MapUtils = shaka.util.MapUtils;
if (this.destroyed_) return;
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
// Sanity check.
goog.asserts.assert(
!mediaState.performingUpdate && (mediaState.updateTimer != null),
logPrefix + ' unexpected call to onUpdate_()');
if (mediaState.performingUpdate || (mediaState.updateTimer == null)) return;
goog.asserts.assert(
!mediaState.clearingBuffer,
logPrefix + ' onUpdate_() should not be called when clearing the buffer');
if (mediaState.clearingBuffer) return;
mediaState.updateTimer = null;
// Handle pending buffer clears.
if (mediaState.waitingToClearBuffer) {
// Note: clearBuffer_() will schedule the next update.
shaka.log.debug(logPrefix, 'skipping update and clearing the buffer');
this.clearBuffer_(
mediaState, mediaState.waitingToFlushBuffer,
mediaState.clearBufferSafeMargin);
return;
}
// Update the MediaState.
try {
let delay = this.update_(mediaState);
if (delay != null) {
this.scheduleUpdate_(mediaState, delay);
mediaState.hasError = false;
}
} catch (error) {
this.handleStreamingError_(error);
return;
}
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
let mediaStates = MapUtils.values(this.mediaStates_);
// Check if we've buffered to the end of the Period.
this.handlePeriodTransition_(mediaState);
// Check if we've buffered to the end of the presentation.
if (mediaStates.every(function(ms) { return ms.endOfStream; })) {
shaka.log.v1(logPrefix, 'calling endOfStream()...');
this.playerInterface_.mediaSourceEngine.endOfStream().then(function() {
if (this.destroyed_) {
return;
}
// If the media segments don't reach the end, then we need to update the
// timeline duration to match the final media duration to avoid buffering
// forever at the end. We should only do this if the duration needs to
// shrink. Growing it by less than 1ms can actually cause buffering on
// replay, as in https://github.com/google/shaka-player/issues/979
let duration = this.playerInterface_.mediaSourceEngine.getDuration();
if (duration < this.manifest_.presentationTimeline.getDuration()) {
this.manifest_.presentationTimeline.setDuration(duration);
}
}.bind(this));
}
};
/**
* Updates the given MediaState.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @return {?number} The number of seconds to wait until updating again or
* null if another update does not need to be scheduled.
* @throws {!shaka.util.Error} if an error occurs.
* @private
*/
shaka.media.StreamingEngine.prototype.update_ = function(mediaState) {
goog.asserts.assert(this.manifest_, 'manifest_ should not be null');
goog.asserts.assert(this.config_, 'config_ should not be null');
const MapUtils = shaka.util.MapUtils;
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
// Compute how far we've buffered ahead of the playhead.
let playheadTime = this.playerInterface_.playhead.getTime();
// Get the next timestamp we need.
let timeNeeded = this.getTimeNeeded_(mediaState, playheadTime);
shaka.log.v2(logPrefix, 'timeNeeded=' + timeNeeded);
let currentPeriodIndex = this.findPeriodContainingStream_(mediaState.stream);
let needPeriodIndex = this.findPeriodContainingTime_(timeNeeded);
// Get the amount of content we have buffered, accounting for drift. This
// is only used to determine if we have meet the buffering goal. This should
// be the same method that PlayheadObserver uses.
let bufferedAhead = this.playerInterface_.mediaSourceEngine.bufferedAheadOf(
mediaState.type, playheadTime);
shaka.log.v2(logPrefix,
'update_:',
'playheadTime=' + playheadTime,
'bufferedAhead=' + bufferedAhead);
let unscaledBufferingGoal = Math.max(
this.manifest_.minBufferTime || 0,
this.config_.rebufferingGoal,
this.config_.bufferingGoal);
let scaledBufferingGoal = unscaledBufferingGoal * this.bufferingGoalScale_;
// Check if we've buffered to the end of the presentation.
if (timeNeeded >= this.manifest_.presentationTimeline.getDuration()) {
// We shouldn't rebuffer if the playhead is close to the end of the
// presentation.
shaka.log.debug(logPrefix, 'buffered to end of presentation');
mediaState.endOfStream = true;
return null;
}
mediaState.endOfStream = false;
// Check if we've buffered to the end of the Period. This should be done
// before checking segment availability because the new Period may become
// available once it's switched to. Note that we don't use the non-existence
// of SegmentReferences as an indicator to determine Period boundaries
// because a SegmentIndex can provide SegmentReferences outside its Period.
mediaState.needPeriodIndex = needPeriodIndex;
if (needPeriodIndex != currentPeriodIndex) {
shaka.log.debug(logPrefix,
'need Period ' + needPeriodIndex,
'playheadTime=' + playheadTime,
'timeNeeded=' + timeNeeded,
'currentPeriodIndex=' + currentPeriodIndex);
return null;
}
// If we've buffered to the buffering goal then schedule an update.
if (bufferedAhead >= scaledBufferingGoal) {
shaka.log.v2(logPrefix, 'buffering goal met');
// Do not try to predict the next update. Just poll twice every second.
// The playback rate can change at any time, so any prediction we make now
// could be terribly invalid soon.
return 0.5;
}
let bufferEnd =
this.playerInterface_.mediaSourceEngine.bufferEnd(mediaState.type);
let reference = this.getSegmentReferenceNeeded_(
mediaState, playheadTime, bufferEnd, currentPeriodIndex);
if (!reference) {
// The segment could not be found, does not exist, or is not available. In
// any case just try again... if the manifest is incomplete or is not being
// updated then we'll idle forever; otherwise, we'll end up getting a
// SegmentReference eventually.
return 1;
}
// Do not let any one stream get far ahead of any other.
let minTimeNeeded = Infinity;
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
const mediaStates = MapUtils.values(this.mediaStates_);
mediaStates.forEach((otherState) => {
const timeNeeded = this.getTimeNeeded_(otherState, playheadTime);
minTimeNeeded = Math.min(minTimeNeeded, timeNeeded);
});
const maxSegmentDuration =
this.manifest_.presentationTimeline.getMaxSegmentDuration();
const maxRunAhead =
maxSegmentDuration * shaka.media.StreamingEngine.MAX_RUN_AHEAD_SEGMENTS_;
if (timeNeeded >= minTimeNeeded + maxRunAhead) {
// Wait and give other media types time to catch up to this one.
// For example, let video buffering catch up to audio buffering before
// fetching another audio segment.
return 1;
}
mediaState.resumeAt = 0;
this.fetchAndAppend_(mediaState, playheadTime, currentPeriodIndex, reference);
return null;
};
/**
* Gets the next timestamp needed. Returns the playhead's position if the
* buffer is empty; otherwise, returns the time at which the last segment
* appended ends.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} playheadTime
* @return {number} The next timestamp needed.
* @throws {!shaka.util.Error} if the buffer is inconsistent with our
* expectations.
* @private
*/
shaka.media.StreamingEngine.prototype.getTimeNeeded_ = function(
mediaState, playheadTime) {
// Get the next timestamp we need. We must use |lastSegmentReference|
// to determine this and not the actual buffer for two reasons:
// 1. Actual segments end slightly before their advertised end times, so
// the next timestamp we need is actually larger than |bufferEnd|.
// 2. There may be drift (the timestamps in the segments are ahead/behind
// of the timestamps in the manifest), but we need drift-free times when
// comparing times against presentation and Period boundaries.
if (!mediaState.lastStream || !mediaState.lastSegmentReference) {
return Math.max(playheadTime, mediaState.resumeAt);
}
let lastPeriodIndex =
this.findPeriodContainingStream_(mediaState.lastStream);
let lastPeriod = this.manifest_.periods[lastPeriodIndex];
return lastPeriod.startTime + mediaState.lastSegmentReference.endTime;
};
/**
* Gets the SegmentReference of the next segment needed.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} playheadTime
* @param {?number} bufferEnd
* @param {number} currentPeriodIndex
* @return {shaka.media.SegmentReference} The SegmentReference of the
* next segment needed. Returns null if a segment could not be found, does not
* exist, or is not available.
* @private
*/
shaka.media.StreamingEngine.prototype.getSegmentReferenceNeeded_ = function(
mediaState, playheadTime, bufferEnd, currentPeriodIndex) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
if (mediaState.lastSegmentReference &&
mediaState.stream == mediaState.lastStream) {
// Something is buffered from the same Stream.
let position = mediaState.lastSegmentReference.position + 1;
shaka.log.v2(logPrefix, 'next position known:', 'position=' + position);
return this.getSegmentReferenceIfAvailable_(
mediaState, currentPeriodIndex, position);
}
let position;
if (mediaState.lastSegmentReference) {
// Something is buffered from another Stream.
goog.asserts.assert(mediaState.lastStream, 'lastStream should not be null');
shaka.log.v1(logPrefix, 'next position unknown: another Stream buffered');
let lastPeriodIndex =
this.findPeriodContainingStream_(mediaState.lastStream);
let lastPeriod = this.manifest_.periods[lastPeriodIndex];
position = this.lookupSegmentPosition_(
mediaState,
lastPeriod.startTime + mediaState.lastSegmentReference.endTime,
currentPeriodIndex);
} else {
// Either nothing is buffered, or we have cleared part of the buffer. If
// we still have some buffered, use that time to find the segment, otherwise
// start at the playhead time.
goog.asserts.assert(!mediaState.lastStream, 'lastStream should be null');
shaka.log.v1(logPrefix, 'next position unknown: nothing buffered');
position = this.lookupSegmentPosition_(
mediaState, bufferEnd || playheadTime, currentPeriodIndex);
}
if (position == null) {
return null;
}
let reference = null;
if (bufferEnd == null) {
// If there's positive drift then we need to get the previous segment;
// however, we don't actually know how much drift there is, so we must
// unconditionally get the previous segment. If it turns out that there's
// non-positive drift then we'll just end up buffering beind the playhead a
// little more than we needed.
let optimalPosition = Math.max(0, position - 1);
reference = this.getSegmentReferenceIfAvailable_(
mediaState, currentPeriodIndex, optimalPosition);
}
return reference ||
this.getSegmentReferenceIfAvailable_(
mediaState, currentPeriodIndex, position);
};
/**
* Looks up the position of the segment containing the given timestamp.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} presentationTime The timestamp needed, relative to the
* start of the presentation.
* @param {number} currentPeriodIndex
* @return {?number} A segment position, or null if a segment was not be found.
* @private
*/
shaka.media.StreamingEngine.prototype.lookupSegmentPosition_ = function(
mediaState, presentationTime, currentPeriodIndex) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
let currentPeriod = this.manifest_.periods[currentPeriodIndex];
shaka.log.debug(logPrefix,
'looking up segment:',
'presentationTime=' + presentationTime,
'currentPeriod.startTime=' + currentPeriod.startTime);
let lookupTime = Math.max(0, presentationTime - currentPeriod.startTime);
let position = mediaState.stream.findSegmentPosition(lookupTime);
if (position == null) {
shaka.log.warning(logPrefix,
'cannot find segment:',
'currentPeriod.startTime=' + currentPeriod.startTime,
'lookupTime=' + lookupTime);
}
return position;
};
/**
* Gets the SegmentReference at the given position if it's available.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} currentPeriodIndex
* @param {number} position
* @return {shaka.media.SegmentReference}
*
* @private
*/
shaka.media.StreamingEngine.prototype.getSegmentReferenceIfAvailable_ =
function(mediaState, currentPeriodIndex, position) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
let currentPeriod = this.manifest_.periods[currentPeriodIndex];
let reference = mediaState.stream.getSegmentReference(position);
if (!reference) {
shaka.log.v1(logPrefix,
'segment does not exist:',
'currentPeriod.startTime=' + currentPeriod.startTime,
'position=' + position);
return null;
}
let timeline = this.manifest_.presentationTimeline;
let availabilityStart = timeline.getSegmentAvailabilityStart();
let availabilityEnd = timeline.getSegmentAvailabilityEnd();
if ((currentPeriod.startTime + reference.endTime < availabilityStart) ||
(currentPeriod.startTime + reference.startTime > availabilityEnd)) {
shaka.log.v2(logPrefix,
'segment is not available:',
'currentPeriod.startTime=' + currentPeriod.startTime,
'reference.startTime=' + reference.startTime,
'reference.endTime=' + reference.endTime,
'availabilityStart=' + availabilityStart,
'availabilityEnd=' + availabilityEnd);
return null;
}
return reference;
};
/**
* Fetches and appends the given segment. Sets up the given MediaState's
* associated SourceBuffer and evicts segments if either are required
* beforehand. Schedules another update after completing successfully.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} playheadTime
* @param {number} currentPeriodIndex The index of the current Period.
* @param {!shaka.media.SegmentReference} reference
* @private
*/
shaka.media.StreamingEngine.prototype.fetchAndAppend_ = function(
mediaState, playheadTime, currentPeriodIndex, reference) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
const ContentType = shaka.util.ManifestParserUtils.ContentType;
let currentPeriod = this.manifest_.periods[currentPeriodIndex];
shaka.log.v1(logPrefix,
'fetchAndAppend_:',
'playheadTime=' + playheadTime,
'currentPeriod.startTime=' + currentPeriod.startTime,
'reference.position=' + reference.position,
'reference.startTime=' + reference.startTime,
'reference.endTime=' + reference.endTime);
// Subtlety: The playhead may move while asynchronous update operations are
// in progress, so we should avoid calling playhead.getTime() in any
// callbacks. Furthermore, switch() may be called at any time, so we should
// also avoid using mediaState.stream or mediaState.needInitSegment in any
// callbacks.
let stream = mediaState.stream;
// Compute the append window.
let duration = this.manifest_.presentationTimeline.getDuration();
let followingPeriod = this.manifest_.periods[currentPeriodIndex + 1];
// Rounding issues can cause us to remove the first frame of the Period, so
// reduce the start time slightly.
let windowFudge = shaka.media.StreamingEngine.APPEND_WINDOW_START_FUDGE_;
let appendWindowStart = Math.max(0, currentPeriod.startTime - windowFudge);
let appendWindowEnd = followingPeriod ? followingPeriod.startTime : duration;
goog.asserts.assert(
reference.startTime <= appendWindowEnd,
logPrefix + ' segment should start before append window end');
let initSourceBuffer = this.initSourceBuffer_(
mediaState, currentPeriodIndex, appendWindowStart, appendWindowEnd);
mediaState.performingUpdate = true;
// We may set |needInitSegment| to true in switch(), so set it to false here,
// since we want it to remain true if switch() is called.
mediaState.needInitSegment = false;
shaka.log.v2(logPrefix, 'fetching segment');
let fetchSegment = this.fetch_(reference);
Promise.all([initSourceBuffer, fetchSegment]).then(function(results) {
if (this.destroyed_ || this.fatalError_) return;
return this.append_(mediaState,
playheadTime,
currentPeriod,
stream,
reference,
results[1]);
}.bind(this)).then(function() {
if (this.destroyed_ || this.fatalError_) return;
mediaState.performingUpdate = false;
mediaState.recovering = false;
if (!mediaState.waitingToClearBuffer) {
this.playerInterface_.onSegmentAppended();
}
// Update right away.
this.scheduleUpdate_(mediaState, 0);
// Subtlety: handleStartup_() calls onStartupComplete() which may call
// switch() or seeked(), so we must schedule an update beforehand so
// |updateTimer| is set.
this.handleStartup_(mediaState, stream);
shaka.log.v1(logPrefix, 'finished fetch and append');
}.bind(this)).catch(function(error) {
if (this.destroyed_ || this.fatalError_) return;
goog.asserts.assert(error instanceof shaka.util.Error,
'Should only receive a Shaka error');
mediaState.performingUpdate = false;
if (mediaState.type == ContentType.TEXT &&
this.config_.ignoreTextStreamFailures) {
if (error.code == shaka.util.Error.Code.BAD_HTTP_STATUS) {
shaka.log.warning(logPrefix,
'Text stream failed to download. Proceeding without it.');
} else {
shaka.log.warning(logPrefix,
'Text stream failed to parse. Proceeding without it.');
}
delete this.mediaStates_[ContentType.TEXT];
} else if (error.code == shaka.util.Error.Code.QUOTA_EXCEEDED_ERROR) {
this.handleQuotaExceeded_(mediaState, error);
} else {
shaka.log.error(logPrefix, 'failed fetch and append: code=' + error.code);
mediaState.hasError = true;
error.severity = shaka.util.Error.Severity.CRITICAL;
this.handleStreamingError_(error);
}
}.bind(this));
};
/**
* Clear per-stream error states and retry any failed streams.
* @return {boolean} False if unable to retry.
*/
shaka.media.StreamingEngine.prototype.retry = function() {
if (this.destroyed_) {
shaka.log.error('Unable to retry after StreamingEngine is destroyed!');
return false;
}
if (this.fatalError_) {
shaka.log.error('Unable to retry after StreamingEngine encountered a ' +
'fatal error!');
return false;
}
for (let type in this.mediaStates_) {
let mediaState = this.mediaStates_[type];
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
if (mediaState.hasError) {
shaka.log.info(logPrefix, 'Retrying after failure...');
mediaState.hasError = false;
this.scheduleUpdate_(mediaState, 0.1);
}
}
return true;
};
/**
* Handles a QUOTA_EXCEEDED_ERROR.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {!shaka.util.Error} error
* @private
*/
shaka.media.StreamingEngine.prototype.handleQuotaExceeded_ = function(
mediaState, error) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
// The segment cannot fit into the SourceBuffer. Ideally, MediaSource would
// have evicted old data to accommodate the segment; however, it may have
// failed to do this if the segment is very large, or if it could not find
// a suitable time range to remove.
//
// We can overcome the latter by trying to append the segment again;
// however, to avoid continuous QuotaExceededErrors we must reduce the size
// of the buffer going forward.
//
// If we've recently reduced the buffering goals, wait until the stream
// which caused the first QuotaExceededError recovers. Doing this ensures
// we don't reduce the buffering goals too quickly.
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
let mediaStates = shaka.util.MapUtils.values(this.mediaStates_);
let waitingForAnotherStreamToRecover = mediaStates.some(function(ms) {
return ms != mediaState && ms.recovering;
});
if (!waitingForAnotherStreamToRecover) {
// Reduction schedule: 80%, 60%, 40%, 20%, 16%, 12%, 8%, 4%, fail.
// Note: percentages are used for comparisons to avoid rounding errors.
let percentBefore = Math.round(100 * this.bufferingGoalScale_);
if (percentBefore > 20) {
this.bufferingGoalScale_ -= 0.2;
} else if (percentBefore > 4) {
this.bufferingGoalScale_ -= 0.04;
} else {
shaka.log.error(
logPrefix, 'MediaSource threw QuotaExceededError too many times');
mediaState.hasError = true;
this.fatalError_ = true;
this.playerInterface_.onError(error);
return;
}
let percentAfter = Math.round(100 * this.bufferingGoalScale_);
shaka.log.warning(
logPrefix,
'MediaSource threw QuotaExceededError:',
'reducing buffering goals by ' + (100 - percentAfter) + '%');
mediaState.recovering = true;
} else {
shaka.log.debug(
logPrefix,
'MediaSource threw QuotaExceededError:',
'waiting for another stream to recover...');
}
// QuotaExceededError gets thrown if evication didn't help to make room
// for a segment. We want to wait for a while (4 seconds is just an
// arbitrary number) before updating to give the playhead a chance to
// advance, so we don't immidiately throw again.
this.scheduleUpdate_(mediaState, 4);
};
/**
* Sets the given MediaState's associated SourceBuffer's timestamp offset and
* init segment if either are required. If an error occurs then neither the
* timestamp offset or init segment are unset, since another call to switch()
* will end up superseding them.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} currentPeriodIndex
* @param {number} appendWindowStart
* @param {number} appendWindowEnd
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.initSourceBuffer_ = function(
mediaState, currentPeriodIndex, appendWindowStart, appendWindowEnd) {
if (!mediaState.needInitSegment) {
return Promise.resolve();
}
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
let currentPeriod = this.manifest_.periods[currentPeriodIndex];
// If we need an init segment then the Stream switched, so we've either
// changed bitrates, Periods, or both. If we've changed Periods then we must
// set a new timestamp offset and append window end. Note that by setting
// these values here, we avoid having to co-ordinate ongoing updates, which
// we would have to do if we instead set them in switch().
let timestampOffset =
currentPeriod.startTime - mediaState.stream.presentationTimeOffset;
shaka.log.v1(logPrefix, 'setting timestamp offset to ' + timestampOffset);
shaka.log.v1(logPrefix,
'setting appstart window start to ' + appendWindowStart);
shaka.log.v1(logPrefix, 'setting append window end to ' + appendWindowEnd);
let setStreamProperties =
this.playerInterface_.mediaSourceEngine.setStreamProperties(
mediaState.type, timestampOffset, appendWindowStart, appendWindowEnd);
if (!mediaState.stream.initSegmentReference) {
// The Stream is self initializing.
return setStreamProperties;
}
shaka.log.v1(logPrefix, 'fetching init segment');
let fetchInit = this.fetch_(mediaState.stream.initSegmentReference);
let appendInit = fetchInit.then(function(initSegment) {
if (this.destroyed_) return;
shaka.log.v1(logPrefix, 'appending init segment');
return this.playerInterface_.mediaSourceEngine.appendBuffer(
mediaState.type, initSegment, null /* startTime */, null /* endTime */);
}.bind(this)).catch(function(error) {
mediaState.needInitSegment = true;
return Promise.reject(error);
});
return Promise.all([setStreamProperties, appendInit]);
};
/**
* Appends the given segment and evicts content if required to append.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} playheadTime
* @param {shaka.extern.Period} period
* @param {shaka.extern.Stream} stream
* @param {!shaka.media.SegmentReference} reference
* @param {!ArrayBuffer} segment
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.append_ = function(
mediaState, playheadTime, period, stream, reference, segment) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
if (stream.emsgSchemeIdUris != null && stream.emsgSchemeIdUris.length > 0) {
new shaka.util.Mp4Parser()
.fullBox(
'emsg',
this.parseEMSG_.bind(
this, period, reference, stream.emsgSchemeIdUris))
.parse(segment);
}
return this.evict_(mediaState, playheadTime).then(function() {
if (this.destroyed_) return;
shaka.log.v1(logPrefix, 'appending media segment');
return this.playerInterface_.mediaSourceEngine.appendBuffer(
mediaState.type, segment, reference.startTime, reference.endTime);
}.bind(this)).then(function() {
if (this.destroyed_) return;
shaka.log.v2(logPrefix, 'appended media segment');
// We must use |stream| because switch() may have been called.
mediaState.lastStream = stream;
mediaState.lastSegmentReference = reference;
return Promise.resolve();
}.bind(this));
};
/**
* Parse the EMSG box from a MP4 container.
*
* @param {!shaka.extern.Period} period
* @param {!shaka.media.SegmentReference} reference
* @param {?Array.<string>} emsgSchemeIdUris Array of emsg
* scheme_id_uri for which emsg boxes should be parsed.
* @param {!shaka.extern.ParsedBox} box
* @private
*/
shaka.media.StreamingEngine.prototype.parseEMSG_ = function(
period, reference, emsgSchemeIdUris, box) {
let schemeId = box.reader.readTerminatedString();
// Read the rest of the data.
let value = box.reader.readTerminatedString();
let timescale = box.reader.readUint32();
let presentationTimeDelta = box.reader.readUint32();
let eventDuration = box.reader.readUint32();
let id = box.reader.readUint32();
let messageData = box.reader.readBytes(
box.reader.getLength() - box.reader.getPosition());
let startTime = period.startTime + reference.startTime +
(presentationTimeDelta / timescale);
// See DASH sec. 5.10.3.3.1
// If a DASH client detects an event message box with a scheme that is not
// defined in MPD, the client is expected to ignore it.
if (emsgSchemeIdUris.indexOf(schemeId) != -1) {
// See DASH sec. 5.10.4.1
// A special scheme in DASH used to signal manifest updates.
if (schemeId == 'urn:mpeg:dash:event:2012') {
this.playerInterface_.onManifestUpdate();
} else {
/** @type {shaka.extern.EmsgInfo} */
let emsg = {
startTime: startTime,
endTime: startTime + (eventDuration / timescale),
schemeIdUri: schemeId,
value: value,
timescale: timescale,
presentationTimeDelta: presentationTimeDelta,
eventDuration: eventDuration,
id: id,
messageData: messageData,
};
// Dispatch an event to notify the application about the emsg box.
let event = new shaka.util.FakeEvent('emsg', {'detail': emsg});
this.playerInterface_.onEvent(event);
}
}
};
/**
* Evicts media to meet the max buffer behind limit.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} playheadTime
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.evict_ = function(
mediaState, playheadTime) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.v2(logPrefix, 'checking buffer length');
// Use the max segment duration, if it is longer than the bufferBehind, to
// avoid accidentally clearing too much data when dealing with a manifest
// with a long keyframe interval.
let bufferBehind = Math.max(this.config_.bufferBehind,
this.manifest_.presentationTimeline.getMaxSegmentDuration());
let startTime =
this.playerInterface_.mediaSourceEngine.bufferStart(mediaState.type);
if (startTime == null) {
shaka.log.v2(logPrefix,
'buffer behind okay because nothing buffered:',
'playheadTime=' + playheadTime,
'bufferBehind=' + bufferBehind);
return Promise.resolve();
}
let bufferedBehind = playheadTime - startTime;
let overflow = bufferedBehind - bufferBehind;
if (overflow <= 0) {
shaka.log.v2(logPrefix,
'buffer behind okay:',
'playheadTime=' + playheadTime,
'bufferedBehind=' + bufferedBehind,
'bufferBehind=' + bufferBehind,
'underflow=' + (-overflow));
return Promise.resolve();
}
shaka.log.v1(logPrefix,
'buffer behind too large:',
'playheadTime=' + playheadTime,
'bufferedBehind=' + bufferedBehind,
'bufferBehind=' + bufferBehind,
'overflow=' + overflow);
return this.playerInterface_.mediaSourceEngine.remove(
mediaState.type, startTime, startTime + overflow).then(function() {
if (this.destroyed_) return;
shaka.log.v1(logPrefix, 'evicted ' + overflow + ' seconds');
}.bind(this));
};
/**
* Sets up all known Periods when startup completes; otherwise, does nothing.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState The last
* MediaState updated.
* @param {shaka.extern.Stream} stream
* @private
*/
shaka.media.StreamingEngine.prototype.handleStartup_ = function(
mediaState, stream) {
const Functional = shaka.util.Functional;
const MapUtils = shaka.util.MapUtils;
const ContentType = shaka.util.ManifestParserUtils.ContentType;
if (this.startupComplete_) {
return;
}
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
let mediaStates = MapUtils.values(this.mediaStates_);
this.startupComplete_ = mediaStates.every(function(ms) {
// Startup completes once we have buffered at least one segment from each
// MediaState, not counting text.
if (ms.type == ContentType.TEXT) return true;
return !ms.waitingToClearBuffer &&
!ms.clearingBuffer &&
ms.lastSegmentReference;
});
if (!this.startupComplete_) {
return;
}
shaka.log.debug(logPrefix, 'startup complete');
// We must use |stream| because switch() may have been called.
let currentPeriodIndex = this.findPeriodContainingStream_(stream);
goog.asserts.assert(
mediaStates.every(function(ms) {
// It is possible for one stream (usually text) to buffer the whole
// Period and need the next one.
return ms.needPeriodIndex == currentPeriodIndex ||
ms.needPeriodIndex == currentPeriodIndex + 1;
}),
logPrefix + ' expected all MediaStates to need same Period');
// Setup the current Period if necessary, which is likely since the current
// Period is probably the initial one.
if (!this.canSwitchPeriod_[currentPeriodIndex]) {
this.setupPeriod_(currentPeriodIndex).then(function() {
if (this.destroyed_) {
return;
}
shaka.log.v1(logPrefix, 'calling onCanSwitch()...');
this.playerInterface_.onCanSwitch();
}.bind(this)).catch(Functional.noop);
}
// Now setup all known Periods.
for (let i = 0; i < this.manifest_.periods.length; ++i) {
this.setupPeriod_(i).catch(Functional.noop);
}
if (this.playerInterface_.onStartupComplete) {
shaka.log.v1(logPrefix, 'calling onStartupComplete()...');
this.playerInterface_.onStartupComplete();
}
};
/**
* Calls onChooseStreams() when necessary.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState The last
* MediaState updated.
* @private
*/
shaka.media.StreamingEngine.prototype.handlePeriodTransition_ = function(
mediaState) {
const Functional = shaka.util.Functional;
const MapUtils = shaka.util.MapUtils;
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
const ContentType = shaka.util.ManifestParserUtils.ContentType;
let currentPeriodIndex = this.findPeriodContainingStream_(mediaState.stream);
if (mediaState.needPeriodIndex == currentPeriodIndex) {
return;
}
let needPeriodIndex = mediaState.needPeriodIndex;
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
let mediaStates = MapUtils.values(this.mediaStates_);
// For a Period transition to work, all media states must need the same
// Period. If a stream needs a different Period than the one it currently
// has, it will try to transition or stop updates assuming that another stream
// will handle it. This only works when all streams either need the same
// Period or are still performing updates.
goog.asserts.assert(
mediaStates.every(function(ms) {
return ms.needPeriodIndex == needPeriodIndex || ms.hasError ||
!shaka.media.StreamingEngine.isIdle_(ms);
}),
'All MediaStates should need the same Period or be performing updates.');
// Only call onChooseStreams() when all MediaStates need the same Period.
let needSamePeriod = mediaStates.every(function(ms) {
return ms.needPeriodIndex == needPeriodIndex;
});
if (!needSamePeriod) {
shaka.log.debug(
logPrefix, 'not all MediaStates need Period ' + needPeriodIndex);
return;
}
// Only call onChooseStreams() once per Period transition.
let allAreIdle = mediaStates.every(shaka.media.StreamingEngine.isIdle_);
if (!allAreIdle) {
shaka.log.debug(
logPrefix,
'all MediaStates need Period ' + needPeriodIndex + ', ' +
'but not all MediaStates are idle');
return;
}
shaka.log.debug(logPrefix, 'all need Period ' + needPeriodIndex);
// Ensure the Period which we need to buffer is set up and then call
// onChooseStreams().
this.setupPeriod_(needPeriodIndex).then(function() {
if (this.destroyed_) return;
// If we seek during a Period transition, we can start another transition.
// So we need to verify that:
// 1. We are still in need of the same Period.
// 2. All streams are still idle.
// 3. The current stream is not in the needed Period (another transition
// handled it).
let allReady = mediaStates.every(function(ms) {
let isIdle = shaka.media.StreamingEngine.isIdle_(ms);
let currentPeriodIndex = this.findPeriodContainingStream_(ms.stream);
return isIdle && ms.needPeriodIndex == needPeriodIndex &&
currentPeriodIndex != needPeriodIndex;
}.bind(this));
if (!allReady) {
// TODO: Write unit tests for this case.
shaka.log.debug(logPrefix, 'ignoring transition to Period',
needPeriodIndex, 'since another is happening');
return;
}
let needPeriod = this.manifest_.periods[needPeriodIndex];
shaka.log.v1(logPrefix, 'calling onChooseStreams()...');
let chosenStreams = this.playerInterface_.onChooseStreams(needPeriod);
let streamsByType = {};
if (chosenStreams.variant && chosenStreams.variant.video) {
streamsByType[ContentType.VIDEO] = chosenStreams.variant.video;
}
if (chosenStreams.variant && chosenStreams.variant.audio) {
streamsByType[ContentType.AUDIO] = chosenStreams.variant.audio;
}
if (chosenStreams.text) {
streamsByType[ContentType.TEXT] = chosenStreams.text;
}
// Vet |streamsByType| before switching.
for (let type in this.mediaStates_) {
if (streamsByType[type] || type == ContentType.TEXT) continue;
shaka.log.error(logPrefix,
'invalid Streams chosen: missing ' + type + ' Stream');
this.playerInterface_.onError(new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INVALID_STREAMS_CHOSEN));
return;
}
for (let type in streamsByType) {
if (this.mediaStates_[/** @type {!ContentType} */(type)]) continue;
if (type == ContentType.TEXT) {
// initStreams_ will switch streams and schedule an update.
this.initStreams_(
{text: streamsByType[ContentType.TEXT]}, needPeriod.startTime);
delete streamsByType[type];
continue;
}
shaka.log.error(logPrefix,
'invalid Streams chosen: unusable ' + type + ' Stream');
this.playerInterface_.onError(new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INVALID_STREAMS_CHOSEN));
return;
}
for (let type in this.mediaStates_) {
let stream = streamsByType[type];
if (stream) {
this.switchInternal_(stream, /* clearBuffer */ false, 0);
this.scheduleUpdate_(this.mediaStates_[type], 0);
} else {
goog.asserts.assert(type == ContentType.TEXT, 'Invalid streams chosen');
delete this.mediaStates_[type];
}
}
// We've already set up the Period so call onCanSwitch() right now.
shaka.log.v1(logPrefix, 'calling onCanSwitch()...');
this.playerInterface_.onCanSwitch();
}.bind(this)).catch(Functional.noop);
};
/**
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @return {boolean} True if the given MediaState is idle; otherwise, return
* false.
* @private
*/
shaka.media.StreamingEngine.isIdle_ = function(mediaState) {
return !mediaState.performingUpdate &&
(mediaState.updateTimer == null) &&
!mediaState.waitingToClearBuffer &&
!mediaState.clearingBuffer;
};
/**
* @param {number} time The time, in seconds, relative to the start of the
* presentation.
* @return {number} The index of the Period which starts after |time|
* @private
*/
shaka.media.StreamingEngine.prototype.findPeriodContainingTime_ = function(
time) {
goog.asserts.assert(this.manifest_, 'Must not be destroyed');
return shaka.util.StreamUtils.findPeriodContainingTime(this.manifest_, time);
};
/**
* @param {!shaka.extern.Stream} stream
* @return {number} The index of the Period which contains |stream|, or -1 if
* no Period contains |stream|.
* @private
*/
shaka.media.StreamingEngine.prototype.findPeriodContainingStream_ = function(
stream) {
goog.asserts.assert(this.manifest_, 'Must not be destroyed');
return shaka.util.StreamUtils.findPeriodContainingStream(
this.manifest_, stream);
};
/**
* Fetches the given segment.
*
* @param {(!shaka.media.InitSegmentReference|!shaka.media.SegmentReference)}
* reference
*
* @return {!Promise.<!ArrayBuffer>}
* @private
*/
shaka.media.StreamingEngine.prototype.fetch_ = function(reference) {
const requestType = shaka.net.NetworkingEngine.RequestType.SEGMENT;
let request = shaka.net.NetworkingEngine.makeRequest(
reference.getUris(), this.config_.retryParameters);
// Set the Range header. Note that some web servers don't accept Range
// headers, so don't set one if it's not strictly required.
if ((reference.startByte != 0) || (reference.endByte != null)) {
let range = 'bytes=' + reference.startByte + '-';
if (reference.endByte != null) range += reference.endByte;
request.headers['Range'] = range;
}
shaka.log.v2('fetching: reference=' + reference);
let op = this.playerInterface_.netEngine.request(requestType, request);
return op.promise.then(function(response) {
return response.data;
});
};
/**
* Clears the buffer and schedules another update.
* The optional parameter safeMargin allows to retain a certain amount
* of buffer, which can help avoiding rebuffering events.
* The value of the safe margin should be provided by the ABR manager.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @param {boolean} flush
* @param {number} safeMargin
* @private
*/
shaka.media.StreamingEngine.prototype.clearBuffer_ =
function(mediaState, flush, safeMargin) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
goog.asserts.assert(
!mediaState.performingUpdate && (mediaState.updateTimer == null),
logPrefix + ' unexpected call to clearBuffer_()');
mediaState.waitingToClearBuffer = false;
mediaState.waitingToFlushBuffer = false;
mediaState.clearBufferSafeMargin = 0;
mediaState.clearingBuffer = true;
shaka.log.debug(logPrefix, 'clearing buffer');
let p;
if (safeMargin) {
let playheadTime = this.playerInterface_.playhead.getTime();
let duration = this.playerInterface_.mediaSourceEngine.getDuration();
p = this.playerInterface_.mediaSourceEngine.remove(
mediaState.type, playheadTime + safeMargin, duration);
} else {
p = this.playerInterface_.mediaSourceEngine.clear(mediaState.type).then(
function() {
if (!this.destroyed_ && flush) {
return this.playerInterface_.mediaSourceEngine.flush(
mediaState.type);
}
}.bind(this));
}
p.then(function() {
if (this.destroyed_) return;
shaka.log.debug(logPrefix, 'cleared buffer');
mediaState.lastStream = null;
mediaState.lastSegmentReference = null;
mediaState.clearingBuffer = false;
mediaState.endOfStream = false;
this.scheduleUpdate_(mediaState, 0);
}.bind(this));
};
/**
* Schedules |mediaState|'s next update.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} delay The delay in seconds.
* @private
*/
shaka.media.StreamingEngine.prototype.scheduleUpdate_ = function(
mediaState, delay) {
let logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.v2(logPrefix, 'updating in ' + delay + ' seconds');
goog.asserts.assert(mediaState.updateTimer == null,
logPrefix + ' did not expect update to be scheduled');
mediaState.updateTimer = window.setTimeout(
this.onUpdate_.bind(this, mediaState), delay * 1000);
};
/**
* Cancels |mediaState|'s next update if one exists.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @private
*/
shaka.media.StreamingEngine.prototype.cancelUpdate_ = function(mediaState) {
if (mediaState.updateTimer != null) {
window.clearTimeout(mediaState.updateTimer);
mediaState.updateTimer = null;
}
};
/**
* Handle streaming errors by delaying, then notifying the application by error
* callback and by streaming failure callback.
*
* @param {!shaka.util.Error} error
* @private
*/
shaka.media.StreamingEngine.prototype.handleStreamingError_ = function(error) {
// If we invoke the callback right away, the application could trigger a
// rapid retry cycle that could be very unkind to the server. Instead,
// use the backoff system to delay and backoff the error handling.
this.failureCallbackBackoff_.attempt().then(function() {
if (this.destroyed_) {
return;
}
// First fire an error event.
this.playerInterface_.onError(error);
// If the error was not handled by the application, call the failure
// callback.
if (!error.handled) {
this.config_.failureCallback(error);
}
}.bind(this));
};
/**
* @param {shaka.media.StreamingEngine.MediaState_} mediaState
* @return {string} A log prefix of the form ($CONTENT_TYPE:$STREAM_ID), e.g.,
* "(audio:5)" or "(video:hd)".
* @private
*/
shaka.media.StreamingEngine.logPrefix_ = function(mediaState) {
return '(' + mediaState.type + ':' + mediaState.stream.id + ')';
};