/**
* @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.media.MediaSourceEngine');
goog.require('shaka.media.Playhead');
goog.require('shaka.net.NetworkingEngine');
goog.require('shaka.util.Error');
goog.require('shaka.util.Functional');
goog.require('shaka.util.IDestroyable');
goog.require('shaka.util.MapUtils');
goog.require('shaka.util.PublicPromise');
/**
* 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.media.Playhead} playhead The Playhead. The caller retains
* ownership.
* @param {!shaka.media.MediaSourceEngine} mediaSourceEngine The
* MediaSourceEngine. The caller retains ownership.
* @param {shaka.net.NetworkingEngine} netEngine
* @param {shakaExtern.Manifest} manifest
* @param {function(!shakaExtern.Period): !Object.<string, shakaExtern.Stream>}
* onChooseStreams Called when the given Period needs to be buffered. The
* StreamingEngine will switch to the Streams returned from this function.
* The caller cannot call switch() directly until the StreamingEngine calls
* onCanSwitch()
* @param {function()} onCanSwitch Called when any Stream within the current
* Period may be switched to.
* @param {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.
* @param {function()=} opt_onInitialStreamsSetup Optional callback which
* is called when the initial set of Streams have been setup. Intended
* to be used by tests.
* @param {function()=} opt_onStartupComplete Optional callback which
* is called when startup has completed. Intended to be used by tests.
*
* @constructor
* @struct
* @implements {shaka.util.IDestroyable}
*/
shaka.media.StreamingEngine = function(
playhead, mediaSourceEngine, netEngine, manifest,
onChooseStreams, onCanSwitch, onError,
opt_onInitialStreamsSetup, opt_onStartupComplete) {
/** @private {shaka.media.Playhead} */
this.playhead_ = playhead;
/** @private {shaka.media.MediaSourceEngine} */
this.mediaSourceEngine_ = mediaSourceEngine;
/** @private {shaka.net.NetworkingEngine} */
this.netEngine_ = netEngine;
/** @private {?shakaExtern.Manifest} */
this.manifest_ = manifest;
/**
* @private
* {?function(!shakaExtern.Period): !Object.<string, shakaExtern.Stream>}
*/
this.onChooseStreams_ = onChooseStreams;
/** @private {?function()} */
this.onCanSwitch_ = onCanSwitch;
/** @private {?function(!shaka.util.Error)} */
this.onError_ = onError;
/** @private {?function()} */
this.onInitialStreamsSetup_ = opt_onInitialStreamsSetup || null;
/** @private {?function()} */
this.onStartupComplete_ = opt_onStartupComplete || null;
/** @private {?shakaExtern.StreamingConfiguration} */
this.config_ = null;
/** @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.<string, !shaka.media.StreamingEngine.MediaState_>}
*/
this.mediaStates_ = {};
/**
* Set to true once one segment of each content type has been buffered.
*
* @private {boolean}
*/
this.startupComplete_ = false;
/** @private {boolean} */
this.destroyed_ = false;
};
/**
* @typedef {{
* type: string,
* stream: shakaExtern.Stream,
* lastStream: ?shakaExtern.Stream,
* lastSegmentReference: shaka.media.SegmentReference,
* needInitSegment: boolean,
* needRebuffering: boolean,
* needPeriodIndex: number,
* endOfStream: boolean,
* performingUpdate: boolean,
* updateTimer: ?number,
* waitingToClearBuffer: boolean,
* clearingBuffer: boolean
* }}
*
* @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 {string} type
* The stream's content type, e.g., 'audio', 'video', or 'text'.
* @property {shakaExtern.Stream} stream
* The current Stream.
* @property {?shakaExtern.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 {boolean} needInitSegment
* True indicates that |stream|'s init segment must be inserted before the
* next media segment is appended.
* @property {boolean} needRebuffering
* True indicates that startup or re- buffering is required.
* @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} clearingBuffer
* True indicates that the buffer is being cleared.
*/
shaka.media.StreamingEngine.MediaState_;
/**
* The minimum number seconds that will remain buffered after evicting media.
*
* @const {number}
*/
shaka.media.StreamingEngine.prototype.MIN_BUFFER_LENGTH = 2;
/**
* Gets the StreamingEngine's rebuffering goal.
*
* @param {shakaExtern.Manifest} manifest
* @param {shakaExtern.StreamingConfiguration} config
* @return {number}
*/
shaka.media.StreamingEngine.getRebufferingGoal = function(manifest, config) {
return Math.max(manifest.minBufferTime || 0, config.rebufferingGoal);
};
/** @override */
shaka.media.StreamingEngine.prototype.destroy = function() {
for (var type in this.mediaStates_) {
this.cancelUpdate_(this.mediaStates_[type]);
}
this.playhead_ = null;
this.mediaSourceEngine_ = null;
this.netEngine_ = null;
this.manifest_ = null;
this.setupPeriodPromise_ = null;
this.onChooseStreams_ = null;
this.onCanSwitch_ = null;
this.onError_ = null;
this.onInitialStreamsSetup_ = null;
this.onStartupComplete_ = 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.
* Will be called at least once before init().
*
* @param {shakaExtern.StreamingConfiguration} config
*/
shaka.media.StreamingEngine.prototype.configure = function(config) {
this.config_ = config;
goog.asserts.assert(this.manifest_, 'manifest_ should not be null');
var rebufferingGoal = shaka.media.StreamingEngine.getRebufferingGoal(
this.manifest_, this.config_);
this.playhead_.setRebufferingGoal(rebufferingGoal);
};
/**
* 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() {
var MapUtils = shaka.util.MapUtils;
goog.asserts.assert(this.config_,
'StreamingEngine configure() must be called before init()!');
// Determine which Period we must buffer.
var playheadTime = this.playhead_.getTime();
var needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
// Get the initial set of Streams.
var streamsByType =
this.onChooseStreams_(this.manifest_.periods[needPeriodIndex]);
if (MapUtils.empty(streamsByType)) {
shaka.log.error('init: no Streams chosen');
return Promise.reject(new shaka.util.Error(
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_(streamsByType).then(function() {
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.onInitialStreamsSetup_) {
shaka.log.v1('init: calling onInitialStreamsSetup_()...');
this.onInitialStreamsSetup_();
}
}.bind(this));
};
/**
* Gets the current Period the stream is in. This Period may not be initialized
* yet if canSwitch(period) has not been called yet.
* @return {shakaExtern.Period}
*/
shaka.media.StreamingEngine.prototype.getCurrentPeriod = function() {
var playheadTime = this.playhead_.getTime();
var needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
return this.manifest_.periods[needPeriodIndex];
};
/**
* Gets a map of all the active streams.
* @return {!Object.<string, shakaExtern.Stream>}
*/
shaka.media.StreamingEngine.prototype.getActiveStreams = function() {
goog.asserts.assert(this.mediaStates_, 'Must be initialized');
var MapUtils = shaka.util.MapUtils;
return MapUtils.map(
this.mediaStates_, function(state) { return state.stream; });
};
/**
* Notifies StreamingEngine that a new stream was added to the manifest. This
* initializes the given stream. This returns a Promise that resolves when
* the stream has been set up.
*
* @param {string} type
* @param {shakaExtern.Stream} stream
* @return {!Promise}
*/
shaka.media.StreamingEngine.prototype.notifyNewStream = function(type, stream) {
/** @type {!Object.<string, shakaExtern.Stream>} */
var streamsByType = {};
streamsByType[type] = stream;
return this.initStreams_(streamsByType);
};
/**
* Switches to the given Stream. |stream| may be from any StreamSet or any
* Period.
*
* @param {string} contentType |stream|'s content type.
* @param {shakaExtern.Stream} stream
* @param {boolean=} opt_clearBuffer
*/
shaka.media.StreamingEngine.prototype.switch = function(
contentType, stream, opt_clearBuffer) {
// TODO: Change opt_clearBuffer to a number so only part of the buffer is
// cleared.
var mediaState = this.mediaStates_[contentType];
goog.asserts.assert(mediaState, 'switch: expected mediaState to exist');
if (!mediaState) return;
// Ensure the Period is ready.
var periodIndex = this.findPeriodContainingStream_(stream);
var 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) {
var streamTag = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.debug('switch: Stream ' + streamTag + ' already active');
return;
}
mediaState.stream = stream;
mediaState.needInitSegment = true;
var streamTag = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.debug('switch: switching to Stream ' + streamTag);
if (opt_clearBuffer) {
// Ignore if we are already clearing the buffer.
if (!mediaState.waitingToClearBuffer && !mediaState.clearingBuffer) {
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.
mediaState.waitingToClearBuffer = true;
} else {
this.cancelUpdate_(mediaState);
this.clearBuffer_(mediaState);
}
}
}
};
/**
* Notifies the StreamingEngine that the playhead has moved to a valid time
* within the presentation timeline.
*/
shaka.media.StreamingEngine.prototype.seeked = function() {
for (var type in this.mediaStates_) {
var mediaState = this.mediaStates_[type];
var 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, 'seeked: already clearing the buffer');
continue;
}
var playheadTime = this.playhead_.getTime();
var bufferedAhead = this.mediaSourceEngine_.bufferedAheadOf(
type, playheadTime, 0.1);
if (bufferedAhead > 0) {
// The playhead has moved into a buffered region, so we don't need to
// clear the buffer.
shaka.log.debug(logPrefix,
'seeked: buffered seek:',
'playheadTime=' + playheadTime,
'bufferedAhead=' + bufferedAhead);
mediaState.waitingToClearBuffer = false;
continue;
}
// The playhead has moved into an unbuffered region, so we might have to
// clear the buffer.
if (mediaState.waitingToClearBuffer) {
shaka.log.debug(logPrefix, 'seeked: unbuffered seek: 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, 'seeked: unbuffered seek: currently updating');
mediaState.waitingToClearBuffer = true;
continue;
}
if (this.mediaSourceEngine_.bufferStart(type) == null) {
// Nothing buffered.
shaka.log.debug(logPrefix, 'seeked: unbuffered seek: 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, 'seeked: unbuffered seek: handling right now');
this.cancelUpdate_(mediaState);
this.clearBuffer_(mediaState);
}
};
/**
* Initializes the given streams and media states if required. This will
* schedule updates for the given types.
*
* @param {!Object.<string, shakaExtern.Stream>} streamsByType
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.initStreams_ = function(streamsByType) {
var MapUtils = shaka.util.MapUtils;
goog.asserts.assert(this.config_,
'StreamingEngine configure() must be called before init()!');
// Determine which Period we must buffer.
var playheadTime = this.playhead_.getTime();
var needPeriodIndex = this.findPeriodContainingTime_(playheadTime);
// Init MediaSourceEngine.
var typeConfig = MapUtils.map(streamsByType, function(stream) {
return stream.mimeType +
(stream.codecs ? '; codecs="' + stream.codecs + '"' : '');
});
this.mediaSourceEngine_.init(typeConfig);
this.setDuration_();
// Setup the initial set of Streams and then begin each update cycle. After
// startup completes onUpdate_() will set up the remaining Periods.
var streams = MapUtils.values(streamsByType);
return this.setupStreams_(streams).then(function() {
for (var type in streamsByType) {
var stream = streamsByType[type];
if (!this.mediaStates_[type]) {
this.mediaStates_[type] = {
stream: stream,
type: type,
lastStream: null,
lastSegmentReference: null,
needInitSegment: true,
needRebuffering: false,
needPeriodIndex: needPeriodIndex,
endOfStream: false,
performingUpdate: false,
updateTimer: null,
waitingToClearBuffer: false,
clearingBuffer: false
};
this.scheduleUpdate_(this.mediaStates_[type], 0);
}
}
}.bind(this));
};
/**
* 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 is resolved when the given Period is
* setup.
* @private
*/
shaka.media.StreamingEngine.prototype.setupPeriod_ = function(periodIndex) {
var Functional = shaka.util.Functional;
var 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;
var streams = this.manifest_.periods[periodIndex].streamSets
.map(function(streamSet) { return streamSet.streams; })
.reduce(Functional.collapseArrays, []);
// 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.reject();
delete this.canSwitchPeriod_[periodIndex];
shaka.log.warning('(all) failed to setup Period ' + periodIndex);
this.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.<!shakaExtern.Stream>} streams
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.setupStreams_ = function(streams) {
// Parallelize Stream set up.
var async = [];
for (var i = 0; i < streams.length; ++i) {
var stream = streams[i];
var 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 (var i = 0; i < streams.length; ++i) {
var stream = streams[i];
var 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;
this.canSwitchStream_[stream.id].promise.reject();
delete this.canSwitchStream_[stream.id];
return Promise.reject(error);
}.bind(this));
};
/**
* Sets the MediaSource's duration.
* @private
*/
shaka.media.StreamingEngine.prototype.setDuration_ = function() {
var duration = this.manifest_.presentationTimeline.getDuration();
if (duration < Number.POSITIVE_INFINITY) {
this.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.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) {
var MapUtils = shaka.util.MapUtils;
if (this.destroyed_) return;
var 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);
return;
}
// Update the MediaState.
try {
var delay = this.update_(mediaState);
if (delay != null) {
this.scheduleUpdate_(mediaState, delay);
}
} catch (error) {
this.onError_(error);
return;
}
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
var mediaStates = MapUtils.values(this.mediaStates_);
// Handle startup and re- buffering.
this.playhead_.setBuffering(
mediaStates.some(function(ms) { return ms.needRebuffering; }));
// 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.mediaSourceEngine_.endOfStream();
}
};
/**
* 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) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
// Compute how far we've buffered ahead of the playhead.
var playheadTime = this.playhead_.getTime();
var bufferedAhead = this.mediaSourceEngine_.bufferedAheadOf(
mediaState.type, playheadTime, 0.1);
goog.asserts.assert(this.manifest_, 'manifest_ should not be null');
goog.asserts.assert(this.config_, 'config_ should not be null');
var rebufferingGoal = shaka.media.StreamingEngine.getRebufferingGoal(
this.manifest_, this.config_);
shaka.log.v2(logPrefix,
'update_:',
'playheadTime=' + playheadTime,
'bufferedAhead=' + bufferedAhead);
// If we've buffered to the buffering goal then schedule an update.
var bufferingGoal = Math.max(rebufferingGoal, this.config_.bufferingGoal);
if (bufferedAhead >= bufferingGoal) {
shaka.log.v2(logPrefix, 'buffering goal met');
mediaState.needRebuffering = false;
// Do not try to schedule 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;
}
// Get the next timestamp we need.
var bufferEnd = this.mediaSourceEngine_.bufferEnd(mediaState.type);
var timeNeeded = this.getTimeNeeded_(
mediaState, playheadTime, bufferedAhead, bufferEnd);
shaka.log.v2(logPrefix, 'timeNeeded=' + timeNeeded);
// 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.needRebuffering = false;
mediaState.endOfStream = true;
return null;
}
mediaState.endOfStream = false;
// Handle startup and re- buffering state.
if ((!this.startupComplete_ && bufferedAhead < rebufferingGoal) ||
(bufferedAhead <= 1)) {
shaka.log.v1(logPrefix, 'need startup or re- buffering');
mediaState.needRebuffering = true;
} else if (bufferedAhead >= rebufferingGoal) {
mediaState.needRebuffering = false;
}
var currentPeriodIndex = this.findPeriodContainingStream_(mediaState.stream);
// 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 SegmentIndexes can provide SegmentReferences outside its Period.
var needPeriodIndex = this.findPeriodContainingTime_(timeNeeded);
if (needPeriodIndex != currentPeriodIndex) {
shaka.log.debug(logPrefix,
'need Period ' + needPeriodIndex,
'playheadTime=' + playheadTime,
'timeNeeded=' + timeNeeded,
'currentPeriodIndex=' + currentPeriodIndex);
mediaState.needPeriodIndex = needPeriodIndex;
return null;
}
var reference = this.getSegmentReferenceNeeded_(
mediaState, playheadTime, 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;
}
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
* @param {number} bufferedAhead
* @param {?number} bufferEnd
* @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, bufferedAhead, bufferEnd) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
// 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|; and
// 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 (bufferedAhead == 0) {
// The playhead is in an unbuffered region.
if (bufferEnd == null) {
// The buffer is empty.
if (mediaState.lastStream != null ||
mediaState.lastSegmentReference) {
shaka.log.error(logPrefix, 'lastSegmentReference should be null');
throw new shaka.util.Error(
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INCONSISTENT_BUFFER_STATE,
mediaState.type);
}
return playheadTime;
} else if (bufferEnd > playheadTime) {
// We may find ourseleves in this state for two reasons:
// 1. there is a significant amount of positive drift; or
// 2. the user agent seeked backwards but seeked() was not called or has
// not been called yet (because it's a race).
// For case 1 we'll idle forever, and for case 2 we'll end up buffering a
// segment, removing it, and then buffering it again (note that this case
// should be rare).
shaka.log.debug(logPrefix,
'playhead in unbuffered region (behind buffer):',
'playheadTime=' + playheadTime,
'bufferEnd=' + bufferEnd);
} else {
// We may find ourseleves in this state for four reasons:
// 1. the playhead is exactly at the end of the buffer;
// 2. the browser allowed the playhead to proceed past the end of
// the buffer (either under normal or accelerated playback rates);
// 3. there is a significant amount of negative drift; or
// 4. the user agent seeked forwards but seeked() was not called or has
// not been called yet (because it's a race).
// For cases 1 and 2 we'll end up buffering the next segment we want
// anyways, for case 3 we'll end up buffering behind the playhead until
// we catch up, and for case 4 we'll proceed as in case 2 of the previous
// block.
shaka.log.debug(logPrefix,
'playhead in unbuffered region (ahead of buffer):',
'playheadTime=' + playheadTime,
'bufferEnd=' + bufferEnd);
}
}
// The buffer is non-empty.
if (mediaState.lastStream == null ||
mediaState.lastSegmentReference == null) {
shaka.log.error(logPrefix, 'lastSegmentReference should not be null');
throw new shaka.util.Error(
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INCONSISTENT_BUFFER_STATE,
mediaState.type);
}
var lastPeriodIndex =
this.findPeriodContainingStream_(mediaState.lastStream);
var 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} currentPeriodIndex
* @return {shaka.media.SegmentReference} The SegmentReference of the
* next segment needed, or null if a segment could not be found, does not
* exist, or is not available.
* @private
*/
shaka.media.StreamingEngine.prototype.getSegmentReferenceNeeded_ = function(
mediaState, playheadTime, currentPeriodIndex) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
if (mediaState.lastSegmentReference &&
mediaState.stream == mediaState.lastStream) {
// Something is buffered from the same Stream.
var position = mediaState.lastSegmentReference.position + 1;
shaka.log.v2(logPrefix, 'next position known:', 'position=' + position);
return this.getSegmentReferenceIfAvailable_(
mediaState, currentPeriodIndex, position);
}
var 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');
var lastPeriodIndex =
this.findPeriodContainingStream_(mediaState.lastStream);
var lastPeriod = this.manifest_.periods[lastPeriodIndex];
position = this.lookupSegmentPosition_(
mediaState,
lastPeriod.startTime + mediaState.lastSegmentReference.endTime,
currentPeriodIndex);
} else {
// Nothing is buffered.
goog.asserts.assert(!mediaState.lastStream, 'lastStream should be null');
shaka.log.v1(logPrefix, 'next position unknown: nothing buffered');
position = this.lookupSegmentPosition_(
mediaState, playheadTime, currentPeriodIndex);
}
if (position == null)
return 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.
var optimalPosition = Math.max(0, position - 1);
var reference =
this.getSegmentReferenceIfAvailable_(
mediaState, currentPeriodIndex, optimalPosition) ||
this.getSegmentReferenceIfAvailable_(
mediaState, currentPeriodIndex, position);
return reference;
};
/**
* 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) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
var currentPeriod = this.manifest_.periods[currentPeriodIndex];
shaka.log.debug(logPrefix,
'looking up segment:',
'presentationTime=' + presentationTime,
'currentPeriod.startTime=' + currentPeriod.startTime);
var lookupTime = Math.max(0, presentationTime - currentPeriod.startTime);
var 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) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
var currentPeriod = this.manifest_.periods[currentPeriodIndex];
var reference = mediaState.stream.getSegmentReference(position);
if (!reference) {
shaka.log.v1(logPrefix,
'segment does not exist:',
'currentPeriod.startTime=' + currentPeriod.startTime,
'position=' + position);
return null;
}
var timeline = this.manifest_.presentationTimeline;
var availabilityStart = timeline.getSegmentAvailabilityStart();
var 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) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
var 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 too.
var stream = mediaState.stream;
// Compute the append window end.
var followingPeriod = this.manifest_.periods[currentPeriodIndex + 1];
var appendWindowEnd = null;
if (followingPeriod) {
appendWindowEnd = followingPeriod.startTime;
} else {
appendWindowEnd = this.manifest_.presentationTimeline.getDuration();
}
goog.asserts.assert(
(appendWindowEnd == null) || (reference.startTime <= appendWindowEnd),
logPrefix + ' segment should start before append window end');
var initSourceBuffer =
this.initSourceBuffer_(mediaState, currentPeriodIndex, 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');
var fetchSegment = this.fetch_(reference);
Promise.all([initSourceBuffer, fetchSegment]).then(function(results) {
if (this.destroyed_) return;
return this.append_(mediaState,
playheadTime,
stream,
reference,
results[1]);
}.bind(this)).then(function() {
mediaState.performingUpdate = false;
// 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.
if (!this.destroyed_)
this.handleStartup_(mediaState, stream);
shaka.log.v1(logPrefix, 'finished fetch and append');
}.bind(this)).catch(function(error) {
if (this.destroyed_) return;
this.onError_(error);
}.bind(this));
};
/**
* 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} appendWindowEnd
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.initSourceBuffer_ = function(
mediaState, currentPeriodIndex, appendWindowEnd) {
if (!mediaState.needInitSegment)
return Promise.resolve();
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
var 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().
var timestampOffset =
currentPeriod.startTime - mediaState.stream.presentationTimeOffset;
shaka.log.v1(logPrefix, 'setting timestamp offset to ' + timestampOffset);
var setTimestampOffset = this.mediaSourceEngine_.setTimestampOffset(
mediaState.type, timestampOffset);
if (appendWindowEnd != null) {
shaka.log.v1(logPrefix, 'setting append window end to ' + appendWindowEnd);
var setAppendWindowEnd = this.mediaSourceEngine_.setAppendWindowEnd(
mediaState.type, appendWindowEnd);
} else {
setAppendWindowEnd = Promise.resolve();
}
if (!mediaState.stream.initSegmentReference) {
// The Stream is self initializing.
return Promise.all([setTimestampOffset, setAppendWindowEnd]);
}
shaka.log.v1(logPrefix, 'fetching init segment');
var fetchInit = this.fetch_(mediaState.stream.initSegmentReference);
var appendInit = fetchInit.then(function(initSegment) {
if (this.destroyed_) return;
shaka.log.v1(logPrefix, 'appending init segment');
return this.mediaSourceEngine_.appendBuffer(
mediaState.type, initSegment, null /* startTime */, null /* endTime */);
}.bind(this));
return Promise.all([setTimestampOffset, setAppendWindowEnd, appendInit]);
};
/**
* Appends the given segment and evicts content if required to append.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @param {number} playheadTime
* @param {shakaExtern.Stream} stream
* @param {!shaka.media.SegmentReference} reference
* @param {!ArrayBuffer} segment
* @return {!Promise}
* @private
*/
shaka.media.StreamingEngine.prototype.append_ = function(
mediaState, playheadTime, stream, reference, segment) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
return this.evict_(mediaState, playheadTime).then(function() {
if (this.destroyed_) return;
shaka.log.v1(logPrefix, 'appending media segment');
return this.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));
};
/**
* 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) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
shaka.log.v2(logPrefix, 'checking buffer length');
var startTime = this.mediaSourceEngine_.bufferStart(mediaState.type);
if (startTime == null) {
shaka.log.v2(logPrefix,
'buffer behind okay because nothing buffered:',
'playheadTime=' + playheadTime,
'bufferBehind=' + this.config_.bufferBehind);
return Promise.resolve();
}
var bufferedBehind = playheadTime - startTime;
var overflow = bufferedBehind - this.config_.bufferBehind;
if (overflow <= 0) {
shaka.log.v2(logPrefix,
'buffer behind okay:',
'playheadTime=' + playheadTime,
'bufferedBehind=' + bufferedBehind,
'bufferBehind=' + this.config_.bufferBehind,
'underflow=' + (-overflow));
return Promise.resolve();
}
shaka.log.v1(logPrefix,
'buffer behind too large:',
'playheadTime=' + playheadTime,
'bufferedBehind=' + bufferedBehind,
'bufferBehind=' + this.config_.bufferBehind,
'overflow=' + overflow);
return this.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 {shakaExtern.Stream} stream
* @private
*/
shaka.media.StreamingEngine.prototype.handleStartup_ = function(
mediaState, stream) {
var Functional = shaka.util.Functional;
var MapUtils = shaka.util.MapUtils;
if (this.startupComplete_)
return;
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
var mediaStates = MapUtils.values(this.mediaStates_);
this.startupComplete_ = mediaStates.every(function(ms) {
// Startup completes once we have buffered at least one segment from each
// MediaState.
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.
var currentPeriodIndex = this.findPeriodContainingStream_(stream);
goog.asserts.assert(
mediaStates.every(function(ms) {
return ms.needPeriodIndex == currentPeriodIndex;
}),
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() {
shaka.log.v1(logPrefix, 'calling onCanSwitch_()...');
this.onCanSwitch_();
}.bind(this)).catch(Functional.noop);
}
// Now setup all known Periods.
for (var i = 0; i < this.manifest_.periods.length; ++i) {
this.setupPeriod_(i).catch(Functional.noop);
}
if (this.onStartupComplete_) {
shaka.log.v1(logPrefix, 'calling onStartupComplete_()...');
this.onStartupComplete_();
}
};
/**
* Calls onChooseStreams_() when necessary.
*
* @param {shaka.media.StreamingEngine.MediaState_} mediaState The last
* MediaState updated.
* @private
*/
shaka.media.StreamingEngine.prototype.handlePeriodTransition_ = function(
mediaState) {
var Functional = shaka.util.Functional;
var MapUtils = shaka.util.MapUtils;
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
var currentPeriodIndex = this.findPeriodContainingStream_(mediaState.stream);
if (mediaState.needPeriodIndex == currentPeriodIndex)
return;
var needPeriodIndex = mediaState.needPeriodIndex;
goog.asserts.assert(this.mediaStates_, 'must not be destroyed');
var mediaStates = MapUtils.values(this.mediaStates_);
// Only call onChooseStreams_() when all MediaStates need the same Period.
var 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.
var 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 setup and then call
// onChooseStreams_().
this.setupPeriod_(needPeriodIndex).then(function() {
if (this.destroyed_) return;
var needPeriod = this.manifest_.periods[needPeriodIndex];
shaka.log.v1(logPrefix, 'calling onChooseStreams_()...');
var streamsByType = this.onChooseStreams_(needPeriod);
// Vet |streamsByType| before switching.
for (var type in this.mediaStates_) {
if (streamsByType[type]) continue;
shaka.log.error(logPrefix,
'invalid Streams chosen: missing ' + type + ' Stream');
this.onError_(new shaka.util.Error(
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INVALID_STREAMS_CHOSEN));
return;
}
for (var type in streamsByType) {
if (this.mediaStates_[type]) continue;
shaka.log.error(logPrefix,
'invalid Streams chosen: unusable ' + type + ' Stream');
this.onError_(new shaka.util.Error(
shaka.util.Error.Category.STREAMING,
shaka.util.Error.Code.INVALID_STREAMS_CHOSEN));
return;
}
for (var type in this.mediaStates_) {
var stream = streamsByType[type];
this.switch(type, stream);
var mediaState = this.mediaStates_[type];
if (shaka.media.StreamingEngine.isIdle_(mediaState)) {
this.scheduleUpdate_(mediaState, 0);
} else {
// TODO: Write unit tests to cover this case.
shaka.log.debug(logPrefix,
'seeked() was called while waiting for setupPeriod_()');
}
}
// We've already set up the Period so call onCanSwitch_() right now.
shaka.log.v1(logPrefix, 'calling onCanSwitch_()...');
this.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) {
for (var i = this.manifest_.periods.length - 1; i > 0; --i) {
var period = this.manifest_.periods[i];
if (time >= period.startTime)
return i;
}
return 0;
};
/**
* @param {!shakaExtern.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) {
for (var i = 0; i < this.manifest_.periods.length; ++i) {
var period = this.manifest_.periods[i];
for (var j = 0; j < period.streamSets.length; ++j) {
var streamSet = period.streamSets[j];
var index = streamSet.streams.indexOf(stream);
if (index >= 0)
return i;
}
}
return -1;
};
/**
* Fetches the given segment.
*
* @param {(!shaka.media.InitSegmentReference|!shaka.media.SegmentReference)}
* reference
*
* @return {!Promise.<!ArrayBuffer>}
* @private
*/
shaka.media.StreamingEngine.prototype.fetch_ = function(reference) {
var requestType = shaka.net.NetworkingEngine.RequestType.SEGMENT;
var request = shaka.net.NetworkingEngine.makeRequest(
reference.uris, this.config_.retryParameters);
// Set 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)) {
var range = 'bytes=' + reference.startByte + '-';
if (reference.endByte != null) range += reference.endByte;
request.headers['Range'] = range;
}
shaka.log.v2('fetching: reference=' + reference);
var p = this.netEngine_.request(requestType, request);
return p.then(function(response) {
return response.data;
});
};
/**
* Clears the buffer and schedules another update.
*
* @param {!shaka.media.StreamingEngine.MediaState_} mediaState
* @private
*/
shaka.media.StreamingEngine.prototype.clearBuffer_ = function(
mediaState) {
var logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);
goog.asserts.assert(
!mediaState.performingUpdate && (mediaState.updateTimer == null),
logPrefix + ' unexpected call to clearBuffer_()');
mediaState.waitingToClearBuffer = false;
mediaState.clearingBuffer = true;
shaka.log.debug(logPrefix, 'clearing buffer');
this.mediaSourceEngine_.clear(mediaState.type).then(function() {
if (this.destroyed_) return;
shaka.log.debug(logPrefix, 'cleared buffer');
mediaState.lastStream = null;
mediaState.lastSegmentReference = null;
mediaState.clearingBuffer = 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) {
var 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;
}
};
/**
* @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 + ')';
};