/**
* @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.VideoWrapper');
goog.require('goog.asserts');
goog.require('shaka.log');
goog.require('shaka.util.EventManager');
goog.require('shaka.util.IDestroyable');
goog.require('shaka.util.Timer');
/**
* Creates a new VideoWrapper that manages setting current time and playback
* rate. This handles seeks before content is loaded and ensuring the video
* time is set properly. This doesn't handle repositioning within the
* presentation window.
*
* @param {!HTMLMediaElement} video
* @param {function()} onSeek Called when the video seeks.
* @param {number} startTime The time to start at.
*
* @constructor
* @struct
* @implements {shaka.util.IDestroyable}
*/
shaka.media.VideoWrapper = function(video, onSeek, startTime) {
/** @private {HTMLMediaElement} */
this.video_ = video;
/** @private {?function()} */
this.onSeek_ = onSeek;
/** @private {number} */
this.startTime_ = startTime;
/** @private {shaka.util.EventManager} */
this.eventManager_ = new shaka.util.EventManager();
/** @private {number} */
this.playbackRate_ = 1;
/** @private {boolean} */
this.buffering_ = false;
/** @private {shaka.util.Timer} */
this.trickPlayTimer_ = null;
// Check if the video has already loaded some metadata.
if (video.readyState > 0) {
this.onLoadedMetadata_();
} else {
this.eventManager_.listenOnce(
video, 'loadedmetadata', this.onLoadedMetadata_.bind(this));
}
this.eventManager_.listen(video, 'ratechange', this.onRateChange_.bind(this));
};
/** @override */
shaka.media.VideoWrapper.prototype.destroy = function() {
let p = this.eventManager_.destroy();
this.eventManager_ = null;
if (this.trickPlayTimer_ != null) {
this.trickPlayTimer_.cancel();
this.trickPlayTimer_ = null;
}
this.video_ = null;
this.onSeek_ = null;
return p;
};
/**
* Gets the video's current (logical) position.
*
* @return {number}
*/
shaka.media.VideoWrapper.prototype.getTime = function() {
if (this.video_.readyState > 0) {
return this.video_.currentTime;
} else {
return this.startTime_;
}
};
/**
* Sets the current time of the video.
*
* @param {number} time
*/
shaka.media.VideoWrapper.prototype.setTime = function(time) {
if (this.video_.readyState > 0) {
this.movePlayhead_(this.video_.currentTime, time);
} else {
this.startTime_ = time;
setTimeout(this.onSeek_, 0);
}
};
/**
* Gets the current effective playback rate. This may be negative even if the
* browser does not directly support rewinding.
* @return {number}
*/
shaka.media.VideoWrapper.prototype.getPlaybackRate = function() {
return this.playbackRate_;
};
/**
* Sets the playback rate.
* @param {number} rate
*/
shaka.media.VideoWrapper.prototype.setPlaybackRate = function(rate) {
if (this.trickPlayTimer_ != null) {
this.trickPlayTimer_.cancel();
this.trickPlayTimer_ = null;
}
this.playbackRate_ = rate;
// All major browsers support playback rates above zero. Only need fake
// trick play for negative rates.
this.video_.playbackRate = (this.buffering_ || rate < 0) ? 0 : rate;
if (!this.buffering_ && rate < 0) {
// Defer creating the timer until we stop buffering. This function will be
// called again from setBuffering().
let trickPlay = () => { this.video_.currentTime += rate / 4; };
this.trickPlayTimer_ = new shaka.util.Timer(trickPlay);
this.trickPlayTimer_.scheduleRepeated(0.25);
}
};
/**
* Stops the playhead for buffering, or resumes the playhead after buffering.
*
* @param {boolean} buffering True to stop the playhead; false to allow it to
* continue.
*/
shaka.media.VideoWrapper.prototype.setBuffering = function(buffering) {
if (buffering != this.buffering_) {
this.buffering_ = buffering;
this.setPlaybackRate(this.playbackRate_);
}
};
/**
* Handles a 'ratechange' event.
*
* @private
*/
shaka.media.VideoWrapper.prototype.onRateChange_ = function() {
// NOTE: This will not allow explicitly setting the playback rate to 0 while
// the playback rate is negative. Pause will still work.
let expectedRate =
this.buffering_ || this.playbackRate_ < 0 ? 0 : this.playbackRate_;
// Native controls in Edge trigger a change to playbackRate and set it to 0
// when seeking. If we don't exclude 0 from this check, we will force the
// rate to stay at 0 after a seek with Edge native controls.
// https://github.com/google/shaka-player/issues/951
if (this.video_.playbackRate && this.video_.playbackRate != expectedRate) {
shaka.log.debug('Video playback rate changed to', this.video_.playbackRate);
this.setPlaybackRate(this.video_.playbackRate);
}
};
/**
* Handles a 'loadedmetadata' event.
*
* @private
*/
shaka.media.VideoWrapper.prototype.onLoadedMetadata_ = function() {
if (Math.abs(this.video_.currentTime - this.startTime_) < 0.001) {
this.onSeekingToStartTime_();
} else {
this.eventManager_.listenOnce(
this.video_, 'seeking', this.onSeekingToStartTime_.bind(this));
// If the currentTime != 0, it indicates that the user has seeked after
// calling load(), so it is intended to start from a specific timestamp
// when playback, and should not be overriden by the startTime.
if (this.video_.currentTime == 0) {
this.video_.currentTime = this.startTime_;
} else {
// This is a workaround solution. If the currentTime is not set again, the
// video is stuck and could not be played.
// TODO: Need further investigation why it happens. Before and after
// setting the current time, video.readyState is 1, video.paused is true,
// and video.buffered's TimeRanges length is 0.
// See: https://github.com/google/shaka-player/issues/1298
this.video_.currentTime = this.video_.currentTime;
}
}
};
/**
* Handles the 'seeking' event from the initial jump to the start time (if
* there is one).
*
* @private
*/
shaka.media.VideoWrapper.prototype.onSeekingToStartTime_ = function() {
goog.asserts.assert(this.video_.readyState > 0,
'readyState should be greater than 0');
this.eventManager_.listen(this.video_, 'seeking', () => this.onSeek_());
};
/**
* Moves the playhead to the target time, triggering a call to onSeeking_().
*
* @param {number} currentTime
* @param {number} targetTime
* @private
*/
shaka.media.VideoWrapper.prototype.movePlayhead_ = function(
currentTime, targetTime) {
shaka.log.debug('Moving playhead...',
'currentTime=' + currentTime,
'targetTime=' + targetTime);
this.video_.currentTime = targetTime;
// Sometimes, IE and Edge ignore re-seeks. Check every 100ms and try
// again if need be, up to 10 tries.
// Delay stats over 100 runs of a re-seeking integration test:
// IE - 0ms - 47%
// IE - 100ms - 63%
// Edge - 0ms - 2%
// Edge - 100ms - 40%
// Edge - 200ms - 32%
// Edge - 300ms - 24%
// Edge - 400ms - 2%
// Chrome - 0ms - 100%
// TODO: File a bug on IE/Edge about this.
let tries = 0;
let recheck = () => {
if (!this.video_) return;
if (tries++ >= 10) return;
if (this.video_.currentTime == currentTime) {
// Sigh. Try again.
this.video_.currentTime = targetTime;
setTimeout(recheck, 100);
}
};
setTimeout(recheck, 100);
};