/
mediasource.js
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/
mediasource.js
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/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.polyfill.MediaSource');
goog.require('shaka.log');
goog.require('shaka.polyfill');
goog.require('shaka.util.MimeUtils');
goog.require('shaka.util.Platform');
/**
* @summary A polyfill to patch MSE bugs.
* @export
*/
shaka.polyfill.MediaSource = class {
/**
* Install the polyfill if needed.
* @export
*/
static install() {
shaka.log.debug('MediaSource.install');
// MediaSource bugs are difficult to detect without checking for the
// affected platform. SourceBuffer is not always exposed on window, for
// example, and instances are only accessible after setting up MediaSource
// on a video element. Because of this, we use UA detection and other
// platform detection tricks to decide which patches to install.
const safariVersion = shaka.util.Platform.safariVersion();
if (!window.MediaSource) {
shaka.log.info('No MSE implementation available.');
} else if (window.cast && cast.__platform__ &&
cast.__platform__.canDisplayType) {
shaka.log.info('Patching Chromecast MSE bugs.');
// Chromecast cannot make accurate determinations via isTypeSupported.
shaka.polyfill.MediaSource.patchCastIsTypeSupported_();
} else if (safariVersion) {
// NOTE: shaka.Player.isBrowserSupported() has its own restrictions on
// Safari version.
if (safariVersion <= 12) {
shaka.log.info('Patching Safari 11 & 12 MSE bugs.');
// Safari 11 & 12 do not correctly implement abort() on SourceBuffer.
// Calling abort() before appending a segment causes that segment to be
// incomplete in the buffer.
// Bug filed: https://bugs.webkit.org/show_bug.cgi?id=165342
shaka.polyfill.MediaSource.stubAbort_();
// If you remove up to a keyframe, Safari 11 & 12 incorrectly will also
// remove that keyframe and the content up to the next.
// Offsetting the end of the removal range seems to help.
// Bug filed: https://bugs.webkit.org/show_bug.cgi?id=177884
shaka.polyfill.MediaSource.patchRemovalRange_();
} else {
shaka.log.info('Patching Safari 13 MSE bugs.');
// Safari 13 does not correctly implement abort() on SourceBuffer.
// Calling abort() before appending a segment causes that segment to be
// incomplete in the buffer.
// Bug filed: https://bugs.webkit.org/show_bug.cgi?id=165342
shaka.polyfill.MediaSource.stubAbort_();
}
} else if (shaka.util.Platform.isTizen2() ||
shaka.util.Platform.isTizen3() ||
shaka.util.Platform.isTizen4()) {
shaka.log.info('Rejecting Opus.');
// Tizen's implementation of MSE does not work well with opus. To prevent
// the player from trying to play opus on Tizen, we will override media
// source to always reject opus content.
shaka.polyfill.MediaSource.rejectCodec_('opus');
} else {
shaka.log.info('Using native MSE as-is.');
}
if (window.MediaSource &&
MediaSource.isTypeSupported('video/webm; codecs="vp9"') &&
!MediaSource.isTypeSupported('video/webm; codecs="vp09.00.10.08"')) {
shaka.log.info('Patching vp09 support queries.');
// Only the old, deprecated style of VP9 codec strings is supported.
// This occurs on older smart TVs.
// Patch isTypeSupported to translate the new strings into the old one.
shaka.polyfill.MediaSource.patchVp09_();
}
}
/**
* Stub out abort(). On some buggy MSE implementations, calling abort()
* causes various problems.
*
* @private
*/
static stubAbort_() {
/* eslint-disable no-restricted-syntax */
const addSourceBuffer = MediaSource.prototype.addSourceBuffer;
MediaSource.prototype.addSourceBuffer = function(...varArgs) {
const sourceBuffer = addSourceBuffer.apply(this, varArgs);
sourceBuffer.abort = function() {}; // Stub out for buggy implementations.
return sourceBuffer;
};
/* eslint-enable no-restricted-syntax */
}
/**
* Patch remove(). On Safari 11, if you call remove() to remove the content
* up to a keyframe, Safari will also remove the keyframe and all of the data
* up to the next one. For example, if the keyframes are at 0s, 5s, and 10s,
* and you tried to remove 0s-5s, it would instead remove 0s-10s.
*
* Offsetting the end of the range seems to be a usable workaround.
*
* @private
*/
static patchRemovalRange_() {
// eslint-disable-next-line no-restricted-syntax
const originalRemove = SourceBuffer.prototype.remove;
// eslint-disable-next-line no-restricted-syntax
SourceBuffer.prototype.remove = function(startTime, endTime) {
// eslint-disable-next-line no-restricted-syntax
return originalRemove.call(this, startTime, endTime - 0.001);
};
}
/**
* Patch |MediaSource.isTypeSupported| to always reject |codec|. This is used
* when we know that we are on a platform that does not work well with a given
* codec.
*
* @param {string} codec
* @private
*/
static rejectCodec_(codec) {
const isTypeSupported = MediaSource.isTypeSupported;
MediaSource.isTypeSupported = (mimeType) => {
const actualCodec = shaka.util.MimeUtils.getCodecBase(mimeType);
return actualCodec != codec && isTypeSupported(mimeType);
};
}
/**
* Patch isTypeSupported() to chain to a private API on the Chromecast which
* can query for support of detailed content parameters.
*
* @private
*/
static patchCastIsTypeSupported_() {
const originalIsTypeSupported = MediaSource.isTypeSupported;
MediaSource.isTypeSupported = (mimeType) => {
// Parse the basic MIME type from its parameters.
const pieces = mimeType.split(/ *; */);
pieces.shift(); // Remove basic MIME type from pieces.
const hasCodecs = pieces.some((piece) => piece.startsWith('codecs='));
if (!hasCodecs) {
// Though the original reason for this special case was not documented,
// it is presumed to be because the platform won't accept a MIME type
// without codecs in canDisplayType. It is valid, however, in
// isTypeSupported.
return originalIsTypeSupported(mimeType);
}
// Only canDisplayType can check extended MIME type parameters on this
// platform (such as frame rate, resolution, etc).
// In previous versions of this polyfill, the MIME type parameters were
// manipulated, filtered, or extended. This is no longer true, so we pass
// the full MIME type to the platform as we received it.
return cast.__platform__.canDisplayType(mimeType);
};
}
/**
* Patch isTypeSupported() to translate vp09 codec strings into vp9, to allow
* such content to play on older smart TVs.
*
* @private
*/
static patchVp09_() {
const originalIsTypeSupported = MediaSource.isTypeSupported;
if (shaka.util.Platform.isWebOS()) {
// Don't do this on LG webOS as otherwise it is unable
// to play vp09 at all.
return;
}
MediaSource.isTypeSupported = (mimeType) => {
// Split the MIME type into its various parameters.
const pieces = mimeType.split(/ *; */);
const codecsIndex =
pieces.findIndex((piece) => piece.startsWith('codecs='));
if (codecsIndex < 0) {
// No codec? Call the original without modifying the MIME type.
return originalIsTypeSupported(mimeType);
}
const codecsParam = pieces[codecsIndex];
const codecs = codecsParam
.replace('codecs=', '').replace(/"/g, '').split(/\s*,\s*/);
const vp09Index = codecs.findIndex(
(codecName) => codecName.startsWith('vp09'));
if (vp09Index >= 0) {
// vp09? Replace it with vp9.
codecs[vp09Index] = 'vp9';
pieces[codecsIndex] = 'codecs="' + codecs.join(',') + '"';
mimeType = pieces.join('; ');
}
return originalIsTypeSupported(mimeType);
};
}
};
shaka.polyfill.register(shaka.polyfill.MediaSource.install);