/** @license
* 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.
*/
shaka.polyfill.MediaSource = class {
/**
* Install the polyfill if needed.
*/
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) {
// TS content is broken on Safari in general.
// See https://github.com/google/shaka-player/issues/743
// and https://bugs.webkit.org/show_bug.cgi?id=165342
shaka.polyfill.MediaSource.rejectTsContent_();
// 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()) {
// 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.');
}
}
/**
* 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 isTypeSupported() to reject TS content. Used to avoid TS-related MSE
* bugs on Safari.
*
* @private
*/
static rejectTsContent_() {
const originalIsTypeSupported = MediaSource.isTypeSupported;
MediaSource.isTypeSupported = (mimeType) => {
// Parse the basic MIME type from its parameters.
const pieces = mimeType.split(/ *; */);
const basicMimeType = pieces[0];
const container = basicMimeType.split('/')[1];
if (container.toLowerCase() == 'mp2t') {
return false;
}
return originalIsTypeSupported(mimeType);
};
}
/**
* 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 parse for HDR-related clues and chain to a
* private API on the Chromecast which can query for support.
*
* @private
*/
static patchCastIsTypeSupported_() {
const originalIsTypeSupported = MediaSource.isTypeSupported;
// Docs from Dolby detailing profile names: https://bit.ly/2T2wKbu
const dolbyVisionRegex = /^dv(?:h[e1]|a[v1])\./;
MediaSource.isTypeSupported = (mimeType) => {
// Parse the basic MIME type from its parameters.
const pieces = mimeType.split(/ *; */);
const basicMimeType = pieces.shift(); // Remove pieces[0].
// Parse the parameters into key-value pairs.
/** @type {Object.<string, string>} */
const parameters = {};
for (const piece of pieces) {
const kv = piece.split('=');
const k = kv[0];
const v = kv[1].replace(/"(.*)"/, '$1');
parameters[k] = v;
}
const codecs = parameters['codecs'];
if (!codecs) {
return originalIsTypeSupported(mimeType);
}
let isHDR = false;
let isDolbyVision = false;
const codecList = codecs.split(',').filter((codec) => {
if (dolbyVisionRegex.test(codec)) {
isDolbyVision = true;
}
// We take this string as a signal for HDR, but don't remove it.
// This regex matches the strings "hev1.2" and "hvc1.2".
if (/^(hev|hvc)1\.2/.test(codec)) {
isHDR = true;
}
// Keep all other strings in the list.
return true;
});
// If the content uses Dolby Vision, we take this as a sign that the
// content is not HDR after all.
if (isDolbyVision) {
isHDR = false;
}
// Reconstruct the "codecs" parameter from the results of the filter.
parameters['codecs'] = codecList.join(',');
// If the content is HDR, we add this additional parameter so that the
// Cast platform will check for HDR support.
if (isHDR) {
parameters['eotf'] = 'smpte2084';
}
// Reconstruct the MIME type, possibly with additional parameters.
let extendedMimeType = basicMimeType;
for (const k in parameters) {
const v = parameters[k];
extendedMimeType += '; ' + k + '="' + v + '"';
}
return cast.__platform__.canDisplayType(extendedMimeType);
};
}
};
shaka.polyfill.register(shaka.polyfill.MediaSource.install);