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Update MediaSource polyfills for Safari 13
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Safari 13 is out, and needs polyfills just like Safari 12 did
(although one fewer).  This assumes that Safari 13+ all need the same
polyfills (to avoid surprise failures when Safari 14 comes out).

This also raises the minimum version from Safari 9 to Safari 11, since
usage stats for Safari 9 and 10 are vanishingly small.  Dropping
support for Safari 9 and 10 allows us to delete a complicated polyfill
used for those versions.

Change-Id: I8f833d915215fc19a89e3aea292b67c5d677c779
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@joeyparrish
joeyparrish committed Oct 8, 2019
1 parent 9e92167 commit 65370b4
Showing 1 changed file with 21 additions and 136 deletions.
157 changes: 21 additions & 136 deletions lib/polyfill/mediasource.js
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Original file line number Diff line number Diff line change
Expand Up @@ -46,50 +46,45 @@ shaka.polyfill.MediaSource = class {
// Chromecast cannot make accurate determinations via isTypeSupported.
shaka.polyfill.MediaSource.patchCastIsTypeSupported_();
} else if (shaka.util.Platform.isApple()) {
const version = navigator.appVersion;
const match = navigator.appVersion.match(/Version\/(\d+)/);
const version = parseInt(match[1], /* base */ 10);

// 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_();

if (version.includes('Version/8')) {
// Safari 8 does not implement appendWindowEnd. If we ignore the
// incomplete MSE implementation, some content (especially multi-period)
// will fail to play correctly. The best we can do is blacklist Safari
// 8.
shaka.log.info('Blacklisting Safari 8 MSE.');
shaka.polyfill.MediaSource.blacklist_();
} else if (version.includes('Version/9')) {
shaka.log.info('Patching Safari 9 MSE bugs.');
// Safari 9 does not correctly implement abort() on SourceBuffer.
// Calling abort() causes a decoder failure, rather than resetting the
// decode timestamp as called for by the spec.
if (version <= 10) {
// Safari 8 does not implement appendWindowEnd.
// Safari 9 & 10 do not correctly implement abort() on SourceBuffer.
// Bug filed: https://bugs.webkit.org/show_bug.cgi?id=160316
shaka.polyfill.MediaSource.stubAbort_();
} else if (version.includes('Version/10')) {
shaka.log.info('Patching Safari 10 MSE bugs.');
// Safari 10 does not correctly implement abort() on SourceBuffer.
// Calling abort() before appending a segment causes that segment to be
// incomplete in buffer.
// Bug filed: https://bugs.webkit.org/show_bug.cgi?id=165342
shaka.polyfill.MediaSource.stubAbort_();
// Safari 10 fires spurious 'updateend' events after endOfStream().
// Bug filed: https://bugs.webkit.org/show_bug.cgi?id=165336
shaka.polyfill.MediaSource.patchEndOfStreamEvents_();
} else if (version.includes('Version/11') ||
version.includes('Version/12')) {
shaka.log.info('Patching Safari 11/12 MSE bugs.');
// Safari 11 does not correctly implement abort() on SourceBuffer.

// Blacklist these very outdated versions.
shaka.log.info('Blacklisting MSE on Safari <= 10.');
shaka.polyfill.MediaSource.blacklist_();
} else if (version <= 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 incorrectly will also

// 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.isTizen()) {
// Tizen's implementation of MSE does not work well with opus. To prevent
Expand Down Expand Up @@ -151,116 +146,6 @@ shaka.polyfill.MediaSource = class {
};
}

/**
* Patch endOfStream() to get rid of 'updateend' events that should not fire.
* These extra events confuse MediaSourceEngine, which relies on correct
* events to manage SourceBuffer state.
*
* @private
*/
static patchEndOfStreamEvents_() {
// eslint-disable-next-line no-restricted-syntax
const endOfStream = MediaSource.prototype.endOfStream;
// eslint-disable-next-line no-restricted-syntax
MediaSource.prototype.endOfStream = function(...varArgs) {
// This bug manifests only when endOfStream() results in the truncation
// of the MediaSource's duration. So first we must calculate what the
// new duration will be.
let newDuration = 0;
for (const buffer of this.sourceBuffers || []) {
const bufferEnd = buffer.buffered.end(buffer.buffered.length - 1);
newDuration = Math.max(newDuration, bufferEnd);
}

// If the duration is going to be reduced, suppress the next 'updateend'
// event on each SourceBuffer.
if (!isNaN(this.duration) &&
newDuration < this.duration) {
this.ignoreUpdateEnd_ = true;
for (const buffer of this.sourceBuffers || []) {
buffer.eventSuppressed_ = false;
}
}

// eslint-disable-next-line no-restricted-syntax
return endOfStream.apply(this, varArgs);
};

let cleanUpHandlerInstalled = false;
// eslint-disable-next-line no-restricted-syntax
const addSourceBuffer = MediaSource.prototype.addSourceBuffer;
// eslint-disable-next-line no-restricted-syntax
MediaSource.prototype.addSourceBuffer = function(...varArgs) {
// After adding a new source buffer, add an event listener to allow us to
// suppress events.
// eslint-disable-next-line no-restricted-syntax
const sourceBuffer = addSourceBuffer.apply(this, varArgs);
sourceBuffer['mediaSource_'] = this;
sourceBuffer.addEventListener('updateend',
shaka.polyfill.MediaSource.ignoreUpdateEnd_, false);

if (!cleanUpHandlerInstalled) {
// If we haven't already, install an event listener to allow us to clean
// up listeners when MediaSource is torn down.
this.addEventListener('sourceclose',
shaka.polyfill.MediaSource.cleanUpListeners_, false);
cleanUpHandlerInstalled = true;
}
return sourceBuffer;
};
}

/**
* An event listener for 'updateend' which selectively suppresses the events.
*
* @see shaka.polyfill.MediaSource.patchEndOfStreamEvents_
*
* @param {Event} event
* @private
*/
static ignoreUpdateEnd_(event) {
const sourceBuffer = event.target;
const mediaSource = sourceBuffer['mediaSource_'];

if (mediaSource.ignoreUpdateEnd_) {
event.preventDefault();
event.stopPropagation();
event.stopImmediatePropagation();
sourceBuffer.eventSuppressed_ = true;

for (const buffer of mediaSource.sourceBuffers) {
if (buffer.eventSuppressed_ == false) {
// More events need to be suppressed.
return;
}
}

// All events have been suppressed, all buffers are out of 'updating'
// mode. Stop suppressing events.
mediaSource.ignoreUpdateEnd_ = false;
}
}

/**
* An event listener for 'sourceclose' which cleans up listeners for
* 'updateend' to avoid memory leaks.
*
* @see shaka.polyfill.MediaSource.patchEndOfStreamEvents_
* @see shaka.polyfill.MediaSource.ignoreUpdateEnd_
*
* @param {Event} event
* @private
*/
static cleanUpListeners_(event) {
const mediaSource = /** @type {!MediaSource} */ (event.target);
for (const buffer of mediaSource.sourceBuffers || []) {
buffer.removeEventListener('updateend',
shaka.polyfill.MediaSource.ignoreUpdateEnd_, false);
}
mediaSource.removeEventListener('sourceclose',
shaka.polyfill.MediaSource.cleanUpListeners_, false);
}

/**
* Patch isTypeSupported() to reject TS content. Used to avoid TS-related MSE
* bugs on Safari.
Expand Down

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