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Bug 1306999 - Make HTMLMediaElement::CanActivateAutoplay() spec compliant. r=jya,jib

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HTMLMediaElement::CanActivateAutoplay() had an exception for MediaStreams in its
check for whether autoplay can be activated. This removes that exception and
requires us to be in HAVE_ENOUGH_DATA regardless of source, per spec.

Doing this broke autoplay of an ended media element that's playing a
MediaStream, since autoplay of this MediaStream could no longer be immediately
activated. The exact sequence algorithm for autoplaying the stream in this case
is not defined in mediacapture-main, but we know we must reach HAVE_ENOUGH_DATA
to play, and we must run the load algorithm to reach HAVE_ENOUGH_DATA, that's
what we do:
When the MediaStream we're autoplaying once again becomes active, we run the
media element load algorithm.

Differential Revision: https://phabricator.services.mozilla.com/D33298
This commit is contained in:
Andreas Pehrson
2019-06-10 13:11:49 +00:00
parent f0be05e744
commit aea5aa6bd6
1 changed files with 31 additions and 11 deletions
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42
dom/html/HTMLMediaElement.cpp
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@@ -4584,9 +4584,36 @@ class HTMLMediaElement::MediaStreamTrackListener
if (!mElement) {
return;
}
LOG(LogLevel::Debug, ("%p, mSrcStream %p became active", mElement.get(),
mElement->mSrcStream.get()));
mElement->CheckAutoplayDataReady();
// mediacapture-main says:
// Note that once ended equals true the HTMLVideoElement will not play media
// even if new MediaStreamTracks are added to the MediaStream (causing it to
// return to the active state) unless autoplay is true or the web
// application restarts the element, e.g., by calling play().
//
// This is vague on exactly how to go from becoming active to playing, when
// autoplaying. However, per the media element spec, to play an autoplaying
// media element, we must load the source and reach readyState
// HAVE_ENOUGH_DATA [1]. Hence, a MediaStream being assigned to a media
// element and becoming active runs the load algorithm, so that it can
// eventually be played.
//
// [1]
// https://html.spec.whatwg.org/multipage/media.html#ready-states:event-media-play
LOG(LogLevel::Debug, ("%p, mSrcStream %p became active, checking if we "
"need to run the load algorithm",
mElement.get(), mElement->mSrcStream.get()));
if (!mElement->IsPlaybackEnded()) {
return;
}
if (!mElement->Autoplay()) {
return;
}
LOG(LogLevel::Info, ("%p, mSrcStream %p became active on autoplaying, "
"ended element. Reloading.",
mElement.get(), mElement->mSrcStream.get()));
mElement->DoLoad();
}
void NotifyInactive() override {
@@ -4737,7 +4764,6 @@ void HTMLMediaElement::SetupSrcMediaStreamPlayback(DOMMediaStream* aStream) {
ChangeNetworkState(NETWORK_IDLE);
ChangeDelayLoadStatus(false);
CheckAutoplayDataReady();
// FirstFrameLoaded() will be called when the stream has tracks.
}
@@ -5573,9 +5599,6 @@ void HTMLMediaElement::ChangeNetworkState(nsMediaNetworkState aState) {
}
bool HTMLMediaElement::CanActivateAutoplay() {
// For stream inputs, we activate autoplay on HAVE_NOTHING because
// this element itself might be blocking the stream from making progress by
// being paused. We only check that it has data by checking its active state.
// We also activate autoplay when playing a media source since the data
// download is controlled by the script and there is no way to evaluate
// MediaDecoder::CanPlayThrough().
@@ -5618,10 +5641,7 @@ bool HTMLMediaElement::CanActivateAutoplay() {
}
}
bool hasData = (mDecoder && mReadyState >= HAVE_ENOUGH_DATA) ||
(mSrcStream && mSrcStream->Active());
return hasData;
return mReadyState >= HAVE_ENOUGH_DATA;
}
void HTMLMediaElement::CheckAutoplayDataReady() {