1884016 - [wmfme] some fixes and improvements before enabling media engine pref

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, task, P1)

Description

[Alastor Wu [:alwu]]

There are some fixes and improvement we can do for the media engine playback.

Comment 1

[Alastor Wu [:alwu]]

Attachment: Bug 1884016 - part1 : use ExternalEngineStateMachine for non-mse media only when the media engine pref allows non-encrypted playback.

Comment 2

[Alastor Wu [:alwu]]

Attachment: Bug 1884016 - part2 : do not re-inform the decoder owner about `loadedmetadata` if we've loaded metadata before.

When enalbing media engine playback, we would always start with the
external state machine that would communicate with the media engine.

If the media format or key system is not supported by the media engine,
we would fallback to the MediaDecoderStateMachine (MDSM). In this
situation, we want this transition invisible to users.

Therefore, if the external state machine has loaded and informed the
loadedmetadata to the media element, we shouldn't do it again.
According to the spec [1], the loadedmetadata should only be
dispatched once.

[1] https://html.spec.whatwg.org/multipage/media.html#event-media-loadedmetadata

Comment 3

[Alastor Wu [:alwu]]

Attachment: Bug 1884016 - part3 : add logging.

Comment 4

[Alastor Wu [:alwu]]

Attachment: Bug 1884016 - part4 : update comment.

Comment 5

[Alastor Wu [:alwu]]

Attachment: Bug 1884016 - part5 : only create a remote decoder in the MFCDM process if a media engine ID is provided.

In browser_utility_multipleAudio.js we discover an issue where
we incorrectly create a decoder in the MFCDM process for
non-media-engine playback, which made the playback never start.

Adding this check to ensure that non-media-engine playback would never
use a remote decoder from the MFCDM process.

Comment 6

[Alastor Wu [:alwu]]

Attachment: Bug 1884016 - part6 : avoid re-initialize the video bridge.

There is a timing issue where we would re-initialize the video bridge
causing an assertion, which is discovered by
browser_utility_multipleAudio.js.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d17677f0c58a
part1 : use ExternalEngineStateMachine for non-mse media only when the media engine pref allows non-encrypted playback. r=jolin
https://hg.mozilla.org/integration/autoland/rev/783163d736e5
part2 : do not re-inform the decoder owner about `loadedmetadata` if we've loaded metadata before. r=padenot
https://hg.mozilla.org/integration/autoland/rev/f678e00a9d18
part3 : add logging. r=media-playback-reviewers,padenot
https://hg.mozilla.org/integration/autoland/rev/c2e3aed2c7db
part4 : update comment. r=media-playback-reviewers,padenot
https://hg.mozilla.org/integration/autoland/rev/0aaf120a192d
part5 : only create a remote decoder in the MFCDM process if a media engine ID is provided. r=jolin
https://hg.mozilla.org/integration/autoland/rev/99f73914c529
part6 : avoid re-initialize the video bridge. r=gerard-majax

Comment 8

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/d17677f0c58a
https://hg.mozilla.org/mozilla-central/rev/783163d736e5
https://hg.mozilla.org/mozilla-central/rev/f678e00a9d18
https://hg.mozilla.org/mozilla-central/rev/c2e3aed2c7db
https://hg.mozilla.org/mozilla-central/rev/0aaf120a192d
https://hg.mozilla.org/mozilla-central/rev/99f73914c529