Bug 227756 – [Cocoa] Make Coordinator playback commands more precise

• Component: New Bugs
• Status: RESOLVED FIXED

[Jer Noble]

[Cocoa] Make Coordinator playback commands more precise

[Jer Noble]

Created attachment 433055 [details]
Patch

[Jer Noble]

Created attachment 433059 [details]
Patch

[Jer Noble]

Created attachment 433060 [details]
Patch

[Eric Carlson]

Comment on attachment 433059 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=433059&action=review

> Source/WTF/wtf/CurrentTime.cpp:267
> +MonotonicTime MonotonicTime::fromMachAbsoluteTime(uint64_t machAbsoluteTime)

Can this (and fromMachAbsoluteTime) be const?

> Source/WebCore/Modules/mediasession/MediaSessionCoordinator.h:77
> +    const std::optional<PlaySessionCommand>& currentPlaySessionCommand() const { return m_currentPlaySessionCommand; }

It looks like this isn't used.

> Source/WebCore/html/HTMLMediaElement.cpp:5430
> +        if (!currentPlaySessionCommand->hostTime)
> +            break;

Is it ever valid for the coordinator to have a current play session command without a host time? If not, should this assert?

> Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:1573
> +        [m_avPlayer setAutomaticallyWaitsToMinimizeStalling:shouldAutomaticallyWait];
> +        m_automaticallyWaitsToMinimizeStalling = shouldAutomaticallyWait;

Should we restore this after the setRate completes?

[Eric Carlson]

Comment on attachment 433060 [details]
Patch

r=me once the bots are happy

[Jer Noble]

(In reply to Eric Carlson from comment #4)
> Comment on attachment 433059 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=433059&action=review
> 
> > Source/WTF/wtf/CurrentTime.cpp:267
> > +MonotonicTime MonotonicTime::fromMachAbsoluteTime(uint64_t machAbsoluteTime)
> 
> Can this (and fromMachAbsoluteTime) be const?

They can't be because they're already `static`.

> > Source/WebCore/Modules/mediasession/MediaSessionCoordinator.h:77
> > +    const std::optional<PlaySessionCommand>& currentPlaySessionCommand() const { return m_currentPlaySessionCommand; }
> 
> It looks like this isn't used.

True; it's just there for completeness and as a convenience. I'll remove it.

> > Source/WebCore/html/HTMLMediaElement.cpp:5430
> > +        if (!currentPlaySessionCommand->hostTime)
> > +            break;
> 
> Is it ever valid for the coordinator to have a current play session command
> without a host time?

Yes, there's no guarantee at the WebCore level that a valid hostTime is present; that's a detail of the MediaSessionCoordinatorPrivate.

> > Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:1573
> > +        [m_avPlayer setAutomaticallyWaitsToMinimizeStalling:shouldAutomaticallyWait];
> > +        m_automaticallyWaitsToMinimizeStalling = shouldAutomaticallyWait;
> 
> Should we restore this after the setRate completes?

Interesting question, but it seems improbable. We only call setRate: from this method, so I'm pretty sure it wouldn't have any effect otherwise.

[Jer Noble]

Created attachment 433062 [details]
Patch for landing

[Jer Noble]

Created attachment 433063 [details]
Patch for landing

[EWS]

Committed r279786 (239553@main): <https://commits.webkit.org/239553@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 433063 [details].

[Radar WebKit Bug Importer]

<rdar://problem/80381143>