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Re: [mediacapture-fromelement] Clarify if CanvasCaptureMediaStreamTrack mute, unmute, and ended events are expected to be fired (#82)

From: Andreas Pehrson via GitHub <sysbot+gh@w3.org>
Date: Thu, 05 Dec 2019 15:26:47 +0000
To: public-webrtc-logs@w3.org
Message-ID: <issue_comment.created-562178415-1575559606-sysbot+gh@w3.org>
I'll note that the spec has this language for canvas capture:

> A captured stream MUST immediately cease to capture content if the origin-clean flag of the source canvas becomes false after the stream is created by captureStream(). The captured MediaStreamTrack MUST become muted, producing no new content while the canvas remains in this state.

As guidance, [mediacapture-main](https://w3c.github.io/mediacapture-main/#life-cycle-and-media-flow) says this about muted tracks:
> A MediaStreamTrack is muted when the source is temporarily unable to provide the track with data. A track can be muted by a user. Often this action is outside the control of the application. This could be as a result of the user hitting a hardware switch or toggling a control in the operating system / browser chrome. A track can also be muted by the User Agent.

With my own interpretation, "temporarily unable to provide the track with data" would for a canvas mean that if you were to draw something to the canvas it wouldn't be provided to the track.

I think the spec is good in this regard, and that Chromium is not spec compliant if they fire muted just because the application hasn't done any drawing for a while.

-- 
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Received on Thursday, 5 December 2019 15:26:48 UTC

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