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Re: [mediacapture-fromelement] Is mute event expected to be dispatched at MediaStreamTrack when enabled is set to false? (#80)

From: guest271314 via GitHub <sysbot+gh@w3.org>
Date: Wed, 05 Jun 2019 19:36:23 +0000
To: public-webrtc-logs@w3.org
Message-ID: <issue_comment.created-499224998-1559763382-sysbot+gh@w3.org>

> is what asynchronous to setting enabled?

At `pause` event of `<video>` element, where `ReadableStream` `pull()` method has `if` condition which checks if the current `MediaStreamTrack` of kind `"video"` is `enabled`.

> Media flow turning video black/non-black or audio silent/audible?

In this case a video track captured from an `HTMLVideoElement`. 


The initial motivation was to use `mute` event to pause `MediaRecorder`, set next `MediaStreamTrack`s (specifically derived from `captureStream()`) to be recorded, which given your feedback, is not appropriate; neither is `ended`. `pause` event of `<video>` is the one event from which other events related to processing (recording) multiple `MediaStreamTrack`s at the same `<video>` element where the `src` is changed (without using WebRTC). Which is ok to be aware of. 

> For a bug in Chromium, ask the Chromium folks what is the best workaround.

(Resolved the issue by setting the `ReadableStreamDefaultController` as a property of a `Map` outside of `pull()` then executing `close()` outside of `pull()`. Am still interested in becoming aware of the exact expected control flow between async functions, `DOM` events (`addtrack` of `MediaStream` returned from `captureStream()`; `pause` event of `HTMLVideoElement` where the captured `MediaStreamTrack` media source is derived from, where the `src` of the `HTMLVideoElement` is subsequently changed, which fires `addtrack` again) as to why two versions of the code output different (and variable; perhaps related to garbage collection, "event loop" (`DOM` events), task queues, microtasks (`async/await`; `Promise`?) results, which have asked Chromium developers about)

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Received on Wednesday, 5 June 2019 19:36:25 UTC

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