MSE-in-Workers: Consider adding a "closing" readyState to explain new InvalidStateError exception when closing underway
#276
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TPAC2024
Topic for discussion at TPAC 2024
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wolenetz
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May 26, 2021
Also adds the `github:` respecConfig key and an issues-summary appendix.
wolenetz
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Jun 30, 2021
Also adds the `github:` respecConfig key and an issues-summary appendix.
wolenetz
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Jul 26, 2021
Specifies expansion of MSE API to usage from DedicatedWorker contexts. This is an MSEv2 feature tracked by issue w3c#175. See also earlier WICG explainer [1]. This is a squashed commit of 23 original commits, notably: * Adds `closing` issue and link to w3c#276. * Adds the `github:` respecConfig key and an issues-summary appendix. * Removes redundant 'Repository' otherLinks config (addition of 'github' to respecConfig has make the manual enumeration in the 'Repository' otherLinks portion of respecConfig redundant.) * Adds subsections for each of the extended HTMLMediaElement's .seekable and .buffered attributes. * Adds more normative detail to the .buffered extension. * Specifies what .seekable and .buffered do when worker has terminated, and references w3c#277 for further discussion. * Describes cross-context track object aliasing. AudioTrack, VideoTrack, TextTrack extensions' sourceBuffer attribute must be null in the Window context's alias of the track if the track is an alias to a worker-created track from MSE-in-Worker. This is to prevent any assumption that cross-context object references are somehow now allowed in MSE or HTMLMediaElement+MSE. * Describes a MessageChannel-based cross-context communication mechanism in a new section, including how MessagePorts on that channel are given to each side (media element, MediaSource) for communicating state needed by algorithms. Updates multiple algorithms and methods to use this mechanism where necessary. Resolves w3c#279. * Specifies how to detect this feature using new `canConstructInDedicatedWorker` attribute without requiring the detection happening in a DedicatedWorker context. * Modernizes to use respec's new variable syntax (`|...|` with types inlined)) for related lines. Wider modernization is an editorial item that is out of scope of this feature. * Modernizes to use internal slots for the new cross-context communication mechanism's channel and ports. Wider modernization is an editorial item out of scope of this feature.o Note, multiple simultaneous changes to track's `selected`, `enabled` or `hidden`/`showing` states could be in-flight from window to worker, and from worker to window. A non-normative note might be good to add here to warn API users of this possibility. See w3c#278. Note, {Audio,Video,Track}{,List} IDL need to be exposed in DedicatedWorker. This might need to be directly in the media element spec. See w3c#280. Note, a reference to an MSE-in-Worker example/demo would be good in the merged PR. Such a demo exists already at [2]. [1] https://github.com/wicg/media-source/blob/mse-in-workers-using-handle/mse-in-workers-using-handle-explainer.md [2] https://wolenetz.github.io/mse-in-workers-demo/mse-in-workers-demo.html
wolenetz
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Aug 31, 2021
Specifies expansion of MSE API to usage from DedicatedWorker contexts. This is an MSEv2 feature tracked by issue #175. See also earlier WICG explainer [1]. This is a squashed commit of 23 original commits, notably: * Adds `closing` issue and link to #276. * Adds the `github:` respecConfig key and an issues-summary appendix. * Removes redundant 'Repository' otherLinks config (addition of 'github' to respecConfig has make the manual enumeration in the 'Repository' otherLinks portion of respecConfig redundant.) * Adds subsections for each of the extended HTMLMediaElement's .seekable and .buffered attributes. * Adds more normative detail to the .buffered extension. * Specifies what .seekable and .buffered do when worker has terminated, and references #277 for further discussion. * Describes cross-context track object aliasing. AudioTrack, VideoTrack, TextTrack extensions' sourceBuffer attribute must be null in the Window context's alias of the track if the track is an alias to a worker-created track from MSE-in-Worker. This is to prevent any assumption that cross-context object references are somehow now allowed in MSE or HTMLMediaElement+MSE. * Describes a MessageChannel-based cross-context communication mechanism in a new section, including how MessagePorts on that channel are given to each side (media element, MediaSource) for communicating state needed by algorithms. Updates multiple algorithms and methods to use this mechanism where necessary. Resolves #279. * Specifies how to detect this feature using new `canConstructInDedicatedWorker` attribute without requiring the detection happening in a DedicatedWorker context. * Modernizes to use respec's new variable syntax (`|...|` with types inlined)) for related lines. Wider modernization is an editorial item that is out of scope of this feature. * Modernizes to use internal slots for the new cross-context communication mechanism's channel and ports. Wider modernization is an editorial item out of scope of this feature.o Note, multiple simultaneous changes to track's `selected`, `enabled` or `hidden`/`showing` states could be in-flight from window to worker, and from worker to window. A non-normative note might be good to add here to warn API users of this possibility. See #278. Note, {Audio,Video,Track}{,List} IDL need to be exposed in DedicatedWorker. This might need to be directly in the media element spec. See #280. There were some still unresolved cosmetic comments on this PR during later portion of review that I'll follow-up on in a later PR. Note, a reference to an MSE-in-Worker example/demo would be good in the merged PR. Such a demo exists already at [2]. [1] https://github.com/wicg/media-source/blob/mse-in-workers-using-handle/mse-in-workers-using-handle-explainer.md [2] https://wolenetz.github.io/mse-in-workers-demo/mse-in-workers-demo.html
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MSE-in-Workers feature issue is #175
This issue tracks discussing an additional
readyStateusable by apps to understand when a worker MediaSource object is in the process of being closed or detached-from by the formerly-attachedHTMLMediaElement. Implementations may choose to throwInvalidStateErrorexception when servicing requests on a worker-owned MediaSource or SourceBuffer that requirereadyStateto not beclosed, yet the implementation has begun but not yet fully completed the steps involved in reachingclosedreadyState.For example, setting the
modeattribute of a SourceBuffer requires essentially that the parentMediaSourcenot beclosednorupdating. But if it knows that it will be closing imminently due to some internal notification from the implementation of its attachment toHTMLMediaElement, then it may throw exception. Having a distinctreadyStatefor this scenario would assist worker API usage debugging (see an example of such at #175 (comment)).The text was updated successfully, but these errors were encountered: