maxChannelCount vs sinkId

[chrisguttandin]

Describe the issue

Currently the setter of the channelCount property of the AudioDestinationNode is meant to fire an IndexSizeError if the "value is not within the valid range".

But now that it's possible to change the audio output device the valid range might change at any time. Let's imagine the currently used audio output device has 6 channels and all 6 of them are in use.

audioContext.destination.channelCount = 6;

But later on the audio output device gets changed and the newly selected device only supports 2 channels.

audioContext.setSinkId('id-of-a-device-with-two-channels');

I guess this should throw an IndexSizeError, too.

Where Is It

https://webaudio.github.io/web-audio-api/#AudioDestinationNode

Additional Information

I'm not sure if this case is already handled somewhere in the spec. Theoretically it was already possible before to change the audio output device without setSinkId() by changing the default audio output device on the OS level.

[orottier]

In similar vein: in the future we can choose a render quantum size optimized for the current sink (AudioContextRenderSizeCategory::hardware) which should remain constant for the lifetime of the BaseAudioContext. But what should happen when we change the sinkId?

[mdjp]

After discussion, we will continue to use the downmixing mechanism in the API. A new issue will be raised to ensure that an event is triggered on device change.

[padenot]

After discussion, we will continue to use the downmixing mechanism in the API. A new issue will be raised to ensure that an event is triggered on device change.

This is #2532.