- From: guest271314 via GitHub <sysbot+gh@w3.org>
- Date: Wed, 12 Aug 2020 16:39:26 +0000
- To: public-webrtc-logs@w3.org
Re long-term, at the front-end `getUserMedia({audio:true})` at Chromium is useless relevant to initial device selection
The user does not gain any knowledge about the device being captured other than "microphone".
The order _should be_ `enumerateDevices()` => `getUserMedia(<selected_device(s)>)` for the user to be fully aware of the specific devices selected _before_ the capture actually commences at `getUserMedia()`.
Attempting to massage clarity from `getUserMedia({audio: true})` => `enumerateDevices()` requires calling `getUserMedia()` _at least twice_ when the initial selected device (Default) is not the device intended to be captured.
As you pointed out, attempting to select a device the implementation refuses to support capture of leads to a `DOMException` not even described in the specification, see https://bugs.chromium.org/p/chromium/issues/detail?id=931749
> We use pulse audio to create an audio sink and configure the monitor of that sink as the default/fallback source of that device.
> E.g. a pa configuration like this:
> ```
> load-module module-null-sink sink_name=main_mix
> set-default-source main_mix.monitor
> ```
>
> In Chrome we then try to access this source. The default audio input device is listed in the result of `navigator.mediaDevices.enumerateDevices`, but when we try to access it we get the following error:
> `DOMException: could not start audio source`
To avoid such restrictions implementers might decide to arbtririly incorporate into their version of `getUserMedia()` `enumerateDevices()` should precede `getUserMedia()` so that users can evaluate the list of available devices and either select a device the implementation decides to expose, or not use `getUserMedia()` at all for the use case.
Ideally, there should not be any restrictions at all on which devices can be selected for capture, whether the device identifier is `'speech-dispatcher'`, a monitor device, or virtual device.
The change would break existing web applications, though since this specification is active and users of `getUserMedia()` are well-suited to changing code in response to changes, the users at large should be able to adjust code accordingly rather swiftly.
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Received on Wednesday, 12 August 2020 16:39:29 UTC