Chrome 141 adds getDisplayMedia() windowAudio option

[chrisdavidmills]

Summary

Chrome/Edge desktop 141 add support for the getDisplayMedia() windowAudio option. See https://chromestatus.com/feature/5072779506089984.

This PR adds support for the new option. Note the slightly weird set of default values that differ across browsers and versions, and the partial implementation. I found these results by testing a modified version of https://mdn.github.io/dom-examples/screen-capture-api/basic-screen-capture/ with the new option added in.

Test results and supporting details

Related issues

[github-actions]

Tip: Review these changes grouped by change (recommended for most PRs), or grouped by feature (for large PRs).

[chrisdavidmills]

@eladalon1983, could you have a look at this compat data PR and let me know if it agrees with your understanding? The data is a bit weird, but this is what my tests showed.

[caugner]

Are we sure the default values are inversed between Chrome and Edge?

Your changes state:

• Chrome 141 = system, but Edge 141/142 = exclude
• Chrome 142+ = exclude, but Edge 143+ = system

[caugner]

Let's merge the partial statements:

Suggested change

	"chrome": [
	{
	"version_added": "142",
	"partial_implementation": true,
	"notes": [
	"Default value = `exclude`",
	"`window` value not supported"
	]
	},
	{
	"version_added": "141",
	"version_removed": "142",
	"partial_implementation": true,
	"notes": [
	"Default value = `system`",
	"`window` value not supported"
	]
	}
	],
	"chrome": {
	"version_added": "141",
	"partial_implementation": true,
	"notes": [
	"Defaults to `\"exclude\". Before Chrome 142, it defaulted to `\"system\"`.",
	"Only supports values `\"exclude\"` and `\"system\"`, not `\"window\"`."
	]
	},

[eladalon1983]

@eladalon1983, could you have a look at this compat data PR and let me know if it agrees with your understanding? The data is a bit weird, but this is what my tests showed.

I think @drkron should take it from here. :-)

[chrisdavidmills]

Are we sure the default values are inversed between Chrome and Edge?

Your changes state:

* Chrome 141 = `system`, but Edge 141/142 = `exclude`

* Chrome 142+ = `exclude`, but Edge 143+ = `system`

@caugner it sounds weird, but this is what I found during testing.

I agree with merging the partials; I've implemented the updates locally and then pushed.

[drkron]

Could you share some details on how this was tested?

My understanding is that the default value in Chrome should be system, and my own testing on macOS confirms this behavior. If it's defaulting to something else, that seems like it could be a bug.

[chrisdavidmills]

Could you share some details on how this was tested?

My understanding is that the default value in Chrome should be system, and my own testing on macOS confirms this behavior. If it's defaulting to something else, that seems like it could be a bug.

I tested it using a modified version of the basic demo at https://mdn.github.io/dom-examples/screen-capture-api/basic-screen-capture/. I modified it to add the different windowAudio options in turn to see what the effect was, then removed it altogether to see what the default behavior was.

[drkron]

Can you test on this sample page to if see you get the same behavior?
https://drkron.github.io/system-audio-demo/

If you click the getDisplayMedia button without changing anything, getDisplayMedia() is called without windowAudio being set.

[chrisdavidmills]

Can you test on this sample page to if see you get the same behavior? https://drkron.github.io/system-audio-demo/

If you click the getDisplayMedia button without changing anything, getDisplayMedia() is called without windowAudio being set.

Ah, looks like my testing went wrong somehow. Testing using your demo:

• Chrome shows system as the default all the way through.
• Edge shows system as the default from Edge 142 onwards, and exclude before that.

I'll raise another PR to correct this. Thanks for your help.

[drkron]

Ah, looks like my testing went wrong somehow. Testing using your demo:

• Chrome shows system as the default all the way through.
• Edge shows system as the default from Edge 142 onwards, and exclude before that.

I'll raise another PR to correct this. Thanks for your help.

Thanks for testing again.