1575026 - MediaEngineWebRTC.cpp fires assert MOZ_ASSERT(!preferredDeviceFound); when invoking getUserMedia

Status: RESOLVED FIXED

(Core :: Audio/Video: Recording, defect, P2)

Description

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

I'm able to reliably hit the assert here. I think think is due to having a different default communication device and non-communication device set under Windows sound settings.

STR:

• Have 2+ output devices connected to a Windows 10 machine.
• Navigate to control panel -> hardware and sound -> sound.
• Set the default output device and default communication output device to different devices.
• Open https://simpl.info/mediarecorder/
• Assert fires.

Appears that the check we're hitting is meant to ensure we never have more than one preferred device, but that it's possible to get 2 due to Windows letting us select one for 'normal' usage, and one for communication.

Alex, and idea on how we should handle multiple preferred devices?

Comment 1

[Alex Chronopoulos [:achronop]]

Thanks for bringing it to my attention. I will find a way to support the multiple preferred device. I am adding it to my queue.

Comment 2

[Alex Chronopoulos [:achronop]]

In microphone enumeration, we avoid the assert on windows for the same reason [1]. I'll do the same for output devices.

[1] https://searchfox.org/mozilla-central/rev/428cf94f4ddfb80eebc6028023a7d89eb277791b/dom/media/webrtc/MediaEngineWebRTC.cpp#180-191

Comment 3

[Alex Chronopoulos [:achronop]]

Attachment: Bug 1575026 - Remove an assert on Windows. r?bryce

The assert verifies that there is only one preferred device. On windows it is expected to have more than one preferred device so it is removed.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e3aba6993840
Remove an assert on Windows. r=bryce

Comment 5

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/e3aba6993840