Unable to capture audio from two different devices




WebRTC: Audio/Video
3 years ago
9 months ago


(Reporter: ian.foote, Unassigned)


(Depends on: 1 bug)

39 Branch

Firefox Tracking Flags

(Not tracked)




3 years ago
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.89 Safari/537.36

Steps to reproduce:

I've tested FF using the web audio demo located here:


I used two different external microphones, one a digital stethoscope,
and one integrated into a USB webcam.

I opened the demo in Chrome and connected it to one, and opened it in
FF and connected it to the other, and confirmed that I had good sound
isolation by tapping on each of the microphones in turn with my finger
and observing the response in the audio graph.

Then I opened it in two different FF browsers, and confirmed the following.

Open FF1 connected to the steth.
Tap on it steth, confirm that FF1 is receiving audio.
Open FF2 connected to the webcam microphone.
Tap on webcam, observe that both FF1 and FF2 are showing the exact
same response in the audio graph.
Tap on steth, observe that neither FF1 nor FF2 show any response.
Refresh FF1 and again choose the stethoscope.
Tap on steth, observe that both FF1 and FF2 are showing identical
response in the audio graph.
Tap on webcam, observe that neither FF1 nor FF2 show any response.

Actual results:

Both browsers captured audio from the most recently chosen audio device

Expected results:

The browsers should have captured audio from the device they chose when the call to mozGetUserMedia was made
Component: Untriaged → Web Audio
Product: Firefox → Core
Component: Web Audio → WebRTC: Audio/Video
Note that full_duplex audio totally reworks audio input.  Full_duplex support has landed for linux, and will be preffed-on soon. Right now full_duplex doesn't support two different mics for input at the same time; there's a bug to resolve this.  We expect to pref on the major desktop platforms for full_duplex during 47.

Given the full_duplex work, this bug is mostly moot since I doubt any fix would be upliftable to 46, and the existing bug 1238038 should resolve this.  Once that lands, this likely should be resolved.
backlog: --- → webrtc/webaudio+
Rank: 22
Depends on: 1238038
Ever confirmed: true
Priority: -- → P2
Mass change P2->P3 to align with new Mozilla triage process.
Priority: P2 → P3
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