Mumble: Poor quality audio when using bluetooth headphones

[jackys-95]

I have noticed a strange system wide audio bug when using Mumble with bluetooth headphones. The moment I start Mumble system wide audio reduces in quality drastically e.g. intermittent cutting out, added crackle noise. Normal audio quality resumes when I close Mumble. I am currently using Mumble 1.2.19 on Mac OS High Sierra (10.13.6) with a pair of BeatsX headphones on a MacBook Pro 2018. A friend of mine has reproduced this issue on a MacBook Pro 2015 with a pair of Bose QC35.

[davidebeatrici]

Could you try to install the latest snapshot and check if the issue persists, please?

[jackys-95]

Ive just tried a snapshot (Mumble-1.3.0\~2729\~g2126495\~snapshot.dmg) and the issue is still present.

[davidebeatrici]

Does the issue persist if you unplug the headphones?

[jackys-95]

Upon disconnecting the bluetooth headphones, the audio sounds perfectly normal using the speakers.

[jeto]

Have you tried switching the microphone input from the headphones to internal?

https://superuser.com/questions/12292/bluetooth-headphones-sound-terrible-on-mac-os-x

[adiq]

Switching mic to other input works great, but it still seems like a temporary fix.

[reinoud-jules]

Late to the party, but this has to do with a limitation of the Bluetooth protocol. To allocate for data being sent and received (mic data transmitted, and audio data received), the Bluetooth protocol lowers its quality drastically to save bandwidth. I have been struggling with this for ages, and even bought new headphones only to find out it has nothing to do with the headphones, or macOS in particular.

[adiq]

@reinoud-jules as far as I remember Google ~Hangouts~ Meet or Discord works fine, so I would be skeptical about Bluetooth protocol limitations.

[reinoud-jules]

With Apple Airpods Pro I have the same problem with hangouts, discord, and VoIP calling. When, in those apps, I switch the input source (microphone) to the default source (iMac or MacBook Air), the audio quality is unchanged. As soon as I change the input source to the AirPods mic, the audio becomes low quality. This is, of course, anecdotal evidence, but I read somewhere else that this was due to the limitations of Bluetooth, which I found to be plausible.

[mabbamOG]

Just tried out with both Mumble and Discord. The audio quality is reduced as soon as audio transmission begins.... so it seems to be an issue inherent with either the bloetooth protocol or the headphones.

Anyway, if the devs can't manage to fix this with code, a simple "fix" is to just setup a warning text when the app detects bluetooth headphones. The user can then just jump to audio input and switch it to laptop

[Krzmbrzl]

@mabbamOG so you expierenced this problem with both Mumble and Discord separately (that is by their own respectively. Not just when running both or something like this)?

a simple "fix" is to just setup a warning text when the app detects bluetooth headphones

I'm not sure we can actually determine whether a headphone is using Bluetooth or not...

[ghost]

It's limitation of bluetooth HSP/HFP protocol. If headset doesn't use microphone, it's set to A2DP profile, which may use various low latency, high quality codecs. If microphone is in use, it's switched to low bandwidth HSP/HFP mode, so audio playback is limited to 64 kbit/s 8kHz CVSD voice coding or 16kHz mSbc codec.
It looks like it's possible to use QT 5.6 to detect headset using "Bluetooth LE Central" on all major platforms - https://doc.qt.io/qt-5/qtbluetooth-index.html

[Krzmbrzl]

Thanks for the hint @Reikion! :)

If someone wants to give this a shot, a or would be very welcome.
Don't know if and when I'll have time to look into this...