[WebRTC] Mic Volume slider does not affect transmitted audio loudness in WebRTC mode

Environment

Second Life Release 7.1.9.9604591078 (64bit) Release Notes

You are at 128.0, 128.0, 23.0 in webRTC1 located at simhost-07c23d76c83837d55.aditi SLURL: secondlife://Aditi/secondlife/webRTC1/128/128/23 (global coordinates 259968.0, 245376.0, 23.0) WebRTC-Voice 2024-06-12.9490472357 Release Notes

CPU: Apple M1 Pro (2400 MHz) Memory: 16384 MB OS Version: Mac OS X 14.5.0 Darwin 23.5.0 Darwin Kernel Version 23.5.0: Wed May 1 20:12:58 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T6000 x86_64 Graphics Card Vendor: Apple Graphics Card: Apple M1 Pro

OpenGL Version: 4.1 Metal - 88.1

Window size: 1261x820 Font Size Adjustment: 96pt UI Scaling: 0.75 Draw distance: 96m Bandwidth: 10000kbit/s LOD factor: 1.125 Render quality: 1 Texture memory: 10922MB Disk cache: Max size 1638.4 MB (25.8% used) HiDPI display mode: 0

J2C Decoder Version: KDU v7.10.4 Audio Driver Version: FMOD Studio 2.02.13 Dullahan: 1.14.0.202310131309 CEF: 118.4.1+g3dd6078+chromium-118.0.5993.54 Chromium: 118.0.5993.54 LibVLC Version: 3.0.16 Voice Server Version: Secondlife WebRTC Gateway

Packets Lost: 0/574 (0.0%) June 21 2024 11:02:52

Description

When the 'Mic Volume' setting is adjusted in the webRTC viewer and applied, the viewer shows an updated speaking loudness in the viewer, but the actual loudness heard by other agents is unaffected. This issue only reproduces in webRTC mode; if on a Vivox region, the 'Mic Volume' adjustment has the full effect.

My overall impression is that mic volume filter is not applied to UserA's transmitted stream.

This issue is reproduced with both Mac and Windows viewers.

While the new "Automatic Gain Control" setting (enabled by default) might affect perceived loudness, disabling that feature has no effect on this issue. Even if AGC was normalizing very loud sources, I believe one would still hear some clipping distortion at loud volumes.

Reproduction steps

Login to the same webRTC voice location with 2 viewers
Place the 2 avatars near each other
UserA: Open Preferences -> Sound & Media -> Voice Input & Output Devices, and set the "Mic Volume" slider to 0%
UserA: speak into your microphone and note levels indicated in the loudness meter to the right of the slider
UserA: click "OK" to apply the new setting
UserA: Wait a few seconds for the viewer to reconnect to nearby chat, and begin to speak
- UserA: Note how many lines are shown in your voice indicator (which may be 0)
- UserB: Note how many lines are shown in UserB's voice indicator, and the loudness of UserA's voice
UserA: Open Preferences -> Sound & Media -> Voice Input & Output Devices, and set the "Mic Volume" slider to 100%
Repeat steps (4-6), comparing the effects of 100% volume to what was observed at 0% volume

Expected results:

UserA and UserB should see very low levels over UserA's voice indicator at 0%, which should roughly match the loudness meter preview shown next to "Mic Volume'
UserA should be very quiet to UserB at 0% mic volume
UserA and UserB should see very high levels over UserA's voice indicator at 100%, which should roughly match the loudness meter preview shown next to "Mic Volume"
UserA should be very loud to UserB at 100% mic volume

Actual results:

UserA sees the expected results:
- Voice indicator lines roughly match what the loudness meter preview showed, with almost nothing indicated at 0% mic volume, and many red lines at 100% mic volume
UserB sees no difference in UserA between 0% and 100% volume
- UserA's voice indicator lines always appear midway in-world
- UserA's voice loudness is basically unchanged between 0% and 100% volume, and does not exhibit any distortion

secondlife / viewer