mumble-voip/mumble

WASAPIInput: only enable echo cancellation if the input device is the same as the output device

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#1731 opened on Jun 28, 2015

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clientfeature-requesthelp wanted

Description

This issue came up in https://github.com/mumble-voip/mumble/issues/1722 where a user tried to use a USB soundcard with a USB desk mic. It didn't work, and it was not obvious what was wrong.

Contributor guide

Tech stack
cpp
Domain
backendperformance
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
knowledge of C++WASAPI basicsWindows audio
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
The issue is from 2015 and references another issue (#1722) where a USB soundcard and desk mic caused problems because echo cancellation was incorrectly enabled. The fix involves modifying the WASAPI input code in Mumble to only enable echo cancellation when the input device is the same as the output device. Look for the WASAPI input implementation file, likely src/mumble/WASAPIInput.cpp, and locate where echo cancellation is configured. Check if there is an existing condition comparing device IDs and add a check to skip enabling echo cancellation when devices differ. A similar fix might have been applied in later commit history; examine linked PRs or commits for guidance.