Mute control does not mute on external mixer setup

[Christian]

Problem:
The mute control does not behave as expected: sound is played even when mute is enabled.

Steps to reproduce the problem:
- Start Mixxx with the --developer argument
- Assign a sound device to deck 1,
  do not assign anything to master (Master: ---)
- Play a track in deck 1
- Reduce the volume of deck 1, e.g. to 50%
- Open the developer tools and set "[Channel1],mute" to 1

Expected behavior:
- No sound output for channel 1.

Observed behavior:
- Volume fader for deck 1 has no effect
- Crossfader for deck 1 has no effect
- Effects assigned to deck 1 have no effect
- Volume for deck 1 is at 100%

Environment:
- Mixxx 2.3.0 stable / Linux x86_64 (Ubuntu)
- Mixxx 2.3.0 stable / Windows x64

[ronso0 (ronso0)]

Note that 'mute' does not affect the Vol fader or xfader.

[ronso0 (ronso0)]

Cna confirm mute has no effect when the channel is not routed to the Main output but has an own output.

https://manual.mixxx.org/2.3/en/chapters/appendix/mixxx_controls.html#control-[ChannelN]-mute
says "Mutes the channel" so it's a bug.

[Be (be.ing)]

I can also confirm this. Thank you for the detailed bug report.

[Be (be.ing)]

The mute control is only used to determine whether channels are added to m_activeBusChannels in EngineMaster::processChannels, which only affects the mixed outputs but not the unmixed deck outputs.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/10502