Crossfader doesn't cut sound on Traktor Kontrol Z1 with scratching curve

[ArthurVimond]

Bug Description

Steps to reproduce

• Plug the Traktor Kontrol Z1 to the computer
• Open Mixxx
• In the Controllers settings, Set the Traktor Kontrol Z1 HID mapping
• In the Mixer settings, set the crossfader curve to scratching (slider completely on the right)
• Load and play two songs on decks 1 and 2 respectively
• On the Traktor Kontrol Z1, put the physical crossfader completely on the left
• Notice the song on deck 2 can still be heard
• On the Traktor Kontrol Z1, put the physical crossfader completely on the right
• Notice the song on deck 1 can still be heard

Cause

In theory, the crossfader value range is from 0 to 4095, but in practice, it never reaches the boundaries. On my unit, the minimum safe value is 36 (32 at the lowest) and the maximum safe value is 4083 (4087 at the highest).

Solution

When setting the crossfader parameter value, we should apply those safe "margins" to ensure that the crossfader will always cut the sound.

Version

No response

OS

No response

[ArthurVimond]

The corresponding PR is here: #14451

[SamWhited]

I've seen this same problem on the Hercules DJ Console Mk1. The console appears to be sending 0xFF in this case, but for some reason Mixxx doesn't fully bring the crossfader to the right and you have to bump it over a tiny bit more in the UI to actually cut the audio from the other channel completely out. It may be worth fixing this in a more general way in Mixxx itself.