Implement headphone split cue option

[jus]

Headphones are currently used to monitor a cued channel, but we should implement a split cue option where cued channels are sent to the left headphone channel and master mix to the right, or a way to select between cued channels and master mix.

As suggested by a forum user http://mixxx.org/forums/viewtopic.php?f=1&t=2721
<quote>
Mixxx really needs this function. Just stick a little button next to cue/prgm pan knob graphic.

You could also put something in the options that would override the cue/prgm knob when split is lit, that way they'd be the same volume regardless of where the line is on it when split is active. Some mixers do that and some people like it.

You could also add another option that overrides the cue/prgm knob at all times, with prgm/master being heard on the headphone when no cue is selected. Xone 62 does that.

So add a split cue and selectable (one of three) cueing options and Mixx will have cueing down.
</quote>

[naught101 (naught101)]

I posted a dup at https://bugs.launchpad.net/mixxx/+bug/1268258 - now closed. Same problem, slightly different solution (I don't think it should be a UI option, but in the preferences):

As described here: http://www.digitaldjtips.com/2011/07/djs-guide-to-splitter-cables/ , Stereo to mono splitter cables are useful in situations where you don't have access to a soundcard with multiple outputs, e.g. for practice situations. Also, this is useful in live situations with mono audio (apparently many clubs do this to prevent phasing problems anyway. It would be really useful feature to have in Mixxx.

Basically, in Options > Preferences > Sound Hardware > Output, the Master and Headphone tracks would need a "Mix to channel 1" and "Mix to channel 2" option for each sound device.

[RJ Skerry-Ryan (rryan)]

After reading the manual for the Xone 62, I don't think I understand what the forum user meant:
http://www.allen-heath.com/media/1617.pdf

Here's what I can puzzle out as the options they are talking about:

1) Head/mix as normal in Mixxx
2) Split cue mode obeying head/mix gains.
3) Split cue mode ignoring head/mix gains.
4) Split cue mode where if no deck is in PFL-mode then master output is played through headphones.

2 doesn't seem useful to me.

[Owen Williams (ywwg)]

2 could make sense, you have your headphones on and you mostly hear master but in the left can the pfl is much louder.

[Daniel Schürmann (daschuer)]

The use case for this is if there is a missing or bad monitor box.
If it is would be available you have plf on both ears and you can lift on earphone if you need to hear the master output.

So for me 3 or 2 with pure plf on one ear are reasonable to me.

[RJ Skerry-Ryan (rryan)]

Gotcha -- yea I guess it doesn't hurt to leave head/mix in since it defaults to full head anyway.

So I think a push-button to enable split-cues as Owen implemented would cover the bulk of user need here?

[Owen Williams (ywwg)]

Yes, and then the user can adjust Head/Master mix if they want some presence of master in the headphones. Hm, that means the left channel will have mono mix, stereo left master, and the right channel will have mono master. I guess that'll be fine?

[RJ Skerry-Ryan (rryan)]

Merged by Owen: https://github.com/mixxxdj/mixxx/pull/152

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/5941