minimal stereo looper to test softcut voice drift

cut_sync.lua

--- test softcut voice sync
--- extremely basic stereo looper 
---
--- K2: toggle recording
--- K3: reset to loop start

local s = softcut

local BUFFER_OFFSET = 0.1

state = { 
    loop_set = false,
    recording = false,
    loop_end = s.BUFFER_SIZE - BUFFER_OFFSET - 0.1
}

function softcut_setup()
    s.buffer_clear()

    s.enable(1, 1)
    s.enable(2, 1)
    
    s.buffer(1, 1)
    s.level_input_cut(1, 1, 1)
    s.level_input_cut(2, 1, 0)
    s.pan(1, -1)
    s.rate(1, 1)
    s.loop(1, 0)

    s.buffer(2, 2)
    s.level_input_cut(2, 2, 1)
    s.level_input_cut(1, 2, 0)
    s.pan(2, 1)
    s.rate(2, 1)
    s.loop(2, 0)

    s.pre_level(1, 0)
    s.pre_level(2, 0)
    s.rec_level(1, 0)
    s.rec_level(2, 0)

    s.rec(1, 1)
    s.rec(2, 1)
    s.play(1, 1)
    s.play(2, 1)
    s.level(1, 1)
    s.level(2, 1)

    s.loop_start(1, BUFFER_OFFSET)
    s.loop_start(2, BUFFER_OFFSET)

    s.loop_end(1, state.loop_end)
    s.loop_end(2, state.loop_end)
end


function toggle_record()
    if state.recording then
        finish_recording()
    else
        begin_recording()
    end
end

function reset_position()
    s.position(1, BUFFER_OFFSET)
    s.position(2, BUFFER_OFFSET)
    print("reset")
end

function begin_recording()
    s.position(1, BUFFER_OFFSET)
    s.position(2, BUFFER_OFFSET)
    s.rec_level(1, 1)
    s.rec_level(2, 1)

    state.start_time = util.time()
    state.recording = true
    print("begin_recording...")
    redraw()
end

function finish_recording()
    s.rec_level(1, 0)
    s.rec_level(2, 0)
    s.pre_level(1, 1)
    s.pre_level(2, 1)

    local dt = util.time() - state.start_time
    state.loop_end = BUFFER_OFFSET + dt
    
    s.loop_end(1, state.loop_end)
    s.loop_end(2, state.loop_end)

    s.loop(1, 1)
    s.loop(2, 1)
    
    s.position(1, BUFFER_OFFSET)
    s.position(2, BUFFER_OFFSET)

    state.recording = false
    state.loop_set = true
    redraw()
end


------------------------------------
-- norns API bindings

init = function()
   softcut_setup()
end

key = function(n,z) 
    if z == 1 then
        if n == 2 then
            toggle_record()
        end
        if n == 3 then
            reset_position()
        end
    end
end

redraw = function()
    screen.clear()
    screen.level(15)
    screen.move(10, 10)
    if state.recording then
        screen.text("recording...")
    elseif state.loop_set then
        screen.text("loop set; duration: ")
        screen.move(10, 20)
        screen.text(state.loop_end - BUFFER_OFFSET)
    else
        screen.text("ready")
    end
    screen.update()
end