REAPERの打ち込みを生成AIでサクッと効率化しちゃった話🤖🎸

local hwnd = reaper.MIDIEditor_GetActive()
local take = reaper.MIDIEditor_GetTake(hwnd)

if take then
    reaper.Undo_BeginBlock()

    -- 1. 設定：32分音符の計算 (960 PPQ基準)
    local qn_ppq = 960 
    local offset = qn_ppq / 8 

    -- 2. 選択されたすべてのノートを収集
    local all_selected_notes = {}
    local i = reaper.MIDI_EnumSelNotes(take, -1)
    while i ~= -1 do
        local retval, sel, muted, startppq, endppq, chan, pitch, vel = reaper.MIDI_GetNote(take, i)
        table.insert(all_selected_notes, {
            idx = i, start = startppq, ["end"] = endppq, 
            pitch = pitch, vel = vel, chan = chan
        })
        i = reaper.MIDI_EnumSelNotes(take, i)
    end

    if #all_selected_notes > 0 then
        -- 開始時間順にソート
        table.sort(all_selected_notes, function(a, b) return a.start < b.start end)

        -- 3. ノートを「同時押しグループ」に分ける
        local groups = {}
        local current_group = {}
        local last_start = -1
        for _, n in ipairs(all_selected_notes) do
            if math.abs(n.start - last_start) < 10 then 
                table.insert(current_group, n)
            else
                if #current_group > 0 then table.insert(groups, current_group) end
                current_group = {n}; last_start = n.start
            end
        end
        if #current_group > 0 then table.insert(groups, current_group) end

        local notes_to_delete = {}
        local raw_ks_list = {}

        -- 4. 各グループごとに奏法を判定
        for _, group in ipairs(groups) do
            table.sort(group, function(a, b) return a.pitch < b.pitch end)
            local low_note = group[1]
            local high_note = group[#group]
            local p_list = {}

            if #group == 1 then
                p_list = {26} -- 単音なら D1
            else
                local interval = high_note.pitch - low_note.pitch
                if     interval == 3 then p_list = {12, 15}
                elseif interval == 4 then p_list = {12, 16}
                elseif interval == 5 then p_list = {12, 17}
                elseif interval == 6 then p_list = {12, 18}
                elseif interval == 7 then p_list = {12, 19}
                elseif interval == 8 then p_list = {12, 20}
                elseif interval == 9 then p_list = {12, 21}
                else p_list = {12} end
                -- 和音の上の音を消去予約
                for j = 2, #group do table.insert(notes_to_delete, group[j].idx) end
            end
            
            -- 生のキースイッチデータをリスト化
            local ks_s = math.max(0, low_note.start - offset)
            local ks_e = ks_s + (low_note["end"] - low_note.start)
            table.insert(raw_ks_list, {s = ks_s, e = ks_e, pitches = p_list, v = low_note.vel})
        end

        -- 5. 【新機能】同じキースイッチの連続を結合するロジック
        local merged_ks = {}
        if #raw_ks_list > 0 then
            table.insert(merged_ks, raw_ks_list[1])
            for k = 2, #raw_ks_list do
                local prev = merged_ks[#merged_ks]
                local curr = raw_ks_list[k]

                -- ピッチ構成が完全に一致するかチェック
                local same_pitches = (#prev.pitches == #curr.pitches)
                if same_pitches then
                    for idx, val in ipairs(prev.pitches) do
                        if val ~= curr.pitches[idx] then same_pitches = false; break end
                    end
                end

                -- 前の終点と次の始点が近い（16分音符以内程度）かつ同じピッチなら結合
                local gap = curr.s - prev.e
                if same_pitches and gap < (qn_ppq / 4) then 
                    prev.e = curr.e -- 終点を延長
                else
                    table.insert(merged_ks, curr)
                end
            end
        end

        -- 6. 不要なノートの削除
        table.sort(notes_to_delete, function(a, b) return a > b end)
        for _, idx in ipairs(notes_to_delete) do reaper.MIDI_DeleteNote(take, idx) end

        -- 7. 型抜き (merged_ks の範囲を使用)
        for _, ks in ipairs(merged_ks) do
            local _, note_count = reaper.MIDI_CountEvts(take)
            for j = note_count - 1, 0, -1 do
                local _, _, _, s, e, c, p, v = reaper.MIDI_GetNote(take, j)
                if p >= 12 and p <= 28 then
                    if s < ks.e and e > ks.s then
                        reaper.MIDI_DeleteNote(take, j)
                        if s < ks.s then reaper.MIDI_InsertNote(take, false, false, s, ks.s, c, p, v, false) end
                        if e > ks.e then reaper.MIDI_InsertNote(take, false, false, ks.e, e, c, p, v, false) end
                    end
                end
            end
        end

        -- 8. 結合済みキースイッチの挿入
        for _, ks in ipairs(merged_ks) do
            for _, p in ipairs(ks.pitches) do
                reaper.MIDI_InsertNote(take, false, false, ks.s, ks.e, 0, p, ks.v, false)
            end
        end
    end

    reaper.Undo_EndBlock("V-METAL Smart Batch & Merge", -1)
    reaper.MIDI_Sort(take)
end