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CSound

OpenScofo features a Csound opcode dedicated to real-time score following.

This is a pre-alpha version!

The Csound opcode is not ready yet!

Loading OpenScofo

To load the opcode, reference the compiled library in your <CsOptions> block:

<CsOptions>
--opcode-lib=/path/to/OpenScofo.so
</CsOptions>

Use .dylib for macOS and .dll for Windows.

For Windows use --opcode-lib=/path/to/OpenScofo.dll, for macOS use --opcode-lib=/path/to/OpenScofo.dylib.

Syntax

kEvent, kBPM, kTrig OpenScofoScore aIn, SScorePath, iFFTSize, iHopSize

Inputs

  • aIn (a-rate): The input audio signal (from a file or real-time microphone input).
  • SScorePath (String): The absolute file path to your OpenScofo text score.
  • iFFTSize (i-rate): The FFT size. Recommended value is 2048.
  • iHopSize (i-rate): The Hop size. Recommended value is 512.

Outputs

  • kEvent (k-rate): The current event index in the score. Rests do not count as events.
  • kBPM (k-rate): The estimated live BPM based on the player's execution of the score.
  • kTrig (k-rate): A trigger signal that outputs 1 when a new event index is detected, and 0 otherwise.

Score sendto Actions

Csound receives numeric score actions through named control channels. For a score action:

sendto delay [1 0.5 250 0.4]

OpenScofo writes:

kTrig chnget "OpenScofo/delay/trigger"
kCount chnget "OpenScofo/delay/count"
kArg0 chnget "OpenScofo/delay/0"
kArg1 chnget "OpenScofo/delay/1"
kArg2 chnget "OpenScofo/delay/2"
kArg3 chnget "OpenScofo/delay/3"

Delayed actions are supported:

delay 1 tempo sendto delay [1 0.5 250 0.4]

Only numeric arguments are supported. If a sendto action contains a string or symbol, the Csound wrapper prints a warning and does not write any channels for that action.

Example Usage

This example loads a score file and tracks the incoming audio, printing the current event and BPM whenever a new event is detected.

<CsoundSynthesizer>
<CsOptions>
--opcode-lib=/path/to/OpenScofo.so
</CsOptions>

<CsInstruments>
sr = 48000
ksmps = 64
nchnls = 1
0dbfs = 1

instr 1
    ; Audio input from file (or real-time MIC)
    a1 diskin2 "/path/to/audio.wav", 1, 0, 0

    ; Run OpenScofoScore
    kEvent, kBPM, kTrig OpenScofoScore a1, "/path/to/score.txt", 2048, 512

    kDelayTrig chnget "OpenScofo/delay/trigger"
    if (kDelayTrig == 1) then
        kVoice chnget "OpenScofo/delay/0"
        kGain chnget "OpenScofo/delay/1"
        printf "delay action: voice=%d gain=%.2f\n", kDelayTrig, kVoice, kGain
        chnset 0, "OpenScofo/delay/trigger"
    endif

    ; Print updates only when kTrig is 1
    printf "Event: %03d | BPM: %.2f\n", kTrig, kEvent, kBPM

    out a1
endin

</CsInstruments>

<CsScore>
i1 0 120
</CsScore>
</CsoundSynthesizer>