Files
jack-looper/engine.c
Loic Coenen cce8d05069 feat: add JACK audio looper with clip state machine and tests
Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>
2026-05-01 00:41:53 +00:00

258 lines
8.7 KiB
C

#include "engine.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
// JACK process callback
static int process_callback(jack_nframes_t nframes, void *arg) {
Engine *engine = (Engine *)arg;
// Get ports
jack_default_audio_sample_t *audio_in = (jack_default_audio_sample_t *)
jack_port_get_buffer(engine->audio_in_port, nframes);
jack_default_audio_sample_t *audio_out = (jack_default_audio_sample_t *)
jack_port_get_buffer(engine->audio_out_port, nframes);
void *midi_in_buf = jack_port_get_buffer(engine->midi_in_port, nframes);
void *midi_out_buf = jack_port_get_buffer(engine->midi_out_port, nframes);
// Clear output MIDI buffer
jack_midi_clear_buffer(midi_out_buf);
// Process MIDI input
jack_midi_event_t midi_event;
jack_nframes_t event_index = 0;
while (jack_midi_event_get(&midi_event, midi_in_buf, event_index) == 0) {
event_index++;
uint8_t *data = midi_event.buffer;
uint8_t status = data[0] & 0xF0;
uint8_t channel = data[0] & 0x0F;
uint8_t note = data[1];
uint8_t velocity = data[2];
// Only process note on messages on the control channel
if (status == 0x90 && channel == engine->control_channel && velocity > 0) {
int clip_index = note % MAX_CLIPS;
engine_trigger_clip(engine, clip_index);
// Send note with velocity representing state
uint8_t out_velocity = clip_state_to_velocity(engine->clips[clip_index].state);
uint8_t out_msg[3] = {0x90 | channel, note, out_velocity};
if (jack_midi_event_write(midi_out_buf, midi_event.time, out_msg, 3) != 0) {
fprintf(stderr, "Failed to write MIDI event\n");
}
} else {
// Pass through all other MIDI messages
if (jack_midi_event_write(midi_out_buf, midi_event.time,
midi_event.buffer, midi_event.size) != 0) {
fprintf(stderr, "Failed to write MIDI event\n");
}
}
}
// Process audio
memset(audio_out, 0, sizeof(jack_default_audio_sample_t) * nframes);
for (jack_nframes_t i = 0; i < nframes; i++) {
// Record input to recording clips
for (int c = 0; c < MAX_CLIPS; c++) {
Clip *clip = &engine->clips[c];
if (clip->state == CLIP_RECORDING) {
if (clip->write_position < MAX_BUFFER_SIZE) {
clip->buffer[clip->write_position++] = audio_in[i];
} else {
// Buffer full, stop recording
clip->state = CLIP_LOOPING;
clip->buffer_size = clip->write_position;
clip->read_position = 0;
}
}
// Play looping clips
if (clip->state == CLIP_LOOPING && clip->buffer_size > 0) {
audio_out[i] += clip->buffer[clip->read_position];
clip->read_position = (clip->read_position + 1) % clip->buffer_size;
}
}
}
return 0;
}
// JACK shutdown callback
static void shutdown_callback(jack_status_t code, const char *reason, void *arg) {
Engine *engine = (Engine *)arg;
engine->running = false;
fprintf(stderr, "JACK shutdown: %s\n", reason);
}
int engine_init(Engine *engine, const char *client_name) {
if (!engine || !client_name) return -1;
memset(engine, 0, sizeof(Engine));
engine->control_channel = 0;
engine->running = false;
// Initialize clips
for (int i = 0; i < MAX_CLIPS; i++) {
engine->clips[i].state = CLIP_EMPTY;
engine->clips[i].buffer = (float *)calloc(MAX_BUFFER_SIZE, sizeof(float));
if (!engine->clips[i].buffer) {
// Cleanup on allocation failure
for (int j = 0; j < i; j++) {
free(engine->clips[j].buffer);
}
return -1;
}
engine->clips[i].buffer_size = 0;
engine->clips[i].write_position = 0;
engine->clips[i].read_position = 0;
}
// Open JACK client
jack_status_t status;
engine->client = jack_client_open(client_name, JackNullOption, &status, NULL);
if (!engine->client) {
fprintf(stderr, "Failed to open JACK client, status = 0x%2.0x\n", status);
return -1;
}
// Register ports
engine->audio_in_port = jack_port_register(engine->client, "audio_in",
JACK_DEFAULT_AUDIO_TYPE,
JackPortIsInput, 0);
engine->audio_out_port = jack_port_register(engine->client, "audio_out",
JACK_DEFAULT_AUDIO_TYPE,
JackPortIsOutput, 0);
engine->midi_in_port = jack_port_register(engine->client, "midi_in",
JACK_DEFAULT_MIDI_TYPE,
JackPortIsInput, 0);
engine->midi_out_port = jack_port_register(engine->client, "midi_out",
JACK_DEFAULT_MIDI_TYPE,
JackPortIsOutput, 0);
if (!engine->audio_in_port || !engine->audio_out_port ||
!engine->midi_in_port || !engine->midi_out_port) {
fprintf(stderr, "Failed to register ports\n");
engine_cleanup(engine);
return -1;
}
// Set callbacks
jack_set_process_callback(engine->client, process_callback, engine);
jack_on_shutdown(engine->client, shutdown_callback, engine);
// Get sample rate
engine->sample_rate = jack_get_sample_rate(engine->client);
return 0;
}
void engine_cleanup(Engine *engine) {
if (!engine) return;
if (engine->client) {
jack_client_close(engine->client);
engine->client = NULL;
}
for (int i = 0; i < MAX_CLIPS; i++) {
free(engine->clips[i].buffer);
engine->clips[i].buffer = NULL;
}
}
int engine_start(Engine *engine) {
if (!engine || !engine->client) return -1;
if (jack_activate(engine->client) != 0) {
fprintf(stderr, "Failed to activate JACK client\n");
return -1;
}
engine->running = true;
return 0;
}
void engine_stop(Engine *engine) {
if (!engine || !engine->client) return;
engine->running = false;
jack_deactivate(engine->client);
}
void engine_trigger_clip(Engine *engine, int clip_index) {
if (!engine || clip_index < 0 || clip_index >= MAX_CLIPS) return;
Clip *clip = &engine->clips[clip_index];
switch (clip->state) {
case CLIP_EMPTY:
// Start recording
clip->state = CLIP_RECORDING;
clip->write_position = 0;
clip->buffer_size = 0;
clip->read_position = 0;
printf("Clip %d: Recording started\n", clip_index);
break;
case CLIP_RECORDING:
// Stop recording, start looping
clip->state = CLIP_LOOPING;
clip->buffer_size = clip->write_position;
clip->read_position = 0;
printf("Clip %d: Recording stopped, looping %zu samples\n",
clip_index, clip->buffer_size);
break;
case CLIP_LOOPING:
// Stop looping
clip->state = CLIP_STOPPED;
clip->read_position = 0;
printf("Clip %d: Looping stopped\n", clip_index);
break;
case CLIP_STOPPED:
// Start looping again
clip->state = CLIP_LOOPING;
clip->read_position = 0;
printf("Clip %d: Looping resumed\n", clip_index);
break;
}
}
void engine_reset_clip(Engine *engine, int clip_index) {
if (!engine || clip_index < 0 || clip_index >= MAX_CLIPS) return;
Clip *clip = &engine->clips[clip_index];
clip->state = CLIP_EMPTY;
clip->buffer_size = 0;
clip->write_position = 0;
clip->read_position = 0;
memset(clip->buffer, 0, MAX_BUFFER_SIZE * sizeof(float));
}
const char* clip_state_to_string(ClipState state) {
switch (state) {
case CLIP_EMPTY: return "Empty";
case CLIP_RECORDING: return "Recording";
case CLIP_LOOPING: return "Looping";
case CLIP_STOPPED: return "Stopped";
default: return "Unknown";
}
}
uint8_t clip_state_to_velocity(ClipState state) {
switch (state) {
case CLIP_EMPTY: return 0;
case CLIP_RECORDING: return 64;
case CLIP_LOOPING: return 127;
case CLIP_STOPPED: return 32;
default: return 0;
}
}