feat: add JACK audio looper with clip state machine and tests
Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>
This commit is contained in:
Loic Coenen
257
engine.c
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257
engine.c
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#include "engine.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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// JACK process callback
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static int process_callback(jack_nframes_t nframes, void *arg) {
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Engine *engine = (Engine *)arg;
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// Get ports
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jack_default_audio_sample_t *audio_in = (jack_default_audio_sample_t *)
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jack_port_get_buffer(engine->audio_in_port, nframes);
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jack_default_audio_sample_t *audio_out = (jack_default_audio_sample_t *)
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jack_port_get_buffer(engine->audio_out_port, nframes);
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void *midi_in_buf = jack_port_get_buffer(engine->midi_in_port, nframes);
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void *midi_out_buf = jack_port_get_buffer(engine->midi_out_port, nframes);
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// Clear output MIDI buffer
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jack_midi_clear_buffer(midi_out_buf);
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// Process MIDI input
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jack_midi_event_t midi_event;
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jack_nframes_t event_index = 0;
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while (jack_midi_event_get(&midi_event, midi_in_buf, event_index) == 0) {
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event_index++;
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uint8_t *data = midi_event.buffer;
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uint8_t status = data[0] & 0xF0;
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uint8_t channel = data[0] & 0x0F;
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uint8_t note = data[1];
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uint8_t velocity = data[2];
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// Only process note on messages on the control channel
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if (status == 0x90 && channel == engine->control_channel && velocity > 0) {
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int clip_index = note % MAX_CLIPS;
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engine_trigger_clip(engine, clip_index);
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// Send note with velocity representing state
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uint8_t out_velocity = clip_state_to_velocity(engine->clips[clip_index].state);
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uint8_t out_msg[3] = {0x90 | channel, note, out_velocity};
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if (jack_midi_event_write(midi_out_buf, midi_event.time, out_msg, 3) != 0) {
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fprintf(stderr, "Failed to write MIDI event\n");
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}
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} else {
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// Pass through all other MIDI messages
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if (jack_midi_event_write(midi_out_buf, midi_event.time,
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midi_event.buffer, midi_event.size) != 0) {
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fprintf(stderr, "Failed to write MIDI event\n");
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}
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}
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}
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// Process audio
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memset(audio_out, 0, sizeof(jack_default_audio_sample_t) * nframes);
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for (jack_nframes_t i = 0; i < nframes; i++) {
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// Record input to recording clips
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for (int c = 0; c < MAX_CLIPS; c++) {
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Clip *clip = &engine->clips[c];
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if (clip->state == CLIP_RECORDING) {
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if (clip->write_position < MAX_BUFFER_SIZE) {
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clip->buffer[clip->write_position++] = audio_in[i];
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} else {
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// Buffer full, stop recording
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clip->state = CLIP_LOOPING;
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clip->buffer_size = clip->write_position;
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clip->read_position = 0;
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}
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}
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// Play looping clips
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if (clip->state == CLIP_LOOPING && clip->buffer_size > 0) {
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audio_out[i] += clip->buffer[clip->read_position];
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clip->read_position = (clip->read_position + 1) % clip->buffer_size;
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}
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}
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}
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return 0;
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}
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// JACK shutdown callback
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static void shutdown_callback(jack_status_t code, const char *reason, void *arg) {
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Engine *engine = (Engine *)arg;
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engine->running = false;
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fprintf(stderr, "JACK shutdown: %s\n", reason);
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}
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int engine_init(Engine *engine, const char *client_name) {
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if (!engine || !client_name) return -1;
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memset(engine, 0, sizeof(Engine));
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engine->control_channel = 0;
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engine->running = false;
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// Initialize clips
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for (int i = 0; i < MAX_CLIPS; i++) {
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engine->clips[i].state = CLIP_EMPTY;
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engine->clips[i].buffer = (float *)calloc(MAX_BUFFER_SIZE, sizeof(float));
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if (!engine->clips[i].buffer) {
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// Cleanup on allocation failure
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for (int j = 0; j < i; j++) {
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free(engine->clips[j].buffer);
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}
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return -1;
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}
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engine->clips[i].buffer_size = 0;
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engine->clips[i].write_position = 0;
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engine->clips[i].read_position = 0;
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}
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// Open JACK client
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jack_status_t status;
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engine->client = jack_client_open(client_name, JackNullOption, &status, NULL);
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if (!engine->client) {
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fprintf(stderr, "Failed to open JACK client, status = 0x%2.0x\n", status);
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return -1;
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}
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// Register ports
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engine->audio_in_port = jack_port_register(engine->client, "audio_in",
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JACK_DEFAULT_AUDIO_TYPE,
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JackPortIsInput, 0);
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engine->audio_out_port = jack_port_register(engine->client, "audio_out",
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JACK_DEFAULT_AUDIO_TYPE,
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JackPortIsOutput, 0);
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engine->midi_in_port = jack_port_register(engine->client, "midi_in",
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JACK_DEFAULT_MIDI_TYPE,
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JackPortIsInput, 0);
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engine->midi_out_port = jack_port_register(engine->client, "midi_out",
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JACK_DEFAULT_MIDI_TYPE,
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JackPortIsOutput, 0);
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if (!engine->audio_in_port || !engine->audio_out_port ||
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!engine->midi_in_port || !engine->midi_out_port) {
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fprintf(stderr, "Failed to register ports\n");
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engine_cleanup(engine);
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return -1;
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}
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// Set callbacks
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jack_set_process_callback(engine->client, process_callback, engine);
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jack_on_shutdown(engine->client, shutdown_callback, engine);
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// Get sample rate
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engine->sample_rate = jack_get_sample_rate(engine->client);
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return 0;
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}
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void engine_cleanup(Engine *engine) {
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if (!engine) return;
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if (engine->client) {
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jack_client_close(engine->client);
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engine->client = NULL;
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}
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for (int i = 0; i < MAX_CLIPS; i++) {
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free(engine->clips[i].buffer);
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engine->clips[i].buffer = NULL;
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}
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}
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int engine_start(Engine *engine) {
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if (!engine || !engine->client) return -1;
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if (jack_activate(engine->client) != 0) {
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fprintf(stderr, "Failed to activate JACK client\n");
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return -1;
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}
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engine->running = true;
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return 0;
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}
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void engine_stop(Engine *engine) {
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if (!engine || !engine->client) return;
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engine->running = false;
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jack_deactivate(engine->client);
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}
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void engine_trigger_clip(Engine *engine, int clip_index) {
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if (!engine || clip_index < 0 || clip_index >= MAX_CLIPS) return;
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Clip *clip = &engine->clips[clip_index];
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switch (clip->state) {
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case CLIP_EMPTY:
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// Start recording
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clip->state = CLIP_RECORDING;
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clip->write_position = 0;
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clip->buffer_size = 0;
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clip->read_position = 0;
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printf("Clip %d: Recording started\n", clip_index);
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break;
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case CLIP_RECORDING:
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// Stop recording, start looping
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clip->state = CLIP_LOOPING;
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clip->buffer_size = clip->write_position;
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clip->read_position = 0;
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printf("Clip %d: Recording stopped, looping %zu samples\n",
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clip_index, clip->buffer_size);
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break;
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case CLIP_LOOPING:
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// Stop looping
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clip->state = CLIP_STOPPED;
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clip->read_position = 0;
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printf("Clip %d: Looping stopped\n", clip_index);
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break;
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case CLIP_STOPPED:
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// Start looping again
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clip->state = CLIP_LOOPING;
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clip->read_position = 0;
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printf("Clip %d: Looping resumed\n", clip_index);
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break;
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}
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}
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void engine_reset_clip(Engine *engine, int clip_index) {
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if (!engine || clip_index < 0 || clip_index >= MAX_CLIPS) return;
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Clip *clip = &engine->clips[clip_index];
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clip->state = CLIP_EMPTY;
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clip->buffer_size = 0;
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clip->write_position = 0;
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clip->read_position = 0;
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memset(clip->buffer, 0, MAX_BUFFER_SIZE * sizeof(float));
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}
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const char* clip_state_to_string(ClipState state) {
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switch (state) {
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case CLIP_EMPTY: return "Empty";
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case CLIP_RECORDING: return "Recording";
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case CLIP_LOOPING: return "Looping";
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case CLIP_STOPPED: return "Stopped";
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default: return "Unknown";
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}
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}
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uint8_t clip_state_to_velocity(ClipState state) {
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switch (state) {
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case CLIP_EMPTY: return 0;
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case CLIP_RECORDING: return 64;
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case CLIP_LOOPING: return 127;
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case CLIP_STOPPED: return 32;
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default: return 0;
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}
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}
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