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feat: add per-channel MIDI looping support

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Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>
This commit is contained in:
Loic Coenen
2026-05-10 11:29:41 +00:00
parent 85e828f461
commit ff226a8ea6
4 changed files with 199 additions and 42 deletions
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179
src/looper.c
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@@ -175,49 +175,124 @@ int process_callback(jack_nframes_t nframes, void *arg) {
}
}
jack_nframes_t i;
switch (state) {
case STATE_RECORD:
if (in) {
float *f_out = (float *)out;
const float *f_in = (const float *)in;
for (i = 0; i < nframes; i++) {
if (active_channels[c].record_pos < LOOP_BUF_SIZE)
active_channels[c].loop_buffer[active_channels[c].record_pos++] =
f_in[i];
f_out[i] = f_in[i];
if (active_channels[c].type == CHANNEL_MIDI) {
/* MIDI channel handling */
switch (state) {
case STATE_RECORD: {
void *midi_in_buf = jack_port_get_buffer(active_channels[c].midi_in, nframes);
if (midi_in_buf) {
jack_nframes_t nevents = jack_midi_get_event_count(midi_in_buf);
jack_midi_event_t ev;
for (jack_nframes_t j = 0; j < nevents; j++) {
if (jack_midi_event_get(&ev, midi_in_buf, j) != 0) continue;
if (active_channels[c].record_pos < MAX_MIDI_EVENTS) {
active_channels[c].loop.midi_events[active_channels[c].record_pos].timestamp = ev.time;
active_channels[c].loop.midi_events[active_channels[c].record_pos].status = ev.buffer[0];
active_channels[c].loop.midi_events[active_channels[c].record_pos].note = (ev.size > 1) ? ev.buffer[1] : 0;
active_channels[c].loop.midi_events[active_channels[c].record_pos].velocity = (ev.size > 2) ? ev.buffer[2] : 0;
active_channels[c].record_pos++;
}
}
/* forward incoming MIDI to output during record */
void *midi_out_buf = jack_port_get_buffer(active_channels[c].midi_out, nframes);
if (midi_out_buf) {
jack_midi_clear_buffer(midi_out_buf);
for (jack_nframes_t j = 0; j < nevents; j++) {
if (jack_midi_event_get(&ev, midi_in_buf, j) != 0) continue;
jack_midi_event_write(midi_out_buf, ev.time, ev.buffer, ev.size);
}
}
}
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
break;
}
break;
case STATE_LOOPING:
if (active_channels[c].loop_count > 0) {
float *outf = (float *)out;
for (i = 0; i < nframes; i++) {
outf[i] =
active_channels[c].loop_buffer[active_channels[c].playback_pos];
active_channels[c].playback_pos =
(active_channels[c].playback_pos + 1) %
active_channels[c].loop_count;
case STATE_LOOPING: {
void *midi_out_buf = jack_port_get_buffer(active_channels[c].midi_out, nframes);
if (midi_out_buf) {
jack_midi_clear_buffer(midi_out_buf);
int cnt = active_channels[c].loop_count; /* number of recorded events */
if (cnt > 0) {
/* simple: output all recorded events at frame 0 of each cycle */
for (int e = 0; e < cnt; e++) {
unsigned char msg[3];
msg[0] = active_channels[c].loop.midi_events[e].status;
msg[1] = active_channels[c].loop.midi_events[e].note;
msg[2] = active_channels[c].loop.midi_events[e].velocity;
jack_midi_event_write(midi_out_buf, 0, msg, 3);
}
}
}
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
break;
}
break;
case STATE_PAUSED:
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
break;
default: /* IDLE */
if (in) {
memcpy(out, in, sizeof(jack_default_audio_sample_t) * nframes);
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
case STATE_PAUSED:
/* no output */
break;
default: /* IDLE */
/* pass through MIDI input to output */
{
void *midi_in_buf = jack_port_get_buffer(active_channels[c].midi_in, nframes);
void *midi_out_buf = jack_port_get_buffer(active_channels[c].midi_out, nframes);
if (midi_in_buf && midi_out_buf) {
jack_midi_clear_buffer(midi_out_buf);
jack_nframes_t nevents = jack_midi_get_event_count(midi_in_buf);
jack_midi_event_t ev;
for (jack_nframes_t j = 0; j < nevents; j++) {
if (jack_midi_event_get(&ev, midi_in_buf, j) != 0) continue;
jack_midi_event_write(midi_out_buf, ev.time, ev.buffer, ev.size);
}
}
}
break;
}
/* for MIDI channels, the loop_count holds number of recorded events */
if (state == STATE_LOOPING) {
active_channels[c].loop_count = active_channels[c].record_pos;
}
} else {
/* audio channel handling */
jack_nframes_t i;
switch (state) {
case STATE_RECORD:
if (in) {
float *f_out = (float *)out;
const float *f_in = (const float *)in;
for (i = 0; i < nframes; i++) {
if (active_channels[c].record_pos < LOOP_BUF_SIZE)
active_channels[c].loop.audio_buffer[active_channels[c].record_pos++] =
f_in[i];
f_out[i] = f_in[i];
}
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
}
break;
case STATE_LOOPING:
if (active_channels[c].loop_count > 0) {
float *outf = (float *)out;
for (i = 0; i < nframes; i++) {
outf[i] =
active_channels[c].loop.audio_buffer[active_channels[c].playback_pos];
active_channels[c].playback_pos =
(active_channels[c].playback_pos + 1) %
active_channels[c].loop_count;
}
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
}
break;
case STATE_PAUSED:
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
break;
default: /* IDLE */
if (in) {
memcpy(out, in, sizeof(jack_default_audio_sample_t) * nframes);
} else {
memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);
}
break;
}
break;
}
active_channels[c].prev_state = state;
@@ -341,6 +416,20 @@ void looper_process_commands(jack_client_t *client) {
channel_add(client, idx);
break;
}
case CMD_ADD_MIDI_CHANNEL: {
int cap = atomic_load(&channel_capacity);
struct channel_t *cur = get_channels_array();
int idx;
for (idx = 0; idx < cap; idx++)
if (!atomic_load(&cur[idx].active))
break;
if (idx == cap) {
if (ensure_capacity(client, idx) != 0)
break;
}
channel_add_midi(client, idx);
break;
}
case CMD_REMOVE_CHANNEL: {
int cap = atomic_load(&channel_capacity);
struct channel_t *cur = get_channels_array();
@@ -375,6 +464,20 @@ void looper_process_commands(jack_client_t *client) {
channel_add(client, idx);
break;
}
case CMD_ADD_MIDI_CHANNEL: {
int cap = atomic_load(&channel_capacity);
struct channel_t *cur = get_channels_array();
int idx;
for (idx = 0; idx < cap; idx++)
if (!atomic_load(&cur[idx].active))
break;
if (idx == cap) {
if (ensure_capacity(client, idx) != 0)
break;
}
channel_add_midi(client, idx);
break;
}
case CMD_REMOVE_CHANNEL: {
int cap = atomic_load(&channel_capacity);
struct channel_t *cur = get_channels_array();