docs/1-multichannel.md

@@ -24,12 +24,13 @@ The control key is released either by sending note‑off (note 64 or any note)
 | 61   | **Remove** the highest‑numbered active channel (excluding channel 0).                       |
 | 62   | **Toggle** the current bound channel through its state machine:                              |
 |      | IDLE → RECORD → LOOPING → PAUSED → LOOPING → … (each press advances one step).              |
+| 63   | **Unbind** – reset the bound channel back to **0**.                                          |
 
 > **Notes:**
 > - The default bound channel is **0**. If you never send a bind command, `control+62` controls channel 0.
 > - To bind a different channel, send `control + note <16>` (e.g., control + note 5 binds channel 5).
 > - Bind is sticky – it stays until overwritten by another bind command.
-> - There is **no unbind** command; you can rebind to channel 0 if needed.
+> - To **unbind** (reset to channel 0), send `control + note 63`.
 
 ## Direct Mapping (without control key)
 

src/midi.c

@@ -59,6 +59,9 @@ void midi_handle_events(void *port_buffer, jack_nframes_t nframes)
                                 }
                             }
                             break;
+                        case 63: /* unbind – reset bind to channel 0 */
+                            atomic_store(&bind_channel, 0);
+                            break;
                         default:
                             break;
                         }

tests/integration.c

@@ -628,6 +628,134 @@ static int test_bind_channel(void) {
     return 0;
 }
 
+/* test unbind */
+static int test_bind_unbind(void) {
+    printf("Test: bind to channel 5, unbind, then toggle default (channel 0)\n");
+    pid_t pid = start_looper();
+    if (pid < 0) return 1;
+    jack_client_t *client;
+    jack_status_t status;
+    client = jack_client_open("test_unbind", JackNoStartServer, &status);
+    if (!client) {
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  SKIP: no JACK\n");
+        return 1;
+    }
+    jack_port_t *audio_out = jack_port_register(client, "out",
+                           JACK_DEFAULT_AUDIO_TYPE,
+                           JackPortIsOutput, 0);
+    jack_port_t *audio_in = jack_port_register(client, "in",
+                           JACK_DEFAULT_AUDIO_TYPE,
+                           JackPortIsInput, 0);
+    if (!audio_out || !audio_in) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        return 1;
+    }
+    usleep(200000);
+    char my_out[64], my_in[64];
+    snprintf(my_out, sizeof(my_out), "test_unbind:out");
+    snprintf(my_in,  sizeof(my_in),  "test_unbind:in");
+    if (jack_connect(client, my_out, "looper:input") ||
+        jack_connect(client, "looper:output", my_in)) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        return 1;
+    }
+    /* Bind to channel 5 */
+    if (send_jack_note_on("looper:control", 64, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: send control key failed\n");
+        return 1;
+    }
+    usleep(200000);
+    if (send_jack_note_on("looper:control", 5, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: bind to 5 failed\n");
+        return 1;
+    }
+    usleep(200000);
+    /* Unbind (reset to 0) */
+    if (send_jack_note_on("looper:control", 64, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: control key for unbind\n");
+        return 1;
+    }
+    usleep(200000);
+    if (send_jack_note_on("looper:control", 63, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: send unbind note 63 failed\n");
+        return 1;
+    }
+    usleep(200000);
+    /* Now toggle with control+62 – should affect channel 0 */
+    if (send_jack_note_on("looper:control", 64, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: control key for toggle\n");
+        return 1;
+    }
+    usleep(200000);
+    if (send_jack_note_on("looper:control", 62, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: toggle note 62\n");
+        return 1;
+    }
+    /* Wait for beep and loop */
+    int sr = jack_get_sample_rate(client);
+    continuous_sine = 0;
+    beep_remaining = (int)(0.1f * sr);
+    bursts = 0;
+    prev_above = 0;
+    passthrough_output_port = audio_out;
+    passthrough_input_port = audio_in;
+    passthrough_phase = 0.0f;
+    passthrough_freq = 440.0f;
+    passthrough_sample_rate = sr;
+    passthrough_total_samples = 0;
+    passthrough_sum_sq = 0.0;
+    passthrough_done = 0;
+    jack_set_process_callback(client, passthrough_process, NULL);
+    if (jack_activate(client)) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        return 1;
+    }
+    usleep(200000); /* allow beep */
+    /* second control+62 -> loop */
+    if (send_jack_note_on("looper:control", 64, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: control key for loop\n");
+        return 1;
+    }
+    usleep(200000);
+    if (send_jack_note_on("looper:control", 62, 127) != 0) {
+        jack_client_close(client);
+        kill(pid, SIGTERM); waitpid(pid, NULL, 0);
+        fprintf(stderr, "  FAIL: toggle for loop\n");
+        return 1;
+    }
+    usleep(2000000);
+    jack_deactivate(client);
+    jack_client_close(client);
+    kill(pid, SIGTERM);
+    waitpid(pid, NULL, 0);
+    int got_bursts = bursts;
+    printf("  detected bursts: %d\n", got_bursts);
+    if (got_bursts < 3) {
+        fprintf(stderr, "  FAIL: expected >=3 bursts, got %d\n", got_bursts);
+        return 1;
+    }
+    printf("  PASS (unbind works, toggle channel 0)\n");
+    return 0;
+}
+
 /* test remove channel */
 static int test_remove_channel(void) {
     printf("Test: dynamic channel removal via MIDI command\n");
@@ -738,7 +866,13 @@ int main(void) {
         failures++;
     }
 
-    /* 8. Test channel removal */
+    /* 8. Test unbind */
+    if (test_bind_unbind() != 0) {
+        fprintf(stderr, "  FAILED\n");
+        failures++;
+    }
+
+    /* 9. Test channel removal */
     if (test_remove_channel() != 0) {
         fprintf(stderr, "  FAILED\n");
         failures++;