Basic midi processing

Cargo.lock

@@ -184,6 +184,7 @@ dependencies = [
  "simple_logger",
  "thiserror",
  "tokio",
+ "wmidi",
 ]
 
 [[package]]
@@ -647,3 +648,9 @@ name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "wmidi"
+version = "4.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e55f35b40ad0178422d06e9ba845041baf2faf04627b91fde928d0f6a21c712"

Cargo.toml

@@ -3,10 +3,21 @@ name = "looper"
 version = "0.1.0"
 edition = "2021"
 
+default-run = "looper"
+
+[[bin]]
+name = "looper"
+path = "src/audio_engine.rs"
+
+[[bin]]
+name = "sendmidi"
+path = "src/sendmidi.rs"
+
 [dependencies]
-thiserror = "1.0"
+thiserror = "1"
 jack = "0.13"
-tokio = { version = "1.0", features = ["full"] }
-log = "0.4.27"
-simple_logger = "5.0.0"
-kanal = "0.1.1"
+tokio = { version = "1", features = ["full"] }
+log = "0.4"
+simple_logger = "5"
+kanal = "0.1"
+wmidi = "4"

src/audio_chunk.rs

@@ -362,4 +362,385 @@ mod tests {
         // Clean up the clone reference to avoid unused variable warning
         drop(chunk_clone);
     }
+
+    #[test]
+    fn test_copy_samples_single_chunk_full_copy() {
+        let chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0, 4.0, 5.0].into_boxed_slice(),
+            sample_count: 5,
+            next: None,
+        });
+
+        let mut dest = vec![0.0; 5];
+        let result = chunk.copy_samples(&mut dest, 0);
+
+        assert!(result.is_ok());
+        assert_eq!(dest, vec![1.0, 2.0, 3.0, 4.0, 5.0]);
+    }
+
+    #[test]
+    fn test_copy_samples_single_chunk_partial_copy() {
+        let chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0, 4.0, 5.0].into_boxed_slice(),
+            sample_count: 5,
+            next: None,
+        });
+
+        let mut dest = vec![0.0; 3];
+        let result = chunk.copy_samples(&mut dest, 1); // Start at index 1
+
+        assert!(result.is_ok());
+        assert_eq!(dest, vec![2.0, 3.0, 4.0]);
+    }
+
+    #[test]
+    fn test_copy_samples_single_chunk_zero_samples() {
+        let chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: None,
+        });
+
+        let mut dest: Vec<f32> = vec![];
+        let result = chunk.copy_samples(&mut dest, 0);
+
+        assert!(result.is_ok());
+        assert_eq!(dest, Vec::<f32>::new());
+    }
+
+    #[test]
+    fn test_copy_samples_single_chunk_out_of_bounds() {
+        let chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: None,
+        });
+
+        let mut dest = vec![0.0; 2];
+        let result = chunk.copy_samples(&mut dest, 5); // Start beyond sample_count
+
+        assert!(result.is_err());
+        assert!(matches!(result.unwrap_err(), LooperError::OutOfBounds(_)));
+    }
+
+    #[test]
+    fn test_copy_samples_single_chunk_partial_out_of_bounds() {
+        let chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: None,
+        });
+
+        let mut dest = vec![0.0; 5]; // Want 5 samples starting at index 1, but only 2 available
+        let result = chunk.copy_samples(&mut dest, 1);
+
+        assert!(result.is_err());
+        assert!(matches!(result.unwrap_err(), LooperError::OutOfBounds(_)));
+    }
+
+    #[test]
+    fn test_copy_samples_linked_chunks_single_chunk_boundary() {
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(Arc::new(AudioChunk {
+                samples: vec![4.0, 5.0, 6.0].into_boxed_slice(),
+                sample_count: 3,
+                next: None,
+            })),
+        });
+
+        let mut dest = vec![0.0; 3];
+        let result = chunk1.copy_samples(&mut dest, 3); // Start exactly at chunk boundary
+
+        assert!(result.is_ok());
+        assert_eq!(dest, vec![4.0, 5.0, 6.0]);
+    }
+
+    #[test]
+    fn test_copy_samples_linked_chunks_across_boundary() {
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(Arc::new(AudioChunk {
+                samples: vec![4.0, 5.0, 6.0].into_boxed_slice(),
+                sample_count: 3,
+                next: None,
+            })),
+        });
+
+        let mut dest = vec![0.0; 4];
+        let result = chunk1.copy_samples(&mut dest, 2); // Start in first chunk, cross to second
+
+        assert!(result.is_ok());
+        assert_eq!(dest, vec![3.0, 4.0, 5.0, 6.0]);
+    }
+
+    #[test]
+    fn test_copy_samples_linked_chunks_multiple_spans() {
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0].into_boxed_slice(),
+            sample_count: 2,
+            next: Some(Arc::new(AudioChunk {
+                samples: vec![3.0, 4.0].into_boxed_slice(),
+                sample_count: 2,
+                next: Some(Arc::new(AudioChunk {
+                    samples: vec![5.0, 6.0, 7.0].into_boxed_slice(),
+                    sample_count: 3,
+                    next: None,
+                })),
+            })),
+        });
+
+        let mut dest = vec![0.0; 5];
+        let result = chunk1.copy_samples(&mut dest, 1); // Start in first, span all three chunks
+
+        assert!(result.is_ok());
+        assert_eq!(dest, vec![2.0, 3.0, 4.0, 5.0, 6.0]);
+    }
+
+    #[test]
+    fn test_copy_samples_linked_chunks_out_of_bounds() {
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(Arc::new(AudioChunk {
+                samples: vec![4.0, 5.0].into_boxed_slice(),
+                sample_count: 2,
+                next: None,
+            })),
+        });
+
+        let mut dest = vec![0.0; 3];
+        let result = chunk1.copy_samples(&mut dest, 10); // Start beyond all chunks
+
+        assert!(result.is_err());
+        assert!(matches!(result.unwrap_err(), LooperError::OutOfBounds(_)));
+    }
+
+    #[test]
+    fn test_append_samples_to_partially_filled_chunk() {
+        let mut chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 0.0, 0.0, 0.0].into_boxed_slice(),
+            sample_count: 2, // Already has 2 samples
+            next: None,
+        });
+
+        let mut factory = || panic!("Factory should not be called");
+        let samples = vec![3.0, 4.0];
+        let result = AudioChunk::append_samples(&mut chunk, &samples, &mut factory);
+
+        assert!(result.is_ok());
+        assert_eq!(chunk.sample_count, 4);
+        assert_eq!(chunk.samples[0], 1.0);
+        assert_eq!(chunk.samples[1], 2.0);
+        assert_eq!(chunk.samples[2], 3.0);
+        assert_eq!(chunk.samples[3], 4.0);
+        assert!(chunk.next.is_none());
+    }
+
+    #[test]
+    fn test_append_samples_to_full_chunk_creates_new() {
+        let mut chunk = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3, // Chunk is full
+            next: None,
+        });
+
+        let mut factory = chunk_factory::mock::MockFactory::new(vec![AudioChunk::allocate(3)]);
+        let samples = vec![4.0, 5.0];
+        let result = AudioChunk::append_samples(&mut chunk, &samples, &mut factory);
+
+        assert!(result.is_ok());
+        assert_eq!(chunk.sample_count, 3); // First chunk unchanged
+        
+        let chunk2 = chunk.next.as_ref().unwrap();
+        assert_eq!(chunk2.sample_count, 2);
+        assert_eq!(chunk2.samples[0], 4.0);
+        assert_eq!(chunk2.samples[1], 5.0);
+    }
+
+    #[test]
+    fn test_append_samples_to_middle_of_chain() {
+        // Create a chain: chunk1 -> chunk2 -> chunk3
+        let chunk3 = Arc::new(AudioChunk {
+            samples: vec![7.0, 8.0, 0.0].into_boxed_slice(),
+            sample_count: 2,
+            next: None,
+        });
+
+        let chunk2 = Arc::new(AudioChunk {
+            samples: vec![4.0, 5.0, 6.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(chunk3),
+        });
+
+        let mut chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(chunk2),
+        });
+
+        // Append should go to the last chunk (chunk3)
+        let mut factory = || panic!("Factory should not be called when space available");
+        let samples = vec![9.0];
+        let result = AudioChunk::append_samples(&mut chunk1, &samples, &mut factory);
+
+        assert!(result.is_ok());
+        
+        // Navigate to chunk3 and verify the sample was added
+        let chunk2 = chunk1.next.as_ref().unwrap();
+        let chunk3 = chunk2.next.as_ref().unwrap();
+        assert_eq!(chunk3.sample_count, 3);
+        assert_eq!(chunk3.samples[2], 9.0);
+    }
+
+    #[test]
+    fn test_append_samples_multiple_calls() {
+        let mut chunk = AudioChunk::allocate(5);
+
+        let mut factory = || panic!("Factory should not be called");
+        
+        // First append
+        let result1 = AudioChunk::append_samples(&mut chunk, &[1.0, 2.0], &mut factory);
+        assert!(result1.is_ok());
+        assert_eq!(chunk.sample_count, 2);
+
+        // Second append
+        let result2 = AudioChunk::append_samples(&mut chunk, &[3.0], &mut factory);
+        assert!(result2.is_ok());
+        assert_eq!(chunk.sample_count, 3);
+
+        // Third append
+        let result3 = AudioChunk::append_samples(&mut chunk, &[4.0, 5.0], &mut factory);
+        assert!(result3.is_ok());
+        assert_eq!(chunk.sample_count, 5);
+
+        // Verify all samples
+        assert_eq!(chunk.samples[0], 1.0);
+        assert_eq!(chunk.samples[1], 2.0);
+        assert_eq!(chunk.samples[2], 3.0);
+        assert_eq!(chunk.samples[3], 4.0);
+        assert_eq!(chunk.samples[4], 5.0);
+    }
+
+    #[test]
+    fn test_append_samples_chain_with_overflow() {
+        // Create initial chain with some space in last chunk
+        let chunk2 = Arc::new(AudioChunk {
+            samples: vec![4.0, 5.0, 0.0].into_boxed_slice(),
+            sample_count: 2, // Has space for 1 more
+            next: None,
+        });
+
+        let mut chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(chunk2),
+        });
+
+        let mut factory = chunk_factory::mock::MockFactory::new(vec![AudioChunk::allocate(3)]);
+        let samples = vec![6.0, 7.0, 8.0]; // 3 samples, but only 1 space available
+        let result = AudioChunk::append_samples(&mut chunk1, &samples, &mut factory);
+
+        assert!(result.is_ok());
+        
+        // Check that chunk2 got filled
+        let chunk2 = chunk1.next.as_ref().unwrap();
+        assert_eq!(chunk2.sample_count, 3);
+        assert_eq!(chunk2.samples[2], 6.0);
+        
+        // Check that chunk3 was created with remaining samples
+        let chunk3 = chunk2.next.as_ref().unwrap();
+        assert_eq!(chunk3.sample_count, 2);
+        assert_eq!(chunk3.samples[0], 7.0);
+        assert_eq!(chunk3.samples[1], 8.0);
+    }
+
+    #[test]
+    fn test_consolidate_empty_chunk() {
+        let chunk = Arc::new(AudioChunk {
+            samples: vec![0.0, 0.0, 0.0].into_boxed_slice(),
+            sample_count: 0, // No valid samples
+            next: None,
+        });
+
+        let consolidated = AudioChunk::consolidate(&chunk);
+
+        assert_eq!(consolidated.samples.len(), 0);
+        assert_eq!(consolidated.sample_count, 0);
+        assert!(consolidated.next.is_none());
+    }
+
+    #[test]
+    fn test_consolidate_chain_with_empty_chunks() {
+        let chunk3 = Arc::new(AudioChunk {
+            samples: vec![4.0, 5.0, 0.0].into_boxed_slice(),
+            sample_count: 2,
+            next: None,
+        });
+
+        let chunk2 = Arc::new(AudioChunk {
+            samples: vec![0.0, 0.0].into_boxed_slice(),
+            sample_count: 0, // Empty middle chunk
+            next: Some(chunk3),
+        });
+
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(chunk2),
+        });
+
+        let consolidated = AudioChunk::consolidate(&chunk1);
+
+        assert_eq!(consolidated.samples.len(), 5);
+        assert_eq!(consolidated.sample_count, 5);
+        assert_eq!(consolidated.samples.as_ref(), &[1.0, 2.0, 3.0, 4.0, 5.0]);
+    }
+
+    #[test]
+    fn test_consolidate_all_empty_chunks() {
+        let chunk2 = Arc::new(AudioChunk {
+            samples: vec![0.0, 0.0].into_boxed_slice(),
+            sample_count: 0,
+            next: None,
+        });
+
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![0.0, 0.0, 0.0].into_boxed_slice(),
+            sample_count: 0,
+            next: Some(chunk2),
+        });
+
+        let consolidated = AudioChunk::consolidate(&chunk1);
+
+        assert_eq!(consolidated.samples.len(), 0);
+        assert_eq!(consolidated.sample_count, 0);
+        assert!(consolidated.next.is_none());
+    }
+
+    #[test]
+    fn test_copy_samples_from_consolidated_chunk() {
+        // Test that copy_samples works correctly after consolidation
+        let chunk2 = Arc::new(AudioChunk {
+            samples: vec![4.0, 5.0].into_boxed_slice(),
+            sample_count: 2,
+            next: None,
+        });
+
+        let chunk1 = Arc::new(AudioChunk {
+            samples: vec![1.0, 2.0, 3.0].into_boxed_slice(),
+            sample_count: 3,
+            next: Some(chunk2),
+        });
+
+        let consolidated = AudioChunk::consolidate(&chunk1);
+
+        let mut dest = vec![0.0; 3];
+        let result = consolidated.copy_samples(&mut dest, 2);
+
+        assert!(result.is_ok());
+        assert_eq!(dest, vec![3.0, 4.0, 5.0]);
+    }
 }

src/audio_engine.rs

@@ -2,6 +2,7 @@ mod allocator;
 mod audio_chunk;
 mod chunk_factory;
 mod looper_error;
+mod midi;
 mod notification_handler;
 mod process_handler;
 mod track;
@@ -17,16 +18,23 @@ use notification_handler::JackNotification;
 use notification_handler::NotificationHandler;
 use process_handler::ProcessHandler;
 use track::Track;
+use track::TrackState;
+
+pub struct JackPorts {
+    pub audio_in: jack::Port<jack::AudioIn>,
+    pub audio_out: jack::Port<jack::AudioOut>, 
+    pub midi_in: jack::Port<jack::MidiIn>,
+}
 
 #[tokio::main]
 async fn main() {
     simple_logger::SimpleLogger::new().init().expect("Could not initialize logger");
 
-    let (jack_client, audio_in, audio_out) = setup_jack();
+    let (jack_client, ports) = setup_jack();
 
     let (allocator, factory_handle) = Allocator::spawn(jack_client.sample_rate(), 3);
 
-    let process_handler = ProcessHandler::new(audio_in, audio_out, allocator)
+    let process_handler = ProcessHandler::new(ports, allocator)
         .expect("Could not create process handler");
 
     let notification_handler = NotificationHandler::new();
@@ -56,7 +64,7 @@ async fn main() {
     }
 }
 
-fn setup_jack() -> (jack::Client, jack::Port<jack::AudioIn>, jack::Port<jack::AudioOut>) {
+fn setup_jack() -> (jack::Client, JackPorts) {
     let (jack_client, jack_status) =
         jack::Client::new("looper", jack::ClientOptions::NO_START_SERVER)
             .expect("Could not create Jack client");
@@ -69,5 +77,15 @@ fn setup_jack() -> (jack::Client, jack::Port<jack::AudioIn>, jack::Port<jack::Au
     let audio_out = jack_client
         .register_port("audio_out", jack::AudioOut::default())
         .expect("Could not create audio_out port");
-    (jack_client, audio_in, audio_out)
+    let midi_in = jack_client
+        .register_port("midi_in", jack::MidiIn::default())
+        .expect("Could not create midi_in port");
+    
+    let ports = JackPorts {
+        audio_in,
+        audio_out,
+        midi_in,
+    };
+    
+    (jack_client, ports)
 }

src/midi.rs

@@ -0,0 +1,67 @@
+use crate::*;
+
+/// Process MIDI events
+pub fn process_events<F: ChunkFactory>(
+    process_handler: &mut ProcessHandler<F>,
+    ps: &jack::ProcessScope,
+) -> Result<()> {
+    // First, collect all MIDI events into a fixed-size array
+    // This avoids allocations while solving borrow checker issues
+    const MAX_EVENTS: usize = 16; // Reasonable limit for real-time processing
+    let mut raw_events = [[0u8; 3]; MAX_EVENTS];
+    let mut event_count = 0;
+    
+    // Collect events from the MIDI input iterator
+    let midi_input = process_handler.ports.midi_in.iter(ps);
+    for midi_event in midi_input {
+        if event_count < MAX_EVENTS && midi_event.bytes.len() >= 3 {
+            raw_events[event_count][0] = midi_event.bytes[0];
+            raw_events[event_count][1] = midi_event.bytes[1];
+            raw_events[event_count][2] = midi_event.bytes[2];
+            event_count += 1;
+        } else {
+            return Err(LooperError::OutOfBounds(std::panic::Location::caller()));
+        }
+    }
+    
+    // Now process the collected events using wmidi
+    // The iterator borrow is dropped, so we can mutably borrow process_handler
+    for i in 0..event_count {
+        let event_bytes = &raw_events[i];
+        
+        // Use wmidi for cleaner MIDI parsing instead of manual byte checking
+        match wmidi::MidiMessage::try_from(&event_bytes[..]) {
+            Ok(message) => {
+                match message {
+                    wmidi::MidiMessage::ControlChange(_, controller, value) => {
+                        // Only process button presses (value > 0)
+                        if u8::from(value) > 0 {
+                            match u8::from(controller) {
+                                20 => {
+                                    // Button 1: Record/Play toggle
+                                    process_handler.record_toggle()?;
+                                }
+                                21 => {
+                                    // Button 2: Play/Mute
+                                    process_handler.play_toggle()?;
+                                }
+                                _ => {
+                                    // Other CC messages - ignore for now
+                                }
+                            }
+                        }
+                    }
+                    _ => {
+                        // Ignore other MIDI messages for now
+                    }
+                }
+            }
+            Err(_) => {
+                // Skip malformed MIDI messages instead of panicking
+                continue;
+            }
+        }
+    }
+    
+    Ok(())
+}

src/process_handler.rs

@@ -3,77 +3,116 @@ use crate::*;
 pub struct ProcessHandler<F: ChunkFactory> {
     track: Track,
     playback_position: usize,
-    input_port: jack::Port<jack::AudioIn>,
-    output_port: jack::Port<jack::AudioOut>,
+    pub ports: JackPorts,
     chunk_factory: F,
 }
 
 impl<F: ChunkFactory> ProcessHandler<F> {
     pub fn new(
-        input_port: jack::Port<jack::AudioIn>,
-        output_port: jack::Port<jack::AudioOut>,
+        ports: JackPorts,
         mut chunk_factory: F,
     ) -> Result<Self> {
         Ok(Self {
             track: Track::new(&mut chunk_factory)?,
             playback_position: 0,
-            input_port,
-            output_port,
+            ports,
             chunk_factory,
         })
     }
+
+    /// Handle record/play toggle button (Button 1)
+    pub fn record_toggle(&mut self) -> Result<()> {
+        match self.track.state() {
+            TrackState::Idle => {
+                // Clear previous recording and start new recording
+                self.track.clear(&mut self.chunk_factory)?;
+                self.playback_position = 0;
+                self.track.set_state(TrackState::Recording);
+            }
+            TrackState::Recording => {
+                self.track.set_state(TrackState::Playing);
+                self.playback_position = 0;
+            }
+            TrackState::Playing => {
+                self.track.set_state(TrackState::Idle);
+            }
+        }
+        Ok(())
+    }
+
+    /// Handle play/mute toggle button (Button 2)
+    pub fn play_toggle(&mut self) -> Result<()> {
+        match self.track.state() {
+            TrackState::Idle | TrackState::Recording => {
+                if self.track.len() > 0 {
+                    self.track.set_state(TrackState::Playing);
+                    self.playback_position = 0;
+                }
+            }
+            TrackState::Playing => {
+                self.track.set_state(TrackState::Idle);
+            }
+        }
+        Ok(())
+    }
 }
 
 impl<F: ChunkFactory> jack::ProcessHandler for ProcessHandler<F> {
     fn process(&mut self, client: &jack::Client, ps: &jack::ProcessScope) -> jack::Control {
-        let input_buffer = self.input_port.as_slice(ps);
-        let output_buffer = self.output_port.as_mut_slice(ps);
+        // Process MIDI first
+        if midi::process_events(self, ps).is_err() {
+            return jack::Control::Quit;
+        }
+        
+        let input_buffer = self.ports.audio_in.as_slice(ps);
+        let output_buffer = self.ports.audio_out.as_mut_slice(ps);
 
         let jack_buffer_size = client.buffer_size() as usize;
-        let recording_samples = (client.sample_rate() as f64 * 0.6) as usize; // 0.6 seconds
 
         let mut index = 0;
 
         while index < jack_buffer_size {
-            if self.track.len() < recording_samples {
-                // recording
+            match self.track.state() {
+                TrackState::Recording => {
+                    // Recording - continue until manually stopped
                     let sample_count_to_append = jack_buffer_size - index;
-                let sample_count_to_append =
-                    sample_count_to_append.min(recording_samples - self.track.len());
                     let samples_to_append = &input_buffer[index..index + sample_count_to_append];
-                if let Err(e) = self
+                    if self
                         .track
                         .append_samples(samples_to_append, &mut self.chunk_factory)
+                        .is_err()
                     {
-                    log::error!("Could not append samples: {e}");
                         return jack::Control::Quit;
                     };
                     output_buffer[index..(index + sample_count_to_append)].fill(0.0);
                     index += sample_count_to_append;
-            } else {
-                // playback
+                }
+                TrackState::Playing => {
+                    // Playback
                     let sample_count_to_play = jack_buffer_size - index;
                     let sample_count_to_play =
                         sample_count_to_play.min(self.track.len() - self.playback_position);
-                if let Err(e) = self
+                    if self
                         .track
                         .copy_samples(
                             &mut output_buffer[index..(index + sample_count_to_play)],
                             self.playback_position,
                         )
+                        .is_err()
                     {
-                    log::error!("Could not copy samples: {e}");
                         return jack::Control::Quit;
                     }
                     index += sample_count_to_play;
                     self.playback_position += sample_count_to_play;
                     if self.playback_position >= self.track.len() {
                         self.playback_position = 0;
-                    if let Err(e) = self.track.clear(&mut self.chunk_factory) {
-                        log::error!("Could not clear track: {e}");
-                        return jack::Control::Quit;
                     }
                 }
+                TrackState::Idle => {
+                    // Idle - output silence
+                    output_buffer[index..jack_buffer_size].fill(0.0);
+                    break;
+                }
             }
         }
         jack::Control::Continue

src/sendmidi.rs

@@ -0,0 +1,194 @@
+use std::io::{self, Write};
+use jack::RawMidi;
+use kanal::{Receiver, Sender};
+
+#[derive(Debug)]
+enum MidiCommand {
+    ControlChange { cc: u8, value: u8 },
+    Quit,
+}
+
+struct MidiSender {
+    midi_out: jack::Port<jack::MidiOut>,
+    command_receiver: Receiver<MidiCommand>,
+}
+
+impl MidiSender {
+    fn new(client: &jack::Client, command_receiver: Receiver<MidiCommand>) -> Result<Self, Box<dyn std::error::Error>> {
+        let midi_out = client
+            .register_port("midi_out", jack::MidiOut::default())
+            .map_err(|e| format!("Could not create MIDI output port: {}", e))?;
+
+        Ok(Self {
+            midi_out,
+            command_receiver,
+        })
+    }
+}
+
+impl jack::ProcessHandler for MidiSender {
+    fn process(&mut self, _client: &jack::Client, ps: &jack::ProcessScope) -> jack::Control {
+        let mut midi_writer = self.midi_out.writer(ps);
+        
+        // Process all pending commands
+        while let Ok(Some(command)) = self.command_receiver.try_recv() {
+            match command {
+                MidiCommand::ControlChange { cc, value } => {
+                    let midi_data = [0xB0, cc, value]; // Control Change on channel 1
+                    if let Err(e) = midi_writer.write(&RawMidi { time: 0, bytes: &midi_data }) {
+                        eprintln!("Failed to send MIDI: {}", e);
+                    }
+                }
+                MidiCommand::Quit => return jack::Control::Quit,
+            }
+        }
+        
+        jack::Control::Continue
+    }
+}
+
+fn show_help() {
+    println!("\nFCB1010 MIDI Simulator (Rust Edition)");
+    println!("=====================================");
+    println!("Button mappings:");
+    println!("1 - Button 1 (CC 20): Record/Arm / Tap Tempo");
+    println!("2 - Button 2 (CC 21): Play/Mute Track / Click Toggle");
+    println!("3 - Button 3 (CC 22): Solo Track");
+    println!("4 - Button 4 (CC 23): Overdub");
+    println!("5 - Button 5 (CC 24): Clear Track / Clear Column");
+    println!("6 - Button 6 (CC 25): Column 1 Select");
+    println!("7 - Button 7 (CC 26): Column 2 Select");
+    println!("8 - Button 8 (CC 27): Column 3 Select");
+    println!("9 - Button 9 (CC 28): Column 4 Select");
+    println!("0 - Button 10 (CC 29): Column 5 Select");
+    println!("u - UP (CC 30): Row Up / Mode Switch");
+    println!("d - DOWN (CC 31): Row Down / Mode Switch");
+    println!("e - Expression A (CC 1): Track/Click Volume (0-127)");
+    println!("m - Master Volume (CC 7): Master Volume (0-127)");
+    println!("h - Show this help");
+    println!("q - Quit\n");
+}
+
+fn auto_connect(active_client: &jack::AsyncClient<(), MidiSender>) {
+    // Try to connect our MIDI output to the looper's MIDI input
+    let our_port = "sendmidi:midi_out";
+    let target_port = "looper:midi_in";
+    
+    match active_client.as_client().connect_ports_by_name(our_port, target_port) {
+        Ok(_) => println!("✓ Auto-connected to looper:midi_in"),
+        Err(e) => println!("⚠ Could not auto-connect to looper:midi_in: {}\n  Make sure the looper is running, then connect manually.", e),
+    }
+}
+
+fn get_expression_value(prompt: &str) -> Result<u8, Box<dyn std::error::Error>> {
+    print!("{}", prompt);
+    io::stdout().flush()?;
+    
+    let mut input = String::new();
+    io::stdin().read_line(&mut input)?;
+    
+    let value: u8 = input.trim().parse()
+        .map_err(|_| "Invalid number. Please enter 0-127")?;
+    
+    if value > 127 {
+        return Err("Value must be 0-127".into());
+    }
+    
+    Ok(value)
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    println!("Starting FCB1010 MIDI Simulator...");
+    
+    // Create JACK client
+    let (client, status) = jack::Client::new("sendmidi", jack::ClientOptions::NO_START_SERVER)?;
+    if !status.is_empty() {
+        eprintln!("JACK client status: {:?}", status);
+    }
+
+    // Create command channel
+    let (command_sender, command_receiver): (Sender<MidiCommand>, Receiver<MidiCommand>) = kanal::bounded(32);
+
+    // Create MIDI sender
+    let midi_sender = MidiSender::new(&client, command_receiver)?;
+
+    // Activate client
+    let active_client = client.activate_async((), midi_sender)?;
+    
+    // Auto-connect after a brief delay to let JACK settle
+    std::thread::sleep(std::time::Duration::from_millis(100));
+    auto_connect(&active_client);
+
+    show_help();
+
+    // Main input loop
+    loop {
+        print!("Command (h for help): ");
+        io::stdout().flush()?;
+
+        let mut input = String::new();
+        io::stdin().read_line(&mut input)?;
+        let input = input.trim().to_lowercase();
+
+        if input.is_empty() {
+            continue;
+        }
+
+        let first_char = input.chars().next().unwrap();
+        
+        let command = match first_char {
+            '1' => Some(MidiCommand::ControlChange { cc: 20, value: 127 }),
+            '2' => Some(MidiCommand::ControlChange { cc: 21, value: 127 }),
+            '3' => Some(MidiCommand::ControlChange { cc: 22, value: 127 }),
+            '4' => Some(MidiCommand::ControlChange { cc: 23, value: 127 }),
+            '5' => Some(MidiCommand::ControlChange { cc: 24, value: 127 }),
+            '6' => Some(MidiCommand::ControlChange { cc: 25, value: 127 }),
+            '7' => Some(MidiCommand::ControlChange { cc: 26, value: 127 }),
+            '8' => Some(MidiCommand::ControlChange { cc: 27, value: 127 }),
+            '9' => Some(MidiCommand::ControlChange { cc: 28, value: 127 }),
+            '0' => Some(MidiCommand::ControlChange { cc: 29, value: 127 }),
+            'u' => Some(MidiCommand::ControlChange { cc: 30, value: 127 }),
+            'd' => Some(MidiCommand::ControlChange { cc: 31, value: 127 }),
+            'e' => {
+                match get_expression_value("Expression A value (0-127): ") {
+                    Ok(value) => Some(MidiCommand::ControlChange { cc: 1, value }),
+                    Err(e) => {
+                        eprintln!("Error: {}", e);
+                        None
+                    }
+                }
+            },
+            'm' => {
+                match get_expression_value("Master volume value (0-127): ") {
+                    Ok(value) => Some(MidiCommand::ControlChange { cc: 7, value }),
+                    Err(e) => {
+                        eprintln!("Error: {}", e);
+                        None
+                    }
+                }
+            },
+            'h' => {
+                show_help();
+                None
+            },
+            'q' => {
+                println!("Exiting...");
+                command_sender.send(MidiCommand::Quit)?;
+                break;
+            },
+            _ => {
+                println!("Unknown command '{}'. Press 'h' for help.", first_char);
+                None
+            }
+        };
+
+        if let Some(cmd) = command {
+            if let MidiCommand::ControlChange { cc, value } = &cmd {
+                println!("Sending CC {} with value {}", cc, value);
+            }
+            command_sender.send(cmd)?;
+        }
+    }
+
+    Ok(())
+}

src/track.rs

@@ -1,8 +1,16 @@
 use crate::*;
 
+#[derive(Debug, Clone)]
+pub enum TrackState {
+    Idle,
+    Playing,
+    Recording,
+}
+
 pub struct Track {
     audio_chunks: Arc<AudioChunk>,
     length: usize,
+    state: TrackState,
 }
 
 impl Track {
@@ -10,6 +18,7 @@ impl Track {
         Ok(Self {
             audio_chunks: chunk_factory.create_chunk()?,
             length: 0,
+            state: TrackState::Idle,
         })
     }
 
@@ -30,10 +39,19 @@ impl Track {
     pub fn clear<F: ChunkFactory>(&mut self, chunk_factory: &mut F) -> Result<()> {
         self.audio_chunks = chunk_factory.create_chunk()?;
         self.length = 0;
+        self.state = TrackState::Idle;
         Ok(())
     }
 
     pub fn copy_samples(&self, dest: &mut [f32], start: usize) -> Result<()> {
         self.audio_chunks.copy_samples(dest, start)
     }
+
+    pub fn state(&self) -> &TrackState {
+        &self.state
+    }
+
+    pub fn set_state(&mut self, state: TrackState) {
+        self.state = state;
+    }
 }