+ all_samples
+}
+
+pub struct Codec2Adapter {
+ state: Arc<Mutex<AdapterState>>,
+ // TODO: make this configurable
+ output_card: String,
+}
+
+impl Codec2Adapter {
+ pub fn new() -> Self {
+ Self {
+ state: Arc::new(Mutex::new(AdapterState {
+ tx: None,
+ out_buf: VecDeque::new(),
+ codec2: Codec2::new(Codec2Mode::MODE_3200),
+ end_tx: None,
+ })),
+ // TODO: this doesn't work on rpi. Use default_output_device() by default
+ output_card: "default".to_owned(),
+ }
+ }
+}
+
+struct AdapterState {
+ tx: Option<TxHandle>,
+ /// Circular buffer of output samples for playback
+ out_buf: VecDeque<i16>,
+ codec2: Codec2,
+ end_tx: Option<Sender<()>>,
+}
+
+impl StreamAdapter for Codec2Adapter {
+ fn adapter_registered(&self, _id: usize, handle: TxHandle) {
+ self.state.lock().unwrap().tx = Some(handle);
+
+ let (end_tx, end_rx) = channel();
+ let state = self.state.clone();
+ let output_card = self.output_card.clone();
+ std::thread::spawn(move || stream_thread(end_rx, state, output_card));
+ self.state.lock().unwrap().end_tx = Some(end_tx);
+ }
+
+ fn adapter_removed(&self) {
+ let mut state = self.state.lock().unwrap();
+ state.tx = None;
+ state.end_tx = None;
+ }
+
+ fn tnc_started(&self) {}
+
+ fn tnc_closed(&self) {}
+
+ fn stream_began(&self, lsf: LsfFrame) {
+ // for now we will assume:
+ // - unencrypted
+ // - data type is Voice (Codec2 3200), not Voice+Data
+ // TODO: is encryption handled here or in M17App, such that we get a decrypted stream?
+ // TODO: handle the Voice+Data combination with Codec2 1600
+ self.state.lock().unwrap().codec2 = Codec2::new(Codec2Mode::MODE_3200);
+ }
+
+ fn stream_data(&self, frame_number: u16, is_final: bool, data: Arc<[u8; 16]>) {
+ let mut state = self.state.lock().unwrap();
+ for encoded in data.chunks(8) {
+ if state.out_buf.len() < 1024 {
+ let mut samples = [i16::EQUILIBRIUM; 160]; // while assuming 3200
+ state.codec2.decode(&mut samples, encoded);
+ // TODO: maybe get rid of VecDeque so we can decode directly into ring buffer?
+ for s in samples {
+ state.out_buf.push_back(s);
+ }
+ } else {
+ debug!("out_buf overflow");
+ }
+ }
+ }
+}
+
+fn output_cb(data: &mut [i16], state: &Mutex<AdapterState>) {
+ let mut state = state.lock().unwrap();
+ debug!(
+ "sound card wants {} samples, we have {} in the buffer",
+ data.len(),
+ state.out_buf.len()
+ );
+ for d in data {
+ *d = state.out_buf.pop_front().unwrap_or(i16::EQUILIBRIUM);
+ }
+}
+
+/// Create and manage the stream from a dedicated thread since it's `!Send`
+fn stream_thread(end: Receiver<()>, state: Arc<Mutex<AdapterState>>, output_card: String) {
+ let host = cpal::default_host();
+ let device = host
+ .output_devices()
+ .unwrap()
+ .find(|d| d.name().unwrap() == output_card)
+ .unwrap();
+ let mut configs = device.supported_output_configs().unwrap();
+ // TODO: channels == 1 doesn't work on a Raspberry Pi
+ // make this configurable and support interleaving LRLR stereo samples if using 2 channels
+ let config = configs
+ .find(|c| c.channels() == 1 && c.sample_format() == SampleFormat::I16)
+ .unwrap()
+ .with_sample_rate(SampleRate(8000));
+ let stream = device
+ .build_output_stream(
+ &config.into(),
+ move |data: &mut [i16], info: &cpal::OutputCallbackInfo| {
+ debug!(
+ "callback {:?} playback {:?}",
+ info.timestamp().callback,
+ info.timestamp().playback
+ );
+ output_cb(data, &state);
+ },
+ |e| {
+ // trigger end_tx here? always more edge cases
+ debug!("error occurred in codec2 playback: {e:?}");
+ },
+ None,
+ )
+ .unwrap();
+ stream.play().unwrap();
+ let _ = end.recv();
+ // it seems concrete impls of Stream have a Drop implementation that will handle termination