Fix playback position timing and stabilize PREV seek

src/player.rs

@@ -103,6 +103,19 @@ fn start_playback(shared: &Arc<SharedState>, req: &PlaybackRequest) {
     });
 }
 
+fn atomic_saturating_sub_u64(value: &AtomicU64, amount: u64) {
+    loop {
+        let current = value.load(Ordering::Relaxed);
+        let next = current.saturating_sub(amount);
+        if value
+            .compare_exchange_weak(current, next, Ordering::Relaxed, Ordering::Relaxed)
+            .is_ok()
+        {
+            return;
+        }
+    }
+}
+
 impl AudioPlayer {
     pub fn new() -> Self {
         let shared = Arc::new(SharedState {
@@ -471,7 +484,7 @@ fn play_stream(
         .ok_or_else(|| anyhow::anyhow!("no audio output device"))?;
     info!("Audio output: {}", device.name().unwrap_or_default());
 
-    let (sample_tx, sample_rx) = std::sync::mpsc::sync_channel::<Vec<f32>>(32);
+    let (sample_tx, sample_rx) = std::sync::mpsc::sync_channel::<Vec<f32>>(4);
 
     let config = cpal::StreamConfig {
         channels: channels as u16,
@@ -480,6 +493,13 @@ fn play_stream(
     };
 
     let shared_out = shared.clone();
+    let played_frames = Arc::new(AtomicU64::new(0));
+    let queued_frames = Arc::new(AtomicU64::new(0));
+    let played_frames_out = played_frames.clone();
+    let queued_frames_out = queued_frames.clone();
+    let base_position_ms_out = base_position_ms;
+    let sample_rate_u64 = sample_rate as u64;
+    let channel_count = channels;
     let mut ring_buf: Vec<f32> = Vec::new();
     let mut ring_pos = 0;
 
@@ -488,12 +508,14 @@ fn play_stream(
         move |out: &mut [f32], _: &cpal::OutputCallbackInfo| {
             let vol = shared_out.volume.load(Ordering::Relaxed) as f32 / 100.0;
             let paused = shared_out.paused.load(Ordering::Relaxed);
+            let mut frames_consumed = 0u64;
 
-            for sample in out.iter_mut() {
+            for frame in out.chunks_mut(channel_count) {
                 if paused {
-                    *sample = 0.0;
+                    frame.fill(0.0);
                     continue;
                 }
+
                 if ring_pos >= ring_buf.len() {
                     match sample_rx.try_recv() {
                         Ok(buf) => {
@@ -501,14 +523,31 @@ fn play_stream(
                             ring_pos = 0;
                         }
                         Err(_) => {
-                            *sample = 0.0;
+                            frame.fill(0.0);
                             continue;
                         }
                     }
                 }
+
+                if ring_pos + channel_count <= ring_buf.len() {
+                    for sample in frame.iter_mut() {
                         *sample = ring_buf[ring_pos] * vol;
                         ring_pos += 1;
                     }
+                    frames_consumed += 1;
+                } else {
+                    frame.fill(0.0);
+                }
+            }
+
+            if frames_consumed > 0 {
+                let total_played = played_frames_out.fetch_add(frames_consumed, Ordering::Relaxed)
+                    + frames_consumed;
+                let played_ms = total_played.saturating_mul(1000) / sample_rate_u64.max(1);
+                let pos_ms = base_position_ms_out.saturating_add(played_ms);
+                shared_out.position_ms.store(pos_ms, Ordering::Relaxed);
+                atomic_saturating_sub_u64(&queued_frames_out, frames_consumed);
+            }
         },
         |err| error!("cpal error: {}", err),
         None,
@@ -517,7 +556,7 @@ fn play_stream(
     stream.play()?;
     info!("Playback started ({}Hz, {}ch)", sample_rate, channels);
 
-    let mut packet_ts_origin: Option<u64> = None;
+    let mut finished_naturally = false;
 
     loop {
         // Check if superseded by a newer Play command (generation changed)
@@ -551,6 +590,7 @@ fn play_stream(
                 if e.kind() == std::io::ErrorKind::UnexpectedEof =>
             {
                 info!("Playback finished (gen={})", generation);
+                finished_naturally = true;
                 break;
             }
             Err(symphonia::core::errors::Error::ResetRequired) => {
@@ -576,12 +616,6 @@ fn play_stream(
             continue;
         }
 
-        let packet_ts = packet.ts();
-        let origin = *packet_ts_origin.get_or_insert(packet_ts);
-        let rel_ts = packet_ts.saturating_sub(origin);
-        let pos_ms = base_position_ms + (rel_ts as f64 / sample_rate as f64 * 1000.0) as u64;
-        shared.position_ms.store(pos_ms, Ordering::Relaxed);
-
         let decoded = match decoder.decode(&packet) {
             Ok(d) => d,
             Err(symphonia::core::errors::Error::DecodeError(e)) => {
@@ -598,14 +632,43 @@ fn play_stream(
         let n_frames = decoded.frames();
         let mut sample_buf = SampleBuffer::<f32>::new(n_frames as u64, spec);
         sample_buf.copy_interleaved_ref(decoded);
+        let samples = sample_buf.samples();
+        let frame_count = (samples.len() / channels) as u64;
+        if frame_count == 0 {
+            continue;
+        }
+        let samples_vec = samples.to_vec();
 
-        if sample_tx.send(sample_buf.samples().to_vec()).is_err() {
+        queued_frames.fetch_add(frame_count, Ordering::Relaxed);
+
+        if sample_tx.send(samples_vec).is_err() {
+            atomic_saturating_sub_u64(&queued_frames, frame_count);
             break;
         }
     }
 
-    // Let audio buffer drain
+    if finished_naturally {
-    std::thread::sleep(std::time::Duration::from_millis(300));
+        let drain_deadline = std::time::Instant::now() + std::time::Duration::from_secs(12);
+        while queued_frames.load(Ordering::Relaxed) > 0 {
+            if shared.generation.load(Ordering::SeqCst) != generation {
+                break;
+            }
+            if shared.stop_signal.load(Ordering::Relaxed) {
+                break;
+            }
+            if std::time::Instant::now() >= drain_deadline {
+                warn!(
+                    "Playback drain timeout with {} queued frames",
+                    queued_frames.load(Ordering::Relaxed)
+                );
+                break;
+            }
+            std::thread::sleep(std::time::Duration::from_millis(20));
+        }
+    } else {
+        std::thread::sleep(std::time::Duration::from_millis(100));
+    }
+
     drop(stream);
 
     // Only clear playing state if we're still the current generation

src/qconnect.rs

@@ -851,6 +851,7 @@ async fn run_connection(
     let mut last_play_command_at: std::time::Instant = std::time::Instant::now();
     let mut has_seen_position_progress = false; // true once we've seen pos > 0 after a Play
     let mut track_ended = false; // true when player finishes track naturally
+    let mut ignore_nonzero_seek_until: Option<std::time::Instant> = None;
 
     // Helper macro: send a state update
     macro_rules! send_state {
@@ -953,8 +954,19 @@ async fn run_connection(
                                         let target_pos = requested_pos.unwrap_or(0);
                                         let status = player.status();
                                         let current_player_pos = status.position_ms;
-                                        let should_seek = target_pos == 0
+                                        let mut should_seek = target_pos == 0
                                             || target_pos.abs_diff(current_player_pos) > 350;
+                                        let suppress_nonzero_seek = target_pos > 0
+                                            && ignore_nonzero_seek_until
+                                                .map(|deadline| std::time::Instant::now() < deadline)
+                                                .unwrap_or(false);
+                                        if suppress_nonzero_seek {
+                                            should_seek = false;
+                                            info!(
+                                                "[STATE] Ignoring non-zero seek {}ms during settle window",
+                                                target_pos
+                                            );
+                                        }
 
                                         info!(
                                             "[STATE] seek-only command: target={}ms local={}ms state={:?} track={} should_seek={}",
@@ -972,6 +984,12 @@ async fn run_connection(
                                             );
                                             player.send(PlayerCommand::Seek(target_pos));
                                             track_ended = false;
+                                            if target_pos == 0 {
+                                                ignore_nonzero_seek_until = Some(
+                                                    std::time::Instant::now()
+                                                        + std::time::Duration::from_secs(2),
+                                                );
+                                            }
                                         }
 
                                         current_position_ms = target_pos;
@@ -998,6 +1016,7 @@ async fn run_connection(
                                             last_play_command_at = std::time::Instant::now();
                                             has_seen_position_progress = false;
                                             track_ended = false;
+                                            ignore_nonzero_seek_until = None;
                                             send_state!(ws_tx, msg_id);
 
                                             let track_id_str = track.track_id.to_string();
@@ -1079,8 +1098,19 @@ async fn run_connection(
                                         let requested = requested_pos.unwrap_or(0);
                                         let status = player.status();
                                         let local = status.position_ms;
-                                        let should_seek = requested == 0
+                                        let mut should_seek = requested == 0
                                             || requested.abs_diff(local) > 350;
+                                        let suppress_nonzero_seek = requested > 0
+                                            && ignore_nonzero_seek_until
+                                                .map(|deadline| std::time::Instant::now() < deadline)
+                                                .unwrap_or(false);
+                                        if suppress_nonzero_seek {
+                                            should_seek = false;
+                                            info!(
+                                                "[STATE] Ignoring non-zero position control {}ms during settle window",
+                                                requested
+                                            );
+                                        }
                                         info!(
                                             "[STATE] position-control command: playing_state={:?} target={}ms local={}ms state={:?} track={} should_seek={}",
                                             playing_state,
@@ -1098,6 +1128,12 @@ async fn run_connection(
                                             );
                                             player.send(PlayerCommand::Seek(requested));
                                             track_ended = false;
+                                            if requested == 0 {
+                                                ignore_nonzero_seek_until = Some(
+                                                    std::time::Instant::now()
+                                                        + std::time::Duration::from_secs(2),
+                                                );
+                                            }
                                         }
                                         current_position_ms = requested;
                                     } else if !loaded_new_track && !is_pause {