fix(session): resume Qobuz streams at saved position without losing seek (#315)

Three bugs were stacking up to make session resume drop the saved offset
for streamed Qobuz tracks:

1. Position save was debounced, not throttled. Each playback tick reset
   the 5s timer, so the save never fired while a track played
   continuously — the persisted position froze at whatever value got
   written during the first quiet window after track start (typically
   ~2s). Switch to throttle: fire the first call immediately, then once
   per 5s window, with a tail call to flush the latest value when the
   window ends.

2. togglePlay tried to apply the restore offset via a separate cmdSeek
   right after cmdPlayTrack. For Qobuz streaming the audio thread's
   Seek handler bails when current_audio_data is unset — streaming
   uses current_streaming_source instead — so the seek was silently
   dropped and the track started at 0:00. Pass start_position_secs
   directly to v2_play_track. The streaming backend (legacy + V2
   player) waits for enough buffer to cover the offset plus 8s
   headroom, then eagerly decode-and-discards decoder output up to
   the offset before engaging the audio engine — no race, no
   first-pull underrun. Plex and local tracks keep the old play+seek
   path; they load full audio_data so Seek works as-is.

3. The seekbar showed 0:00 from app launch until the user hit play,
   even when a saved position was queued. setPendingSessionRestore
   now pre-positions currentTime when positionSecs > 0 so the UI
   reflects "paused at X" the moment the app opens.

Other plumbing:
- AudioCommand::PlayStreaming carries start_position_secs and
  content_length (used to estimate bytes-per-second for the resume
  buffer target).
- Player::play_streaming{,_dynamic} grow a start_position_secs
  parameter; QConnect and api_server callers pass 0 (remote-driven
  playback always starts fresh).
- cmdPlayTrack forwards startPositionSecs as a 5th optional arg.

cc
This commit is contained in:
vicrodh committed 2026-05-14 02:18:59 -06:00
1 parent b2960e8029
commit 921f8e1a49
8 files changed
+331 -66

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+117 -20
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@@ -68,6 +68,13 @@ enum AudioCommand {
sample_rate: u32,
channels: u16,
duration_secs: u64,
/// Resume offset in seconds (#315). When > 0, the audio thread
/// waits for enough buffer to cover the offset and pre-skips
/// decoder output up to that point before engaging audio.
start_position_secs: u64,
/// Total content length in bytes. Combined with `duration_secs`
/// to estimate bytes-per-second when sizing the resume buffer.
content_length: u64,
},
/// Pause playback
Pause,
@@ -1943,13 +1950,16 @@ impl Player {
sample_rate,
channels,
duration_secs,
start_position_secs,
content_length,
} => {
log::info!(
"Audio thread: starting streaming playback for track {} ({}Hz, {} channels, {}s)",
"Audio thread: starting streaming playback for track {} ({}Hz, {} channels, {}s, start={}s)",
track_id,
sample_rate,
channels,
duration_secs
duration_secs,
start_position_secs
);
*pause_suspend_deadline = None;
@@ -2171,12 +2181,44 @@ impl Player {
let volume = thread_state.volume.load(Ordering::SeqCst) as f32 / 100.0;
apply_engine_volume(&stream_opt, &engine, volume);
// Wait for minimum buffer before starting playback
// Wait for minimum buffer before starting playback.
// When start_position_secs > 0 (session resume),
// also wait for enough buffer to cover the resume
// offset plus an 8s headroom — the eager pre-skip
// below decodes-and-discards up to the offset and
// needs the bytes available without blocking the
// audio device on the first pull.
log::info!("Streaming: waiting for initial buffer...");
let start_wait = Instant::now();
let max_wait = Duration::from_secs(30);
let max_wait = Duration::from_secs(60);
while !source.has_min_buffer() && start_wait.elapsed() < max_wait {
let bytes_per_sec_estimate: u64 = if duration_secs > 0
&& content_length > 0
{
content_length / duration_secs
} else {
200_000
};
let resume_buffer_target: u64 = if start_position_secs > 0 {
bytes_per_sec_estimate
.saturating_mul(start_position_secs.saturating_add(8))
} else {
0
};
let buffer_sufficient = |src: &Arc<BufferedMediaSource>| -> bool {
if !src.has_min_buffer() {
return false;
}
if resume_buffer_target == 0 {
return true;
}
(src.buffer_size() as u64) >= resume_buffer_target
};
while !buffer_sufficient(&source)
&& start_wait.elapsed() < max_wait
{
std::thread::sleep(Duration::from_millis(50));
}
@@ -2184,11 +2226,20 @@ impl Player {
log::error!("Streaming: timeout waiting for initial buffer");
return;
}
if resume_buffer_target > 0
&& (source.buffer_size() as u64) < resume_buffer_target
{
log::warn!(
"Streaming: timed out waiting for resume buffer (got {} bytes, wanted {}); pre-skip may underrun briefly",
source.buffer_size(),
resume_buffer_target
);
}
let buffer_wait_ms = start_wait.elapsed().as_millis();
log::info!(
"Streaming: initial buffer ready in {}ms, creating incremental decoder...",
buffer_wait_ms
"Streaming: buffer ready in {}ms ({} bytes, target {}), creating incremental decoder...",
buffer_wait_ms, source.buffer_size(), resume_buffer_target
);
// Create incremental streaming source - this starts playback IMMEDIATELY
@@ -2266,8 +2317,40 @@ impl Player {
thread_state.set_normalization_gain(normalization);
// Box the incremental source to match the expected type
let source_to_play: Box<dyn Source<Item = f32> + Send> =
let mut source_to_play: Box<dyn Source<Item = f32> + Send> =
Box::new(incremental_source);
// Eager pre-skip for session resume. Decode and
// discard samples here so the engine's first pull
// doesn't have to do the work synchronously, which
// would underrun the audio device for multi-second
// offsets. The buffer wait above guarantees
// there's enough downloaded data to feed this loop.
if start_position_secs > 0 {
let target_samples: u64 = (start_position_secs)
.saturating_mul(actual_sr as u64)
.saturating_mul(actual_ch as u64);
let skip_start = Instant::now();
let mut skipped: u64 = 0;
while skipped < target_samples {
if source_to_play.next().is_none() {
log::warn!(
"Resume: source ended before reaching {}s (pre-skipped {} samples)",
start_position_secs,
skipped
);
break;
}
skipped += 1;
}
log::info!(
"Resume: pre-skipped {} samples ({}s) in {}ms",
skipped,
start_position_secs,
skip_start.elapsed().as_millis()
);
}
// Wrap source with diagnostic, normalization, and visualizer
let source_to_play = wrap_source(
source_to_play,
@@ -2282,16 +2365,19 @@ impl Player {
}
thread_state.is_playing.store(true, Ordering::SeqCst);
thread_state.position.store(0, Ordering::SeqCst);
thread_state
.position
.store(start_position_secs, Ordering::SeqCst);
thread_state
.current_track_id
.store(track_id, Ordering::SeqCst);
thread_state.start_playback_timer(0);
thread_state.start_playback_timer(start_position_secs);
*current_engine = Some(engine);
log::info!(
"Audio thread: streaming playback STARTED in {}ms (incremental decode active)",
start_wait.elapsed().as_millis()
"Audio thread: streaming playback STARTED in {}ms at {}s (incremental decode active)",
start_wait.elapsed().as_millis(),
start_position_secs
);
}
AudioCommand::Pause => {
@@ -3301,8 +3387,11 @@ impl Player {
})
}
/// Play from streaming source (starts playback before full download)
/// Returns the BufferWriter so caller can push data as it downloads
/// Play from streaming source (starts playback before full download).
/// Returns the BufferWriter so caller can push data as it downloads.
/// `start_position_secs` > 0 turns this into a session-resume play
/// (#315): the audio thread waits for enough buffer to cover the
/// offset and pre-skips decoder output up to that point.
pub fn play_streaming(
&self,
track_id: u64,
@@ -3311,14 +3400,16 @@ impl Player {
content_length: u64,
buffer_seconds: u8,
duration_secs: u64,
start_position_secs: u64,
) -> Result<BufferWriter, String> {
log::info!(
"Player: Starting streaming playback for track {} ({}Hz, {}ch, {} bytes total, {}s)",
"Player: Starting streaming playback for track {} ({}Hz, {}ch, {} bytes total, {}s, start={}s)",
track_id,
sample_rate,
channels,
content_length,
duration_secs
duration_secs,
start_position_secs
);
// Use StreamingConfig::from_seconds for proper buffer sizing
@@ -3334,6 +3425,8 @@ impl Player {
sample_rate,
channels,
duration_secs,
start_position_secs,
content_length,
})
.map_err(|e| {
log::error!("Player: Failed to send streaming command: {}", e);
@@ -3344,8 +3437,8 @@ impl Player {
Ok(writer)
}
/// Play from streaming source with dynamic buffer based on measured speed
/// Returns the BufferWriter so caller can push data as it downloads
/// Play from streaming source with dynamic buffer based on measured speed.
/// `start_position_secs` > 0 signals session resume (see `play_streaming`).
pub fn play_streaming_dynamic(
&self,
track_id: u64,
@@ -3355,16 +3448,18 @@ impl Player {
content_length: u64,
speed_mbps: f64,
duration_secs: u64,
start_position_secs: u64,
) -> Result<BufferWriter, String> {
log::info!(
"Player: Starting dynamic streaming for track {} ({}Hz, {}ch, {}-bit, {:.2} MB, {:.1} MB/s, {}s)",
"Player: Starting dynamic streaming for track {} ({}Hz, {}ch, {}-bit, {:.2} MB, {:.1} MB/s, {}s, start={}s)",
track_id,
sample_rate,
channels,
bit_depth,
content_length as f64 / (1024.0 * 1024.0),
speed_mbps,
duration_secs
duration_secs,
start_position_secs
);
// Update shared state with actual stream quality
@@ -3383,6 +3478,8 @@ impl Player {
sample_rate,
channels,
duration_secs,
start_position_secs,
content_length,
})
.map_err(|e| {
log::error!("Player: Failed to send streaming command: {}", e);