Make sure that decoder picks up where it left of going from paused to play

Since we are including the pipeline latency in the position we need to seek to the correct position when going from paused to play.

We can also drop the ALSA and PulseAudio buffers instead of draining them since their latency's are factored in.

playback/src/audio_backend/alsa.rs

@@ -52,9 +52,6 @@ enum AlsaError {
     #[error("<AlsaSink> Device {device} May be Invalid, Busy, or Already in Use, {e}")]
     PcmSetUp { device: String, e: alsa::Error },
 
-    #[error("<AlsaSink> Failed to Drain PCM Buffer, {0}")]
-    DrainFailure(alsa::Error),
-
     #[error("<AlsaSink> {0}")]
     OnWrite(alsa::Error),
 
@@ -76,7 +73,7 @@ impl From<AlsaError> for SinkError {
         use AlsaError::*;
         let es = e.to_string();
         match e {
-            DrainFailure(_) | OnWrite(_) => SinkError::OnWrite(es),
+            OnWrite(_) => SinkError::OnWrite(es),
             PcmSetUp { .. } => SinkError::ConnectionRefused(es),
             _ => SinkError::InvalidParams(es),
         }
@@ -239,11 +236,8 @@ impl Sink for AlsaSink {
     }
 
     fn stop(&mut self) -> SinkResult<()> {
-        self.write_buf()?;
-
-        if let Some(pcm) = self.pcm.take() {
-            pcm.drain().map_err(AlsaError::DrainFailure)?;
-        }
+        self.period_buffer.clear();
+        self.pcm = None;
 
         Ok(())
     }

playback/src/audio_backend/pulseaudio.rs

@@ -137,7 +137,7 @@ impl Sink for PulseAudioSink {
 
     fn stop(&mut self) -> SinkResult<()> {
         if let Some(sink) = self.sink.take() {
-            sink.drain().map_err(PulseError::DrainFailure)?;
+            sink.flush().map_err(PulseError::DrainFailure)?;
         }
 
         Ok(())

playback/src/player.rs

@@ -676,7 +676,7 @@ impl PlayerState {
             Paused {
                 track_id,
                 play_request_id,
-                decoder,
+                mut decoder,
                 audio_item,
                 normalisation_data,
                 stream_loader_controller,
@@ -686,6 +686,8 @@ impl PlayerState {
                 suggested_to_preload_next_track,
                 is_explicit,
             } => {
+                let stream_position_ms = decoder.seek(stream_position_ms).unwrap_or_default();
+
                 *self = Playing {
                     track_id,
                     play_request_id,