Reorganize top-level directories with clearer naming convention

app -> app-desktop-macos, presets -> app-presets, server -> remote-server,
daw-config-reaper -> osc-config-daw, plugin-reaper-realearn -> plugin-reaper-relearn.
Updated run.py and presets.py path references accordingly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

plugin-reaper-relearn/base/src/sound_player.rs

@@ -0,0 +1,92 @@
+use anyhow::{ensure, Context};
+use camino::Utf8Path;
+use reaper_high::Reaper;
+use reaper_low::raw;
+use reaper_medium::{
+    FlexibleOwnedPcmSource, Handle, MeasureAlignment, MidiImportBehavior, OwnedPreviewRegister,
+    PositionInSeconds, ReaperMutex, ReaperMutexGuard, ReaperVolumeValue,
+};
+use std::cell::Cell;
+use std::sync::Arc;
+
+#[derive(Clone, Debug)]
+pub struct SoundPlayer {
+    preview_register: Arc<ReaperMutex<OwnedPreviewRegister>>,
+    play_handle: Cell<Option<Handle<raw::preview_register_t>>>,
+}
+
+unsafe impl Send for SoundPlayer {}
+
+impl Default for SoundPlayer {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl SoundPlayer {
+    pub fn new() -> Self {
+        let mut register = OwnedPreviewRegister::new();
+        register.set_volume(ReaperVolumeValue::ZERO_DB);
+        let preview_register = Arc::new(ReaperMutex::new(register));
+        Self {
+            preview_register,
+            play_handle: Cell::new(None),
+        }
+    }
+
+    pub fn load_file(&mut self, path_to_file: &Utf8Path) -> anyhow::Result<()> {
+        ensure!(path_to_file.exists(), "sound file doesn't exist");
+        let source = Reaper::get()
+            .medium_reaper()
+            .pcm_source_create_from_file_ex(path_to_file, MidiImportBehavior::UsePreference)?;
+        self.load_pcm_source(FlexibleOwnedPcmSource::Reaper(source))
+    }
+
+    pub fn load_pcm_source(&mut self, source: FlexibleOwnedPcmSource) -> anyhow::Result<()> {
+        let mut preview_register = self.lock_preview_register()?;
+        preview_register.set_src(Some(source));
+        Ok(())
+    }
+
+    pub fn volume(&self) -> anyhow::Result<ReaperVolumeValue> {
+        let preview_register = self.lock_preview_register()?;
+        Ok(preview_register.volume())
+    }
+
+    pub fn set_volume(&self, volume: ReaperVolumeValue) -> anyhow::Result<()> {
+        let mut preview_register = self.lock_preview_register()?;
+        preview_register.set_volume(volume);
+        Ok(())
+    }
+
+    pub fn play(&self) -> anyhow::Result<()> {
+        if self.play_handle.get().is_some() {
+            // Is playing already. Simply rewind.
+            let mut preview_register = self.lock_preview_register()?;
+            preview_register.set_cur_pos(PositionInSeconds::ZERO);
+        } else {
+            // Is not yet playing. Start playing.
+            let handle = Reaper::get().medium_session().play_preview_ex(
+                self.preview_register.clone(),
+                Default::default(),
+                MeasureAlignment::PlayImmediately,
+            )?;
+            self.play_handle.set(Some(handle));
+        }
+        Ok(())
+    }
+
+    pub fn stop(&self) -> anyhow::Result<()> {
+        let play_handle = self.play_handle.take().context("not playing")?;
+        Reaper::get().medium_session().stop_preview(play_handle)?;
+        self.lock_preview_register()?
+            .set_cur_pos(PositionInSeconds::ZERO);
+        Ok(())
+    }
+
+    fn lock_preview_register(&self) -> anyhow::Result<ReaperMutexGuard<OwnedPreviewRegister>> {
+        self.preview_register
+            .lock()
+            .context("couldn't acquire preview register lock in sound player")
+    }
+}