Merge pull request #235 from kono-dada/fix/inplace-model-load

- Avoid removing and re-inserting model entries during load
- Preserve metadata (bytes, style_vectors) when evicting
- Ensure eviction targets a different loaded model, not always the first
- Reduce unnecessary memory allocations and keep list order stable

crates/sbv2_core/src/jtalk.rs

@@ -127,20 +127,20 @@ impl JTalkProcess {
             Ok(phone_tone_list)
         } else if tone_values.len() == 2 {
             if tone_values == hash_set![0, 1] {
-                return Ok(phone_tone_list);
+                Ok(phone_tone_list)
             } else if tone_values == hash_set![-1, 0] {
-                return Ok(phone_tone_list
+                Ok(phone_tone_list
                     .iter()
                     .map(|x| {
                         let new_tone = if x.1 == -1 { 0 } else { 1 };
                         (x.0.clone(), new_tone)
                     })
-                    .collect());
+                    .collect())
             } else {
-                return Err(Error::ValueError("Invalid tone values 0".to_string()));
+                Err(Error::ValueError("Invalid tone values 0".to_string()))
             }
         } else {
-            return Err(Error::ValueError("Invalid tone values 1".to_string()));
+            Err(Error::ValueError("Invalid tone values 1".to_string()))
         }
     }
 

crates/sbv2_core/src/tts.rs

@@ -240,39 +240,43 @@ impl TTSModelHolder {
     }
     fn find_and_load_model<I: Into<TTSIdent>>(&mut self, ident: I) -> Result<bool> {
         let ident = ident.into();
-        let (bytes, style_vectors) = {
-            let model = self
-                .models
-                .iter()
-                .find(|m| m.ident == ident)
-                .ok_or(Error::ModelNotFoundError(ident.to_string()))?;
-            if model.vits2.is_some() {
-                return Ok(true);
-            }
-            (model.bytes.clone().unwrap(), model.style_vectors.clone())
-        };
-        self.unload(ident.clone());
-        let s = model::load_model(&bytes, false)?;
-        if let Some(max) = self.max_loaded_models {
-            if self.models.iter().filter(|x| x.vits2.is_some()).count() >= max {
-                self.unload(self.models.first().unwrap().ident.clone());
-            }
-        }
-        self.models.push(TTSModel {
-            bytes: Some(bytes.to_vec()),
-            vits2: Some(s),
-            style_vectors,
-            ident: ident.clone(),
-        });
-        let model = self
+        // Locate target model entry
+        let target_index = self
             .models
             .iter()
-            .find(|m| m.ident == ident)
+            .position(|m| m.ident == ident)
             .ok_or(Error::ModelNotFoundError(ident.to_string()))?;
-        if model.vits2.is_some() {
+
+        // Already loaded
+        if self.models[target_index].vits2.is_some() {
             return Ok(true);
         }
-        Err(Error::ModelNotFoundError(ident.to_string()))
+
+        // Get bytes to build a Session
+        let bytes = self.models[target_index]
+            .bytes
+            .clone()
+            .ok_or(Error::ModelNotFoundError(ident.to_string()))?;
+
+        // Enforce max loaded models by evicting a different loaded model's session, not removing the entry
+        if let Some(max) = self.max_loaded_models {
+            let loaded_count = self.models.iter().filter(|m| m.vits2.is_some()).count();
+            if loaded_count >= max {
+                if let Some(evict_index) = self
+                    .models
+                    .iter()
+                    .position(|m| m.vits2.is_some() && m.ident != ident)
+                {
+                    // Drop only the session to free memory; keep bytes/style for future reload
+                    self.models[evict_index].vits2 = None;
+                }
+            }
+        }
+
+        // Build and set session in-place for the target model
+        let s = model::load_model(&bytes, false)?;
+        self.models[target_index].vits2 = Some(s);
+        Ok(true)
     }
 
     /// Get style vector by style id and weight

crates/sbv2_core/src/tts_util.rs

@@ -173,8 +173,15 @@ pub fn parse_text_blocking(
 }
 
 pub fn array_to_vec(audio_array: Array3<f32>) -> Result<Vec<u8>> {
+    // If SBV2_FORCE_STEREO is set ("1"/"true"), duplicate mono to stereo
+    let force_stereo = std::env::var("SBV2_FORCE_STEREO")
+        .ok()
+        .map(|v| matches!(v.as_str(), "1" | "true" | "TRUE" | "True"))
+        .unwrap_or(false);
+
+    let channels: u16 = if force_stereo { 2 } else { 1 };
     let spec = WavSpec {
-        channels: 1,
+        channels,
         sample_rate: 44100,
         bits_per_sample: 32,
         sample_format: SampleFormat::Float,
@@ -183,8 +190,16 @@ pub fn array_to_vec(audio_array: Array3<f32>) -> Result<Vec<u8>> {
     let mut writer = WavWriter::new(&mut cursor, spec)?;
     for i in 0..audio_array.shape()[0] {
         let output = audio_array.slice(s![i, 0, ..]).to_vec();
-        for sample in output {
-            writer.write_sample(sample)?;
+        if force_stereo {
+            for sample in output {
+                // Write to Left and Right channels
+                writer.write_sample(sample)?;
+                writer.write_sample(sample)?;
+            }
+        } else {
+            for sample in output {
+                writer.write_sample(sample)?;
+            }
         }
     }
     writer.finalize()?;