Update app.py

app.py

@@ -481,7 +481,7 @@ def generate_voiceover_clone(translated_json, desired_duration, target_language,
         #     logger.warning(f"⚠️ Text too long for TTS model ({len(tokens)} tokens). Truncating to {MAX_TTS_TOKENS} tokens.")
         #     full_text = " ".join(tokens[:MAX_TTS_TOKENS])
 
-        speed_tts = calculate_speed(full_text, desired_duration)
+        speed_tts = calibrated_speed(full_text, desired_duration)
         tts.tts_to_file(
             text=full_text,
             speaker_wav=speaker_wav_path,
@@ -506,25 +506,27 @@ def generate_voiceover_clone(translated_json, desired_duration, target_language,
         logger.error(traceback.format_exc())
         return None, err_msg, err_msg
 
-def truncated_linear(x):
-    if x < 15:
-        return 1.01  # Ensure speed is strictly > 1
-    elif x > 25:
-        return 1.3
+def calibrated_speed(text, desired_duration):
+    """
+    Compute a speed factor to help TTS fit audio into desired duration,
+    using a simple truncated linear function of characters per second.
+    """
+    char_count = len(text.strip())
+    if char_count == 0 or desired_duration <= 0:
+        return 1.0  # fallback
+
+    cps = char_count / desired_duration  # characters per second
+
+    # Truncated linear mapping
+    if cps < 10:
+        return 1.0
+    elif cps > 25:
+        return 1.4
     else:
-        slope = (1.3 - 1) / (25 - 15)
-        speed = 1 + slope * (x - 15)
-        return max(speed, 1.01)  # Ensure lower bound is > 1
-
-def calculate_speed(text, desired_duration):
-    # Calculate characters per second
-    char_count = len(text)
-    chars_per_second = char_count / (desired_duration + 0.001)
-    
-    # Apply truncated linear function to get speed
-    speed = truncated_linear(chars_per_second)
-    
-    return speed
+        # Linearly scale between cps 10 -> 25 and speed 1.0 -> 1.3
+        slope = (1.4 - 1.0) / (25 - 10)
+        return 1.0 + slope * (cps - 10)
+
 
 def upload_and_manage(file, target_language, mode="transcription"):
     if file is None: