Deploy Music Generation Studio - 2025-12-12 21:06

backend/services/export_service.py

@@ -57,8 +57,52 @@ class ExportService:
                 
                 audio_data.append(audio)
             
-            # Concatenate all clips
-            merged_audio = np.concatenate(audio_data)
+            # Apply crossfading between clips (2 second overlap)
+            crossfade_duration = 2.0  # seconds
+            crossfade_samples = int(crossfade_duration * sample_rate)
+            
+            if len(audio_data) == 1:
+                # Single clip, no crossfading needed
+                merged_audio = audio_data[0]
+            else:
+                # Start with first clip
+                merged_audio = audio_data[0].copy()
+                
+                # Crossfade each subsequent clip
+                for i in range(1, len(audio_data)):
+                    current_clip = audio_data[i]
+                    
+                    # Calculate overlap region
+                    overlap_samples = min(crossfade_samples, len(merged_audio), len(current_clip))
+                    
+                    if overlap_samples > 0:
+                        # Create fade out curve for end of previous audio
+                        fade_out = np.linspace(1.0, 0.0, overlap_samples)
+                        # Create fade in curve for start of current clip
+                        fade_in = np.linspace(0.0, 1.0, overlap_samples)
+                        
+                        # Handle stereo vs mono
+                        if merged_audio.ndim == 2:
+                            fade_out = fade_out[:, np.newaxis]
+                            fade_in = fade_in[:, np.newaxis]
+                        
+                        # Apply crossfade
+                        merged_audio[-overlap_samples:] = (
+                            merged_audio[-overlap_samples:] * fade_out +
+                            current_clip[:overlap_samples] * fade_in
+                        )
+                        
+                        # Append the rest of the current clip
+                        if len(current_clip) > overlap_samples:
+                            merged_audio = np.concatenate([
+                                merged_audio,
+                                current_clip[overlap_samples:]
+                            ])
+                        
+                        logger.info(f"Applied {crossfade_duration}s crossfade between clips {i-1} and {i}")
+                    else:
+                        # No overlap possible, just concatenate
+                        merged_audio = np.concatenate([merged_audio, current_clip])
             
             # Normalize
             max_val = np.abs(merged_audio).max()