trying to fix crashes

backend/main.py

@@ -2,12 +2,15 @@ import logging
 import os
 import stat
 import sys
+import tempfile
 from contextlib import asynccontextmanager
 from pathlib import Path
 
 from fastapi import FastAPI, Query, Request, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
-from fastapi.responses import StreamingResponse
+from fastapi.responses import StreamingResponse, FileResponse
+
+import ffmpeg
 
 from routers import transcribe, export, ai, captions, audio
 
@@ -61,20 +64,69 @@ MIME_MAP = {
 
 
 @app.get("/file")
-async def serve_local_file(request: Request, path: str = Query(...)):
-    """Stream a local file with HTTP Range support (required for video seeking)."""
+async def serve_local_file(request: Request, path: str = Query(...), format: str = Query(None)):
+    """Stream a local file with HTTP Range support (required for video seeking).
+    Optionally transcode audio files to MP3 for better browser compatibility."""
     file_path = Path(path)
     if not file_path.is_file():
         logger.warning(f"[serve_file] File not found: {path}")
         raise HTTPException(status_code=404, detail=f"File not found: {path}")
 
     file_size = file_path.stat().st_size
-    content_type = MIME_MAP.get(file_path.suffix.lower(), "application/octet-stream")
+    original_ext = file_path.suffix.lower()
+
+    # Check if we should transcode this file
+    should_transcode = (
+        original_ext == '.wav' and
+        (format == 'mp3' or file_size > 10 * 1024 * 1024)  # Transcode WAV if > 10MB or explicitly requested
+    )
+
+    if should_transcode:
+        logger.info(f"[serve_file] Transcoding {file_path.name} to MP3 (size: {file_size})")
+
+        # Create cache directory
+        cache_dir = Path(__file__).parent / "cache"
+        cache_dir.mkdir(exist_ok=True)
+
+        # Create cache filename
+        import hashlib
+        file_hash = hashlib.md5(str(file_path).encode()).hexdigest()
+        cache_path = cache_dir / f"{file_hash}.mp3"
+
+        # Check if cached version exists
+        if not cache_path.exists():
+            logger.info(f"[serve_file] Creating cached MP3: {cache_path}")
+
+            try:
+                # Transcode to MP3 using ffmpeg
+                (
+                    ffmpeg
+                    .input(str(file_path))
+                    .output(str(cache_path), acodec='libmp3lame', ab='128k')
+                    .run(overwrite_output=True, quiet=True)
+                )
+            except ffmpeg.Error as e:
+                logger.error(f"[serve_file] Transcoding failed: {e}")
+                # Fall back to original file
+                cache_path = file_path
+            else:
+                logger.info(f"[serve_file] Transcoding completed: {cache_path}")
+        else:
+            logger.info(f"[serve_file] Using cached MP3: {cache_path}")
+
+        # Use the transcoded file
+        file_path = cache_path
+        file_size = file_path.stat().st_size
+        content_type = "audio/mpeg"
+
+    else:
+        content_type = MIME_MAP.get(original_ext, "application/octet-stream")
+
     range_header = request.headers.get("range")
 
     logger.info(
-        f"[serve_file] {file_path.name} | size={file_size} | "
-        f"type={content_type} | range={range_header or 'none'}"
+        f"[serve_file] Serving {file_path.name} | size={file_size} | "
+        f"type={content_type} | range={range_header or 'none'} | transcoded={should_transcode}"
     )
 
     if content_type == "application/octet-stream":