implemented 15,12,18 didn't check 18

backend/routers/audio.py

@@ -11,7 +11,7 @@ from fastapi import APIRouter, HTTPException, Query, Request
 from fastapi.responses import FileResponse
 from pydantic import BaseModel
 
-from services.audio_cleaner import clean_audio, detect_silence_ranges, is_deepfilter_available
+from services.audio_cleaner import clean_audio, detect_silence_ranges, is_deepfilter_available, normalize_audio
 
 logger = logging.getLogger(__name__)
 router = APIRouter()
@@ -164,3 +164,30 @@ async def get_waveform_audio(request: Request, path: str = Query(...)):
     )
     _waveform_cache[cache_key] = str(out_wav)
     return FileResponse(str(out_wav), media_type="audio/wav")
+
+
+class NormalizeRequest(BaseModel):
+    input_path: str
+    output_path: Optional[str] = None
+    target_lufs: float = -14.0
+
+
+@router.post("/audio/normalize")
+async def normalize_audio_endpoint(req: NormalizeRequest):
+    """Normalize audio loudness to a target LUFS level using FFmpeg loudnorm."""
+    if req.target_lufs < -70 or req.target_lufs > 0:
+        raise HTTPException(status_code=400, detail="target_lufs must be between -70 and 0")
+    try:
+        output = normalize_audio(
+            req.input_path,
+            req.output_path or "",
+            target_lufs=req.target_lufs,
+        )
+        return {
+            "status": "ok",
+            "output_path": output,
+            "target_lufs": req.target_lufs,
+        }
+    except Exception as e:
+        logger.error(f"Audio normalization failed: {e}", exc_info=True)
+        raise HTTPException(status_code=500, detail=str(e))