Update app.py

app.py

@@ -7,28 +7,65 @@ import io
 
 app = FastAPI()
 
-def process_video(input_bytes, speed=1.5):
-    """
-    Process video to change playback speed and compress.
-    """
+def build_atempo_filter(speed: float) -> str:
+    """Build a valid FFmpeg atempo chain for any 0.25–4.0 speed."""
+    filters = []
+    while speed > 2.0:
+        filters.append("atempo=2.0")
+        speed /= 2.0
+    while speed < 0.5:
+        filters.append("atempo=0.5")
+        speed *= 2.0
+    filters.append(f"atempo={speed}")
+    return ",".join(filters)
+
+@app.post("/process_video")
+async def process_video_endpoint(file: UploadFile = File(...), speed: float = 1.5):
+    if not (0.25 <= speed <= 4.0):
+        raise HTTPException(status_code=400, detail="Speed must be between 0.25x and 4x.")
+
+    # Save uploaded file
+    video_bytes = await file.read()
     with tempfile.NamedTemporaryFile(delete=False, suffix=".mp4") as tmp_input:
-        tmp_input.write(input_bytes)
+        tmp_input.write(video_bytes)
         input_path = tmp_input.name
 
     output_path = tempfile.NamedTemporaryFile(delete=False, suffix=".mp4").name
 
+    # Check if input has audio
+    probe_audio = subprocess.run(
+        ["ffprobe", "-v", "error", "-select_streams", "a",
+         "-show_entries", "stream=codec_type", "-of", "csv=p=0", input_path],
+        stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True
+    )
+    has_audio = bool(probe_audio.stdout.strip())
+
+    # Build filters
     video_speed = 1 / speed
-    audio_speed = speed
+    filters = [f"[0:v]setpts={video_speed}*PTS[v]"]
+
+    if has_audio:
+        audio_filter = build_atempo_filter(speed)
+        filters.append(f"[0:a]{audio_filter}[a]")
+
+    filter_complex = ";".join(filters)
 
     cmd = [
         "ffmpeg", "-i", input_path,
-        "-filter_complex", f"[0:v]setpts={video_speed}*PTS[v];[0:a]atempo={audio_speed}[a]",
-        "-map", "[v]", "-map", "[a]",
+        "-filter_complex", filter_complex,
+        "-map", "[v]"
+    ]
+
+    if has_audio:
+        cmd += ["-map", "[a]"]
+
+    cmd += [
         "-vcodec", "libx264", "-crf", "28", "-preset", "fast",
         "-movflags", "+faststart",
         "-y", output_path
     ]
 
+    # Run ffmpeg
     process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, text=True)
     process.wait()
 
@@ -37,28 +74,15 @@ def process_video(input_bytes, speed=1.5):
         os.remove(output_path)
         raise HTTPException(status_code=500, detail="Video processing failed.")
 
+    # Return file
     with open(output_path, "rb") as f:
-        output_data = f.read()
+        processed_data = f.read()
 
     os.remove(input_path)
     os.remove(output_path)
 
-    return output_data
-
-
-@app.post("/process_video")
-async def upload_video(file: UploadFile = File(...), speed: float = 1.5):
-    """
-    Upload a video file and return processed video.
-    """
-    if not (0.25 <= speed <= 4.0):
-        raise HTTPException(status_code=400, detail="Speed must be between 0.25x and 4x.")
-
-    video_bytes = await file.read()
-    processed_video = process_video(video_bytes, speed)
-
     return StreamingResponse(
-        io.BytesIO(processed_video),
+        io.BytesIO(processed_data),
         media_type="video/mp4",
         headers={"Content-Disposition": "attachment; filename=processed_video.mp4"}
     )