# Function to preprocess audio: convert to 16kHz mono WAV
# def preprocess_audio(input_path):
#     audio = AudioSegment.from_file(input_path)
#     audio = audio.set_frame_rate(16000).set_channels(1)
#     # Export to temp WAV file for Whisper input
#     with tempfile.NamedTemporaryFile(delete=False, suffix=".wav") as tmp_wav:
#         audio.export(tmp_wav.name, format="wav")
#         return tmp_wav.name