Issue with load_audio function from UploadFile input

[Waligator97420]

Hello everyone.

I am using whisper with FastApi and trying to pass my uploaded file (which is an audio .m4a) to transcribe function.

As suggested in this discussion https://github.com/openai/whisper/discussions/380, I understand that I need to use load_audio function to pass the result to transcribe function because there is a preprocessing by ffmeg behind.

But for a reason that I don't understand, I have an error when ffmpeg command is executed:

Here's my code:

@app.post("/transcribe")
async def transcribe(file: UploadFile):
    audio = await file.read()

    audio_array = load_audio(audio)
    if audio_array is not None and len(audio_array) > 0:
        result = model.transcribe(audio_array)
        return {"text": result["text"]}
    else:
        return {"text": "none"}`

For this one, I've inspire me from the discussion above and the beautiful work of @jianfch which give more logs here https://github.com/jianfch/stable-ts/blob/main/stable_whisper/audio/utils.py

def load_audio(file: Union[str, bytes], sr: int = 16000):
    """
    Open an audio file and read as mono waveform, resampling as necessary

    Parameters
    ----------
    file: (str, bytes)
        The audio file to open or bytes of audio file

    sr: int
        The sample rate to resample the audio if necessary

    Returns
    -------
    A NumPy array containing the audio waveform, in float32 dtype.
    """

    # if isinstance(file, bytes):
    #     inp = file
    #     file = 'pipe:'
    # else:
    #     inp = None

    try:
        # This launches a subprocess to decode audio while down-mixing and resampling as necessary.
        # Requires the ffmpeg CLI package to be installed.
        cmd = [
            "ffmpeg",
            "-nostdin",
            "-threads", "0",
            "-i", file if isinstance(file, str) else "pipe:",
            "-f", "s16le",
            "-ac", "1",
            "-acodec", "pcm_s16le",
            "-ar", str(sr),
            "-"
        ]
        if isinstance(file, str):
            out = subprocess.run(cmd, capture_output=True, check=True).stdout
        else:
            cmd = cmd[:1] + ["-loglevel", "error"] + cmd[1:]
            stdin = subprocess.PIPE if isinstance(file, bytes) else file
            out = subprocess.Popen(cmd, stdout=subprocess.PIPE, stdin=stdin)
            out = out.communicate(input=file if isinstance(file, bytes) else None)[0]
            if not out:
                raise RuntimeError(f"FFmpeg failed to load audio from bytes ({len(file)}).")
    except (subprocess.CalledProcessError, subprocess.SubprocessError) as e:
        raise RuntimeError(f"FFmpeg failed to load audio: {e.stderr.decode()}") from e

    return np.frombuffer(out, np.int16).flatten().astype(np.float32) / 32768.0

Hope someone can help me on it!

I'm a newbie to Pyhton and this is my first discussion.
Sorry if I'm mistaken on some things.