local-whisper/local_whisper/audio.py

from typing import BinaryIO

import ffmpeg
import numpy as np

from .settings import whisper_settings

DEFAULT_SAMPLE_RATE = whisper_settings.default_sample_rate


# TODO probably can offload this on a worker queue too
def load_audio(file: BinaryIO, encode=True, sr: int = DEFAULT_SAMPLE_RATE):
    """
    Open an audio file object and read as mono waveform, resampling as necessary.
    Modified from https://github.com/openai/whisper/blob/main/whisper/audio.py
    to accept a file object

    Parameters
    ----------
    file: BinaryIO
        The audio file like object
    encode: Boolean
        If true, encode audio stream to WAV before sending to whisper
    sr: int
        The sample rate to resample the audio if necessary
    Returns
    -------
    A NumPy array containing the audio waveform, in float32 dtype.
    """
    if encode:
        try:
            # This launches a subprocess to decode audio while down-mixing and resampling as necessary.
            # Requires the ffmpeg CLI and `ffmpeg-python` package to be installed.
            out, _ = (
                ffmpeg.input("pipe:", threads=0)
                .output("-", format="s16le", acodec="pcm_s16le", ac=1, ar=sr)
                .run(
                    cmd="ffmpeg",
                    capture_stdout=True,
                    capture_stderr=True,
                    input=file.read(),
                )
            )
        except ffmpeg.Error as e:
            raise RuntimeError(f"Failed to load audio: {e.stderr.decode()}") from e
    else:
        out = file.read()

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