无法将含音频的BytesIO正确传入AudioSegment.from_file的问题

问题场景 #

使用PyTube下载YouTube音频文件，尝试通过BytesIO流转码为MP3时，AudioSegment.from_file执行失败，触发FFmpeg解码错误。

原始代码 #

yt = YouTube(youtube_link)
# Download file
audio = yt.streams.filter(only_audio=True).first()
audio_bytes = io.BytesIO()
print('Getting audio bytes')
audio.stream_to_buffer(audio_bytes)
print('Converting format')
sound = AudioSegment.from_file(file=audio_bytes).export(io.BytesIO(), 'mp3')
return dcc.send_bytes(sound.getvalue(), f'{yt.streams[0].title}.mp3')

错误信息 #

raise CouldntDecodeError(
pydub.exceptions.CouldntDecodeError: Decoding failed. ffmpeg returned error code: 1

Output from ffmpeg/avlib:

ffmpeg version 2022-07-04-git-dba7376d59-full_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 12.1.0 (Rev2, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      57. 27.100 / 57. 27.100
  libavcodec     59. 36.100 / 59. 36.100
  libavformat    59. 26.100 / 59. 26.100
  libavdevice    59.  6.100 / 59.  6.100
  libavfilter     8. 41.100 /  8. 41.100
  libswscale      6.  6.100 /  6.  6.100
  libswresample   4.  6.100 /  4.  6.100
  libpostproc    56.  5.100 / 56.  5.100
[cache @ 0000022fcb016200] Statistics, cache hits:0 cache misses:0
cache:pipe:0: Invalid data found when processing input

解决办法 #

核心原因 #

audio.stream_to_buffer(audio_bytes)执行后，BytesIO的文件指针停留在缓冲区末尾，AudioSegment.from_file读取时从末尾开始，无法获取有效音频数据，导致FFmpeg解码失败。

修复步骤 #

1. 在调用AudioSegment.from_file前，重置BytesIO指针到起始位置：

   audio_bytes.seek(0)
   

2. 可选但推荐：明确指定音频格式（PyTube下载的音频通常为mp4或webm），帮助FFmpeg精准识别解码格式：

   audio_format = audio.mime_type.split('/')[-1]
   

完整修复代码 #

import io
from pytube import YouTube
from pydub import AudioSegment
import dash_core_components as dcc

def download_convert_yt_audio(youtube_link):
    yt = YouTube(youtube_link)
    # 筛选仅音频流
    audio = yt.streams.filter(only_audio=True).first()
    audio_bytes = io.BytesIO()
    
    print('Getting audio bytes')
    audio.stream_to_buffer(audio_bytes)
    # 重置缓冲区指针到起始位置
    audio_bytes.seek(0)
    
    print('Converting format')
    # 获取音频格式，辅助FFmpeg解码
    audio_format = audio.mime_type.split('/')[-1]
    sound_segment = AudioSegment.from_file(file=audio_bytes, format=audio_format)
    
    mp3_buffer = io.BytesIO()
    sound_segment.export(mp3_buffer, format='mp3')
    mp3_buffer.seek(0)
    
    return dcc.send_bytes(mp3_buffer.getvalue(), f'{yt.title}.mp3')

额外注意事项 #

• 确保FFmpeg已正确安装并添加至系统环境变量，pydub依赖FFmpeg完成格式转换
• 若仍存在解码问题，可手动指定FFmpeg路径：

  AudioSegment.converter = "你的FFmpeg可执行文件路径"
  

内容的提问来源于stack exchange，提问作者Gus Montano