node.js - fluff-ffmpeg使用流媒体提取音频

我正在尝试从视频中提取音频。这段代码运作良好:

ffmpeg('1.mp4').output('1.mp3')
.noVideo()
.format('mp3')
.outputOptions('-ab','192k')
.run();

但是，如果我使用这样的流读取文件:

var video = fs.createReadStream('1.mp4');
var audio = fs.createWriteStream('1.mp3');
ffmpeg(video).output(audio)
.noVideo()
.format('mp3')
.outputOptions('-ab','192k')
.run();

输出文件的大小为1KB，其中没有任何内容。

如何使用流提取音频？

最佳答案

为了进一步研究，我添加了一个回调，用于转码时的其他错误以及其他事件。第一个提示是progress事件的以下回调:

{ frames: NaN,
  currentFps: NaN,
  currentKbps: NaN,
  targetSize: 0,
  timemark: '00:00:00.00' }

同样，还有一个stderr事件:

ffmpeg version n4.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 8.2.1 (GCC) 20180831
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562c9e18de80] stream 0, offset 0x30: partial file
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562c9e18de80] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none, 240x180, 374 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'pipe:0':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf54.63.104
  Duration: 00:00:14.72, start: 0.000000, bitrate: N/A
    Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 240x180, 374 kb/s, 25 fps, 25 tbr, 12800 tbn, 25600 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 75 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:1 -> #0:0 (aac (native) -> mp3 (libmp3lame))
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x562c9e18de80] stream 1, offset 0xa1e: partial file
pipe:0: Invalid data found when processing input
Output #0, mp3, to 'pipe:1':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    TSSE            : Lavf58.20.100
    Stream #0:0(und): Audio: mp3 (libmp3lame), 44100 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      encoder         : Lavc58.35.100 libmp3lame
size=       0kB time=00:00:00.00 bitrate=N/A speed=   0x
{ frames: NaN,
  currentFps: NaN,
  currentKbps: NaN,
  targetSize: 0,
  timemark: '00:00:00.00' }
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)

后者解释了您在输出中看到的空文件。至于为什么错误仅在流式传输文件时发生，而不是在通过其他方法打开文件时发生，为什么这个答案解释了细节:https://stackoverflow.com/a/40028894/1494833

不幸的是，该库尚不支持上面建议的movflags输入选项(https://github.com/fluent-ffmpeg/node-fluent-ffmpeg/issues/823)。

关于node.js - fluff-ffmpeg使用流媒体提取音频，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/53917893/