dongliao1860 2019-03-18 07:24
浏览 949

ffmpeg将m4a转换为wav,字节不起作用

some reason I need convert audio data with bytes ,for example data from http or grpc client

so I want to use ffmpeg to convert audio by os/exec.Command

the strange thing is when I convert audio bytes directly will failure, but convet with save file ,it work well

two test below

// ffmpeg work well with file's io.Reader
func TestMp4ToWav(t *testing.T) {
    var f io.Reader
    var err error
    f, err = os.Open("test.m4a")
    require.NoError(t, err)
    cmdStr := strings.Split("-f mp4 -i /dev/stdin -ar 16000 -ac 1 -f wav -", " ")
    cmd := exec.Command("ffmpeg", cmdStr...)
    cmd.Stdin = f
    var errBuff bytes.Buffer
    cmd.Stderr = &errBuff
    d, err := cmd.Output()
    t.Log(errBuff.String())
    if err != nil {
        t.Error(err)
    }

    err = ioutil.WriteFile("output.wav", d, 0644)
    assert.NoError(t, err)

}

// but not work with bytes.Buffer
func TestMp4ToWavWithBuff(t *testing.T) {
    var data []byte
    var err error
    data, err = ioutil.ReadFile("test.m4a")
    require.NoError(t, err)

    cmdStr := strings.Split("-f mp4 -i /dev/stdin -ar 16000 -ac 1 -f wav -", " ")
    cmd := exec.Command("ffmpeg", cmdStr...)
    cmd.Stdin = bytes.NewBuffer(data)
    var errBuff bytes.Buffer
    cmd.Stderr = &errBuff
    d, err := cmd.Output()
    t.Log(errBuff.String())
    require.NoError(t, err)
    err = ioutil.WriteFile("output.wav", d, 0644)
    assert.NoError(t, err)
}

first test output

ffmpeg_test.go:54: ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
      built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
      configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
      libavutil      54. 31.100 / 54. 31.100
      libavcodec     56. 60.100 / 56. 60.100
      libavformat    56. 40.101 / 56. 40.101
      libavdevice    56.  4.100 / 56.  4.100
      libavfilter     5. 40.101 /  5. 40.101
      libavresample   2.  1.  0 /  2.  1.  0
      libswscale      3.  1.101 /  3.  1.101
      libswresample   1.  2.101 /  1.  2.101
      libpostproc    53.  3.100 / 53.  3.100
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/dev/stdin':
      Metadata:
        major_brand     : M4A 
        minor_version   : 512
        compatible_brands: isomiso2
        encoder         : Lavf56.40.101
      Duration: 00:00:05.02, start: 0.023220, bitrate: 136 kb/s
        Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 134 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
    Output #0, wav, to 'pipe:':
      Metadata:
        major_brand     : M4A 
        minor_version   : 512
        compatible_brands: isomiso2
        ISFT            : Lavf56.40.101
        Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, mono, s16, 256 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
          encoder         : Lavc56.60.100 pcm_s16le
    Stream mapping:
      Stream #0:0 -> #0:0 (aac (native) -> pcm_s16le (native))
    size=     158kB time=00:00:05.03 bitrate= 256.1kbits/s    
    video:0kB audio:157kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.048375%

second test output

ffmpeg_test.go:77: ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
      built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
      configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
      libavutil      54. 31.100 / 54. 31.100
      libavcodec     56. 60.100 / 56. 60.100
      libavformat    56. 40.101 / 56. 40.101
      libavdevice    56.  4.100 / 56.  4.100
      libavfilter     5. 40.101 /  5. 40.101
      libavresample   2.  1.  0 /  2.  1.  0
      libswscale      3.  1.101 /  3.  1.101
      libswresample   1.  2.101 /  1.  2.101
      libpostproc    53.  3.100 / 53.  3.100
    [mov,mp4,m4a,3gp,3g2,mj2 @ 0x17454c0] stream 0, offset 0x28: partial file
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/dev/stdin':
      Metadata:
        major_brand     : M4A 
        minor_version   : 512
        compatible_brands: isomiso2
        encoder         : Lavf56.40.101
      Duration: 00:00:05.02, bitrate: N/A
        Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 134 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
    Output #0, wav, to 'pipe:':
      Metadata:
        major_brand     : M4A 
        minor_version   : 512
        compatible_brands: isomiso2
        ISFT            : Lavf56.40.101
        Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, mono, s16, 256 kb/s (default)
        Metadata:
          handler_name    : SoundHandler
          encoder         : Lavc56.60.100 pcm_s16le
    Stream mapping:
      Stream #0:0 -> #0:0 (aac (native) -> pcm_s16le (native))
    [mov,mp4,m4a,3gp,3g2,mj2 @ 0x17454c0] stream 0, offset 0x28: partial file
    /dev/stdin: Invalid data found when processing input
    size=       0kB time=00:00:00.00 bitrate=N/A    
    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)

test.m4a audio download address

PS I also try to fake os.File object still not work

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