FFmpeg音頻通道rematrix（5.1到立體聲）

我有一個（非常大！）帶有16ch音頻的Apple ProRes 422文件。爲了能夠在不太強大的電腦上使用它，我想將它轉換爲標準的MP4文件（h264視頻編解碼器，立體聲音頻）。原始文件有16個音頻通道，但是，當我嘗試轉換它時（'需要Rematrix'），FFmpeg會給出錯誤信息。我如何重新映射音頻通道？是否需要額外的步驟？FFmpeg音頻通道rematrix（5.1到立體聲）

這FFmpeg的命令我使用：

ffmpeg -y -i Capture0000.mov -vcodec libx264 -vb 2000k -pix_fmt yuv420p -coder 0 -profile:v baseline -acodec libfaac -ab 128k /tmp/out.mp4

這FFmpeg的輸出：

ffmpeg version 2.2.git Copyright (c) 2000-2014 the FFmpeg developers 
     built on May 8 2014 14:17:45 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5) 
     configuration: --prefix=/usr/local/ffmpeg_build --extra-cflags=-I/usr/local/ffmpeg_build/include --extra-ldflags=-L/usr/local/ffmpeg_build/lib --bindir=/usr/local/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab --enable-libxvid --enable-libfaac 
     libavutil  52. 81.100/52. 81.100 
     libavcodec  55. 60.103/55. 60.103 
     libavformat 55. 37.102/55. 37.102 
     libavdevice 55. 13.101/55. 13.101 
     libavfilter  4. 5.100/4. 5.100 
     libswscale  2. 6.100/2. 6.100 
     libswresample 0. 18.100/0. 18.100 
     libpostproc 52. 3.100/52. 3.100 
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Capture0000.mov': 
     Metadata: 
     creation_time : 2014-08-17 18:30:31 
     Duration: 01:01:22.52, start: 0.000000, bitrate: 202001 kb/s 
     Stream #0:0(eng): Video: prores (apch/0x68637061), yuv422p10le, 1920x1080, 183513 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 2500 tbn, 2500 tbc (default) 
     Metadata: 
      creation_time : 2014-08-17 18:30:31 
      handler_name : Apple Alias Data Handler 
      encoder   : Apple ProRes 422 (HQ) 
     Stream #0:1(eng): Audio: pcm_s24le (lpcm/0x6D63706C), 48000 Hz, 16 channels, s32, 18432 kb/s (default) 
     Metadata: 
      creation_time : 2014-08-17 18:30:31 
      handler_name : Apple Alias Data Handler 
    [auto-inserted resampler 0 @ 0x3943da0] [SWR @ 0x39441a0] Rematrix is needed between 16 channels and 5.1 but there is not enough information to do it 
    [auto-inserted resampler 0 @ 0x3943da0] Failed to configure output pad on auto-inserted resampler 0 
    Error opening filters!

這是FFprobe輸出：

ffprobe version 2.2.git Copyright (c) 2007-2014 the FFmpeg developers 
    built on May 8 2014 14:17:45 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5) 
    configuration: --prefix=/usr/local/ffmpeg_build --extra-cflags=-I/usr/local/ffmpeg_build/include --extra-ldflags=-L/usr/local/ffmpeg_build/lib --bindir=/usr/local/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab --enable-libxvid --enable-libfaac 
    libavutil  52. 81.100/52. 81.100 
    libavcodec  55. 60.103/55. 60.103 
    libavformat 55. 37.102/55. 37.102 
    libavdevice 55. 13.101/55. 13.101 
    libavfilter  4. 5.100/4. 5.100 
    libswscale  2. 6.100/2. 6.100 
    libswresample 0. 18.100/0. 18.100 
    libpostproc 52. 3.100/52. 3.100 
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Capture0000.mov': 
    Metadata: 
    creation_time : 2014-08-17 18:30:31 
    Duration: 01:01:22.52, start: 0.000000, bitrate: 202001 kb/s 
    Stream #0:0(eng): Video: prores (apch/0x68637061), yuv422p10le, 1920x1080, 183513 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 2500 tbn, 2500 tbc (default) 
    Metadata: 
     creation_time : 2014-08-17 18:30:31 
     handler_name : Apple Alias Data Handler 
     encoder   : Apple ProRes 422 (HQ) 
    Stream #0:1(eng): Audio: pcm_s24le (lpcm/0x6D63706C), 48000 Hz, 16 channels, s32, 18432 kb/s (default) 
    Metadata: 
     creation_time : 2014-08-17 18:30:31 
     handler_name : Apple Alias Data Handler

來源

2014-10-29 Flock Dawson

如果使用libfaac，則應該使用libfdk_aac。它會爲每比特率提供更好的質量。請參閱[AAC指南]（http://trac.ffmpeg.org/wiki/Encode/AAC）。另外，我很高興你找到了答案，但是請注意，[所以]是不涉及編程的問題。下次嘗試[su]（我們也有ffmpeg的回答者）。 – LordNeckbeard 2014-10-29 17:32:51

找到了！僅提取音頻後，它變成了前兩個頻道分別爲立體聲和其他四個空的，所以我說這一點：

-af 'pan=stereo:c0=FL:c1=FR'

這隻需左前和右前聲道的立體聲混音。

來源

2014-10-29 08:56:30

FFmpeg音頻通道rematrix（5.1到立體聲）

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