我似乎无法弄清楚如何做到这一点。我一直在盯着这些命令： https://trac.ffmpeg.org/wiki/AudioChannelManipulation
但无济于事。可悲的是，这比我的水平还要高。这是相关视频的ffmpeg -i输出：
ffmpeg version N-64012-g61df081 Copyright (c) 2000-2014 the FFmpeg developers
built on Jun 16 2014 22:01:59 with gcc 4.8.3 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex--enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib
libavutil 52. 89.100 / 52. 89.100
libavcodec 55. 67.100 / 55. 67.100
libavformat 55. 43.100 / 55. 43.100
libavdevice 55. 13.101 / 55. 13.101
libavfilter 4. 8.100 / 4. 8.100
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 19.100 / 0. 19.100
libpostproc 52. 3.100 / 52. 3.100
Input #0, matroska,webm, from '[Coalgirls]_Spirited_Away_(1920x1038_Blu-ray_FLAC)_[92372194].mkv':
Metadata:
title : Spirited Away
encoder : libebml v1.3.0 + libmatroska v1.4.0
creation_time : 2014-07-03 01:32:13
Duration: 02:04:32.29, start: 0.000000, bitrate: 15972 kb/s
Chapter #0.0: start 0.000000, end 99.099000
Metadata:
title : 00:00:00.000
Chapter #0.1: start 99.099000, end 196.238000
Metadata:
title : 00:01:39.099
Chapter #0.2: start 196.238000, end 443.526000
Metadata:
title : 00:03:16.238
Chapter #0.3: start 443.526000, end 645.395000
Metadata:
title : 00:07:23.526
Chapter #0.4: start 645.395000, end 1023.022000
Metadata:
title : 00:10:45.395
Chapter #0.5: start 1023.022000, end 1368.534000
Metadata:
title : 00:17:03.022
Chapter #0.6: start 1368.534000, end 1716.048000
Metadata:
title : 00:22:48.534
Chapter #0.7: start 1716.048000, end 2008.173000
Metadata:
title : 00:28:36.048
Chapter #0.8: start 2008.173000, end 2301.674000
Metadata:
title : 00:33:28.173
Chapter #0.9: start 2301.674000, end 2651.816000
Metadata:
title : 00:38:21.674
Chapter #0.10: start 2651.816000, end 2906.821000
Metadata:
title : 00:44:11.816
Chapter #0.11: start 2906.821000, end 3271.351000
Metadata:
title : 00:48:26.821
Chapter #0.12: start 3271.351000, end 3729.017000
Metadata:
title : 00:54:31.351
Chapter #0.13: start 3729.017000, end 4091.587000
Metadata:
title : 01:02:09.017
Chapter #0.14: start 4091.587000, end 4476.847000
Metadata:
title : 01:08:11.587
Chapter #0.15: start 4476.847000, end 4750.579000
Metadata:
title : 01:14:36.847
Chapter #0.16: start 4750.579000, end 5139.760000
Metadata:
title : 01:19:10.579
Chapter #0.17: start 5139.760000, end 5478.890000
Metadata:
title : 01:25:39.760
Chapter #0.18: start 5478.890000, end 5853.806000
Metadata:
title : 01:31:18.890
Chapter #0.19: start 5853.806000, end 6318.937000
Metadata:
title : 01:37:33.806
Chapter #0.20: start 6318.937000, end 6625.118000
Metadata:
title : 01:45:18.937
Chapter #0.21: start 6625.118000, end 6771.098000
Metadata:
title : 01:50:25.118
Chapter #0.22: start 6771.098000, end 6914.199000
Metadata:
title : 01:52:51.098
Chapter #0.23: start 6914.199000, end 7253.580000
Metadata:
title : 01:55:14.199
Chapter #0.24: start 7253.580000, end 7472.288000
Metadata:
title : 02:00:53.580
Stream #0:0: Video: h264 (High 10), yuv420p10le(tv, bt709), 1920x1038, SAR 1:1 DAR 320:173, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
Metadata:
title : Spirited Away
Stream #0:1(jpn): Audio: flac, 48000 Hz, 6.1, s32 (default)
Metadata:
title : 6.1 FLAC
Stream #0:2(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Metadata:
title : 5.1 AC3
Stream #0:3(fre): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Metadata:
title : 5.1 AC3
Stream #0:4(ger): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Metadata:
title : 5.1 AC3
Stream #0:5(fin): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
Metadata:
title : 2.0 AC3
Stream #0:6(kor): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Metadata:
title : 5.1 AC3
Stream #0:7(chi): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Metadata:
title : 5.1 AC3
Stream #0:8(chi): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s
Metadata:
title : 5.1 AC3
Stream #0:9(eng): Subtitle: ssa (default)
Metadata:
title : English
Stream #0:10(fre): Subtitle: ssa
Metadata:
title : French
Stream #0:11(ger): Subtitle: ssa
Metadata:
title : German
Stream #0:12(eng): Subtitle: ssa
Metadata:
title : Songs + Signs
Stream #0:13: Attachment: ttf
Metadata:
filename : MyriadPro-Regular.otf
mimetype : application/x-truetype-font
Stream #0:14: Attachment: ttf
Metadata:
filename : MyriadPro-SemiboldIt.otf
mimetype : application/x-truetype-font
Stream #0:15: Attachment: ttf
Metadata:
filename : Vesta-Bold.otf
mimetype : application/x-truetype-font
Stream #0:16: Attachment: ttf
Metadata:
filename : Vesta-Bold_2.otf
mimetype : application/x-truetype-font
Stream #0:17: Attachment: ttf
Metadata:
filename : AR CENA_0.TTF
mimetype : application/x-truetype-font
Stream #0:18: Attachment: ttf
Metadata:
filename : tahomabd.ttf
mimetype : application/x-truetype-font
Stream #0:19: Attachment: ttf
Metadata:
filename : palai.ttf
mimetype : application/x-truetype-font
Stream #0:20: Attachment: ttf
Metadata:
filename : pala.ttf
mimetype : application/x-truetype-font
如您所见，其中一个流是FLAC 6.1流。我想把它转换成AAC，我知道怎么做，基本上就是这样：
ffmpeg -i "input.mkv" -codec:v copy -codec:a aac -strict -2 -b:a 320k -f matroska "output.mkv"
但显然AAC不支持6.1音频：
...
[aac @ 03b26860] Unsupported number of channels: 7
Output #0, matroska, to 'd:\Movies\[Coalgirls]_Spirited_Away_(1920x1038_Blu-ray_FLAC)_[92372194].aac.mkv':
Stream #0:0(jpn): Video: h264, yuv420p10le, 1920x1038 [SAR 1:1 DAR 320:173], q=2-31, 23.98 fps, 90k tbn, 1k tbc (default)
Stream #0:1(jpn): Audio: aac, 0 channels, 128 kb/s (default)
Metadata:
encoder : Lavc55.67.100 aac
Stream #0:2(eng): Subtitle: ssa, 128 kb/s (default)
Metadata:
encoder : Lavc55.67.100 ssa
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (flac (native) -> aac (aac))
Stream #0:9 -> #0:2 (ssa (native) -> ssa (native))
Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height
没关系，所以我想将它缩混为5.1并编码为AAC。但我似乎无法弄清楚如何。有什么建议吗？
答案 0 :(得分：0)
最后我听说，ffmpeg的aac编码器被认为是实验性的。它通常被推荐为：
我不能保证你会支持6.1 in / 5.1 out，但是它有可能比ffmpeg的内置aac编码器更好。