AAC 7.1 possible?

Windows 8.1; Audacity 2.1.1 from .exe

I understand you can’t export some multichannel AAC files unless exporting via an “external program”. I tried following the steps that I found elsewhere in this forum using the command:

ffmpeg -i - -strict experimental -c:a aac -q:a 10 “%f”

But it pops up with an error box. I am trying to output 8 channels. Is this not possible? Or am I missing something?

Here is the error message

ffmpeg -i - -strict experimental -c:a aac -q:a 10 “C:\Video\file”

ffmpeg version 2.2.2 Copyright (c) 2000-2014 the FFmpeg developers
built on May 22 2014 19:56:44 with gcc 4.8.2 (GCC)
configuration: --disable-static --enable-shared --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. 66.100 / 52. 66.100
libavcodec 55. 52.102 / 55. 52.102
libavformat 55. 33.100 / 55. 33.100
libavdevice 55. 10.100 / 55. 10.100
libavfilter 4. 2.100 / 4. 2.100
libswscale 2. 5.102 / 2. 5.102
libswresample 0. 18.100 / 0. 18.100
libpostproc 52. 3.100 / 52. 3.100
Guessed Channel Layout for Input Stream #0.0 : 7.1
Input #0, wav, from ‘pipe:’:
Duration: N/A, bitrate: 6144 kb/s
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 7.1, s16, 6144 kb/s
[NULL @ 01cf40e0] Unable to find a suitable output format for ‘C:\Video\file’
C:\Video\file: Invalid argument
Conversion failed!

Does FFMpeg claim it can export AAC 7.1?

I note that you didn’t say you installed FFMpeg. It’s an external plugin program. Did you?



Yes, I have audacity linked to ffmpeg-2.2.2. I have typically (if not exclusively) used audacity to output ac3, ogg and flac all in more than 2 channels, but I can’t get the aac to work. I downloaded the newest version of ffmpeg (2.8.1) off their website, but I can’t seem to find the “avformat-55” file that audacity wants to link to to try it.

Your syntax:

ffmpeg -i - -strict experimental -c:a aac -q:a 10 "C:\Video\file"

will not work in Audacity. That is why it says it find a suitable output format for ‘C:\Video\file’. Use the syntax you quoted “as is”:

ffmpeg -i - -strict experimental -c:a aac -q:a 10 "%f"

then in the export dialogue, switch to the folder you want to export to and specify the file name and extension in the “File name:” box.

The native AAC encoder in FFmpeg 2.2.2 is limited to 6 channels output, so Audacity export will also fail.

The native AAC encoder in the latest git FFmpeg does support 8 channels output, but FFmpeg don’t offer Windows binaries of FFmpeg (ffmpeg.exe) themselves, which is what you need.

You can download the latest git FFmpeg from http://ffmpeg.zeranoe.com/builds/. You can download the “shared” or “static” build but if you download the shared build, do not delete any of the DLL files that sit alongside ffmpeg.exe or ffmpeg won’t work.

Then point the Audacity command to git FFmpeg, for example:

"C:\Program Files (x86)\ffmpeg-20151022-git-a7c5005-win32-static\bin\ffmpeg.exe" -i - -strict experimental -c:a aac -q:a 10 "%f"