Audacity Forum

Hello, I've post my problem on the french's forum but i've received any answers. So sorry for my english.
So, this is my problem : i can not export my 8 track .wav to a 7.1 track, in my case this is aac (m4a). When i choose this codec i pick 8 channels and when the process begin it stop itself 2 seconds later as it is finish and i get a 0ko m4a files. I' ve tried to export in others codecs like .flac ou .ogg but it's not very decisive. So if anybody has an answer, i will be very happy to thanks him.

Can you please state what operating system you are using. See the pink panel above.

I am afraid I don't have any easy answer to this.

I too can only produce a zero bytes 8-channel file using Audacity and FFmpeg 0.5 or 0.6.2 on Windows 7 (or a later FFmpeg on Ubuntu 13.04). Audacity doesn't encode the file because the libfaac (AAC) encoder FFmpeg is built with seems to have a maximum 6-channel limit. It exports a 5.1 file but it's of poor quality.

I tried a recent build of FFmpeg I happened to have on Windows using Audacity's command-line encoder but that FFmpeg is built with libvo-aacenc and that can only cope with mono or stereo export apparently.

Unfortunately iTunes doesn't seem to accept 8-channel WAV or AIFF, so I cannot try converting to AAC there.

The command-line NeroAAC encoder produces only seven channels and qtaacenc (another command-line AAC encoder) produces seven channels with a silent eighth channel. I don't understand that because although AAC encoders have previously had trouble with 7.1, as far as I can see from searching they should produce 7.1 nowadays.

You could try building FFmpeg with their native AAC encoder if you like but I have no idea if that would help.

8-channel OGG should definitely be exported correctly from Audacity. What do you mean by it is not decisive?


Gale

Thank you very much to answered me. I'm like you on Windows 7 64bits. I've ever tried to export on OGG but I don't think so it's compatible with mkv's containers. So I also saw that We could export on flac 7.1 so i will probably picked it. I've also a more technical question : I'm using a optical cable to join my computer to my speakers could 7.1 tracks "travel" it because i've heard about a limit of flow (bitrate) and frequence of the track and if i decrease both could the track "travel" (get through) it ?

DanielJackson39 wrote:I've ever tried to export on OGG but I don't think so it's compatible with mkv's containers.

Could it be an issue with the audio or video software you are using to write the Matroska container?

According to http://www.matroska.org/technical/guides/faq/index.html Matroska "can support all known audio and video compression formats by design."

If you are distributing files, MKV files containing OGG audio may not play on everyone's computer without extra plug-ins or codecs.

DanielJackson39 wrote:We could export on flac 7.1 so i will probably picked it.

OK but it will be much larger than OGG.

DanielJackson39 wrote:I'm using a optical cable to join my computer to my speakers could 7.1 tracks "travel" it because i've heard about a limit of flow (bitrate) and frequence of the track and if i decrease both could the track "travel" (get through) it ?

S/PDIF should support 5.1 or 7.1 if the format is compressed (like OGG or AAC). FLAC 5.1 or 7.1 would seem to be too much for S/PDIF based on the 6144 kbp/s bandwidth quoted on the Wiki page.


Gale