7.1 AAC wrong channel mapping

[GoogleCodeExporter]

Looking at the specification from
http://developer.apple.com/library/mac/#documentation/MusicAudio/Reference/CoreA
udioDataTypesRef/Reference/reference.html#//apple_ref/doc/c_ref/kAudioChannelLay
outTag_AAC_7_1
the channels are decoded correctly for 7.1 aac files but it looks like they're 
mapped/mixed in the wrong way resulting in the following output behaviour:
left -> left + center
center -> center
right -> right + center
right surround -> right
left surround -> left
right rear surround -> right rear surround
left rear surround -> left rear surround
lfe -> lfe

As a side note VLC seems to map these channels correctly but that's the only 
decoder / player which was able to play 7.1 aac files correctly so far.

If you need a test sample refer to the dropbox link here: 
http://forum.xbmc.org/showthread.php?tid=147170&pid=1259665#pid1259665

If you need anything I'll be willing to help as far as I can.

Original issue reported on code.google.com by KayAcker...@gmx.de on 18 Dec 2012 at 4:49

[GoogleCodeExporter]

Thanks for the report, this should be fixed in the next version.

Original comment by h.lepp...@gmail.com on 18 Dec 2012 at 5:08

• Changed state: Fixed
• Added labels: Component-ffmpeg, Filter-Audio, Usability

[GoogleCodeExporter]

Actually, re-checking the Spec from Apple, it did properly handle it, however 
not many audio systems actually know how to deal with "Left Center" and "Right 
Center" channels, and usually output them in the wrong place.

According to the Spec, "Left Center" is the usual "Left" channel (left of the 
center), and the "Left" channel is then more of a side/left surround channel.

I changed the mapping to a more standard layout, even if that is technically 
not 100% spec compliant.

Original comment by h.lepp...@gmail.com on 18 Dec 2012 at 5:21

[GoogleCodeExporter]

Thought so. I guess that's what the guys from VLC did, too. In the worst case 
just offer a switch, but since at least none of my systems did honor this front 
left/right center layout correctly I guess it's save to simply change the 
mapping as you said.
Thanks for your work and fast reply to this issue!

Original comment by KayAcker...@gmx.de on 18 Dec 2012 at 6:08