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Topic: HE-AAC channel order (Read 3841 times) previous topic - next topic
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HE-AAC channel order

I´ve been having issues compressing with HE-AAC, regarding the channel order for the output file
and the software that outputted it.
I create the surround mix with Audition, then export it to 6-ch interleaved with the Multichannel
encoder. But FAAC and AACEnc32 don´t seem to be able to open it while Nero Digital 7 Encoder does
without a problem, wich makes me wonder what kind of header is Audition outputting in the file.
Minor glitch, I just open it as RAW PCM with Soft Encode, and save it as 6-ch with the proper order
for .WAVs (L-R-C-LFE-SL-SR). This file IS accepted by FAAC and AACEnc32.
Anyway...
Once the file is "ready" to be encoded, the channels are all messed up: the Left channel is comming
out of the center, the lfe out of the sr, and the center out of my armpit... a disaster, sort of speaking.
The 1rst ch in the .wav (L) becomes the 3rd ch in the .aac file (and so on...).
2nd --> 1rst
3rd --> 2nd
4th --> 5th
5th --> 6th
6th --> 4th

Then:
L --> C
R --> L
C --> R
LFE --> SL
SL --> SR
SR --> LFE

Is this the correct order for output for HE-AAC: C-L-R-LFE-SL-SR? AC3, DTS, OGG, and
AAC-LC/MAIN/LTP play in the proper order.
This forces me to re-order the channels in Soft Encode as I said before. Once i do, the order
plays fine. EXCEPT.... when I use Nero Digital, wich completely changes the channel order comparing
with AACENC32. For Nero Digital, the channel order in the .wav must be R-C-L-SR-LFE-SL (from Soft
Encode).
Any thougts, comments?
"Screw u guys, I´m going home."

HE-AAC channel order

Reply #1
ac3 (3/2)  - L, C, R, SL, SR
vorbis 5.1 - L, C, R, SL, SR, LFE
wav 5.1     - L, R, C, LFE, SL, SR
aac 5.1     - C, L, R, SL, SR, LFE

nero7 should accept correct 5.1 wavs now afaik
I know, that I know nothing (Socrates)

 

HE-AAC channel order

Reply #2
Yeah, no, i know the order the different formats use, but the HE-AAC compression is remapping every channel and does it in different mappings ofr the same codec in different apps (say Nero Digital on one hand and AACENC32 in the other, wich doesn´t make sense since AACENC32 is a frontend for the Nero DLLs).

Quote
nero7 should accept correct 5.1 wavs now afaik

No, it does remapping in different order, but still incorrect, as I stated before
Quote
when I use Nero Digital, wich completely changes the channel order comparing
with AACENC32. For Nero Digital, the channel order in the .wav must be R-C-L-SR-LFE-SL (from Soft
Encode).


I´m decoding with CoreAAC, FFDShow and Nero Showtime and they all play the same altered channel order.

Quote
aac 5.1 - C, L, R, SL, SR, LFE

The problem is not that the channel order is different for the aac, but that the aac channel order is not mantained as it should, so with a proper-order 5.1 wav, i don´t get a proper-order HE-AAC. But I do get a proper-order AAC LC/MAIN/LTP, or AC3, DTS or OGG.
"Screw u guys, I´m going home."

 
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