How to encode ac3 2.1 to aac 2.1 correctly

[lennox]

I've tried 2 ways to encode:
1. Using megui, just put ac3 as is - produce 2 channel aac (L,R)
2. Using nicaudio.dll and avs script through megui - result is 3 channel aac - L,R, Center.
How to get aac 2.1 with LFE?

[shon3i]

Did you try with both CT and Nero encoder's ?? anyway somewhere on forum some of nero dev's says that there is no such aac decoder which can propertly decode 2.1 stream.

[tebasuna51]

I've tried 2 ways to encode:
1. Using megui, just put ac3 as is - produce 2 channel aac (L,R)
2. Using nicaudio.dll and avs script through megui - result is 3 channel aac - L,R, Center.
How to get aac 2.1 with LFE?

Is a real 2.1 or is only a joke?

I never see that. Can you put a sample?

BTW, you can safely downmix to 2.0 and when play in systems with subwoofer the low frequencies are automatically redirected.

[lennox]

shon3i, no I've tried Nero encoder only.
tebasuna51, ok downmix is the solution, but what aac specification says? It's impossible at all?
Here is the sample (http://rapidshare.de/files/41295247/2.1.ac3.html)

[tebasuna51]

... but what aac specification says? It's impossible at all?

Maybe in mp4 container but in .aac with ADTS header is not possible. Only exist a 3 bits field to store the numchannels, nothing about the present channels.