Encoding AAC on Linux

[rondari]

Hi all.

I've given up on faac ... I'm trying to encode a 4 channel wav file into a quadraphonic AAC file (5.1 without the centre and LFE). This line doesn't work (it creates a 2 channel AAC file which sounds Ok for the first 5 sec then turns to noise):

faac -q 100 -c 44100 -P -B 16 -R 44100 -C 4 -o warbirds.m4a warbirds.wav

So I downloaded and tried NeroAacEnc.... but it does a Segmentation Fault when I try to encode the same 4 channel wav file:

neroAacEnc -if warbirds.wav -of warbirds.ma4

it all feels like really flaky software ... does anyone have any suggestions/hints?

[menno]

Hi all.

So I downloaded and tried NeroAacEnc.... but it does a Segmentation Fault when I try to encode the same 4 channel wav file:

neroAacEnc -if warbirds.wav -of warbirds.ma4

it all feels like really flaky software ... does anyone have any suggestions/hints?

On 4 channels it should return an error as it is not supported. I will check what is going on.

EDIT: doesn't crash here with a 4ch file, just shows an error

[rondari]

On 4 channels it should return an error as it is not supported.

really? that's not documented anywhere .. either on the site nor in the downloaded packages.

I'm wondering why only 2 channels are supported? Is it an extra layer of complexity to have 4 channels?

[menno]

really? that's not documented anywhere .. either on the site nor in the downloaded packages.

I'm wondering why only 2 channels are supported? Is it an extra layer of complexity to have 4 channels?

1, 2, 2.1 and 5.1 are supported right now, 7.1 will be supported in the next version.
Yes it adds extra complexity, if you want to do it right in the psychoacoustic sense. Also we have to make some special changes in some parts to support different configurations. I'm considering to add all "default" AAC channel configurations.

Your case is extra special as it is not a "normal" configuration for AAC. Normal 4 channel configuration for AAC is L/C/R + LFE.

[rondari]

Your case is extra special as it is not a "normal" configuration for AAC. Normal 4 channel configuration for AAC is L/C/R + LFE.

ah OK .. I understand, I thought you were saying that it couldn't do multi-channel at all.

I think the Apple quicktime encoder allows what they clal 'quadraphonic'.

In anycase, If I put in an empty centre channel, and an empty LFE, would that create a significantly larger file? (or would the codec cope well with it?)

[menno]

In anycase, If I put in an empty centre channel, and an empty LFE, would that create a significantly larger file? (or would the codec cope well with it?)

That should work quite well. You do have some small overhead of course, and you probably shouldn't use CBR ;)