Nero AAC and mono

[pogo stick]

There are some strange issues with Nero AAC and mono encoding.
I made AAC from mono wav and it should be mono. But decoders are giving different infos:
3ivx D4 Audio Decoder, CoreAAC Decoder 1.0b9 (from Jan 11 2004 and Feb 5 2004) - mono
Nero Wave Editor, Nero ShowTime, Foobar2000 0.8.2 and CoreAAC Decoder 1.0b9 (from Apr 22 2004) - stereo
For encoding I used: Nero Wave Editor, Foobar2000, nencode. I tried HE and LC. All the same.
BeSweet don't work right with mono. It produces double slow output with double file size.
-soundtouch( -rate 100 ) helps. But does the quality suffer?

[Tuning]

I think foobar2000 with " Downmix to mono" (DSP settings) will work. :rolleyes:

[pogo stick]

But why downmix? It is already mono.

[Tuning]

Sorry, I havent understood the question clearly, but Ok now.
I was describing :o that any stereo / multichannel sound downmixed to mono and encoded to He_AAC would work fine in foobar.

btw, do you tried the above settings for mono files ? ( Just because of curiosity..:rolleyes: )

[SeeMoreDigital]

I must admit I've not had much success with mono Nero AAC-LC or HE streams!

I have no problem generating them, either from 2Ch WAV's or 6Ch AC3's. And mp4UI reports the finished stream as having just 1Ch.

My problem comes when I play them back. As they are slowed down to half speed...

I've not tried any other AAC codecs!


Cheers

[Stux]

Originally posted by pogo stick
There are some strange issues with Nero AAC and mono encoding.
I made AAC from mono wav and it should be mono. But decoders are giving different infos:
3ivx D4 Audio Decoder, CoreAAC Decoder 1.0b9 (from Jan 11 2004 and Feb 5 2004) - mono
Nero Wave Editor, Nero ShowTime, Foobar2000 0.8.2 and CoreAAC Decoder 1.0b9 (from Apr 22 2004) - stereo
For encoding I used: Nero Wave Editor, Foobar2000, nencode. I tried HE and LC. All the same.
BeSweet don't work right with mono. It produces double slow output with double file size.
-soundtouch( -rate 100 ) helps. But does the quality suffer?

Most likely the latest versions of Nero and FAAD2's AAC decoder have support for Parametric Stereo (PS) and are assuming all mono files are PS files and need to be upmixed to stereo.

(They do a similar thing with files < 24000hz needed to be frequency doubled)

[pogo stick]

Thanks for replies. :)
Originally posted by Tuning
btw, do you tried the above settings for mono files ? ( Just because of curiosity..:rolleyes: )
I didn't try it. I think encoding side is OK. And I didn't have much time lately.
Originally posted by SeeMoreDigital
My problem comes when I play them back. As they are slowed down to half speed...
And you must be encoding them with BeSweet?
Originally posted by Stux
Most likely the latest versions of Nero and FAAD2's AAC decoder have support for Parametric Stereo (PS) and are assuming all mono files are PS files and need to be upmixed to stereo.
So, there is no way to differ mono and parametric stereo on decoding?
And all decoders supporting PS will act this way with mono files?

[SeeMoreDigital]

Originally posted by pogo stick
And you must be encoding them with BeSweet? Nope!

I used Foobar2000, but it also happens with dBpowerAMP!


Cheers

[Stux]

Originally posted by pogo stick
So, there is no way to differ mono and parametric stereo on decoding?


I didn't say that ;)


And all decoders supporting PS will act this way with mono files?

*if* 3ivx were to add support for PS we would probably only output stereo for true PS files, just like we only do samplerate doubling for true SBR files