[Mp4-tech] public AAC at 128kbps listening test open

[Hans-Juergen Bardenhagen]

Hi Jenn(y),
on 20.02.04, 00:28 local time (received 20.02.04, 12:18 GMT+1) you wrote:
> Glad to see this is happening. However, I am sorry (and hate) to say
> that the result may not have any value because it is comparing apples
> with oranges. The average bitrate for Ahead/Nero AACenc (a VBR codec)
> to encode these test samples is as high as 141 kb/s!!!!! However, CBR
> codecs like iTunes and Real are only at 128 kb/s for all these test
> samples.

The problem with Nero is that it does not allow a fine-tuning of its VBR  
mode like e.g. FAAC does or its predecessor PsyTEL could do with -qvbr.  
So the VBR preset closest to ~128 kbps had to be used, and this seems to  
be -internet (not -streaming like the online help suggests).
> Any experienced AAC developer will tell you that at this
> high bitrate 7-8 kb more will significantly improve the resulting
> sound quality. It would really be a surprise if iTunes or Real can
> beat Nero with such a lower bitrate. This is just not a test at 128
> kb/s as the title called. It is comparing samples encoded at 141 kb/s
> and at 128 kb/s. I think the winner is obvious without going thru the
> test...

The purpose of this second test was to compare AAC codecs at their best  
settings for approximately 128 kbps/stereo (not forced to CBR mode like  
the first one), and so you have to live with the differences in  
resulting VBR bitrates. But you would be partly correct if the results  
should not point out these differences and simply claim e.g. Nero to be  
the winner (which in my opinion is not so sure as you seem to think).
A bigger problem might be the lack of a low-quality anchor, so the  
differences and rankings between the competitors could be exaggerated  
again which would not give a "real life" perspective compared to MP3  
codecs for example. But all this is speculation and might come out  
completely different in the end.
ZZee ya, Hans-Jürgen