Aac : differences between 100 VBR and others

[ramirez]

Hi, I was wondering about the main differences between encoding a Wave using 100 VBR AAC quality and 500 VBR.....Space taked is not the same,of course,but what does these setting mean exactly??
They are using a 32/320 kbit range like common VBR MP3 or it's something completely different?
What should be better for quality?

[Spoon]

Re: Aac : differences between 100 VBR and others

A higher value for VBR is the quality criteria, and will result in higher bitrates being used.

[xoas]

Re: Aac : differences between 100 VBR and others

Actual bitrates for quality settings will vary somewhat depending on the music being encoded. A sample of tracks converted to AAC at the 500 quality setting ended up (per their tags) showing vbr's of 270 kbs to 310 kbs. The same tracks encoded at the 100 quality setting ended up showing vbr's of roughly 120 kbs to 145 kbs.

Best wishes,
Bill

[ramirez]

Re: Aac : differences between 100 VBR and others

Thank you very much!
But I have another one question : there's a range for AAC like that for VBR MP3 (using db power I usually set a range from 32 to 320 Kbit)
In other words.........the main difference between the 500/100 VBR AAC preset is the highest value of the aac encoding range of something else?
It's something like an ABR MP3 (with a maximum bitrate value chosen from the beginning) ?

[xoas]

Re: Aac : differences between 100 VBR and others

In other words.........the main difference between the 500/100 VBR AAC preset is the highest value of the aac encoding range of something else

The difference affects the whole range, not just the highest value. You can test this by converting tracks to both quality settings and then watching the bitrates as the trtacks play. With two tracks I tried this on, at the 500 quality vbr AAC setting the ranges were 230 kbs to 360 kbs and 260 kbs to 353 kbs (the first track had a single isolated dip to 15 kbs which was far lower than the corresponding dip at the 100 quality setting). At the 100 quality vbr AAC setting the ranges were 93 to 180 kbs and 120 to 168 kbs.

While the quality settings may have relatively fixed maximum and minimum bitrates attached to them I have not yet seen this. For further details on AAC and the FAAC codec (used by dMC and dAP) see:

http://www.audiocoding.com/modules/wiki/?page=AAC&PHPSESSID=2cc20c69e87c5dbb5b6595ea84a1761c

http://wiki.hydrogenaudio.org/index.php?title=AAC and

http://www.audiocoding.com/modules/wiki/?page=FAAC

Best wishes,
Bill

[ramirez]

Re: Aac : differences between 100 VBR and others

The links you posted were very useful,so let me thank you again!
If I'm right, VBR AAC in simply different from VBR MP3, although I still don't understand why it doesn't use a slower bitrate sometimes...well, maybe there' s a reason....or I hope so....
The Nero encoder works like FAAC or the preset are completely different?