Does AAC/m4a in VBR mode have an upper bit-rate limit for each Quality setting, in the same way as LAME MP3 VBR has an upper limit of 320kbps?

Specifically I'm interested in the .55/.6/.65 sort of range, or rather, what's the highest Quality setting which will never exceed 320kbps?

Anyone know if there's a chart of this anywhere?

Thanks.

There is chart on this thread http://www.hydrogenaudio.org/forums/index....showtopic=44310

I believe that the Nero AAC encoder has a 320kbps upper limit at the settings that you want. I think that changes once you get up to 0.7 and above but I am not 100% sure. I tried looking around on the internet and no one had any real answers, only guesses. I think you will be safe though. I can tell you that I have encoded metal songs at -q0.65 in the past and they played just fine on all my mpeg-4 AAC devices which included my Zune, 5G 60GB iPod, 16GB iPod touch, and Kenwood car CD deck via a USB storage device. The overall average bitrate for those songs was around 265kbps as well.

As long as I know the limit is: -q 1.0 = 400 kbps (could be with a CD rip)
Try the q factor you want and then check the file properties (under Windows).

Thanks for the info!

Well, as far as I know, neither Windows Vista nor Windows XP have the ability to display the bitrate of mpeg-4 AAC files without using some type of 3rd party application such as dBpowerAMP. Even then, the overall average bitrate isn't an indication of what each frame is encoded at. A file with an overall average bitrate of 256kbps can still theoretically have some frames encoded at 400kbps. It shouldn't matter if you are looking for iPod compatibility as I have had no issues playing AAC files with a bitrate above 320kbps. You might have issues on other devices though.