[AAC] HE codec bitrate up to 128kbit ?!

[Phunction]

I was test-encoding a movie with the new Nero Digital AVC codec, with AAC HE 5.1. Problem was, the guide on Doom9 describes a bitrate of 256kbit, but I can only select 96 or 128kbit. Is this per stereo channel or 6 channel total ? And if the latter, why can't I select a higher bitrate ?

http://users.edpnet.be/phunc/aac.jpg

This was all done with the latest NeroVision Express, using Recode 2 BTW.

[Kurtnoise]

Hi,

IIRC, audio bitrate depends of the Video profiles (Portable, Standard, Cinema, HDTV).

[bond]

try enabling the "unrestriced profile"

[Phunction]

I thought Cinema AVC would be reasonably high quality :D
But that is the strange part, the audio sounds high quality, but 128kbit isn't something I would relate to high quality. I'll try, thank you !

Can someone answer me where the 128kbit stands for ? Each stereo channel or the combined 6 channels ? Because I find it hard to believe good quality 6 channel sound can be compressed to 128kbit...

Edit: Setting it to "Maximum Definition - AVC" did the trick, up to 448kbit now !! Thank you !

[Kurtnoise]

Originally posted by Phunction
Can someone answer me where the 128kbit stands for ? Each stereo channel or the combined 6 channels ? Because I find it hard to believe good quality 6 channel sound can be compressed to 128kbit...

It stands for 6 channels...;) A bitrate at 128 kbps for multichannel HE-AAC corresponds to ~40/50 kbps for Stereo HE-AAC.

[bond]

Originally posted by Phunction
Edit: Setting it to "Maximum Definition - AVC" did the trick, up to 448kbit now !!good to know that this was the reason :)

but if 128kbps 5.1 sounds good, why not keep it ;)

[Phunction]

Well indeed ! I just found it odd this sounded so good for a bitrate this low. I'll listen to it some more and compare it to the DVD source, I'll place my findings here.

[SeeMoreDigital]

Originally posted by Phunction
Well indeed ! I just found it odd this sounded so good for a bitrate this low. I'll listen to it some more and compare it to the DVD source, I'll place my findings here. Remember, the 128kbps setting is a "Variable Bit-Rate" setting, not "Constant".

So during playback, the bitrate can reach quite a bit higher than 128Kbps!


Cheers

[Phunction]

I listened to the track some more and it sounds really good. Although I'd probably pick a higher bitrate the next time, because I noticed some things sound a bit low quality. Thanks for the advice !!