high bitrate AAC - HE or LC?

[pogo stick]

I just found out that there is branch in system register (don't know if I wrote it right in English) that is keeping settings for AAC encoding using BeSweet with Nero's dlls.

[HKEY_CURRENT_USER\Software\Smeshka\Nencode\Nero Digital Audio (HE-AAC)]

"DefBitRate"
in decimal numbers it = constant bitrate

"DefVbrMode"
variable bitrate
0 - (constant bitrate)
3 - tape
4 - radio
5 - intrnet
6 - streaming
7 - normal
8 - etreme
9 - audiophile
10 - transcoding

"DefCodecQuality"
0 - fast
1 - high

"DefAacProfile"
4 - LC
5 - HE

"DefUsePNS" (by the way, what PNS is?)
"DefHintForStreaming"
"DefDownmix"
"DefMuxIntoVideo"
"DefExportAAC"
0 - disable
1 - enable

"DefOptimize" - what is it? it is not in the Nero configuration window.

By setting it manually it is possible to use high bitrates in HE (even audiophile and transcoding), which is not possible with -config in -bsn( ) (it switches on LC).
Why high bitrate modes in HE are disabled in configuration?
Are LC better then HE at higher bitrates?
Or it doesn't make quality difference in HE?
Are there any tests between HE and LC?
And one more thing.
When using -config in -bsn( ) AAC coming out resampled to 44100 Hz.
And the same command without -config is at 48000 Hz.
Is it good to resample?

[echo]

I bet that even if you change that value manually and use a high bitrate LC will get used anyway. AFAIK HE works only on low bitrates.

regards
echo

[echo]

Originally posted by pogo stick
When using -config in -bsn( ) AAC coming out resampled to 44100 Hz.
And the same command without -config is at 48000 Hz.
Is it good to resample?
In short, yes. Nero AAC is tuned for different sampling frequencies according to the bitrate used AFAIK. I remember there was a thread about that a while ago...

regards
echo

[bond]

Originally posted by pogo stick
Why high bitrate modes in HE are disabled in configuration?
Are LC better then HE at higher bitrates?
Or it doesn't make quality difference in HE?
Are there any tests between HE and LC?he-aac is an extension for low bitrates, it doesnt make sense to use it at high bitrates
as you might know besweet graps the encoder from ahead, and i know that ahead is doing lots of listening tests to find out what settings suit best and if he-aac would make sense at high bitrates they surely would have allowed it by default

so plz no private hacks making things work, which actually shouldnt work for good reasons!

[pogo stick]

Originally posted by echo
I bet that even if you change that value manually and use a high bitrate LC will get used anyway. AFAIK HE works only on low bitrates.

regards
echo
I made this test.
Configurated through registry:

VbrMode - transcoding
AacProfile - HE
CodecQuality - high
ExportAAC - enable
everyhing else disable

"d:\Programs\BeSweet\BeSweet.exe" -core( -input "G:\test\1.ac3" -output "G:\test\1.mp4" ) -azid( -c normal --maximize ) -bsn( -6chnew )

sample time: 22:16

AC3 was:
(foobar2000 info)
samplerate = 48000
channels = 6
bitrate = 384
codec = ATSC A/52
----------
64149504 samples @ 48000Hz
File size: 64 149 504 bytes

MP4 went out:
(foobar2000 info)
bitrate = 357
samplerate = 48000
channels = 6
aac_profile = HE AAC
codec = AAC
tool = Nero AAC Codec 2.6.2.0
----------
64149504 samples @ 48000Hz
File size: 59 803 406 bytes

(CoreAAC info)
AAC+SBR
24000 -> 48000
6 -> 6

Don't get me wrong. I am not trying to make private hacks. I even don't have enough knowledge for that.
I was little bit surprised that it worked and decided to ask (as I always do if I don't understand something).
Anyway even if it works right then it doesn't make sense to encode AAC at this bitrate from AC3.
Filesizes are almost the same. Maybe for other proposes.
And do anyone know what "DefOptimize" and PNS is?

[Teegedeck]

I expect some radical improvements for an upcoming (the next?) Nero version. It will include newly tuned settings, among other stuff HE AAC as an option to be used at higher bitrates. Not as a bitrate-saver but kind of as an extension of quality for the upper frequencies - where the HE part of an encoding should give extra quality but should not be missed if for example an iPod cannot decode it. PNS will also be activated by default in those bitrate-ranges where it's an overall improvement. As will be parametric stereo (encoding mono and storing additional stereo information). Just wait for that listening-test based and tuned release. You cannot tune the encoder well enough yourself by editing registry entries.

Also I'm looking forward to 'spatial' encoding which should lower the bitrate for 5.1 encodings. (Though the claim of 48 kbps by the developer seems a bit drastic.)

I'm only worried about plans to give up the 'profiles' in favour of a 'quality slider'.

(Infos from diverse threads at HA, too lazy to search their database again. :p )

[bond]

Originally posted by Teegedeck
It will include newly tuned settings, among other stuff HE AAC as an option to be used at higher bitrates. Not as a bitrate-saver but kind of as an extension of quality for the upper frequencies - where the HE part of an encoding should give extra quality but should not be missed if for example an iPod cannot decode it.hum interesting, i think till now i only read ivan dimkovic always saying that he-aac should not be used higher than 96kbps

edit: found it, its called "downsampled sbr":
Originally posted by Ivan Dimkovic
No no, it is a special SBR mode called "Downsampled SBR" that will be used for 72-128 Kb/s AAC - basically the SBR codec operates at 88.2 kHz, istead of 44.1 kHz - improving pre-echo performance for the overal combination, and allowing usage of the SBR at very high frequencies

For example - AAC 0 - 16 kHz, SBR 16-22.05 kHz

But it seems it is not very good at very low bit rates :)I'm only worried about plans to give up the 'profiles' in favour of a 'quality slider'.hm i am not so worried about that, in fact this also worked pretty well already with other encoders, like vorbis

[P0l1m0rph1c]

Originally posted by Teegedeck
I expect some radical improvements for an upcoming (the next?) Nero version. It will include newly tuned settings, among other stuff HE AAC as an option to be used at higher bitrates. Not as a bitrate-saver but kind of as an extension of quality for the upper frequencies - where the HE part of an encoding should give extra quality but should not be missed if for example an iPod cannot decode it. PNS will also be activated by default in those bitrate-ranges where it's an overall improvement. As will be parametric stereo (encoding mono and storing additional stereo information).

I'm only worried about plans to give up the 'profiles' in favour of a 'quality slider'.


That's actually DSBR (Downsampled SBR). It takes the best of two worlds: it encodes LC AAC at high bitrates, and also the extra high frequencies with SBR. So, either way, you've got very good quality, even on devices that don't know SBR.

Yeah, the slider thing also worries me too. I hope we'll have some kind of choice...

[bond]

Originally posted by Teegedeck
Thank to bond for reminding me how lossy human memory is. I could have sworn to have read about that new use for SBR but couldn't find proof,now. Well, actually my memory seems to substitute fact by fiction when necessary and in that way works very efficiently.well in my case its even worse, cause i didnt know "downsampled sbr" anymore altough the quote from ivan dimkovic was actually an explanation he gave to me on HA about dsbr :D