First post. Hi everyone
I have come to the conclusion that AAC encoding is better then MP3 for some of the following reasons...

1) Sample frequencies from 8 Hz to 96 kHz (official MP3: 16 Hz to 48 kHz)
2) Up to 48 channels
3) Higher efficiency and simpler filterbank (hybrid → pure MDCT)
4) Higher coding efficiency for stationary signals (blocksize: 576 → 1024 samples)
5) Higher coding efficiency for transient signals (blocksize: 192 → 128 samples)
6) Much better handling of frequencies above 16 kHz
7) More flexible joint stereo (separate for every scale band)

But you guys already knew that. Getting to my question... When I am trying to encode to AAC using the iTunes encoder, I use VBR settings, but my ouput is NOT VBR, and not even ABR. My songs remain at a constant bitrate throughout, as reported by iTunes, WMP, and even Foobar2000. This is very irritating to say the least. Back in the old days when I would rip to LAME mp3 using CDex, I would have control of VBR settings (32 kbps to 320 kbps Joint Stereo I found to be the best) and I would also be able to normalize the output so my library would have realitively uniform volume throughout.

My question to you AAC gurus out there... is there any way to make Nero AAC LC encode with true variable bitrates? And is there any way to get info from CDDB or some sort of database for tagging the AAC files (.m4a) properly so that I don't have to maunally edit them in iTunes? And finally, is there are good app out there that can "normalize" the encoding so that all of my AAC files come out with similar volume.

My current set up is crappy. I am using Nero AAC encoding through the command line tool called "NAACEnc.exe" (witch comes with some nice presets, but even those VBR settings aren't reading as VBR) I use a batch file to encode all of my uncompressed .wav files into .m4a Nero AAC with the NAACEnc tool. This leaves me with some excellent quality songs, but no tags on my files, and no normalizing. Is there anybody who can point me in the direction of a superior front-end to Nero AAC that has all of the features I am looking for? I use Nero because it has gapless support, unlike iTunes.

In conclusion I am looking for...
1) AAC true VBR encoding
2) proper tagging from a CD database lookup
3) normalizing dB for a "standard" volume on my encodes

Sadly I could easily do all of this with CDex and LAME.

Your iTunes encoded AAC files should be VBR, check your sttings. Foobar should show bitrate fluctuations during playback, also keep in mind that VBR is not available for every bitrate option from the drop-down menu in iTunes.

Hi skelly, thanks for your quick reply. I've tried a couple of different settings with iTunes VBR and didn't end up with Foobar2000 reporting anything close to VBR. I am using iTunes 6. I tried 192 kbps VBR and 256 kbps VBR and didn't get it to come out with a variable bitrate at all. By any chance do you know which settings definately output VBR? Also I would prefer a Nero solution, as it supports gapless and IMHO is a better encoder. (The old saying: You get what you pay for)

Nero AAC is true VBR, like LAME, it will use the bitrate which suits the file and the quality you've chosen... Itunes CBR is actually ABR, and iTunes VBR (I don't know how Devs of Apple define CBR & VBR).You can't get a true CBR encoding with iTunes



If you don't like to use command lines, use a GUI app, try dbpoweramp Music Converter with nero aac plugin. Its free!!
http://www.dbpoweramp.com/dmc.htm
http://www.dbpoweramp.com/codec-central-mp4.htm

Besides Nero AAC plugin, download " m4a, mp4 and Apple Lossless Codec" to support tagging and encoding

You don't have to "normlize"" before encoding, just apply replaygain with foobar2000 after encoding....Dbpoweramp supports normalize before encoding, not free though

Apparenlty 320, 224 and 112kbps aren't available as VBR, but 128, 160, 192, 256 are. Are you shure you checked the "Use Variable Bit Rate Encoding" box?, either way those AAC files should show bitrate fluctuations, because CBR AAC works like ABR.

Thanks for your reply kotrtim. I could handle a command line solution if that is a viable option. Thanks for your help, I'm gonna give your suggestion with dbpoweramp a shot.

I am 100% positive I have the VBR option checked in iTunes, and the AAC files didn't show any fluxuation in iTunes or in Foobar2000. Maybe I am missing something, because from what I understand, AAC should at least report ABR playback.

Have you turned off the VBR display (bitrate updater) in foobar2000?
Set it to 16 frames, then you should see it fluctuates, if not you can just play it with Winamp

Coz even iTunes CBR fluctuates

Ok you're definatly right! Sorry about the confusion, I thought I had this option enabled, but turns out I didn't. It's fluxuating like mad now thanks for the help. What makes it really confusing is that if you click "show info" in iTunes 6, it doesn't show it as being variable bitrate, whereas with mp3s it clearly marks is as such. I suppose this functionality will come with a later version...

As a followup, does anybody have an opinion as to which preset they recommend using in Nero AAC? I am currently using -audiophile preset, but I wonder if this is overkill, as AAC is lossy anyway, and I can't tell a difference between this and the one lower -extreme preset. I also use the fast quality option (-fq) as opposed to the high quality option (-hq) as I've heard that you actually get better quality with fast. Is this still the case for the very latest version of Nero AAC Codec (4.2.1.0) with Nero 7?

Since the latest Nero AAC Codec was only just released, I don't believe there have been any public listening tests done on it.

However, one may be in the works:
http://www.hydrogenaudio.org/forums/index....showtopic=38516
This also has a bearing on the whole bitrate reporting thing.

Just to add, iTunes won't display any VBR mpeg-4 AAC bitrate as actually being VBR. For example, I can rip a song to -V 2 --vbr-new with Lame 3.97b1 and it will come out to around 235kbps VBR. For the bitrate, iTunes will display 235kbps (VBR). For mpeg-4 AAC songs, it will just display the avergae bitrate without the extra (VBR). I think that Apple hasn't ironed out the proper VBR mpeg-4 AAC display bitrate in iTunes.

On with what bitrate to choose with the Nero mpeg-4 AAC (or Nero AAC) encoder. You would be better off choosing a lower bitrate than the audiophile setting, this is kinda pointless for the AAC file format. For me, the point of AAC is to have a song at a lower bitrate than mp3. If you go with the audiophile setting, you might as well use -V 2 or -V 0 with Lame 3.97b1. Only you can decide which bitrate (or setting) is right for you. I have personally found the VBR stereo streaming setting to be quite good. For the metal tracks that I tested (Dimmu Borgir - Leapers Umong Us and Judas Priest - Judas Rising), the bitrate would come out to around 160kbps VBR. For the transparent setting, the bitrate would come out to arond 192kbps VBR.

Still, it is all up to you and your equipment. I used iPod ABX for my tests as I normally listen to my music on my iPod.

What's Nero's aac default setting for Nero7
is it fast or high?

I think you should just use the preset offered by Nero devs. The default is still "high" for Nero 6.6.... don't know about 7
Unless the fast setting offers significant speed advantage over High, if this is not the case, use default setting. Coz there is no serious ABX test done on comparing "fast" and "high" for different genres, I think Nero devs set "high" as default for some reasons......

You can also use QuickTime to see the average bitrate for VBR AACs

Note that in Nero 7 the workings of "fast" and "high" are significantly changed. The recommendations to use "fast" mode are certainly outdated now.

You're right. I just did my own test and I cannot tell the difference between -audiophile and -normal on my iPod, and that is what counts for me. I had the midset that more bitrate will get you better quality, but with AAC being so good already, it seems transparent to me at normal settings, which will end up saving me a TON of space on my iPod, because I used to rip mp3 256 Stereo CBR.

I know AAC is still lossy, but it is much much much richer then LAME mp3 at equivilant bitrates. IMHO.



While I don't have anything to back this up, I believe you're right. The "fast" setting no longer appears to be the best for Nero 7. I tried a blind sound test encoding with high quailty mode, and I think it sounded a little better.

Could you explain what do you mean by "richer"? And at what bitrate did you tried? On latest collective listening test, AAC was slightly better than MP3 at ~130 kbps. The difference is even more subtle with higher bitrate. The "much much much richer" only applies at very low bitrate, and only with High Efficiency AAC profile. But you're talking about LC profile and iPod support, and I really wonder in which conditions (bitrate, encoder, setting, samples...) you found AAC to be that better than MP3.

With Blade? Plugger? Shine? Or is Randall311 a true Golden Ear able to hear many difference between differnt good CBR encoders at 256 kbps?

You've forgotten one very fomous codec that comes with audio grabber

x3enc, tompg.....Actually I do believe that Nero could be richer than xing, as xing
320 kbps cuts off at 16 kHz and he can hear the additional bandwidth stored by AAC, or maybe the mp3 codec he used has serious pre-echo problems?



iTunes AAC at lower bitrates has improved a lot, 64-96 kbps, the 64 kbps, 44kHz could be on par with WMA.

Not a very hard task I suppose.
AAC was already tied to WMA on the (old) collective listening tests organized par Roberto:

http://rjamorim.com/test/64test/results.html
WMA hasn't really improved since, but QuickTime AAC was updated many times.

Were there any tests done between Nero AAC and iTunes (QuickTime) AAC?

Collective tests:
128 kbps: http://www.rjamorim.com/test/aac128test/results.html
~130 kbps: http://www.rjamorim.com/test/aac128v2/results.html

Personnal tests:
~130 kbps: http://www.hydrogenaudio.org/forums/index....topic=16395&hl=
~130 kbps: http://www.hydrogenaudio.org/forums/index....topic=29924&hl=
80 kbps: http://www.hydrogenaudio.org/forums/index....topic=35438&hl=
96 kbps: http://forum.hardware.fr/forum2.php?config...&nojs=0#t921999

Thank you for taking the time to test those codecs and posting results. iTunes looks like the winner in collective tests, Nero holds it's own though at the bitrates ~130 kbps. I wonder which codec wins out in iTunes 6 AAC vs Nero AAC 4.2.1.0?

I'm currently testing both encoders in VBR mode at ~130 kbps. It's only a personnal evaluation, but all samples should be online: therefore, everyone is free to perform another test in the same conditions.
I will post the result when the test will be over. ~120 samples are currently tested; ~80 samples remain.
SebastianMares is also interested to start a collective listening test: it's a different approach, with much more testers but also much less samples.

So fast will be the new experimental development version right?

I am in the same boat. 0% of my 160 aac VBR's are showing up as VBR. I have checked the box for VBR and have the newest itunes. I use custom 160kps.

any suggestions out there? What am I not doing?

Thanks for the info. Now I can see that it's VBR!

Looking down the list, it appears that the VBR does not show up IN I-tunes, but it IS recording VBR. These are the best 160s I've ripped. a/b'd with LAME these sound better to me. I will be re-ripping many of my discs in this format.