For instance, is the older Nero Digital still better than the current new version? (If so, has anyone contacted Nero to tell them about the defects in the newer versions? It shouldn't get worse.)
It would also be interesting to hear how the current Itunes stacks up against the current version of Nero Digital. Itunes is certainly more convenient to use. (Do you use some kind of GUI with Nero Digital? Or straight command-line usage?)
Guruboolez, have you tried the new AAC encoder in iTunes 7.5 / QuickTime 7.3 yet? I've encoded about 20 CDs from various genres to do comparisons... and I'm finding that at the 128 VBR setting, I'm getting lower bitrate and lower quality files than I did with the same settings in iTunes 7.4 / QuickTime 7.2. I'm not entirely sure what the changes are... but this new encoder seems to be a step backward... especially when you consider that upping the settings to 160 VBR creates a significantly higher bitrate and larger sized file.
I stay with lossless and wait for an update because in some very silent parts (also classical here) the encoder chooses very low bitrates even at q6, resulting in kind of digital hiss artifacts.
The most reliable VBR LC-AAC encoder in this situation seems to be iTunes which isn't (unfortunately) the most efficient one.
I just re-encoded some tracks to see what I got. With the current Apple encoder I get higher bitrates on the sample I tried -- recordings of Clifford Curzon playing piano. With an older version of Apple's AAC I had got: 165, 164, 163, 162, 161, 160, 160. With the latest I get: 175, 173, 170, 170, 168, 168.I didn't make a note of when I made the original encoding. In both cases the encodings were made using Max, which uses Apple's Core Audio. The interface in Max allows one to access options that are in Core Audio but not revealed in iTunes GUI. (Presumably, Apple, like the GNOME people, consider a simpler UI with fewer options is better.) Anyway, in both cases the encoding chosen was 160 kbps + VBR + a "Maximum quality" switch. (Core audio, apparently, has -- had? -- five different switches for VBR, although you can only either enable or not enable VBR in iTunes.)In general, I'd say Core Audio's AAC was giving me bitrates less than I seem to be getting with the latest version with the settings I use. With Nero's AAC encoder (latest version) at q 0.5 I often get bitrates of 145 or 150 with quiet stuff -- particularly guitar music -- it can drop down to 130 or less. Steve Hackett's latest album "Tribute", where he plays various Bach pieces and so forth gets encoded by Nero at around 110 kbps.
AFAIK Max can use different profiles than iTunes to encode, i.e. Max, through Core Audio, has access to the "true" VBR profile in QuickTime, while iTunes uses the "VBR_Constrained" profile. Therefore I would expect very different results using Max than iTunes, even using the same version of QuickTime.
Since a vast majority of iTunes users are on Windows, expect most listening tests of "iTunes" to use the "VBR_Constrained" profile. The "true" VBR used by Core Audio may sound better... but that won't do me much good unless I purchase a mac.
It's more fun to get the upcoming new Apple's vbr aac encoder in this test in the near future. With all fixes of the regressions found maybe the next version of Nero digital would get much better, which is also worth waiting.