Interesting to see what's new

http://www.apple.com/quicktime/download/

funny that their aac page is still linked to 6.3
http://www.apple.com/mpeg4/aac/

Do we have VBR AAC?

AFAICT based on iTunes for Windows, no.

says so on the page i linked to:

That info is there since QT 6.0. For Apple (or maybe Dolby), VBR = CBR + bit reservoir.

Someone inside Apple hinted me that really true VBR encoding is being developed, but it wasn't supposed to be released with QuickTime 6.4

I know one new feature in 6.4, that is support for multichannel AAC encoding and decoding. Dunno if that feature is Mac-only or also available for Windows, I'm typing from a dial-up connection and not willing to download 10+Mb of QuickTime setup

Not as far as I can tell. The main difference seems to be improved speed and that 3GPP no longer requires a separate download.

I just took a peak at the speed; iTunes 4.1 and QuickTime 6.4 now seem to require slightly less CPU resources.

I don't see any multichannel options in QT 6.4. And it doesn't accept multichannel wavs, maybe it accepts aiff.. Gotta check.

Edit. No, it can't encode multichannel aif either.. Seems that multichannel is not supported at least with win32 version.

can somebody tell me why them apple wimps still maintain 2 different AAC implementations? I mean, does it make sense that QT en iT have different AAC encoders? I don't see why they would do that.

Erm... they use the same encoder, man. Get informed before calling someone "wimp"

iTunes uses the QuickTime AAC codec at "better" quality.

They don't. If they did, why would iTunes require QuickTime?

They parse MP4s different, but both seem to use the QuickTime AAC codec.

well well, ok i didn'tstate my toughts correctly, of course i knew it couldn't be 2 completely different encoders, but still there's a few differences, and i found that a bit weird.

There are three different quality settings. Here are their purposes:

Best: Good for 24bit streams. Is theoretically an overkill for 16bit streams.
Better: High quality/slow mode for 16bit streams
Good: Lower quality/fast mode

And that's it.

Not only that, but it produces bitwise identical output to Better (according to Marc Heijligers).

If Best where to be better than Better it would have to apply a special twist to the 1's and 0's in the file to make them sound better and give you that special Warm Fuzzy Feeling. However, I would venture that this feeling is really the extra heat your computer just generated whilst doing absolutely nothing useful what so ever.

With QT 6.4 (Win), BETTER and BEST produce different files :

INFO (foo_bitcompare) : first different sample found
INFO (foo_bitcompare) : differences found: 718254 sample(s), starting at 2,345215 second(s), peak: 9,285901e-002 at 206,3811 second(s), 2ch
INFO (foo_bitcompare) : finished successfully

Umm...

I've test this on QT 6.3 for Windows, "Better" and "Best" setting produce the same file for 44.1kHz/16bit PCM source.

Last time I checked 6.3 != 6.4, unless Apple enjoys wasting bandwidth.

I think bandwidth is the least of their worries.

Anyway, for those that just want the raw playback, Quicktime Alternative 1.21 has been released with the latest 6.4 codecs and is available here.

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