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Has the iTunes AAC encoder changed recently?, specifically between version 7.0.2.16 and the current 7.3.4
chrisgeleven
post Oct 27 2007, 02:08
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Great info. Thank you.

Too bad you can't access the true VBR mode from iTunes itself.


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ShowsOn
post Oct 27 2007, 05:35
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QUOTE (chrisgeleven @ Oct 27 2007, 10:08) *
Great info. Thank you.

Too bad you can't access the true VBR mode from iTunes itself.


Hopefully this comes soon, but it seems Apple like keeping the iTunes settings simple.

I suggest people send a feature request suggesting an ADVANCED tab that reveals full customisation of the AAC encoder.

http://www.apple.com/feedback/itunesapp.html

If this happens then it would make it possible to conduct listening tests to determine and what setting the VBR mode is transperant 95%+ of the time. My guess is it would produce files with sizes closer to 100 Kbps than 128 Kbps, thus enabling excelleng space saving compared to iTunes 128 Kbps default setting.

In fact, has the new iTunes in Leopard changed the default to ABR rather than CBR? Or is it still CBR (which I understand isn't actually true CBR due to the way AAC uses the bit resivour).


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WarChild
post Oct 27 2007, 07:20
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Many thanks for the info skuo. It is very helpful.

Is there any way to set the quality rate higher? I've been playing around and see no effect in tuning the numbers to higher than 127. This seems to give a 192 kbs type file.

This post has been edited by WarChild: Oct 27 2007, 16:19
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Busemann
post Oct 27 2007, 17:30
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QUOTE (skuo @ Oct 26 2007, 16:43) *
QUOTE (Busemann @ Oct 26 2007, 11:51) *

Is there a way to make the true vbr mode aim for transparency and higher bitrate files?

The command line for the true VBR mode is as follows:

afconvert -f m4af -d aac -s 3 -u vbrq 127

In VBR mode (-s 3), bitrate option (-b) is ignored because the mode is configured by sound quality which is set by "-u vbrq <sound_quality>" where <sound_quality>: 0-127. Note that the ABR and VBR modes are new features supported in Leopard. CBR and VBR_Constrained modes were in previous Mac OS X.



Hmm.. for some reason I can only make it work with AIFF files, converting alac files gives this message: "Error: Couldn't set audio converter property ('prop')".

Anyway, this setting is probably exactly what I've been looking for since it seems more or less like an equivalent to the V2 setting in LAME for producing true VBR files around the 192kbps mark.

This post has been edited by Busemann: Oct 27 2007, 17:33
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adlai
post Oct 28 2007, 05:03
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QUOTE (Busemann @ Oct 27 2007, 08:30) *
QUOTE (skuo @ Oct 26 2007, 16:43) *

QUOTE (Busemann @ Oct 26 2007, 11:51) *

Is there a way to make the true vbr mode aim for transparency and higher bitrate files?

The command line for the true VBR mode is as follows:

afconvert -f m4af -d aac -s 3 -u vbrq 127

In VBR mode (-s 3), bitrate option (-b) is ignored because the mode is configured by sound quality which is set by "-u vbrq <sound_quality>" where <sound_quality>: 0-127. Note that the ABR and VBR modes are new features supported in Leopard. CBR and VBR_Constrained modes were in previous Mac OS X.



Hmm.. for some reason I can only make it work with AIFF files, converting alac files gives this message: "Error: Couldn't set audio converter property ('prop')".

Anyway, this setting is probably exactly what I've been looking for since it seems more or less like an equivalent to the V2 setting in LAME for producing true VBR files around the 192kbps mark.


any idea how to pick up this new encoder for us windows folks? and does it work in foobar?
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chrisgeleven
post Oct 28 2007, 23:32
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I imagine you would have to wait for a new Windows QuickTime version.


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iTunes 10 - Mac OS X 10.6
256kbps AAC VBR
iPhone 4 32GB
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Enig123
post Nov 6 2007, 01:36
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Apple have their iTunes 7.5, together with QuickTime 7.3 for windows available. Can someone confirm if these product included the latest aac codec?
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chichazor
post Nov 6 2007, 01:53
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I don't know if is the latest aac codec but is a different version than the previous version of iTunes. I could not prove it in depth, but at first glance I notice that bitrates are higher when using VBR. I do not know whether this has a direct impact on the quality...


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chrisgeleven
post Nov 6 2007, 02:40
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Well in theory, you would think that the QuickTime 7.3 version will have at least the same if not newer AAC codec compared to the one that shipped with Leopard. Else it would be a downgrade for us Leopard users wink.gif


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ozmosis82
post Nov 6 2007, 05:12
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Is there a frontend or AppleScript available that one could use to batch encode a few files with the afconvert command?
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Pepzhez
post Nov 6 2007, 06:35
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I'm pretty confused over what portion of the AAC encoding is OS dependent, and how much of it (if any) has to do with updating QuickTime. An earlier post states that the codec versions are embedded in the OS; other posts indicate that they are updated via QuickTime. Does anyone know which surmise is the correct one?

I'm still running Tiger, as I haven't yet come up with enough reason to substantiate an immediate move to Leopard. Earlier this evening I ran the new iTunes and QT updates.

Now, running the new iTunes and QuickTime on Tiger (10.4), here is what I notice:

- The MP4 music export options in QT 7.3 (Pro) are 'None', 'CELP (Speech)', 'AAC-LC (Music)', 'AAC-LC VBR (Music)' and 'Pass Through'. However, each option aside from 'AAC-LC (music)' is greyed out. Seems that I cannot choose any of these other options. What's up with that? Guess I need 10.5 in order to use those?

- With iTunes 7.5, the 'VBR' checkbox for AAC encoding is still there, and still works. Now, why can I choose a VBR option in iTunes but not with QuickTime? This is really confusing.


EDIT: Never mind. I found the new options. I was looking in the wrong place.


- I haven't yet checked thoroughly enough to find out about the actual AAC encoder. It does seem to be different, and a cursory encoding test of the 'glockenspiel' test WAV shows that the AAC encoder may now be fixed. At least the glockenspiel WAV doesn't appear to be tripping up the AAC encoder like it had in the past. But I need to run a few more tests before I am can say that with any degree of real certainty.

Just where are the AAC codecs located, and how to tell which versions they are? For what it's worth, the MPEG component now found in the QT Library folder is version 7.3.

This post has been edited by Pepzhez: Nov 6 2007, 07:27
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WarChild
post Nov 6 2007, 13:31
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QUOTE (Pepzhez @ Nov 6 2007, 05:35) *
EDIT: Never mind. I found the new options. I was looking in the wrong place.[/b]


Where's the right place?
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Pepzhez
post Nov 6 2007, 14:26
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QUOTE (WarChild @ Nov 6 2007, 04:31) *
QUOTE (Pepzhez @ Nov 6 2007, 05:35) *


EDIT: Never mind. I found the new options. I was looking in the wrong place.[/b]


Where's the right place?


Export -> Movie to QuickTime Movie -> Options -> Sound -> Format (Choose AAC) -> Encoding Strategy (that's where you'll find the four options)

QT's screwy export menu is the same non-intuitive mess it's been since the stone age. I wonder why no one at Apple has ever shown the slightest inclination to redesign its user interface?
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Enig123
post Nov 6 2007, 15:26
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Oh, what a mess to get a true vbr encoded mp4 file. You have to encode with true vbr mode to a mov container (please tell me it's not the only way to access true vbr mode) and then export it with standard mp4 container format.
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WarChild
post Nov 6 2007, 16:54
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QUOTE (Pepzhez @ Nov 6 2007, 13:26) *
Export -> Movie to QuickTime Movie -> Options -> Sound -> Format (Choose AAC) -> Encoding Strategy (that's where you'll find the four options)

QT's screwy export menu is the same non-intuitive mess it's been since the stone age. I wonder why no one at Apple has ever shown the slightest inclination to redesign its user interface?


Ah well, how screwy is that!
The files QT generates appear to be identical with what you get from the command line.
How much easier it would have been to extend the same funtionality to iTunes.
Thanks for the heads up. I never would have even thought of looking there.
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Serge Smirnoff
post Nov 7 2007, 21:29
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QUOTE (Enig123 @ Nov 6 2007, 04:36) *
Apple have their iTunes 7.5, together with QuickTime 7.3 for windows available. Can someone confirm if these product included the latest aac codec?

I can confirm that aac encoder from iTunes 7.5 (Win) is exactly the same as the new one from iTunes 7.4 (Mac) shipped with Leopard. The encoder will appear in SoundExpert 256kbit/s page in a few days.


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dbAmp
post Nov 8 2007, 02:00
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So I don't know who else has looked into this yet... but I'm not entirely happy with the results I'm getting with the new encoder. I don't think the encoder has necessarily gotten worse... but the old settings I use are no longer producing acceptable results. I've tested this across many tracks. With both the old and new versions, I've encoded using iTunes at 128 AAC w/VBR.

For example, AC/DC - What Do You Do For Money Honey? encoded with iTunes 7.4/QT 7.2 produced a 143 kbps file that I could not ABX from the WavPack source with any reasonable consistency. Encoding the same file with the same settings with iTunes 7.5/QT 7.3 produced a 138 kpbs file with a noticeable artifacts in the high end (primarily ringing and smearing in the cymbals) that was easily ABX-able 100% of the time.

I'm not saying that the new encoder is worse... just that the same setting produce worse results. Your millage may vary. Has anyone else been experience this type of behavior with the new codec?
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dbAmp
post Nov 13 2007, 01:32
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So I usually avoid bumping my own posts... but I have a lot of files to encode and I'm trying to figure out if the quality problems I'm experiencing with the new AAC encoder are unique to my system or the fault of the encoder.

Has anyone else had quality problems encoding with the new iTunes 7.5 / QuickTime 7.3 128 AAC VBR_Constrained (iTunes with VBR checked) encoder?
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doubrown
post Nov 14 2007, 23:28
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I'm (temporarily I hope) swithching to the iTunes encoder as Nero Digital encoded AAC files will not play on the Creatize ZEN 16 GB flash player. How can I access VBR mode via command line using Windows XP? I have a large collection in FLAC and use Foobar to bulk convert to AAC. I searched for the afconvert executeable and can't find it.
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jamesbaud
post Nov 15 2007, 05:59
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QUOTE (doubrown @ Nov 14 2007, 15:28) *
I'm (temporarily I hope) swithching to the iTunes encoder as Nero Digital encoded AAC files will not play on the Creatize ZEN 16 GB flash player. How can I access VBR mode via command line using Windows XP? I have a large collection in FLAC and use Foobar to bulk convert to AAC. I searched for the afconvert executeable and can't find it.


I can't answer your question about encoding with the iTunes encoder on the command line.
However, it's possible to encode with the iTunes encoder using dbpoweramp as your secure ripper and itunesencode. Details here:

http://forum.dbpoweramp.com/showthread.php?t=14103
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doubrown
post Nov 15 2007, 16:24
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Thanks. How would I utilize the true VBR mode from the lastest iTunes/Quicktime encoder from Windows XP command line?
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Junon
post Nov 15 2007, 16:33
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QUOTE (doubrown @ Nov 14 2007, 23:28) *
I'm (temporarily I hope) swithching to the iTunes encoder as Nero Digital encoded AAC files will not play on the Creatize ZEN 16 GB flash player.

Have you already tried the "Optimize MP4 Layout" switch, available in both MP3tag and foobar2000? This one's reported to fix the Nero AAC problems with several hardware devices. The extension also has has to be set to .m4a instead of the default .mp4 one in many cases (though I guess you're already aware of this old "problem").
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dougscripts
post Nov 16 2007, 21:41
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QUOTE (chrisgeleven @ Nov 5 2007, 20:40) *
Is there a frontend or AppleScript available that one could use to batch encode a few files with the afconvert command?

I've posted a basic AppleScript wrapper for AAC CBR here. I'm not happy with the "C" of it though.


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ozmosis82
post Nov 16 2007, 22:44
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QUOTE (dougscripts @ Nov 16 2007, 14:41) *
I've posted a basic AppleScript wrapper for AAC CBR here. I'm not happy with the "C" of it though.

AWESOME! Any plans for changing that C to a V? Or could one modify the script so that it encodes using the new VBR? Also, I've noticed that it seems to be intended for ripping only, and not converting already ripped files... is that right?

I'm currently trying to figure out how to streamline the encoding process with QT.

This post has been edited by ozmosis82: Nov 16 2007, 22:57
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ozmosis82
post Nov 18 2007, 22:04
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Has anyone been able to figure out how to get files encoded with Quicktime (using the new VBR mode) to go from being MOVs to M4As? I encoded in OS X, the tried simply changing the extensions (in Windows, mind you), but foobar doesn't recognise them as playable media files.
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