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Which VBR mode of Apple AAC encoder do you want to see in public test?, True or constricted VBR?
True vs Constrained VBR mode
True vs Constrained VBR mode
True VBR [ 32 ] ** [65.31%]
Constrained VBR [ 17 ] ** [34.69%]
Total Votes: 65
post Dec 30 2009, 00:43
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Advantages and disadvantages.

True VBR:
+Probably has higher efficiency comparing to constricted VBR
-It's available only via QuickTime player (not iTunes) or MAC OS.
- (for Windows users) Each track should be encoded separately and then remuxed MOV->M4A(or MP4)

Constrained VBR:
+(for Windows users) It's easy accesible from Itunes
-Probably less efficient comparing to true VBR.

The discussion is here http://www.hydrogenaudio.org/forums/index....st&p=675923

This post has been edited by IgorC: Dec 30 2009, 01:33
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post Dec 30 2009, 02:55
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I'm curious, has anyone done much testing of Apple's Constrained vs True VBR, other than just thinking "it's 'true' so it MUST be better"?

I'm just asking because I've spent the past few days reencoding my library to various formats. One of the most interesting things I've noticed is that at ~130 kbps, bitrate spread between songs vary a lot between TVBR and other encoders. It goes something like this: general difference in bitrates of songs from average of TVBR > Nero ~ CVBR. The difference is stark enough that, to me, this implies either Apple's TVBR is being too aggressive with ramping up/down bitrates in VBR mode or Nero is being too conservative.

This post has been edited by mavere: Dec 30 2009, 02:59
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post Dec 30 2009, 05:49
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These threads should catch you up:

The iTunes settings and what Quicktime actually produces:

IgorC's own listening test (with instructions on how to encode files in QT's true vbr mode):

And the discussion thread on Quicktime's true vbr mode:

And the high swings in bitrates are discussed in there too.
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