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iTunes Settings for High-Quality AAC, Questions, Answers, and Ideas
post Dec 16 2012, 17:11
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I am somewhat inexperienced with ripping and encoding music. I spent a lot of time reading articles and Hydrogenaudio forum posts last winter in an effort to come up with a procedure for ripping and encoding that would best suit my tastes. I posted some questions in the forums, and from the answers I received it sounded like the AAC encoder that comes with iTunes will create top-quality lossy audio (depending on the settings). I never quite nailed-down what encoding settings would be the best for me and am only just now looking into it again.

About CVBR and TVBR, one person who replied to my post said, "CVBR is an Apple (iTunes) AAC phenomenon and it stands for Constrained VBR. It is necessary (for iTunes) if you plan to use HE encoding (typically ~64kbps). TVBR stands for True VBR and is somewhat difficult to actually get iTunes to do (if you select 'use VBR' in iTunes, it will use Constrained VBR regardless of format, you have to do something special to get True VBR). The most recent listening test at ~96kbps suggests no statistical significance between the quality of CVBR and TVBR, (at least at that bitrate)." (Thanks for that info, buklau)

However, he also said "It's probably better to get True VBR if you can", suggesting that TVBR might be better than CVBR in some way, which is odd because he had just told me there was no statistically significant difference between the two in the listening test.

So my first question today is, why might TVBR be better than CVBR? Does the potential advantage lie with something other than output sound quality, such as output file size? All I know about the difference between the two is that "CVBR is constrained VBR which prevents the VBR mechanism from going extremely low with bitrate." (Thanks for that info, halb27)

Secondly, I would just like some input on other encoding settings for AAC. iTunes has an AAC preset called "iTunes Plus" which consists of the following settings: "128 kbps (mono)/256 kbps (stereo), 44.100 kHz, VBR, optimized for MMX/SSE2." (I don't know what MMX and SSE2 are.)

I have the option to customize the stereo bit rate, sample rate, or number of channels, as well as enable/disable VBR, High Efficiency, or "Optimize for voice".

I assume I do not need to worry about "Optimize for voice" if I am going for higher-bitrate audio (but I would be interested to know what this setting does). I have also read that High Efficiency is for lower-bitrate audio, so I shouldn't need to use that. I have read that VBR is good, so I should leave that enabled. Number of channels should probably be left on "Auto" so I don't constrain the number of channels in the output.

Is 44.100 kHz a good sample rate? ...Is that the standard and/or best sample rate? Because it doesn't allow me to select any other sample rates except "Auto".

And as for the 128 kbps (mono)/256 kbps (stereo) bitrate, in your opinion, is that overkill for lossy music; or is it worth going for a higher bitrate? I know it all depends on the listener and the amount of storage space, but I would just like opinions and ideas. If I remember right, 256 kbps is on the high end of the bitrate spectrum for lossy audio, but I've never compared music at various bitrates. I do want to make sure that I can get the best possible quality that I can fit on my iPhone, so I want to start with a bitrate that is considered to be very good quality lossy audio, convert some albums to AAC with that bitrate setting, estimate how many albums I could fit on my iPhone at that setting, and then lower it if necessary. Is 256 kbps a reasonable place to start, or should I go with one of the other presets in iTunes and/or a custom bitrate setting?

Lastly, are there any reasons why I might be better off encoding outside of iTunes? For example, it sounds like I would need to use something other than iTunes if I want to use TVBR encoding (but as of now I don't know the benefit of TVBR over CVBR). I plan to use FFMPEG with EAC to immediately encode my rips to ALAC as described here: http://wiki.hydrogenaudio.org/index.php?title=EAC_and_ALAC , and then I was thinking I would just drag the ALAC files into iTunes, right-click on them, and create AAC versions of them. Would I be missing out on anything by not using some other program to encode to AAC? Would I benefit by using something like foobar2000 to pass some command-line arguments to the encoder? If so, what arguments do you recommend?

Thanks! I appreciate any input.
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post Dec 22 2012, 16:29
Post #2

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I changed the comment and band tags in my arguments for ALAC encoding:

--alac %source% -o %dest% --artist="%artist%" --title="%title%" --album="%albumtitle%" --date="%year%" --track="%tracknr%/%numtracks%" --disk="%cdnumber%/%totalcds%" --genre="%genre%" --band="%albumartist%" --composer="%composer%" --comment="CRC: %trackcrc%" %haslyrics%--lyrics="%lyricsfile%"%haslyrics% %hascover%--artwork="%coverfile%"%hascover%

%albuminterpret% refers to the contents of the "CD Performer" box in the main interface of EAC, whereas %albumartist% refers to the contents of the "CD Artist" box, and it seems the "CD Artist" box is more likely to get filled in when you download metadata from an online database. So I replaced %albuminterpret% with %albumartist%.

I probably won't actually utilize EAC's ability to embed album art in each track via these commands, since the artwork can simply be included as one separate file in the same folder as the ripped tracks. But I still left the necessary commands in place so that I have the option of doing so.

See here for a more detailed discussion about the similar arguments I plan to use for FLAC encoding:

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Posts in this topic
- heyo_speaker   iTunes Settings for High-Quality AAC   Dec 16 2012, 17:11
- - Seren   If you are on windows you'll want to use QAAC ...   Dec 16 2012, 23:19
|- - Neuron   QUOTE (Seren @ Dec 16 2012, 23:19) If you...   Dec 16 2012, 23:29
- - heyo_speaker   I thought I remembered QAAC being a recommended en...   Dec 17 2012, 04:38
|- - Seren   QUOTE (heyo_speaker @ Dec 17 2012, 11:38)...   Dec 17 2012, 05:41
- - twostar   QUOTE And as for the 128 kbps (mono)/256 kbps (ste...   Dec 17 2012, 05:41
|- - Seren   QUOTE (twostar @ Dec 17 2012, 12:41) In m...   Dec 17 2012, 05:53
- - heyo_speaker   On the QAAC homepage ( https://sites.google.com/si...   Dec 17 2012, 09:24
|- - nu774   When the identical setting is used, the resulting ...   Dec 17 2012, 10:34
|- - heyo_speaker   Thanks, nu774. I was thinking I would use Exact A...   Dec 17 2012, 11:17
|- - nu774   To my knowledge, TVBR has no practical superiorit...   Dec 17 2012, 11:40
- - heyo_speaker   Actually, I've been reading the QAAC homepage ...   Dec 17 2012, 11:33
- - nu774   About EAC configuration, read this: https://sites....   Dec 17 2012, 11:43
- - heyo_speaker   Thanks for that link! I read the "Using ...   Dec 17 2012, 14:52
|- - nu774   QUOTE (heyo_speaker @ Dec 17 2012, 22:52)...   Dec 17 2012, 15:40
|- - heyo_speaker   QUOTE (nu774 @ Dec 17 2012, 08:40) (Perso...   Dec 18 2012, 14:25
|- - nu774   QUOTE (heyo_speaker @ Dec 18 2012, 22:25)...   Dec 18 2012, 15:51
|- - heyo_speaker   Thank you. "Super easy to use (compared to E...   Dec 18 2012, 16:35
|- - Dynamic   QUOTE (heyo_speaker @ Dec 18 2012, 15:35)...   Dec 18 2012, 16:51
- - Dynamic   I use CUEripper, which provides EAC-like logs. For...   Dec 18 2012, 16:41
- - heyo_speaker   Thanks, Dynamic. It sounds like CUERipper is a lo...   Dec 20 2012, 11:27
- - Dynamic   Now you have EAC set up properly, you can still be...   Dec 20 2012, 21:04
- - heyo_speaker   UPDATE: I changed the comment and band tags in my ...   Dec 22 2012, 16:29
- - heyo_speaker   I removed the album art tag from my ALAC qaac argu...   Jan 3 2013, 05:15
- - heyo_speaker   I am wondering what I should put for "Highest...   Jan 9 2013, 22:15
- - nu774   QUOTE (heyo_speaker @ Jan 10 2013, 06:15)...   Jan 10 2013, 02:13

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