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Topic: OS X FLAC --> Gapless AAC, how? (Read 12866 times) previous topic - next topic
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OS X FLAC --> Gapless AAC, how?

So, I have a GBs upon GBs of FLAC backups that I want to convert to gapless AAC now that itunes and apple supports it, but how do I do it?  Itunes doesn't recognize FLAC.

OS X FLAC --> Gapless AAC, how?

Reply #1 –
Try Max, XLD or Toast Titanium 7.1 (will not preserve tagging).

OS X FLAC --> Gapless AAC, how?

Reply #2 –
Quote from: ffooky on
Try Max, XLD or Toast Titanium 7.1 (will not preserve tagging).


Those will convert to AAC just fine, but they won't encode as gapless for use in itunes and on the ipod.  Hopefully functionality will be added soon. 

OS X FLAC --> Gapless AAC, how?

Reply #3 –
XLD seems to add gapless information for iTunes/iPod.
There is a check box for this setting in the option dialog of AAC encoder.

OS X FLAC --> Gapless AAC, how?

Reply #4 –
Quote from: haze on
So, I have a GBs upon GBs of FLAC backups that I want to convert to gapless AAC now that itunes and apple supports it, but how do I do it?  Itunes doesn't recognize FLAC.


This may seem like an oversimplified approach, but what about converting to WAV and importing that into iTunes and then convert to AAC?

This is what I would do on a PC - can you do the same on a Mac?

OS X FLAC --> Gapless AAC, how?

Reply #5 –
There's no such thing as gapless AAC. When you add files to iTunes it works out the relevant information to play them back gaplessly as long as they are in a compatible format and encoded with certain software. As all three of the applications I recommended use either QuickTime or Core Audio for the conversion, they all produce files that iTunes can play back gaplessly.

OS X FLAC --> Gapless AAC, how?

Reply #6 –
Quote from: ffooky on
There's no such thing as gapless AAC. When you add files to iTunes it works out the relevant information to play them back gaplessly as long as they are in a compatible format and encoded with certain software. As all three of the applications I recommended use either QuickTime or Core Audio for the conversion, they all produce files that iTunes can play back gaplessly.
The gapless info is put there by iTunes from what I've seen. If you use Max to encode to AAC the files will not have this data. When imported into iTunes it will scan these files to try and recreate this missing data but it's not completely native like it would have been if iTunes created the file.
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

OS X FLAC --> Gapless AAC, how?

Reply #7 –
Native, schmative....Core Audio is Core Audio no matter what application is using it, that's the whole point of it. LAME isn't even an Apple encoder but iTunes will play back LAME encoded files gaplessly.

Why not convert some FLAC files to AAC with XLD/Max and hear for yourself that they are gapless ?

OS X FLAC --> Gapless AAC, how?

Reply #8 –
Quote from: ffooky on
Native, schmative....Core Audio is Core Audio no matter what application is using it, that's the whole point of it. LAME isn't even an Apple encoder but iTunes will play back LAME encoded files gaplessly.

Yes, because both Lame and iTunes store the encoder-delay and sample-padding data in their files, CoreAudio doesn't. That's why Lame and iTunes created files are 'native', all other files* can only be guessed by iTunes afterwards.

* NeroAAC stores this data as well but in a different way from iTunes, apparently Winamp stores this data in AAC files it creates since a recent version.
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead
 

OS X FLAC --> Gapless AAC, how?

Reply #9 –
Quote from: Maurits on
Yes, because both Lame and iTunes store the encoder-delay and sample-padding data in their files, CoreAudio doesn't. That's why Lame and iTunes created files are 'native', all other files* can only be guessed by iTunes afterwards.


I shall shut my ill-informed mouth while still maintaining, however, that Max-encoded files play back gaplessly 

OS X FLAC --> Gapless AAC, how?

Reply #10 –
Quote from: ffooky on
Quote from: Maurits on
Yes, because both Lame and iTunes store the encoder-delay and sample-padding data in their files, CoreAudio doesn't. That's why Lame and iTunes created files are 'native', all other files* can only be guessed by iTunes afterwards.


I shall shut my ill-informed mouth while still maintaining, however, that Max-encoded files play back gaplessly 

You are right though, iTunes does a pretty good job at recreating this missing data. It might work out fine so it is indeed worth a try. There is just no guarantee it'll be 100% perfect all of the time, that's why the 'native' route is nice if you can get it.
Every night with my star friends / We eat caviar and drink champagne
Sniffing in the VIP area / We talk about Frank Sinatra
Do you know Frank Sinatra? / He's dead

OS X FLAC --> Gapless AAC, how?

Reply #11 –
If you decode(not play) a file with gapless info by iTunes, you will get a file that is exactly the same total sample number as the original pcm data. But without gapless info, the total sample number of decoded file will be different from the original.

The AAC file created by XLD has the same gapless info as iTunes', I confirmed. It uses CoreAudio API to encode AAC like Max does, but it seems to add gapless info by postprocessing.

OS X FLAC --> Gapless AAC, how?

Reply #12 –
Quote from: nao on
The AAC file created by XLD has the same gapless info as iTunes', I confirmed. It uses CoreAudio API to encode AAC like Max does, but it seems to add gapless info by postprocessing.

I can confirm that the gapless info is added during postprocessing- I just poked through the XLD source and it adds some atoms (see XLDAacOutputTask.m:474).  I should probably add this code to Max as well.

OS X FLAC --> Gapless AAC, how?

Reply #13 –
The Apple implementation sounds gimmicky.  Perhaps I am just better off going with .ogg and Rockbox.  I pretty much hate iTunes as a player anyway.  I am awaiting a native Amarok or even Foobar OS X version.