View Full Version : Convert AAC to FLAC ?

2005-02-25, 04:37
Easy - use DBPowerAmp (www.dbpoweramp.com) - install
the correct codecs, and it'll do it in a breeze (well
actually, it tool about 15 hours to convert my huge
collection of lossless Apple stuff to lossless WMA,
but the point is it's all automated using the file
selector tool). The beauty of lossless of course is
that you're not stuff to one format.



--- Phil Karn <karn (AT) ka9q (DOT) net> wrote:
> Vince wrote:
> > Hi,
> > I'd like to know if it's ok to convert AAC files
> that are supposed to
> > be loseless files to FLAC formats ? and if so how
> can I do in under mac
> > osx or linux ?
> I assume you are actually referring to Apple's
> lossLESS format, as it
> wouldn't make much sense to convert something in
> Apple's lossY Advanced
> Audio Coding (AAC) format to FLAC. The file wouldn't
> sound any better;
> it would only get bigger. You might as well keep it
> in AAC and let
> Slimserver convert it on the fly to PCM whenever you
> actually play it.
> Files in Apple's lossless format have the same
> extension (.m4a) as files
> in AAC (Advanced Audio Coding), Apple's lossy format
> widely used on the
> iPod. As others have pointed out, Apple uses MPEG-4
> containers for both
> formats, hence the common file extension, but inside
> they're quite
> different.
> The big problem with Apple's lossless format is that
> it's proprietary,
> and open-source decoders like faad2 that handle .m4a
> files containing
> AAC can't handle it. I haven't seen any
> documentation that would allow
> someone to write an open source implementation that
> could be dropped
> into Slimserver, for example.
> However, you can use iTunes to convert Apple's
> lossless compression
> format into something more friendly, like WAV, and
> then feed that to
> flac. To do this, bring up the Preferences panel in
> iTunes and select
> the "WAV Encoder" option for the "Import Using"
> field. Close the
> preferences window. This will put the entry "Convert
> Selection to WAV"
> on the iTunes "Advanced" menu. Assuming the files
> you want to convert
> are already in your iTunes library, select them and
> then the
> aforementioned "Convert Selection to WAV" command.
> This will add entries
> to your iTunes library for the selected items in WAV
> format. On my
> version of iTunes (4.7.1 on Mac OS X), at least, it
> leaves the originals
> intact.
> Now you can extract the new WAV files from your
> iTunes library and do
> whatever you want with them.
> There doesn't seem to be a "convert selection to
> FOO" command in iTunes,
> where FOO is any one of its supported formats. It
> only seems to have the
> one command that will convert a selection into
> whatever your currently
> selected format is for importing music from a CD.
> It really is too bad that Apple -- who made a
> seminal breakthrough in
> adopting an open-source operating system (BSD) as
> its foundation for OS
> X -- chose to ignore a perfectly good open lossless
> compression
> technology (FLAC) in favor of its own proprietary
> scheme. I just can't
> see any advantages to it, other than built-in
> support in iTunes. Both
> lossless compression algorithms (Apple and FLAC)
> have about the same
> compression ratio, about 50% on average and somewhat
> better on quiet
> classical music.
> --Phil