[Flac-dev] Support for CAF in flac command-line?

Brian Willoughby
Mon, 13 Oct 2008 04:58:14 -0000

Thanks for the interest, Michael.

I don't use Ogg, so I'm a little wary that standard FLAC would be
left out of any Ogg Frog implementation.  But I say that mostly out
of ignorance.  I have noticed that there seem to be two worlds for
FLAC, inside Ogg and outside.  It's important to be aware of the fact
that many hardware devices support the FLAC format directly, without
the Ogg container/wrapper.  I would want the ability to convert FLAC
to CAF directly, hopefully without an intermediate Ogg file (since
I'm talking about file sizes where each is over 4 GB).

QuickTime is a very good suggestion, and gets two platforms supported
rather than one, as the AudioFile API in CoreAudio would do.
However, QuickTime tends to be rather limited, and when developers
run into those limitations, Apple engineers tend to recommend that
folks turn to CoreAudio for full support.  Also, I really would like
to support Unix, assuming that there are as many Unix folks using
FLAC as there are Windows users taking advantage of this underground
format.

As for the patent question, it's a very smart question, but I think
as soon as any interested developer looks at the CAF specification
from Apple, it should be readily apparent what the legal
ramifications are.  My hunch is that Apple does not want to encumber
the format, but I'll let their public documents speak for them.  In
any event, it's a very good issue to be aware of from the start.

Thanks again for the comments, and be sure to keep us informed if you
do anything.

Brian Willoughby
Sound Consulting


On Oct 12, 2008, at 21:25, Michael Crawford wrote:

On Sun, Oct 12, 2008 at 7:26 PM, Brian Willoughby
<brianw at sounds.wa.com> wrote:
> Is anyone here potentially up to the task of adding support for CAF
> (the CoreAudio Format) into the flac command-line?  This would
> present minimal difficulty under OSX, due to the presence of the
> CoreAudio API, but the real challenge would be to support CAF on Unix
> and Windows - everywhere that flac is now available.

I expect I could do it as part of my work on Ogg Frog:

http://www.oggfrog.com/free-music-software

In the short term, I would do it by accessing the QuickTime APIs -
which *are* available on Windows, if you install either iTunes or
QuickTime for Windows.  (The iTunes install includes QuickTime.)

In the long term, I could write a codec for it that would be
straightforward to integrate into the flac command-line tool.  That
would allow its use on UNIX.

HOWEVER!

Is the CoreAudio file format or its associated algorithms patented?
QuickTime in general has many patents.

A patent wouldn't stop me from writing the source code, but a binary
couldn't be provided by anyone in a country that recognizes software
patents.

Mike