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

[Erik de Castro Lopo]

Brian Willoughby wrote:
 
> Hopefully, libsndfile no longer uses the incorrect 0x7FFF (32767)  
> factor for float to 16-bit integer conversions, because that would  
> make it unacceptable for lossless file conversions.

That is a statement of opinion rather than fact but I won't go into
that here.

However, there is a way avoid that feature of libsndfile by avoiding
the use of floats during the conversion. For instance, when convering
from one format to another, sndfile-convert does this:

if ((outfileminor == SF_FORMAT_DOUBLE) || (outfileminor == 
SF_FORMAT_FLOAT)
|| (infileminor == SF_FORMAT_DOUBLE) || (infileminor == 
SF_FORMAT_FLOAT)
|| (infileminor == SF_FORMAT_VORBIS) || (outfileminor 
== SF_FORMAT_VORBIS))
sfe_copy_data_fp (outfile, infile, sfinfo.channels) ;
else
sfe_copy_data_int (outfile, infile, sfinfo.channels) ;

That is the second path (sfe_copy_data_int) would be used for FLAC
-> CAF and CAF -> FLAC conversions.

Erik
-- 
--
Erik de Castro Lopo
http://www.mega-nerd.com/
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Re: [Flac-dev] Support for CAF in flac command-line?

[Brian Willoughby]

On Oct 12, 2008, at 22:32, Paul Davis wrote:
> On Sun, 2008-10-12 at 19:26 -0700, Brian Willoughby 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.
>>
>> Although the format is rather unknown, there are some very specific
>> advantages to adding CAF support.
>
> I am a little suprised that you don't know that CAF is already  
> supported
> by libsndfile, on every platform where libsndfile works (which  
> includes
> just about every unix and windows platforms i know of).

I realize that I'm a couple of years late in saying so, but you're  
right.

I finally took the time to download libsndfile and compile it (for  
Leopard), and sndfile-convert easily handled converting a 1.8 GB FLAC  
recording (from a Sound Devices 702) to a 2.9 GB CAF file.  I haven't  
done extensive testing for conversion errors, but a quick scan of the  
file seems to indicate that it plays fine.  The true test will be the  
next time I master a recording of a long performance.

I still support enhancements to the flac command line to support  
direct conversion to one or more formats that do not have a 2 GB  
limit, but for most audio formats libsndfile might be acceptable.   
Hopefully, libsndfile no longer uses the incorrect 0x7FFF (32767)  
factor for float to 16-bit integer conversions, because that would  
make it unacceptable for lossless file conversions.

Brian Willoughby
Sound Consulting

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