[Flac-dev] Is FLAC fully cooked for OS X yet?

Evan Olcott ev at audiofile-engineering.com
Wed Jan 3 13:48:55 PST 2007

On Jan 3, 2007, at 3:28 PM, Josh Coalson wrote:

> the FLAC parts look OK but I don't know how the audio converter
> works.  I think that's where the problem is.  it is probably
> converting float to 32-bit int full scale.

well, here's what I found out about the 32-bit integer conversion.

If the original 16-bit sample is 0x52F3, it goes through floating  
point, then comes to the 32-bit integer as 0x52F30000
As far as I know that's the proper conversion, yes? Simple adding  
some LSB to make it 32-bit.

> but if [audioFile range] is 16 (i.e. 16 bits per sample), then
> after conversion, the integer PCM samples in outputBuffers
> should all be in the range [-32768,32767], that's the first
> thing I'd check.

OH so wait...
What you're saying then is that the buffers always have to be filled  
with 32-bit-SIZED-FIELDS, inside of which
exists a low-aligned integer sample value?

So the VALUES aren't 32-bit integer, but the SPACE FOR THE SAMPLE  
VALUE is 32-bit.
Wow, that's very trippy. Honestly, I *never* would have guessed that  
from the documentation.

That would explain the silence, too.

Technical Knowledge Officer
Head Programmer/Designer
Audiofile Engineering


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