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

Josh Coalson xflac at yahoo.com
Wed Jan 3 13:10:57 PST 2007


--- Evan Olcott <ev at audiofile-engineering.com> wrote:
> 
> On Jan 2, 2007, at 1:54 PM, Josh Coalson wrote:
> 
> > this is reported a lot.  usually it is a misunderstanding in how
> > to send samples to FLAC__stream_encoder_process() or
> > FLAC__stream_encoder_process_interleaved().  if you could send
> > your code where you are doing that, it would help.
> >
> > note that samples going in to the process calls must be converted
> > to signed 32-bit integers (this is lossless) regardless of the
> > initial format.  see also:
> >
>
http://flac.sourceforge.net/api/group__flac__stream__encoder.html#ga63
> >
> > from your description it sounds like you might be sending packed
> > 16-bit samples somehow which could cause every other sample to get
> > encoded.
> 
> OK, now I'm totally stumped.
> 
> I can confirm that I'm sending the encoder 32-bit signed integers,  
> and that they are correctly representing the original file. I still  
> get a silent file.
> 
> I tried making the resulting integers forcibly little-endian, and I  
> got a FLAC file result that sounded like what a byte-reversal might  
> sound like - noisy when there's data, but 0 is 0. I've heard it  
> before, I recognize it...
> 
> But why when I send it *correctly* to the encoder do I get silence?
> 
> Another clue is that they see to be super-small files, but with the  
> proper length.

it's probably getting buffers of zeroes (or a constant number);
that compresses really well with FLAC.

at this point I think I'll need to see your code up to and including
your call to FLAC__stream_encoder_process() where it fills the
buffer in order to be able to figure it out.

Josh


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