Problems when using libFLAC to encode 24 bit content

Hi everybody,

We have FLAC supported for input/output in REAPER (http://www.reaper.fm), and
the problem is that
when writing 24 bit FLAC files, the data isn't compressed
(i.e. the FLAC is slightly larger than
if it was writing to .WAV). The files play back fine,
however, and 16 bit mode works great.

We're using flac-1.1.2, built on win32 with MSVC6 w/ SP5 +
VCPP, and NASM version 0.98.39

Any help would be greatly appreciated.

Thanks,

Justin Frankel
justinblorp.com
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--- Justin Frankel <justinblorp.com> wrote:
> Hi everybody,
> 
> We have FLAC supported for input/output in REAPER
> (http://www.reaper.fm), and
the problem is that
> when writing 24 bit FLAC files, the data isn't
compressed (i.e. the
> FLAC is slightly larger than
> if it was writing to .WAV). The files play back fine,
however, and 16
> bit mode works great.
> 
> We're using flac-1.1.2, built on win32 with MSVC6 w/
SP5 + VCPP, and
> NASM version 0.98.39

hmm... on the encoding side there are quite a few things
that could
affect that, so first I'll ask:

- are you calling the flac binary or calling into libFLAC?
  - if flac, what is the command-line string?
  - if libFLAC, can you post the calls you are using to set
up
    the encoder before initialization?
- if you do 'flac -a some24bitfile.flac' that you made,
are most/all
of the subframe types VERBATIM?

Josh


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We are calling libFLAC. Here is the the initialization code:

          m_enc=FLAC__file_encoder_new ();
          FLAC__file_encoder_set_client_data(m_enc, this);
         
FLAC__file_encoder_set_progress_callback(m_enc,progressCB);
          FLAC__file_encoder_set_channels (m_enc, m_nch);
          FLAC__file_encoder_set_bits_per_sample (m_enc,
m_bps);
          FLAC__file_encoder_set_sample_rate (m_enc,
m_srate);
          FLAC__file_encoder_set_filename (m_enc, fn);

	int ems=0, ec=0, ms=0, lms=0, qlp=0, minr=2, maxr=2,
rice=0, lpc=0;
	// this is what we do for "level 5" but all of
them don't work in 24 bit
            ems = false;
	    ec = false;
	    ms = true;
	    lms = false;
	    qlp = 0;
	    minr = 0;
            maxr = 3;
	    rice = 0;
	    lpc = 8;            


          if(m_nch == 1)
          {
            ms = false; lms = false;
          }


         
FLAC__file_encoder_set_do_exhaustive_model_search(m_enc,
ems);
          FLAC__file_encoder_set_do_escape_coding(m_enc,
ec);
          FLAC__file_encoder_set_do_mid_side_stereo(m_enc,
ms);
         
FLAC__file_encoder_set_loose_mid_side_stereo(m_enc, lms);
          FLAC__file_encoder_set_qlp_coeff_precision(m_enc,
qlp);
         
FLAC__file_encoder_set_min_residual_partition_order(m_enc,
minr);
         
FLAC__file_encoder_set_max_residual_partition_order(m_enc,
maxr);
         
FLAC__file_encoder_set_rice_parameter_search_dist(m_enc,
rice);
          FLAC__file_encoder_set_max_lpc_order(m_enc, lpc);


          FLAC__file_encoder_init (m_enc);


and yes, flac -a results in all VERBATIM. and using this
exact code in 16 bit 
mode works fine, too.


Thanks,

Justin

On Fri, Jul 14, 2006 at 05:52:57PM -0700, Josh Coalson
wrote:
> --- Justin Frankel <justinblorp.com> wrote:
> > Hi everybody,
> > 
> > We have FLAC supported for input/output in REAPER
> > (http://www.reaper.fm), and
the problem is that
> > when writing 24 bit FLAC files, the data isn't
compressed (i.e. the
> > FLAC is slightly larger than
> > if it was writing to .WAV). The files play back
fine, however, and 16
> > bit mode works great.
> > 
> > We're using flac-1.1.2, built on win32 with MSVC6
w/ SP5 + VCPP, and
> > NASM version 0.98.39
> 
> hmm... on the encoding side there are quite a few
things that could
> affect that, so first I'll ask:
> 
> - are you calling the flac binary or calling into
libFLAC?
>   - if flac, what is the command-line string?
>   - if libFLAC, can you post the calls you are using to
set up
>     the encoder before initialization?
> - if you do 'flac -a some24bitfile.flac' that you
made, are most/all
> of the subframe types VERBATIM?
> 
> Josh
> 
> 
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam
protection around 
> http://mail.yahoo.com 
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