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resampled_source.cc

/*
    Copyright (C) 2007 Paul Davis 

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <pbd/error.h>
#include <ardour/resampled_source.h>
#include <pbd/failed_constructor.h>

#include "i18n.h"

using namespace ARDOUR;
using namespace PBD;

const uint32_t ResampledImportableSource::blocksize = 16384U;

ResampledImportableSource::ResampledImportableSource (boost::shared_ptr<ImportableSource> src, nframes_t rate, SrcQuality srcq)
      : source (src)
{
      int err;
      
      source->seek (0);
      
      /* Initialize the sample rate converter. */
      
      int src_type;

      switch (srcq) {
      case SrcBest:
            src_type = SRC_SINC_BEST_QUALITY;
            break;
      case SrcGood:
            src_type = SRC_SINC_MEDIUM_QUALITY;
            break;
      case SrcQuick:
            src_type = SRC_SINC_FASTEST;
            break;
      case SrcFast:
            src_type = SRC_ZERO_ORDER_HOLD;
            break;
      case SrcFastest:
            src_type = SRC_LINEAR;
            break;
      }
      
      if ((src_state = src_new (src_type, source->channels(), &err)) == 0) {  
            error << string_compose(_("Import: src_new() failed : %1"), src_strerror (err)) << endmsg ;
            throw failed_constructor ();
      }
      
      src_data.end_of_input = 0 ; /* Set this later. */
      
      /* Start with zero to force load in while loop. */
      
      src_data.input_frames = 0 ;
      src_data.data_in = input ;
      
      src_data.src_ratio = ((float) rate) / source->samplerate();
      
      input = new float[blocksize];
}

ResampledImportableSource::~ResampledImportableSource ()
{
      src_state = src_delete (src_state) ;
      delete [] input;
}

nframes_t 
ResampledImportableSource::read (Sample* output, nframes_t nframes)
{
      int err;

      /* If the input buffer is empty, refill it. */
      
      if (src_data.input_frames == 0) {   

            src_data.input_frames = source->read (input, blocksize);

            /* The last read will not be a full buffer, so set end_of_input. */

            if ((nframes_t) src_data.input_frames < blocksize) {
                  src_data.end_of_input = true;
            }           

            src_data.input_frames /= source->channels();
            src_data.data_in = input;
      } 
      
      src_data.data_out = output;

      if (!src_data.end_of_input) {
            src_data.output_frames = nframes / source->channels();
      } else {
            src_data.output_frames = src_data.input_frames;
      }

      if ((err = src_process (src_state, &src_data))) {
            error << string_compose(_("Import: %1"), src_strerror (err)) << endmsg ;
            return 0 ;
      } 
      
      /* Terminate if at end */
      
      if (src_data.end_of_input && src_data.output_frames_gen == 0) {
            return 0;
      }
      
      src_data.data_in += src_data.input_frames_used * source->channels();
      src_data.input_frames -= src_data.input_frames_used ;

      return src_data.output_frames_gen * source->channels();
}


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