floor0.c

fix point版本的Ogg Vorbis decoder

/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2002             *
 * by the XIPHOPHORUS Company http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

 function: floor backend 0 implementation
 last mod: $Id: floor0.c,v 1.51 2002/02/26 05:21:35 xiphmont Exp $

 ********************************************************************/

#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "ogg.h"
#include "vorbis_codec.h"
#include "codec_internal.h"
#include "registry.h"
#include "lpc.h"
#include "lsp.h"
#include "codebook.h"
#include "scales.h"
#include "misc.h"
#include "os.h"

#include "misc.h"
#include <stdio.h>

typedef struct {
  long n;
  int ln;
  int  m;
  int *linearmap;

  vorbis_info_floor0 *vi;
  lpc_lookup lpclook;
  float *lsp_look;

  long bits;
  long frames;
} vorbis_look_floor0;

static void floor0_free_info(vorbis_info_floor *i){
  vorbis_info_floor0 *info=(vorbis_info_floor0 *)i;
  if(info){
    memset(info,0,sizeof(*info));
    _ogg_free(info);
  }
}

static void floor0_free_look(vorbis_look_floor *i){
  vorbis_look_floor0 *look=(vorbis_look_floor0 *)i;
  if(look){

    /*fprintf(stderr,"floor 0 bit usage %f\n",
      (float)look->bits/look->frames);*/

    if(look->linearmap)_ogg_free(look->linearmap);
    if(look->lsp_look)_ogg_free(look->lsp_look);
//    lpc_clear(&look->lpclook);
    memset(look,0,sizeof(*look));
    _ogg_free(look);
  }
}

static vorbis_info_floor *floor0_unpack (vorbis_info *vi,oggpack_buffer *opb){
  codec_setup_info     *ci=vi->codec_setup;
  int j;

  vorbis_info_floor0 *info=_ogg_malloc(sizeof(*info));
  info->order=oggpack_read(opb,8);
  info->rate=oggpack_read(opb,16);
  info->barkmap=oggpack_read(opb,16);
  info->ampbits=oggpack_read(opb,6);
  info->ampdB=oggpack_read(opb,8);
  info->numbooks=oggpack_read(opb,4)+1;
  
  if(info->order<1)goto err_out;
  if(info->rate<1)goto err_out;
  if(info->barkmap<1)goto err_out;
  if(info->numbooks<1)goto err_out;
    
  for(j=0;j<info->numbooks;j++){
    info->books[j]=oggpack_read(opb,8);
    if(info->books[j]<0 || info->books[j]>=ci->books)goto err_out;
  }
  return(info);

 err_out:
  floor0_free_info(info);
  return(NULL);
}

/* initialize Bark scale and normalization lookups.  We could do this
   with static tables, but Vorbis allows a number of possible
   combinations, so it's best to do it computationally.

   The below is authoritative in terms of defining scale mapping.
   Note that the scale depends on the sampling rate as well as the
   linear block and mapping sizes */

static vorbis_look_floor *floor0_look (vorbis_dsp_state *vd,vorbis_info_mode *mi,
                              vorbis_info_floor *i){
  int j;
  float scale;
  vorbis_info        *vi=vd->vi;
  codec_setup_info   *ci=vi->codec_setup;
  vorbis_info_floor0 *info=(vorbis_info_floor0 *)i;
  vorbis_look_floor0 *look=_ogg_calloc(1,sizeof(*look));
  look->m=info->order;
  look->n=ci->blocksizes[mi->blockflag]/2;
  look->ln=info->barkmap;
  look->vi=info;

//  if(vd->analysisp)
//    lpc_init(&look->lpclook,look->ln,look->m);

  /* we choose a scaling constant so that:
     floor(bark(rate/2-1)*C)=mapped-1
     floor(bark(rate/2)*C)=mapped */
  scale=look->ln/toBARK(info->rate/2.f);

  /* the mapping from a linear scale to a smaller bark scale is
     straightforward.  We do *not* make sure that the linear mapping
     does not skip bark-scale bins; the decoder simply skips them and
     the encoder may do what it wishes in filling them.  They're
     necessary in some mapping combinations to keep the scale spacing
     accurate */
  look->linearmap=_ogg_malloc((look->n+1)*sizeof(*look->linearmap));
  for(j=0;j<look->n;j++){
    int val=floor( toBARK((info->rate/2.f)/look->n*j) 
		   *scale); /* bark numbers represent band edges */
    if(val>=look->ln)val=look->ln-1; /* guard against the approximation */
    look->linearmap[j]=val;
  }
  look->linearmap[j]=-1;

#if 0
  look->lsp_look=_ogg_malloc(look->ln*sizeof(*look->lsp_look));
  for(j=0;j<look->ln;j++)
    look->lsp_look[j]=2*cos(M_PI/look->ln*j);
#endif

  return look;
}

static void *floor0_inverse1(vorbis_block *vb,vorbis_look_floor *i){
  vorbis_look_floor0 *look=(vorbis_look_floor0 *)i;
  vorbis_info_floor0 *info=look->vi;
  int j,k;
  
  int ampraw=oggpack_read(&vb->opb,info->ampbits);
  if(ampraw>0){ /* also handles the -1 out of data case */
    unsigned long maxval=(1<<info->ampbits)-1;
#ifndef FIXED_POINT
    float amp=(float)ampraw/maxval*info->ampdB;
#else
    /* FIXP note: 4 fracbits for amp */
    FIXP amp=(ampraw<<4)*info->ampdB/maxval;
#endif
    int booknum=oggpack_read(&vb->opb,_ilog(info->numbooks));
    
    if(booknum!=-1 && booknum<info->numbooks){ /* be paranoid */
      codec_setup_info  *ci=vb->vd->vi->codec_setup;
      codebook *b=ci->fullbooks+info->books[booknum];
      FIXP last=0;
      FIXP *lsp=_vorbis_block_alloc(vb,sizeof(*lsp)*(look->m+1));
            
      for(j=0;j<look->m;j+=b->dim)
	if(vorbis_book_decodev_set(b,lsp+j,&vb->opb,b->dim)==-1)goto eop;
      for(j=0;j<look->m;){
	for(k=0;k<b->dim;k++,j++)lsp[j]+=last;
	last=lsp[j-1];
      }
      
      lsp[look->m]=amp;
      return(lsp);
    }
  }
 eop:
  return(NULL);
}

static int floor0_inverse2(vorbis_block *vb,vorbis_look_floor *i,
			   void *memo,FIXP *out){
  vorbis_look_floor0 *look=(vorbis_look_floor0 *)i;
  vorbis_info_floor0 *info=look->vi;
  
  if(memo){
    FIXP *lsp=(FIXP *)memo;
    FIXP amp=lsp[look->m];

    /* take the coefficients back to a spectral envelope curve */
    vorbis_lsp_to_curve(out,look->linearmap,look->n,look->ln,
			lsp,look->m,amp,info->ampdB);
    return(1);
  }
  memset(out,0,sizeof(*out)*look->n);
  return(0);
}

/* export hooks */
vorbis_func_floor floor0_exportbundle={
  NULL,&floor0_unpack,&floor0_look,NULL,&floor0_free_info,
  &floor0_free_look,NULL,&floor0_inverse1,&floor0_inverse2
};