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synthesis.c
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synthesis.c
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/********************************************************************
* *
* THIS FILE IS PART OF THE OggVorbis 'TREMOR' 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 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2003 *
* BY THE Xiph.Org FOUNDATION http://www.xiph.org/ *
* *
********************************************************************
function: single-block PCM synthesis
last mod: $Id: synthesis.c,v 1.4 2003/03/29 03:07:21 xiphmont Exp $
********************************************************************/
#include <stdio.h>
#include <ogg/ogg.h>
#include "ivorbiscodec.h"
#include "codec_internal.h"
#include "registry.h"
#include "misc.h"
#include "block.h"
static int _vorbis_synthesis1(vorbis_block *vb,ogg_packet *op,int decodep){
vorbis_dsp_state *vd= vb ? vb->vd : 0;
private_state *b= vd ? (private_state *)vd->backend_state: 0;
vorbis_info *vi= vd ? vd->vi : 0;
codec_setup_info *ci= vi ? (codec_setup_info *)vi->codec_setup : 0;
oggpack_buffer *opb=vb ? &vb->opb : 0;
int type,mode,i;
if (!vd || !b || !vi || !ci || !opb) {
return OV_EBADPACKET;
}
/* first things first. Make sure decode is ready */
_vorbis_block_ripcord(vb);
oggpack_readinit(opb,op->packet,op->bytes);
/* Check the packet type */
if(oggpack_read(opb,1)!=0){
/* Oops. This is not an audio data packet */
return(OV_ENOTAUDIO);
}
/* read our mode and pre/post windowsize */
mode=oggpack_read(opb,b->modebits);
if(mode==-1)return(OV_EBADPACKET);
vb->mode=mode;
if(!ci->mode_param[mode]){
return(OV_EBADPACKET);
}
vb->W=ci->mode_param[mode]->blockflag;
if(vb->W){
vb->lW=oggpack_read(opb,1);
vb->nW=oggpack_read(opb,1);
if(vb->nW==-1) return(OV_EBADPACKET);
}else{
vb->lW=0;
vb->nW=0;
}
/* more setup */
vb->granulepos=op->granulepos;
vb->sequence=op->packetno-3; /* first block is third packet */
vb->eofflag=op->e_o_s;
if(decodep){
/* alloc pcm passback storage */
vb->pcmend=ci->blocksizes[vb->W];
vb->pcm=(ogg_int32_t **)_vorbis_block_alloc(vb,sizeof(*vb->pcm)*vi->channels);
for(i=0;i<vi->channels;i++)
vb->pcm[i]=(ogg_int32_t *)_vorbis_block_alloc(vb,vb->pcmend*sizeof(*vb->pcm[i]));
/* unpack_header enforces range checking */
type=ci->map_type[ci->mode_param[mode]->mapping];
return(_mapping_P[type]->inverse(vb,b->mode[mode]));
}else{
/* no pcm */
vb->pcmend=0;
vb->pcm=NULL;
return(0);
}
}
int vorbis_synthesis(vorbis_block *vb,ogg_packet *op){
return _vorbis_synthesis1(vb,op,1);
}
/* used to track pcm position without actually performing decode.
Useful for sequential 'fast forward' */
int vorbis_synthesis_trackonly(vorbis_block *vb,ogg_packet *op){
return _vorbis_synthesis1(vb,op,0);
}
long vorbis_packet_blocksize(vorbis_info *vi,ogg_packet *op){
codec_setup_info *ci=(codec_setup_info *)vi->codec_setup;
oggpack_buffer opb;
int mode;
oggpack_readinit(&opb,op->packet,op->bytes);
/* Check the packet type */
if(oggpack_read(&opb,1)!=0){
/* Oops. This is not an audio data packet */
return(OV_ENOTAUDIO);
}
{
int modebits=0;
int v=ci->modes;
while(v>1){
modebits++;
v>>=1;
}
/* read our mode and pre/post windowsize */
mode=oggpack_read(&opb,modebits);
}
if(mode==-1)return(OV_EBADPACKET);
return(ci->blocksizes[ci->mode_param[mode]->blockflag]);
}