ref: 4da5aaebe94a8a13ceea2c001b1fd5161ef33e9b
dir: /libfaac/backpred.c/
/*
* FAAC - Freeware Advanced Audio Coder
* Copyright (C) 2001 Menno Bakker
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: backpred.c,v 1.1 2001/05/02 05:40:15 menno Exp $
*/
/**********************************************************************
INPUT:
act_spec[]: the current frame's spectral components to be encoded.
last_spec[]: the previous frame's quantized spectral error components
btype: the current frame's window type
nsfb: the number of scalefactor bands
isfb_width[]: scalefactor bandwidth
OUTPUT:
act_spec[]: the current frame's spectral error components to be encoded
pred_global_flag: global prediction enable/disable flag
pred_sbf_glag[]: enable/disable flag for each scalefactor band
reset_group: number for the reset group => if -1, then no reset
***********************************************************************/
#include <math.h>
#include "coder.h"
#include "channels.h"
#include "backpred.h"
/* Make these work for mulitchannels */ /* CL, 1/98 */
/*static int psy_init = 0;
static float dr[LPC][FLEN_LONG/2],e[LPC+1+1][FLEN_LONG/2];
static float K[LPC+1][FLEN_LONG/2], R[LPC+1][FLEN_LONG/2];
static float VAR[LPC+1][FLEN_LONG/2], KOR[LPC+1][FLEN_LONG/2];
static float sb_samples_pred[FLEN_LONG/2];
static int thisLineNeedsResetting[FLEN_LONG/2];
static int reset_count = 0;*/
static int psy_init_mc[MAX_CHANNELS];
static float dr_mc[MAX_CHANNELS][LPC][FLEN_LONG/2],e_mc[MAX_CHANNELS][LPC+1+1][FLEN_LONG/2];
static float K_mc[MAX_CHANNELS][LPC+1][FLEN_LONG/2], R_mc[MAX_CHANNELS][LPC+1][FLEN_LONG/2];
static float VAR_mc[MAX_CHANNELS][LPC+1][FLEN_LONG/2], KOR_mc[MAX_CHANNELS][LPC+1][FLEN_LONG/2];
static float sb_samples_pred_mc[MAX_CHANNELS][FLEN_LONG/2];
static int thisLineNeedsResetting_mc[MAX_CHANNELS][FLEN_LONG/2];
static int reset_count_mc[MAX_CHANNELS];
/* Max prediction band as function of fs index */
int MAX_PRED_SFB[][2] = {
{96000,33},
{88200,33},
{64000,38},
{48000,40},
{44100,40},
{32000,40},
{24000,41},
{22050,41},
{16000,37},
{12000,37},
{11025,37},
{8000,34},
{-1,0}};
int GetMaxPredSfb(int samplingRateIdx)
{
return MAX_PRED_SFB[samplingRateIdx][1];
}
void PredInit()
{
int i;
for (i=0;i<MAX_CHANNELS;i++) {
psy_init_mc[i] = 0;
reset_count_mc[i] = 0;
}
}
void PredCalcPrediction( double *act_spec, double *last_spec, int btype,
int nsfb,
int *isfb_width,
CoderInfo *coderInfo,
ChannelInfo *channelInfo, /* Pointer to Ch_Info */
int chanNum)
{
int i, k, j, cb_long;
int leftChanNum;
int isRightWithCommonWindow;
float small, small_p, num_bit, snr[SBMAX_L];
float energy[FLEN_LONG/2], snr_p[FLEN_LONG/2], temp1, temp2;
ChannelInfo *thisChannel;
/* Set pointers for specified channel number */
/* int psy_init; */
int *psy_init;
float (*dr)[FLEN_LONG/2],(*e)[FLEN_LONG/2];
float (*K)[FLEN_LONG/2], (*R)[FLEN_LONG/2];
float (*VAR)[FLEN_LONG/2], (*KOR)[FLEN_LONG/2];
float *sb_samples_pred;
int *thisLineNeedsResetting;
/* int reset_count; */
int *reset_count;
int *pred_global_flag;
int *pred_sfb_flag;
int *reset_group;
/* Set pointers for this chanNum */
pred_global_flag = &(coderInfo[chanNum].pred_global_flag);
pred_sfb_flag = coderInfo[chanNum].pred_sfb_flag;
reset_group = &(coderInfo[chanNum].reset_group_number);
/* psy_init = psy_init_mc[chanNum]; */
psy_init = &psy_init_mc[chanNum];
dr = &dr_mc[chanNum][0];
e = &e_mc[chanNum][0];
K = &K_mc[chanNum][0];
R = &R_mc[chanNum][0];
VAR = &VAR_mc[chanNum][0];
KOR = &KOR_mc[chanNum][0];
sb_samples_pred = &sb_samples_pred_mc[chanNum][0];
thisLineNeedsResetting = &thisLineNeedsResetting_mc[chanNum][0];
reset_count = &reset_count_mc[chanNum];
thisChannel = &(channelInfo[chanNum]);
*psy_init = (*psy_init && (btype!=2));
if((*psy_init) == 0) {
for (j=0; j<FLEN_LONG/2; j++) {
thisLineNeedsResetting[j]=1;
}
*psy_init = 1;
}
if (btype==2) {
pred_global_flag[0]=0;
/* SHORT WINDOWS reset all the co-efficients */
if (thisChannel->ch_is_left) {
(*reset_count)++;
if (*reset_count >= 31 * RESET_FRAME)
*reset_count = RESET_FRAME;
/* *reset_count = ((*reset_count) / RESET_FRAME) * RESET_FRAME;*/
}
return;
}
/**************************************************/
/* Compute state using last_spec */
/**************************************************/
for (i=0;i<FLEN_LONG/2;i++)
{
/* e[0][i]=last_spec[i]; */
e[0][i]=last_spec[i]+sb_samples_pred[i];
for(j=1;j<=LPC;j++)
e[j][i] = e[j-1][i]-K[j][i]*R[j-1][i];
for(j=1;j<LPC;j++)
dr[j][i] = K[j][i]*e[j-1][i];
for(j=1;j<=LPC;j++) {
VAR[j][i] = ALPHA*VAR[j][i]+.5*(R[j-1][i]*R[j-1][i]+e[j-1][i]*e[j-1][i]);
KOR[j][i] = ALPHA*KOR[j][i]+R[j-1][i]*e[j-1][i];
}
for(j=LPC-1;j>=1;j--)
R[j][i] = A*(R[j-1][i]-dr[j][i]);
R[0][i] = A*e[0][i];
}
/**************************************************/
/* Reset state here if resets were sent */
/**************************************************/
for (i=0;i<FLEN_LONG/2;i++) {
if (thisLineNeedsResetting[i]) {
for (j = 0; j <= LPC; j++)
{
K[j][i] = 0.0;
e[j][i] = 0.0;
R[j][i] = 0.0;
VAR[j][i] = 1.0;
KOR[j][i] = 0.0;
dr[j][i] = 0.0;
}
}
}
/**************************************************/
/* Compute predictor coefficients, predicted data */
/**************************************************/
for (i=0;i<FLEN_LONG/2;i++)
{
for(j=1;j<=LPC;j++) {
if(VAR[j][i]>MINVAR)
K[j][i] = KOR[j][i]/VAR[j][i]*B;
else
K[j][i] = 0;
}
}
for (k=0; k<FLEN_LONG/2; k++)
{
sb_samples_pred[k]=0.0;
for (i=1; i<=LPC; i++)
sb_samples_pred[k]+=K[i][k]*R[i-1][k];
}
/***********************************************************/
/* If this is the right channel of a channel_pair_element, */
/* AND common_window is 1 in this channel_pair_element, */
/* THEN copy predictor data to use from the left channel. */
/* ELSE determine independent predictor data and resets. */
/***********************************************************/
/* BE CAREFUL HERE, this assumes that predictor data has */
/* already been determined for the left channel!! */
/***********************************************************/
isRightWithCommonWindow = 0; /* Is this a right channel with common_window?*/
if ((thisChannel->cpe)&&( !(thisChannel->ch_is_left))) {
leftChanNum = thisChannel->paired_ch;
if (channelInfo[leftChanNum].common_window) {
isRightWithCommonWindow = 1;
}
}
if (isRightWithCommonWindow) {
/**************************************************/
/* Use predictor data from the left channel. */
/**************************************************/
CopyPredInfo(&(coderInfo[chanNum]),&(coderInfo[leftChanNum]));
/* Make sure to turn off bands with intensity stereo */
#if 0
if (thisChannel->is_info.is_present) {
for (i=0; i<nsfb; i++) {
if (thisChannel->is_info.is_used[i]) {
pred_sfb_flag[i] = 0;
}
}
}
#endif
cb_long=0;
for (i=0; i<nsfb; i++)
{
if (!pred_sfb_flag[i]) {
for (j=cb_long; j<cb_long+isfb_width[i]; j++)
sb_samples_pred[j]=0.0;
}
cb_long+=isfb_width[i];
}
/* Disable prediction for bands nsfb through SBMAX_L */
for (i=j;i<FLEN_LONG/2;i++) {
sb_samples_pred[i]=0.0;
}
for (i=nsfb;i<SBMAX_L;i++) {
pred_sfb_flag[i]=0;
}
/* Is global enable set, if not enabled predicted samples are zeroed */
if(!pred_global_flag[0]) {
for (j=0; j<FLEN_LONG/2; j++)
sb_samples_pred[j]=0.0;
}
for (j=0; j<FLEN_LONG/2; j++)
act_spec[j]-=sb_samples_pred[j];
} else {
/**************************************************/
/* Determine whether to enable/disable prediction */
/**************************************************/
for (k=0; k<FLEN_LONG/2; k++)
{energy[k]=act_spec[k]*act_spec[k];
snr_p[k]=(act_spec[k]-sb_samples_pred[k])*(act_spec[k]-sb_samples_pred[k]);
}
cb_long=0;
for (i=0; i<nsfb; i++)
{
pred_sfb_flag[i]=1;
temp1=0.0;
temp2=0.0;
for (j=cb_long; j<cb_long+isfb_width[i]; j++)
{temp1+=energy[j]; temp2+=snr_p[j];}
if(temp2<1.e-20) temp2=1.e-20;
if(temp1!=0.0) {snr[i]=-10.*log10((double ) temp2/temp1);}
else snr[i]=0.0;
if(snr[i]<=0.0) {pred_sfb_flag[i]=0;
for (j=cb_long; j<cb_long+isfb_width[i]; j++)
sb_samples_pred[j]=0.0; }
cb_long+=isfb_width[i];
}
/* Disable prediction for bands nsfb through SBMAX_L */
for (i=j;i<FLEN_LONG/2;i++) {
sb_samples_pred[i]=0.0;
}
for (i=nsfb;i<SBMAX_L;i++) {
pred_sfb_flag[i]=0;
}
num_bit=0.0;
for (i=0; i<nsfb; i++)
if(snr[i]>0.0) num_bit+=snr[i]/6.*isfb_width[i];
/* Determine global enable, if not enabled predicted samples are zeroed */
pred_global_flag[0]=1;
if(num_bit<50) {
pred_global_flag[0]=0; num_bit=0.0;
for (j=0; j<FLEN_LONG/2; j++)
sb_samples_pred[j]=0.0;
}
for (j=0; j<FLEN_LONG/2; j++)
act_spec[j]-=sb_samples_pred[j];
}
/**********************************************************/
/* If this is a left channel, determine pred resets. */
/* If this is a right channel, using pred reset data from */
/* left channel. Keep left and right resets in sync. */
/**********************************************************/
if ((thisChannel->cpe)&&( !(thisChannel->ch_is_left))) {
/* if (!thisChannel->ch_is_left) {*/
/**********************************************************/
/* Using predictor reset data from the left channel. */
/**********************************************************/
reset_count = &reset_count_mc[leftChanNum];
/* Reset the frame counter */
for (i=0;i<FLEN_LONG/2;i++) {
thisLineNeedsResetting[i]=0;
}
reset_group = &(coderInfo[chanNum].reset_group_number);
if (*reset_count % RESET_FRAME == 0)
{ /* Send a reset in this frame */
*reset_group = *reset_count / 8;
for (i = *reset_group - 1; i < FLEN_LONG / 2; i += 30)
{
thisLineNeedsResetting[i]=1;
}
}
else
*reset_group = -1;
} else {
/* Code segment added by JB */
/******************************************************************/
/* Determine whether a prediction reset is required - if so, then */
/* set reset flag for the appropriate group. */
/******************************************************************/
/* Increase counter on left channel, keep left and right resets in sync */
(*reset_count)++;
/* Reset the frame counter */
for (i=0;i<FLEN_LONG/2;i++) {
thisLineNeedsResetting[i]=0;
}
if (*reset_count >= 31 * RESET_FRAME)
*reset_count = RESET_FRAME;
if (*reset_count % RESET_FRAME == 0)
{ /* Send a reset in this frame */
*reset_group = *reset_count / 8;
for (i = *reset_group - 1; i < FLEN_LONG / 2; i += 30)
{
thisLineNeedsResetting[i]=1;
}
}
else
*reset_group = -1;
/* End of code segment */
}
/* Code segment added by JB */
/* Ensure that prediction data is sent when there is a prediction
* reset.
*/
if (*reset_group != -1 && pred_global_flag[0] == 0)
{
pred_global_flag[0] = 1;
for (i = 0; i < nsfb; i++)
pred_sfb_flag[i] = 0;
}
/* End of code segment */
}
void CopyPredInfo(CoderInfo *right, CoderInfo *left)
{
int band;
right->pred_global_flag = left->pred_global_flag;
right->reset_group_number = left->reset_group_number;
for (band = 0; band<MAX_SCFAC_BANDS; band++) {
right->pred_sfb_flag[band] = left->pred_sfb_flag[band];
}
}