son_gc_detecter.c

MPEG2/MPEG4编解码参考程序(实现了MPEG4的部分功能)

/*******************************************************************
This software module was originally developed by

Yoshiaki Oikawa (Sony Corporation) and
Mitsuyuki Hatanaka (Sony Corporation)

and edited by
Takashi Koike (Sony Corporation)
Yasuhiro Toguri (Sony Corporation)

in the course of development of the MPEG-2 NBC/MPEG-4 System/MPEG-4
Video/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and 3. This
software module is an implementation of a part of one or more MPEG-2
NBC/MPEG-4 System/MPEG-4 Video/MPEG-4 Audio tools as specified by the
MPEG-2 NBC/MPEG-4 System/MPEG-4 Video/MPEG-4 Audio standard. ISO/IEC
gives users of the MPEG-2 NBC/MPEG-4 System/MPEG-4 Video/MPEG-4 Audio
standards free license to this software module or modifications
thereof for use in hardware or software products claiming conformance
to the MPEG-2 NBC/MPEG-4 System/MPEG-4 Video/MPEG-4 Audio
standards. Those intending to use this software module in hardware or
software products are advised that this use may infringe existing
patents. The original developer of this software module and his/her
company, the subsequent editors and their companies, and ISO/IEC have
no liability for use of this software module or modifications thereof
in an implementation. Copyright is not released for non MPEG-2
NBC/MPEG-4 System/MPEG-4 Video/MPEG-4 Audio conforming products.The
original developer retains full right to use the code for his/her own
purpose, assign or donate the code to a third party and to inhibit
third party from using the code for non MPEG-2 NBC/MPEG-4
System/MPEG-4 Video/MPEG-4 Audio conforming products. This copyright
notice must be included in all copies or derivative works.

Copyright (C) 1996.
*******************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include "buffersHandle.h"       /* handler, defines, enums */
#include "resilienceHandle.h"    /* handler, defines, enums */
#include "tf_mainHandle.h"       /* handler, defines, enums */

#include "sony_local.h"

int     son_lngainof_id(int);
int     son_idof_lngain(int);
void son_detect_gc_short(double , double *,GAINC *);


/*******************************************************************************
  Detect Peak Value
*******************************************************************************/
double	son_get_peak(
	double	*p_buf,
	int	nsamples,
	int	windowSequence
	)
{

	int	isamp0, nsamps_inpart;
	double	absd, peakmax, peak;
	double	a_peak[NPEPARTS];
	int	i, j, start, end;

	nsamps_inpart = nsamples / NPEPARTS;
	isamp0 = nsamples/2;
	for (i = 0; i < NPEPARTS; ++i) {
		a_peak[i] = 0.0;
		for (j = 0; j < nsamps_inpart; ++j) {
			absd = fabs ((double) p_buf[isamp0 + j]);
			if (absd > a_peak[i]) {
				a_peak[i] = absd;
			}
		}
		isamp0 += nsamps_inpart;
	}

	if(windowSequence == LONG_START_SEQUENCE){
		start = 14;
		end = 18;
	}
	else{
		start = 0;
		end = NPEPARTS/2;
	}

	peakmax = 0.0;
	for (i = start; i < end; ++i) {
		if (a_peak[i] > peakmax) {
			peakmax = a_peak[i];
		}
	}
	peak = peakmax;

	return(peak);
}
	

/*****************************************************************************
  son_detect_gc_short

  Gain changes in the short windows are detected.

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

void 
son_detect_gc_short(double prev_peak, 
					 double *a_peak,
					 GAINC *p_gainc1)
{
	int i, j;

	int s = 1; /* for starting the argument of array from -1 */
	int N;
	float r[5], v[6];
	int g[5]; 

	for( i = 0; i < 8; i++ ) {

		N = 4*i; /* constant value to specify the short window */

		/* peak values are copied to region values */
		if(i==0) v[-1+s] = prev_peak;
		else     v[-1+s] = a_peak[N-1];

		for(j=0; j<4; j++) {
			v[j+s] = a_peak[j+N];
		}
		v[4+s] = a_peak[4+N];

		/* calculate Gain Ratio */
		for(j=-1; j<3; j++) {
			if(v[3+s] >  0.0 && v[j+s] > 0.0) {
				if(v[j+s] > 1.0) r[j+s] = v[3+s] / v[j+s];
				else                     r[j+s] = v[3+s] / 1.0;
			}
			else
			   r[j+s] = 1.0;
		}
		if(v[4+s] >  0.0 && v[3+s] > 0.0) {
			if(v[3+s] > 1.0) r[3+s] = v[4+s] / v[3+s];
			else                     r[3+s] = v[4+s] / 1.0;
		}
		else
		   r[3+s] = 1.0;

		/* calculate log . YT slight modify added (int) */
		for(j=-1; j<4; j++) {
			if(r[j+s] >= 1.0) g[j+s] = (int)floor(log10(r[j+s])/log10(2));
			else             g[j+s] = (int)ceil(log10(r[j+s])/log10(2));
		}

		/* */
      for(j=-1; j<4; j++) {
			if(j == 3) g[j+s] = g[3+s];
			else       g[j+s] = g[j+s] + g[3+s];
		}

		/* limiting */
		for(j=-1; j<4; j++) {
			if(g[j+s] > 11) g[j+s] = 11;
			if(g[j+s] < -4) g[j+s] = -4;
		}

		/* detect gain change */
		p_gainc1[i].natks = 0;
		for(j=0; j<3; j++) {

			/* detect attack */
			if(g[j-1+s] >= g[j+s] && g[j+s] > g[j+1+s]) {
				p_gainc1[i].a_loc[p_gainc1[i].natks] = j;
				p_gainc1[i].a_idgain[p_gainc1[i].natks] 
				= son_idof_lngain(g[j+s]);
				p_gainc1[i].natks++;
			}
			if(p_gainc1[i].natks > 7) break;

			/* detect release */
			if(g[j-1+s] < g[j+s] && g[j+s] <= g[j+1+s]) {
				if(j != 0 || g[j-1+s] != 0) { 
					p_gainc1[i].a_loc[p_gainc1[i].natks] = j;
					p_gainc1[i].a_idgain[p_gainc1[i].natks] 
					= son_idof_lngain(g[j-1+s]);
					p_gainc1[i].natks++;
				}
			}
			if(p_gainc1[i].natks > 7) break;
		}

		/* detect attack for the end of the region */
		if(p_gainc1[i].natks < 7) {
			if(g[3+s] > 1) {
				p_gainc1[i].a_loc[p_gainc1[i].natks] = 3;
				p_gainc1[i].a_idgain[p_gainc1[i].natks] 
				= son_idof_lngain(g[3+s]);
				p_gainc1[i].natks++;
			}
		}

		if(p_gainc1[i].natks > 0 
		&& p_gainc1[i].a_idgain[p_gainc1[i].natks-1] == son_idof_lngain(0)) {
			p_gainc1[i].natks--;
		}
	}

	p_gainc1[j].peak = v[3+s]; /* set the peak value for next frame */

} /* son_detect_gc_short */


/*******************************************************************************
	Locate PreEcho Position 

	I: *p_buf	: Data Buffer to be Scanned
	I: nsamples	: Num of Samples in Data Buffer
	I: *p_gainc0	: Gain Control Info for 1st Half
	O: *p_gainc1	: Gain Control Info for 2nd Half

	"nsamples*(NPEPARTS+1)/NPEPARTS" samples are assumed to be
	in the p_buf[].
*******************************************************************************/

void 
son_set_gainc(double *p_buf, 
			 int nsamples, 
			 GAINC *p_gainc0, 
			 GAINC *p_gainc1)
{
	int	i, j;
	int	isamp0, nsamps_inpart, idgain;
	int	idgain_total;
	double	absd;
	double	a_peak[NPEPARTS];
	GAINC a_attack;

	a_attack.natks = 0;
	idgain_total = 0;
	idgain = 0;

	/* search the max value of each sub_block  */
	nsamps_inpart = nsamples / NPEPARTS;
	isamp0 = 144;
	for (i = 0; i < NPEPARTS; ++i) {
		a_peak[i] = 0.0;
		for (j = 0; j < nsamps_inpart; ++j) {
			absd = fabs ((double) p_buf[j + isamp0]);
			if (absd > a_peak[i]) {
				a_peak[i] = absd;
			}
		}
		isamp0 += nsamps_inpart;
	}

	/**************************/
	/** Detect in Short Area **/
	/**************************/
	son_detect_gc_short(p_gainc0->peak, a_peak, p_gainc1);

} /* set_gainc */


/*******************************************************************************
  gain detect
*******************************************************************************/
void	son_gc_detect(
	double	*bandSigChForGCAnalysis[],
	int	block_size_samples,
	int	window_sequence,
	int	ch,
	GAINC	*g_info_curCh[]
	)
{
	/* This parameter will be removed outside */
	static	GAINC	g_info_prev[MAX_TIME_CHANNELS][NBANDS];

	int	i;

	for (i = 1; i < NBANDS; i++) {
		switch(window_sequence) {
		case EIGHT_SHORT_SEQUENCE:
			son_set_gainc(bandSigChForGCAnalysis[i],
					block_size_samples/NBANDS*2,
					&g_info_prev[ch][i],
					g_info_curCh[i]);
			g_info_prev[ch][i] = g_info_curCh[i][SHORT_WIN_IN_LONG - 1];
			break;
		case ONLY_LONG_SEQUENCE:
			g_info_curCh[i][0].peak =
				son_get_peak(bandSigChForGCAnalysis[i],
						block_size_samples/NBANDS*2,
						ONLY_LONG_SEQUENCE);
			g_info_prev[ch][i] = g_info_curCh[i][0];
			g_info_curCh[i][0].natks = 0;
			break;
		case LONG_START_SEQUENCE:
			g_info_curCh[i][1].peak =
				son_get_peak(bandSigChForGCAnalysis[i],
						block_size_samples/NBANDS*2,
						LONG_START_SEQUENCE);
			g_info_prev[ch][i] = g_info_curCh[i][1];
			g_info_curCh[i][0].natks = 0;
			break;
		case LONG_STOP_SEQUENCE:
			g_info_curCh[i][1].peak =
				son_get_peak(bandSigChForGCAnalysis[i],
						block_size_samples/NBANDS*2,
						LONG_STOP_SEQUENCE);
			g_info_prev[ch][i] = g_info_curCh[i][1];
			g_info_curCh[i][0].natks = 0;
			break;
		default:
			fprintf(stderr, "invalid window_sequence: %d\n", window_sequence);
			exit(-1);
			break;
		}
	}
}