📄 mp4_predict.c
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/**************************************************************************
* *
* This code has been developed by Andrea Graziani. This software is an *
* implementation of a part of one or more MPEG-4 Video tools as *
* specified in ISO/IEC 14496-2 standard. Those intending to use this *
* software module in hardware or software products are advised that its *
* use may infringe existing patents or copyrights, and any such use *
* would be at such party's own risk. The original developer of this *
* software module and his/her company, and subsequent editors and their *
* companies (including Project Mayo), will have no liability for use of *
* this software or modifications or derivatives thereof. *
* *
* Project Mayo gives users of the Codec a license to this software *
* module or modifications thereof for use in hardware or software *
* products claiming conformance to the MPEG-4 Video Standard as *
* described in the Open DivX license. *
* *
* The complete Open DivX license can be found at *
* http://www.projectmayo.com/opendivx/license.php *
* *
**************************************************************************/
/**
* Copyright (C) 2001 - Project Mayo
*
* Andrea Graziani (Ag)
*
* DivX Advanced Research Center <darc@projectmayo.com>
*
**/
// mp4_predict.c //
#include <math.h>
#include "mp4_vars.h"
#include "mp4_predict.h"
/**
*
**/
static void rescue_predict();
/*
B - C
| |
A - x
*/
void dc_recon(int block_num, short * dc_value)
{
if (mp4_state->hdr.prediction_type == P_VOP) {
rescue_predict();
}
if (block_num < 4)
{
int b_xpos = (mp4_state->hdr.mb_xpos << 1) + (block_num & 1);
int b_ypos = (mp4_state->hdr.mb_ypos << 1) + ((block_num & 2) >> 1);
int dc_pred;
// set prediction direction
if (abs(mp4_state->coeff_pred.dc_store_lum[b_ypos+1-1][b_xpos+1-1] -
mp4_state->coeff_pred.dc_store_lum[b_ypos+1][b_xpos+1-1]) < // Fa - Fb
abs(mp4_state->coeff_pred.dc_store_lum[b_ypos+1-1][b_xpos+1-1] -
mp4_state->coeff_pred.dc_store_lum[b_ypos+1-1][b_xpos+1])) // Fb - Fc
{
mp4_state->coeff_pred.predict_dir = TOP;
dc_pred = mp4_state->coeff_pred.dc_store_lum[b_ypos+1-1][b_xpos+1];
}
else
{
mp4_state->coeff_pred.predict_dir = LEFT;
dc_pred = mp4_state->coeff_pred.dc_store_lum[b_ypos+1][b_xpos+1-1];
}
(* dc_value) += _div_div(dc_pred, mp4_state->hdr.dc_scaler);
(* dc_value) *= mp4_state->hdr.dc_scaler;
// store dc value
mp4_state->coeff_pred.dc_store_lum[b_ypos+1][b_xpos+1] = (* dc_value);
}
else // chrominance blocks
{
int b_xpos = mp4_state->hdr.mb_xpos;
int b_ypos = mp4_state->hdr.mb_ypos;
int chr_num = block_num - 4;
int dc_pred;
// set prediction direction
if (abs(mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1-1][b_xpos+1-1] -
mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1][b_xpos+1-1]) < // Fa - Fb
abs(mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1-1][b_xpos+1-1] -
mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1-1][b_xpos+1])) // Fb - Fc
{
mp4_state->coeff_pred.predict_dir = TOP;
dc_pred = mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1-1][b_xpos+1];
}
else
{
mp4_state->coeff_pred.predict_dir = LEFT;
dc_pred = mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1][b_xpos+1-1];
}
(* dc_value) += _div_div(dc_pred, mp4_state->hdr.dc_scaler);
(* dc_value) *= mp4_state->hdr.dc_scaler;
// store dc value
mp4_state->coeff_pred.dc_store_chr[chr_num][b_ypos+1][b_xpos+1] = (* dc_value);
}
}
/***/
static int saiAcLeftIndex[8] =
{
0, 8,16,24,32,40,48,56
};
void ac_recon(int block_num, short * psBlock)
{
int b_xpos, b_ypos;
int i;
if (block_num < 4) {
b_xpos = (mp4_state->hdr.mb_xpos << 1) + (block_num & 1);
b_ypos = (mp4_state->hdr.mb_ypos << 1) + ((block_num & 2) >> 1);
}
else {
b_xpos = mp4_state->hdr.mb_xpos;
b_ypos = mp4_state->hdr.mb_ypos;
}
// predict coefficients
if (mp4_state->hdr.ac_pred_flag)
{
if (block_num < 4)
{
if (mp4_state->coeff_pred.predict_dir == TOP)
{
for (i = 1; i < 8; i++) // [Review] index can become more efficient [0..7]
psBlock[i] += mp4_state->coeff_pred.ac_top_lum[b_ypos+1-1][b_xpos+1][i-1];
}
else // left prediction
{
for (i = 1; i < 8; i++)
psBlock[mp4_tables->saiAcLeftIndex[i]] += mp4_state->coeff_pred.ac_left_lum[b_ypos+1][b_xpos+1-1][i-1];
}
}
else
{
int chr_num = block_num - 4;
if (mp4_state->coeff_pred.predict_dir == TOP)
{
for (i = 1; i < 8; i++)
psBlock[i] += mp4_state->coeff_pred.ac_top_chr[chr_num][b_ypos+1-1][b_xpos+1][i-1];
}
else // left prediction
{
for (i = 1; i < 8; i++)
psBlock[mp4_tables->saiAcLeftIndex[i]] += mp4_state->coeff_pred.ac_left_chr[chr_num][b_ypos+1][b_xpos+1-1][i-1];
}
}
}
}
/***/
void ac_store(int block_num, short * psBlock)
{
int b_xpos, b_ypos;
int i;
// [Review] This lines of code are repeated frequently
if (block_num < 4) {
b_xpos = (mp4_state->hdr.mb_xpos << 1) + (block_num & 1);
b_ypos = (mp4_state->hdr.mb_ypos << 1) + ((block_num & 2) >> 1);
}
else {
b_xpos = mp4_state->hdr.mb_xpos;
b_ypos = mp4_state->hdr.mb_ypos;
}
// store coefficients
if (block_num < 4)
{
for (i = 1; i < 8; i++) {
mp4_state->coeff_pred.ac_top_lum[b_ypos+1][b_xpos+1][i-1] = psBlock[i];
mp4_state->coeff_pred.ac_left_lum[b_ypos+1][b_xpos+1][i-1] = psBlock[mp4_tables->saiAcLeftIndex[i]];
}
}
else
{
int chr_num = block_num - 4;
for (i = 1; i < 8; i++) {
mp4_state->coeff_pred.ac_top_chr[chr_num][b_ypos+1][b_xpos+1][i-1] = psBlock[i];
mp4_state->coeff_pred.ac_left_chr[chr_num][b_ypos+1][b_xpos+1][i-1] = psBlock[mp4_tables->saiAcLeftIndex[i]];
}
}
}
/***/
#define _rescale(predict_quant, current_quant, coeff) (coeff != 0) ? \
_div_div((coeff) * (predict_quant), (current_quant)) : 0
int ac_rescaling(int block_num, short * psBlock)
{
int mb_xpos = mp4_state->hdr.mb_xpos;
int mb_ypos = mp4_state->hdr.mb_ypos;
int current_quant = mp4_state->hdr.quantizer;
int predict_quant = (mp4_state->coeff_pred.predict_dir == TOP) ?
mp4_state->quant_store[mb_ypos][mb_xpos+1] : mp4_state->quant_store[mb_ypos+1][mb_xpos];
int b_xpos, b_ypos; // index for stored coeff matrix
int i;
if ((! mp4_state->hdr.ac_pred_flag) || (current_quant == predict_quant) || (block_num == 3))
return 0;
if ((mb_ypos == 0) && (mp4_state->coeff_pred.predict_dir == TOP))
return 0;
if ((mb_xpos == 0) && (mp4_state->coeff_pred.predict_dir == LEFT))
return 0;
if ((mb_xpos == 0) && (mb_ypos == 0))
return 0;
// [Review] This lines of code are repeated frequently
if (block_num < 4) {
b_xpos = (mp4_state->hdr.mb_xpos << 1) + (block_num & 1);
b_ypos = (mp4_state->hdr.mb_ypos << 1) + ((block_num & 2) >> 1);
}
else {
b_xpos = mp4_state->hdr.mb_xpos;
b_ypos = mp4_state->hdr.mb_ypos;
}
if (mp4_state->coeff_pred.predict_dir == TOP) // rescale only if really needed
{
switch (block_num)
{
case 0: case 1:
for (i = 1; i < 8; i++)
psBlock[i] += _rescale(predict_quant, current_quant, mp4_state->coeff_pred.ac_top_lum[b_ypos][b_xpos+1][i-1]);
return 1;
break;
case 4:
for (i = 1; i < 8; i++)
psBlock[i] += _rescale(predict_quant, current_quant, mp4_state->coeff_pred.ac_top_chr[0][b_ypos][b_xpos+1][i-1]);
return 1;
break;
case 5:
for (i = 1; i < 8; i++)
psBlock[i] += _rescale(predict_quant, current_quant, mp4_state->coeff_pred.ac_top_chr[1][b_ypos][b_xpos+1][i-1]);
return 1;
break;
}
}
else
{
switch (block_num)
{
case 0: case 2:
for (i = 1; i < 8; i++)
psBlock[mp4_tables->saiAcLeftIndex[i]] += _rescale(predict_quant, current_quant, mp4_state->coeff_pred.ac_left_lum[b_ypos+1][b_xpos][i-1]);
return 1;
break;
case 4:
for (i = 1; i < 8; i++)
psBlock[mp4_tables->saiAcLeftIndex[i]] += _rescale(predict_quant, current_quant, mp4_state->coeff_pred.ac_left_chr[0][b_ypos+1][b_xpos][i-1]);
return 1;
break;
case 5:
for (i = 1; i < 8; i++)
psBlock[mp4_tables->saiAcLeftIndex[i]] += _rescale(predict_quant, current_quant, mp4_state->coeff_pred.ac_left_chr[1][b_ypos+1][b_xpos][i-1]);
return 1;
break;
}
}
return 0;
}
/***/
#define _IsIntra(mb_y, mb_x) ((mp4_state->modemap[(mb_y)+1][(mb_x)+1] == INTRA) || \
(mp4_state->modemap[(mb_y)+1][(mb_x)+1] == INTRA_Q))
static void rescue_predict()
{
int mb_xpos = mp4_state->hdr.mb_xpos;
int mb_ypos = mp4_state->hdr.mb_ypos;
int i;
if (! _IsIntra(mb_ypos-1, mb_xpos-1)) {
// rescue -A- DC value
mp4_state->coeff_pred.dc_store_lum[2*mb_ypos+1-1][2*mb_xpos+1-1] = 1024;
mp4_state->coeff_pred.dc_store_chr[0][mb_ypos+1-1][mb_xpos+1-1] = 1024;
mp4_state->coeff_pred.dc_store_chr[1][mb_ypos+1-1][mb_xpos+1-1] = 1024;
}
// left
if (! _IsIntra(mb_ypos, mb_xpos-1)) {
// rescue -B- DC values
mp4_state->coeff_pred.dc_store_lum[2*mb_ypos+1][2*mb_xpos+1-1] = 1024;
mp4_state->coeff_pred.dc_store_lum[2*mb_ypos+1+1][2*mb_xpos+1-1] = 1024;
mp4_state->coeff_pred.dc_store_chr[0][mb_ypos+1][mb_xpos+1-1] = 1024;
mp4_state->coeff_pred.dc_store_chr[1][mb_ypos+1][mb_xpos+1-1] = 1024;
// rescue -B- AC values
for(i = 0; i < 7; i++) {
mp4_state->coeff_pred.ac_left_lum[2*mb_ypos+1][2*mb_xpos+1-1][i] = 0;
mp4_state->coeff_pred.ac_left_lum[2*mb_ypos+1+1][2*mb_xpos+1-1][i] = 0;
mp4_state->coeff_pred.ac_left_chr[0][mb_ypos+1][mb_xpos+1-1][i] = 0;
mp4_state->coeff_pred.ac_left_chr[1][mb_ypos+1][mb_xpos+1-1][i] = 0;
}
}
// top
if (! _IsIntra(mb_ypos-1, mb_xpos)) {
// rescue -C- DC values
mp4_state->coeff_pred.dc_store_lum[2*mb_ypos+1-1][2*mb_xpos+1] = 1024;
mp4_state->coeff_pred.dc_store_lum[2*mb_ypos+1-1][2*mb_xpos+1+1] = 1024;
mp4_state->coeff_pred.dc_store_chr[0][mb_ypos+1-1][mb_xpos+1] = 1024;
mp4_state->coeff_pred.dc_store_chr[1][mb_ypos+1-1][mb_xpos+1] = 1024;
// rescue -C- AC values
for(i = 0; i < 7; i++) {
mp4_state->coeff_pred.ac_top_lum[2*mb_ypos+1-1][2*mb_xpos+1][i] = 0;
mp4_state->coeff_pred.ac_top_lum[2*mb_ypos+1-1][2*mb_xpos+1+1][i] = 0;
mp4_state->coeff_pred.ac_top_chr[0][mb_ypos+1-1][mb_xpos+1][i] = 0;
mp4_state->coeff_pred.ac_top_chr[1][mb_ypos+1-1][mb_xpos+1][i] = 0;
}
}
}
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