?? mp4_iquant.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_iquant.c //
#include "mp4_vars.h"
#include "mp4_predict.h"
#include "mp4_iquant.h"
/**
* inverse quantization for intra blocks
**/
#define _iquant_h263(coeff, q_2scale, q_add) if ((coeff) != 0) { \
if ((coeff) > 0) { \
(coeff) = ((q_2scale) * (coeff)) + (q_add); } \
else if ((coeff) < 0) { \
(coeff) *= -1; \
(coeff) = ((q_2scale) * (coeff)) + (q_add); \
(coeff) *= -1; } \
}
/**
*
**/
// iquant type h.263, not optimized
//
__inline void iquant (short * psblock, int intraFlag)
{
int i;
int q_scale = mp4_state->hdr.quantizer;
int q_2scale = q_scale << 1;
int q_add = (q_scale & 1) ? q_scale : (q_scale - 1);
for (i = intraFlag; i < 64; i++)
{
_iquant_h263(psblock[i], q_2scale, q_add);
}
}
void iquant_typefirst (short * psblock)
{
int i;
for (i = 1; i < 64; i++)
{
if (psblock[i] != 0) {
psblock[i] = (psblock[i] * 2 * mp4_state->hdr.quantizer *
mp4_tables->intra_quant_matrix[mp4_tables->zig_zag_scan[i]]) >> 4;
}
}
}
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