/***************************************************************************** * * XVID MPEG-4 VIDEO CODEC * - Mpeg4 quantization/dequantization functions - * * Copyright(C) 2002 Peter Ross * * This file is part of XviD, a free MPEG-4 video encoder/decoder * * XviD 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 * * Under section 8 of the GNU General Public License, the copyright * holders of XVID explicitly forbid distribution in the following * countries: * * - Japan * - United States of America * * Linking XviD statically or dynamically with other modules is making a * combined work based on XviD. Thus, the terms and conditions of the * GNU General Public License cover the whole combination. * * As a special exception, the copyright holders of XviD give you * permission to link XviD with independent modules that communicate with * XviD solely through the VFW1.1 and DShow interfaces, regardless of the * license terms of these independent modules, and to copy and distribute * the resulting combined work under terms of your choice, provided that * every copy of the combined work is accompanied by a complete copy of * the source code of XviD (the version of XviD used to produce the * combined work), being distributed under the terms of the GNU General * Public License plus this exception. An independent module is a module * which is not derived from or based on XviD. * * Note that people who make modified versions of XviD are not obligated * to grant this special exception for their modified versions; it is * their choice whether to do so. The GNU General Public License gives * permission to release a modified version without this exception; this * exception also makes it possible to release a modified version which * carries forward this exception. * * $Id: quant_mpeg4.c,v 1.8 2002-12-15 01:21:12 edgomez Exp $ * ****************************************************************************/ #include "quant_mpeg4.h" #include "quant_matrix.h" /***************************************************************************** * Function pointers ****************************************************************************/ quant_intraFuncPtr quant4_intra; quant_intraFuncPtr dequant4_intra; dequant_interFuncPtr dequant4_inter; quant_interFuncPtr quant4_inter; /***************************************************************************** * Local data ****************************************************************************/ #define DIV_DIV(A,B) ( (A) > 0 ? ((A)+((B)>>1))/(B) : ((A)-((B)>>1))/(B) ) #define SIGN(A) ((A)>0?1:-1) #define VM18P 3 #define VM18Q 4 /* * divide-by-multiply table * need 17 bit shift (16 causes slight errors when q > 19) */ #define SCALEBITS 17 #define FIX(X) ((1UL << SCALEBITS) / (X) + 1) static const uint32_t multipliers[32] = { 0, FIX(2), FIX(4), FIX(6), FIX(8), FIX(10), FIX(12), FIX(14), FIX(16), FIX(18), FIX(20), FIX(22), FIX(24), FIX(26), FIX(28), FIX(30), FIX(32), FIX(34), FIX(36), FIX(38), FIX(40), FIX(42), FIX(44), FIX(46), FIX(48), FIX(50), FIX(52), FIX(54), FIX(56), FIX(58), FIX(60), FIX(62) }; /***************************************************************************** * Functions ****************************************************************************/ #if 0 /* quantize intra-block */ // const int32_t quantd = DIV_DIV(VM18P*quant, VM18Q); // // level = DIV_DIV(16 * data[i], default_intra_matrix[i]); // coeff[i] = (level + quantd) / quant2; #endif void quant4_intra_c(int16_t * coeff, const int16_t * data, const uint32_t quant, const uint32_t dcscalar) { const uint32_t quantd = ((VM18P * quant) + (VM18Q / 2)) / VM18Q; const uint32_t mult = multipliers[quant]; uint32_t i; int16_t *intra_matrix; intra_matrix = get_intra_matrix(); coeff[0] = (int16_t)(DIV_DIV(data[0], (int32_t) dcscalar)); for (i = 1; i < 64; i++) { if (data[i] < 0) { uint32_t level = -data[i]; level = ((level << 4) + (intra_matrix[i] >> 1)) / intra_matrix[i]; level = ((level + quantd) * mult) >> 17; coeff[i] = -(int16_t) level; } else if (data[i] > 0) { uint32_t level = data[i]; level = ((level << 4) + (intra_matrix[i] >> 1)) / intra_matrix[i]; level = ((level + quantd) * mult) >> 17; coeff[i] = (int16_t)level; } else { coeff[i] = 0; } } } /* dequantize intra-block & clamp to [-2048,2047] */ /* data[i] = (coeff[i] * default_intra_matrix[i] * quant2) >> 4; */ void dequant4_intra_c(int16_t * data, const int16_t * coeff, const uint32_t quant, const uint32_t dcscalar) { uint32_t i; int16_t *intra_matrix; intra_matrix = get_intra_matrix(); data[0] = (int16_t)(coeff[0] * dcscalar); if (data[0] < -2048) { data[0] = -2048; } else if (data[0] > 2047) { data[0] = 2047; } for (i = 1; i < 64; i++) { if (coeff[i] == 0) { data[i] = 0; } else if (coeff[i] < 0) { uint32_t level = -coeff[i]; level = (level * intra_matrix[i] * quant) >> 3; data[i] = (level <= 2048 ? -(int16_t) level : -2048); } else /* if (coeff[i] > 0) */ { uint32_t level = coeff[i]; level = (level * intra_matrix[i] * quant) >> 3; data[i] = (int16_t)(level <= 2047 ? level : 2047); } } } #if 0 /* quantize inter-block */ // level = DIV_DIV(16 * data[i], default_intra_matrix[i]); // coeff[i] = (level + quantd) / quant2; // sum += abs(level); #endif uint32_t quant4_inter_c(int16_t * coeff, const int16_t * data, const uint32_t quant) { const uint32_t mult = multipliers[quant]; uint32_t sum = 0; uint32_t i; int16_t *inter_matrix; inter_matrix = get_inter_matrix(); for (i = 0; i < 64; i++) { if (data[i] < 0) { uint32_t level = -data[i]; level = ((level << 4) + (inter_matrix[i] >> 1)) / inter_matrix[i]; level = (level * mult) >> 17; sum += level; coeff[i] = -(int16_t) level; } else if (data[i] > 0) { uint32_t level = data[i]; level = ((level << 4) + (inter_matrix[i] >> 1)) / inter_matrix[i]; level = (level * mult) >> 17; sum += level; coeff[i] = (int16_t)level; } else { coeff[i] = 0; } } return sum; } /* dequantize inter-block & clamp to [-2048,2047] data = ((2 * coeff + SIGN(coeff)) * inter_matrix[i] * quant) / 16 */ void dequant4_inter_c(int16_t * data, const int16_t * coeff, const uint32_t quant) { uint32_t sum = 0; uint32_t i; int16_t *inter_matrix; inter_matrix = get_inter_matrix(); for (i = 0; i < 64; i++) { if (coeff[i] == 0) { data[i] = 0; } else if (coeff[i] < 0) { int32_t level = -coeff[i]; level = ((2 * level + 1) * inter_matrix[i] * quant) >> 4; data[i] = (level <= 2048 ? -level : -2048); } else /* if (coeff[i] > 0) */ { uint32_t level = coeff[i]; level = ((2 * level + 1) * inter_matrix[i] * quant) >> 4; data[i] = (int16_t)(level <= 2047 ? level : 2047); } sum ^= data[i]; } /* mismatch control */ if ((sum & 1) == 0) { data[63] ^= 1; } }