/************************************************************************** * * XVID MPEG-4 VIDEO CODEC * - quantization/dequantization - * * 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_h263.c,v 1.6 2002/12/15 01:21:12 edgomez Exp $ * *************************************************************************/ #include "quant_h263.h" /* mutliply+shift division table */ #define SCALEBITS 16 #define FIX(X) ((1L << 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) }; #define DIV_DIV(a, b) ((a)>0) ? ((a)+((b)>>1))/(b) : ((a)-((b)>>1))/(b) /* function pointers */ quanth263_intraFuncPtr quant_intra; quanth263_intraFuncPtr dequant_intra; quanth263_interFuncPtr quant_inter; dequanth263_interFuncPtr dequant_inter; /* quantize intra-block */ void quant_intra_c(int16_t * coeff, const int16_t * data, const uint32_t quant, const uint32_t dcscalar) { const uint32_t mult = multipliers[quant]; const uint16_t quant_m_2 = (uint16_t)(quant << 1); uint32_t i; coeff[0] = (int16_t)(DIV_DIV(data[0], (int32_t) dcscalar)); for (i = 1; i < 64; i++) { int16_t acLevel = data[i]; if (acLevel < 0) { acLevel = -acLevel; if (acLevel < quant_m_2) { coeff[i] = 0; continue; } acLevel = (int16_t)(((uint32_t)acLevel * mult) >> SCALEBITS); coeff[i] = -acLevel; } else { if (acLevel < quant_m_2) { coeff[i] = 0; continue; } acLevel = (int16_t)(((uint32_t)acLevel * mult) >> SCALEBITS); coeff[i] = acLevel; } } } /* quantize inter-block */ uint32_t quant_inter_c(int16_t * coeff, const int16_t * data, const uint32_t quant) { const uint32_t mult = multipliers[quant]; const uint16_t quant_m_2 = (uint16_t)(quant << 1); const uint16_t quant_d_2 = (uint16_t)(quant >> 1); int sum = 0; uint32_t i; for (i = 0; i < 64; i++) { int16_t acLevel = data[i]; if (acLevel < 0) { acLevel = (-acLevel) - quant_d_2; if (acLevel < quant_m_2) { coeff[i] = 0; continue; } acLevel = (int16_t)(((uint32_t)acLevel * mult) >> SCALEBITS); sum += acLevel; /* sum += |acLevel| */ coeff[i] = -acLevel; } else { acLevel -= quant_d_2; if (acLevel < quant_m_2) { coeff[i] = 0; continue; } acLevel = (int16_t)(((uint32_t)acLevel * mult) >> SCALEBITS); sum += acLevel; coeff[i] = acLevel; } } return sum; } /* dequantize intra-block & clamp to [-2048,2047] */ void dequant_intra_c(int16_t * data, const int16_t * coeff, const uint32_t quant, const uint32_t dcscalar) { const int32_t quant_m_2 = quant << 1; const int32_t quant_add = (quant & 1 ? quant : quant - 1); uint32_t i; 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++) { int32_t acLevel = coeff[i]; if (acLevel == 0) { data[i] = 0; } else if (acLevel < 0) { acLevel = quant_m_2 * -acLevel + quant_add; data[i] = (acLevel <= 2048 ? -acLevel : -2048); } else /* if (acLevel > 0) { */ { acLevel = quant_m_2 * acLevel + quant_add; data[i] = (acLevel <= 2047 ? acLevel : 2047); } } } /* dequantize inter-block & clamp to [-2048,2047] */ void dequant_inter_c(int16_t * data, const int16_t * coeff, const uint32_t quant) { const uint16_t quant_m_2 = (uint16_t)(quant << 1); const uint16_t quant_add = (uint16_t)(quant & 1 ? quant : quant - 1); uint32_t i; for (i = 0; i < 64; i++) { int16_t acLevel = coeff[i]; if (acLevel == 0) { data[i] = 0; } else if (acLevel < 0) { acLevel = acLevel * quant_m_2 - quant_add; data[i] = (acLevel >= -2048 ? acLevel : -2048); } else /* if (acLevel > 0) */ { acLevel = acLevel * quant_m_2 + quant_add; data[i] = (acLevel <= 2047 ? acLevel : 2047); } } }