1 /* 2 * Copyright (c) 2016, Alliance for Open Media. All rights reserved 3 * 4 * This source code is subject to the terms of the BSD 2 Clause License and 5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License 6 * was not distributed with this source code in the LICENSE file, you can 7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open 8 * Media Patent License 1.0 was not distributed with this source code in the 9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent. 10 */ 11 12 #ifndef AOM_AV1_ENCODER_COST_H_ 13 #define AOM_AV1_ENCODER_COST_H_ 14 15 #include "aom_dsp/prob.h" 16 #include "aom/aom_integer.h" 17 18 #ifdef __cplusplus 19 extern "C" { 20 #endif 21 22 extern const uint16_t av1_prob_cost[128]; 23 24 // The factor to scale from cost in bits to cost in av1_prob_cost units. 25 #define AV1_PROB_COST_SHIFT 9 26 27 // Cost of coding an n bit literal, using 128 (i.e. 50%) probability 28 // for each bit. 29 #define av1_cost_literal(n) ((n) * (1 << AV1_PROB_COST_SHIFT)) 30 31 // Calculate the cost of a symbol with probability p15 / 2^15 32 static INLINE int av1_cost_symbol(aom_cdf_prob p15) { 33 // p15 can be out of range [1, CDF_PROB_TOP - 1]. Clamping it, so that the 34 // following cost calculation works correctly. Otherwise, if p15 = 35 // CDF_PROB_TOP, shift would be -1, and "p15 << shift" would be wrong. 36 p15 = (aom_cdf_prob)clamp(p15, 1, CDF_PROB_TOP - 1); 37 assert(0 < p15 && p15 < CDF_PROB_TOP); 38 const int shift = CDF_PROB_BITS - 1 - get_msb(p15); 39 const int prob = get_prob(p15 << shift, CDF_PROB_TOP); 40 assert(prob >= 128); 41 return av1_prob_cost[prob - 128] + av1_cost_literal(shift); 42 } 43 44 void av1_cost_tokens_from_cdf(int *costs, const aom_cdf_prob *cdf, 45 const int *inv_map); 46 47 #ifdef __cplusplus 48 } // extern "C" 49 #endif 50 51 #endif // AOM_AV1_ENCODER_COST_H_ 52
