1/* 2 * AC-3 DSP utils 3 * Copyright (c) 2011 Justin Ruggles 4 * 5 * This file is part of Libav. 6 * 7 * Libav is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * Libav is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with Libav; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#ifndef AVCODEC_AC3DSP_H 23#define AVCODEC_AC3DSP_H 24 25#include <stdint.h> 26 27/** 28 * Number of mantissa bits written for each bap value. 29 * bap values with fractional bits are set to 0 and are calculated separately. 30 */ 31extern const uint16_t ff_ac3_bap_bits[16]; 32 33typedef struct AC3DSPContext { 34 /** 35 * Set each encoded exponent in a block to the minimum of itself and the 36 * exponents in the same frequency bin of up to 5 following blocks. 37 * @param exp pointer to the start of the current block of exponents. 38 * constraints: align 16 39 * @param num_reuse_blocks number of blocks that will reuse exponents from the current block. 40 * constraints: range 0 to 5 41 * @param nb_coefs number of frequency coefficients. 42 */ 43 void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs); 44 45 /** 46 * Calculate the maximum MSB of the absolute value of each element in an 47 * array of int16_t. 48 * @param src input array 49 * constraints: align 16. values must be in range [-32767,32767] 50 * @param len number of values in the array 51 * constraints: multiple of 16 greater than 0 52 * @return a value with the same MSB as max(abs(src[])) 53 */ 54 int (*ac3_max_msb_abs_int16)(const int16_t *src, int len); 55 56 /** 57 * Left-shift each value in an array of int16_t by a specified amount. 58 * @param src input array 59 * constraints: align 16 60 * @param len number of values in the array 61 * constraints: multiple of 32 greater than 0 62 * @param shift left shift amount 63 * constraints: range [0,15] 64 */ 65 void (*ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift); 66 67 /** 68 * Right-shift each value in an array of int32_t by a specified amount. 69 * @param src input array 70 * constraints: align 16 71 * @param len number of values in the array 72 * constraints: multiple of 16 greater than 0 73 * @param shift right shift amount 74 * constraints: range [0,31] 75 */ 76 void (*ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift); 77 78 /** 79 * Convert an array of float in range [-1.0,1.0] to int32_t with range 80 * [-(1<<24),(1<<24)] 81 * 82 * @param dst destination array of int32_t. 83 * constraints: 16-byte aligned 84 * @param src source array of float. 85 * constraints: 16-byte aligned 86 * @param len number of elements to convert. 87 * constraints: multiple of 32 greater than zero 88 */ 89 void (*float_to_fixed24)(int32_t *dst, const float *src, unsigned int len); 90 91 /** 92 * Calculate bit allocation pointers. 93 * The SNR is the difference between the masking curve and the signal. AC-3 94 * uses this value for each frequency bin to allocate bits. The snroffset 95 * parameter is a global adjustment to the SNR for all bins. 96 * 97 * @param[in] mask masking curve 98 * @param[in] psd signal power for each frequency bin 99 * @param[in] start starting bin location 100 * @param[in] end ending bin location 101 * @param[in] snr_offset SNR adjustment 102 * @param[in] floor noise floor 103 * @param[in] bap_tab look-up table for bit allocation pointers 104 * @param[out] bap bit allocation pointers 105 */ 106 void (*bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end, 107 int snr_offset, int floor, 108 const uint8_t *bap_tab, uint8_t *bap); 109 110 /** 111 * Update bap counts using the supplied array of bap. 112 * 113 * @param[out] mant_cnt bap counts for 1 block 114 * @param[in] bap array of bap, pointing to start coef bin 115 * @param[in] len number of elements to process 116 */ 117 void (*update_bap_counts)(uint16_t mant_cnt[16], uint8_t *bap, int len); 118 119 /** 120 * Calculate the number of bits needed to encode a set of mantissas. 121 * 122 * @param[in] mant_cnt bap counts for all blocks 123 * @return mantissa bit count 124 */ 125 int (*compute_mantissa_size)(uint16_t mant_cnt[6][16]); 126 127 void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs); 128} AC3DSPContext; 129 130void ff_ac3dsp_init (AC3DSPContext *c, int bit_exact); 131void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact); 132void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact); 133 134#endif /* AVCODEC_AC3DSP_H */ 135