/* * AC-3 DSP utils * Copyright (c) 2011 Justin Ruggles * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef AVCODEC_AC3DSP_H #define AVCODEC_AC3DSP_H #include <stdint.h> /** * Number of mantissa bits written for each bap value. * bap values with fractional bits are set to 0 and are calculated separately. */ extern const uint16_t ff_ac3_bap_bits[16]; typedef struct AC3DSPContext { /** * Set each encoded exponent in a block to the minimum of itself and the * exponents in the same frequency bin of up to 5 following blocks. * @param exp pointer to the start of the current block of exponents. * constraints: align 16 * @param num_reuse_blocks number of blocks that will reuse exponents from the current block. * constraints: range 0 to 5 * @param nb_coefs number of frequency coefficients. */ void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs); /** * Calculate the maximum MSB of the absolute value of each element in an * array of int16_t. * @param src input array * constraints: align 16. values must be in range [-32767,32767] * @param len number of values in the array * constraints: multiple of 16 greater than 0 * @return a value with the same MSB as max(abs(src[])) */ int (*ac3_max_msb_abs_int16)(const int16_t *src, int len); /** * Left-shift each value in an array of int16_t by a specified amount. * @param src input array * constraints: align 16 * @param len number of values in the array * constraints: multiple of 32 greater than 0 * @param shift left shift amount * constraints: range [0,15] */ void (*ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift); /** * Right-shift each value in an array of int32_t by a specified amount. * @param src input array * constraints: align 16 * @param len number of values in the array * constraints: multiple of 16 greater than 0 * @param shift right shift amount * constraints: range [0,31] */ void (*ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift); /** * Convert an array of float in range [-1.0,1.0] to int32_t with range * [-(1<<24),(1<<24)] * * @param dst destination array of int32_t. * constraints: 16-byte aligned * @param src source array of float. * constraints: 16-byte aligned * @param len number of elements to convert. * constraints: multiple of 32 greater than zero */ void (*float_to_fixed24)(int32_t *dst, const float *src, unsigned int len); /** * Calculate bit allocation pointers. * The SNR is the difference between the masking curve and the signal. AC-3 * uses this value for each frequency bin to allocate bits. The snroffset * parameter is a global adjustment to the SNR for all bins. * * @param[in] mask masking curve * @param[in] psd signal power for each frequency bin * @param[in] start starting bin location * @param[in] end ending bin location * @param[in] snr_offset SNR adjustment * @param[in] floor noise floor * @param[in] bap_tab look-up table for bit allocation pointers * @param[out] bap bit allocation pointers */ void (*bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end, int snr_offset, int floor, const uint8_t *bap_tab, uint8_t *bap); /** * Update bap counts using the supplied array of bap. * * @param[out] mant_cnt bap counts for 1 block * @param[in] bap array of bap, pointing to start coef bin * @param[in] len number of elements to process */ void (*update_bap_counts)(uint16_t mant_cnt[16], uint8_t *bap, int len); /** * Calculate the number of bits needed to encode a set of mantissas. * * @param[in] mant_cnt bap counts for all blocks * @return mantissa bit count */ int (*compute_mantissa_size)(uint16_t mant_cnt[6][16]); void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs); } AC3DSPContext; void ff_ac3dsp_init (AC3DSPContext *c, int bit_exact); void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact); void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact); #endif /* AVCODEC_AC3DSP_H */