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* AC-3 DSP functions
* Copyright (c) 2011 Justin Ruggles
* This file is part of FFmpeg.
* FFmpeg 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.
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#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);
* 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);
void (*sum_square_butterfly_int32)(int64_t sum[4], const int32_t *coef0,
const int32_t *coef1, int len);
void (*sum_square_butterfly_float)(float sum[4], const float *coef0,
const float *coef1, int len);
int out_channels;
int in_channels;
void (*downmix)(float **samples, float **matrix, int len);
void (*downmix_fixed)(int32_t **samples, int16_t **matrix, int len);
} 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);
void ff_ac3dsp_init_mips(AC3DSPContext *c, int bit_exact);
void ff_ac3dsp_downmix(AC3DSPContext *c, float **samples, float **matrix,
int out_ch, int in_ch, int len);
void ff_ac3dsp_downmix_fixed(AC3DSPContext *c, int32_t **samples, int16_t **matrix,
int out_ch, int in_ch, int len);
void ff_ac3dsp_set_downmix_x86(AC3DSPContext *c);
#endif /* AVCODEC_AC3DSP_H */