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117 lines
4.6 KiB
C
117 lines
4.6 KiB
C
/*
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* AC-3 DSP utils
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* Copyright (c) 2011 Justin Ruggles
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_AC3DSP_H
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#define AVCODEC_AC3DSP_H
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#include <stdint.h>
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typedef struct AC3DSPContext {
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/**
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* Set each encoded exponent in a block to the minimum of itself and the
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* exponents in the same frequency bin of up to 5 following blocks.
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* @param exp pointer to the start of the current block of exponents.
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* constraints: align 16
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* @param num_reuse_blocks number of blocks that will reuse exponents from the current block.
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* constraints: range 0 to 5
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* @param nb_coefs number of frequency coefficients.
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*/
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void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
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/**
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* Calculate the maximum MSB of the absolute value of each element in an
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* array of int16_t.
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* @param src input array
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* constraints: align 16. values must be in range [-32767,32767]
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* @param len number of values in the array
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* constraints: multiple of 16 greater than 0
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* @return a value with the same MSB as max(abs(src[]))
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*/
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int (*ac3_max_msb_abs_int16)(const int16_t *src, int len);
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/**
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* Left-shift each value in an array of int16_t by a specified amount.
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* @param src input array
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* constraints: align 16
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* @param len number of values in the array
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* constraints: multiple of 32 greater than 0
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* @param shift left shift amount
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* constraints: range [0,15]
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*/
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void (*ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift);
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/**
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* Right-shift each value in an array of int32_t by a specified amount.
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* @param src input array
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* constraints: align 16
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* @param len number of values in the array
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* constraints: multiple of 16 greater than 0
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* @param shift right shift amount
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* constraints: range [0,31]
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*/
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void (*ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift);
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/**
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* Convert an array of float in range [-1.0,1.0] to int32_t with range
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* [-(1<<24),(1<<24)]
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*
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* @param dst destination array of int32_t.
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* constraints: 16-byte aligned
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* @param src source array of float.
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* constraints: 16-byte aligned
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* @param len number of elements to convert.
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* constraints: multiple of 32 greater than zero
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*/
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void (*float_to_fixed24)(int32_t *dst, const float *src, unsigned int len);
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/**
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* Calculate bit allocation pointers.
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* The SNR is the difference between the masking curve and the signal. AC-3
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* uses this value for each frequency bin to allocate bits. The snroffset
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* parameter is a global adjustment to the SNR for all bins.
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*
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* @param[in] mask masking curve
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* @param[in] psd signal power for each frequency bin
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* @param[in] start starting bin location
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* @param[in] end ending bin location
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* @param[in] snr_offset SNR adjustment
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* @param[in] floor noise floor
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* @param[in] bap_tab look-up table for bit allocation pointers
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* @param[out] bap bit allocation pointers
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*/
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void (*bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end,
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int snr_offset, int floor,
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const uint8_t *bap_tab, uint8_t *bap);
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/**
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* Calculate the number of bits needed to encode a set of mantissas.
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*/
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int (*compute_mantissa_size)(int mant_cnt[5], uint8_t *bap, int nb_coefs);
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void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs);
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} AC3DSPContext;
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void ff_ac3dsp_init (AC3DSPContext *c, int bit_exact);
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void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact);
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void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact);
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#endif /* AVCODEC_AC3DSP_H */
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