3 * Copyright (c) 2011 Justin Ruggles
5 * This file is part of FFmpeg.
7 * FFmpeg 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.
12 * FFmpeg 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #ifndef AVCODEC_AC3DSP_H
23 #define AVCODEC_AC3DSP_H
27 typedef struct AC3DSPContext {
29 * Set each encoded exponent in a block to the minimum of itself and the
30 * exponents in the same frequency bin of up to 5 following blocks.
31 * @param exp pointer to the start of the current block of exponents.
32 * constraints: align 16
33 * @param num_reuse_blocks number of blocks that will reuse exponents from the current block.
34 * constraints: range 0 to 5
35 * @param nb_coefs number of frequency coefficients.
37 void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
40 * Calculate the maximum MSB of the absolute value of each element in an
42 * @param src input array
43 * constraints: align 16. values must be in range [-32767,32767]
44 * @param len number of values in the array
45 * constraints: multiple of 16 greater than 0
46 * @return a value with the same MSB as max(abs(src[]))
48 int (*ac3_max_msb_abs_int16)(const int16_t *src, int len);
51 * Left-shift each value in an array of int16_t by a specified amount.
52 * @param src input array
53 * constraints: align 16
54 * @param len number of values in the array
55 * constraints: multiple of 32 greater than 0
56 * @param shift left shift amount
57 * constraints: range [0,15]
59 void (*ac3_lshift_int16)(int16_t *src, unsigned int len, unsigned int shift);
62 * Right-shift each value in an array of int32_t by a specified amount.
63 * @param src input array
64 * constraints: align 16
65 * @param len number of values in the array
66 * constraints: multiple of 16 greater than 0
67 * @param shift right shift amount
68 * constraints: range [0,31]
70 void (*ac3_rshift_int32)(int32_t *src, unsigned int len, unsigned int shift);
73 * Convert an array of float in range [-1.0,1.0] to int32_t with range
76 * @param dst destination array of int32_t.
77 * constraints: 16-byte aligned
78 * @param src source array of float.
79 * constraints: 16-byte aligned
80 * @param len number of elements to convert.
81 * constraints: multiple of 32 greater than zero
83 void (*float_to_fixed24)(int32_t *dst, const float *src, unsigned int len);
86 * Calculate bit allocation pointers.
87 * The SNR is the difference between the masking curve and the signal. AC-3
88 * uses this value for each frequency bin to allocate bits. The snroffset
89 * parameter is a global adjustment to the SNR for all bins.
91 * @param[in] mask masking curve
92 * @param[in] psd signal power for each frequency bin
93 * @param[in] start starting bin location
94 * @param[in] end ending bin location
95 * @param[in] snr_offset SNR adjustment
96 * @param[in] floor noise floor
97 * @param[in] bap_tab look-up table for bit allocation pointers
98 * @param[out] bap bit allocation pointers
100 void (*bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end,
101 int snr_offset, int floor,
102 const uint8_t *bap_tab, uint8_t *bap);
105 * Calculate the number of bits needed to encode a set of mantissas.
107 int (*compute_mantissa_size)(int mant_cnt[5], uint8_t *bap, int nb_coefs);
109 void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs);
112 void ff_ac3dsp_init (AC3DSPContext *c, int bit_exact);
113 void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact);
114 void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact);
116 #endif /* AVCODEC_AC3DSP_H */