1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
/*
* Audio Processing Technology codec for Bluetooth (aptX)
*
* Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
*
* 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
* 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_APTX_H
#define AVCODEC_APTX_H
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
#include "mathops.h"
enum channels {
LEFT,
RIGHT,
NB_CHANNELS
};
enum subbands {
LF, // Low Frequency (0-5.5 kHz)
MLF, // Medium-Low Frequency (5.5-11kHz)
MHF, // Medium-High Frequency (11-16.5kHz)
HF, // High Frequency (16.5-22kHz)
NB_SUBBANDS
};
#define NB_FILTERS 2
#define FILTER_TAPS 16
typedef struct {
int pos;
int32_t buffer[2*FILTER_TAPS];
} FilterSignal;
typedef struct {
FilterSignal outer_filter_signal[NB_FILTERS];
FilterSignal inner_filter_signal[NB_FILTERS][NB_FILTERS];
} QMFAnalysis;
typedef struct {
int32_t quantized_sample;
int32_t quantized_sample_parity_change;
int32_t error;
} Quantize;
typedef struct {
int32_t quantization_factor;
int32_t factor_select;
int32_t reconstructed_difference;
} InvertQuantize;
typedef struct {
int32_t prev_sign[2];
int32_t s_weight[2];
int32_t d_weight[24];
int32_t pos;
int32_t reconstructed_differences[48];
int32_t previous_reconstructed_sample;
int32_t predicted_difference;
int32_t predicted_sample;
} Prediction;
typedef struct {
int32_t codeword_history;
int32_t dither_parity;
int32_t dither[NB_SUBBANDS];
QMFAnalysis qmf;
Quantize quantize[NB_SUBBANDS];
InvertQuantize invert_quantize[NB_SUBBANDS];
Prediction prediction[NB_SUBBANDS];
} Channel;
typedef struct {
int hd;
int block_size;
int32_t sync_idx;
Channel channels[NB_CHANNELS];
} AptXContext;
typedef const struct {
const int32_t *quantize_intervals;
const int32_t *invert_quantize_dither_factors;
const int32_t *quantize_dither_factors;
const int16_t *quantize_factor_select_offset;
int tables_size;
int32_t factor_max;
int32_t prediction_order;
} ConstTables;
extern ConstTables ff_aptx_quant_tables[2][NB_SUBBANDS];
/* Rounded right shift with optionnal clipping */
#define RSHIFT_SIZE(size) \
av_always_inline \
static int##size##_t rshift##size(int##size##_t value, int shift) \
{ \
int##size##_t rounding = (int##size##_t)1 << (shift - 1); \
int##size##_t mask = ((int##size##_t)1 << (shift + 1)) - 1; \
return ((value + rounding) >> shift) - ((value & mask) == rounding); \
} \
av_always_inline \
static int##size##_t rshift##size##_clip24(int##size##_t value, int shift) \
{ \
return av_clip_intp2(rshift##size(value, shift), 23); \
}
RSHIFT_SIZE(32)
RSHIFT_SIZE(64)
/*
* Convolution filter coefficients for the outer QMF of the QMF tree.
* The 2 sets are a mirror of each other.
*/
static const int32_t aptx_qmf_outer_coeffs[NB_FILTERS][FILTER_TAPS] = {
{
730, -413, -9611, 43626, -121026, 269973, -585547, 2801966,
697128, -160481, 27611, 8478, -10043, 3511, 688, -897,
},
{
-897, 688, 3511, -10043, 8478, 27611, -160481, 697128,
2801966, -585547, 269973, -121026, 43626, -9611, -413, 730,
},
};
/*
* Convolution filter coefficients for the inner QMF of the QMF tree.
* The 2 sets are a mirror of each other.
*/
static const int32_t aptx_qmf_inner_coeffs[NB_FILTERS][FILTER_TAPS] = {
{
1033, -584, -13592, 61697, -171156, 381799, -828088, 3962579,
985888, -226954, 39048, 11990, -14203, 4966, 973, -1268,
},
{
-1268, 973, 4966, -14203, 11990, 39048, -226954, 985888,
3962579, -828088, 381799, -171156, 61697, -13592, -584, 1033,
},
};
/*
* Push one sample into a circular signal buffer.
*/
av_always_inline
static void aptx_qmf_filter_signal_push(FilterSignal *signal, int32_t sample)
{
signal->buffer[signal->pos ] = sample;
signal->buffer[signal->pos+FILTER_TAPS] = sample;
signal->pos = (signal->pos + 1) & (FILTER_TAPS - 1);
}
/*
* Compute the convolution of the signal with the coefficients, and reduce
* to 24 bits by applying the specified right shifting.
*/
av_always_inline
static int32_t aptx_qmf_convolution(FilterSignal *signal,
const int32_t coeffs[FILTER_TAPS],
int shift)
{
int32_t *sig = &signal->buffer[signal->pos];
int64_t e = 0;
int i;
for (i = 0; i < FILTER_TAPS; i++)
e += MUL64(sig[i], coeffs[i]);
return rshift64_clip24(e, shift);
}
static inline int32_t aptx_quantized_parity(Channel *channel)
{
int32_t parity = channel->dither_parity;
int subband;
for (subband = 0; subband < NB_SUBBANDS; subband++)
parity ^= channel->quantize[subband].quantized_sample;
return parity & 1;
}
/* For each sample, ensure that the parity of all subbands of all channels
* is 0 except once every 8 samples where the parity is forced to 1. */
static inline int aptx_check_parity(Channel channels[NB_CHANNELS], int32_t *idx)
{
int32_t parity = aptx_quantized_parity(&channels[LEFT])
^ aptx_quantized_parity(&channels[RIGHT]);
int eighth = *idx == 7;
*idx = (*idx + 1) & 7;
return parity ^ eighth;
}
void ff_aptx_invert_quantize_and_prediction(Channel *channel, int hd);
void ff_aptx_generate_dither(Channel *channel);
int ff_aptx_init(AVCodecContext *avctx);
#endif /* AVCODEC_APTX_H */
|
