FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/aptx.h
Date: 2022-07-05 19:52:29
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1 /*
2 * Audio Processing Technology codec for Bluetooth (aptX)
3 *
4 * Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #ifndef AVCODEC_APTX_H
24 #define AVCODEC_APTX_H
25
26 #include "libavutil/intreadwrite.h"
27 #include "avcodec.h"
28 #include "mathops.h"
29 #include "audio_frame_queue.h"
30
31
32 enum channels {
33 LEFT,
34 RIGHT,
35 NB_CHANNELS
36 };
37
38 enum subbands {
39 LF, // Low Frequency (0-5.5 kHz)
40 MLF, // Medium-Low Frequency (5.5-11kHz)
41 MHF, // Medium-High Frequency (11-16.5kHz)
42 HF, // High Frequency (16.5-22kHz)
43 NB_SUBBANDS
44 };
45
46 #define NB_FILTERS 2
47 #define FILTER_TAPS 16
48
49 typedef struct {
50 int pos;
51 int32_t buffer[2*FILTER_TAPS];
52 } FilterSignal;
53
54 typedef struct {
55 FilterSignal outer_filter_signal[NB_FILTERS];
56 FilterSignal inner_filter_signal[NB_FILTERS][NB_FILTERS];
57 } QMFAnalysis;
58
59 typedef struct {
60 int32_t quantized_sample;
61 int32_t quantized_sample_parity_change;
62 int32_t error;
63 } Quantize;
64
65 typedef struct {
66 int32_t quantization_factor;
67 int32_t factor_select;
68 int32_t reconstructed_difference;
69 } InvertQuantize;
70
71 typedef struct {
72 int32_t prev_sign[2];
73 int32_t s_weight[2];
74 int32_t d_weight[24];
75 int32_t pos;
76 int32_t reconstructed_differences[48];
77 int32_t previous_reconstructed_sample;
78 int32_t predicted_difference;
79 int32_t predicted_sample;
80 } Prediction;
81
82 typedef struct {
83 int32_t codeword_history;
84 int32_t dither_parity;
85 int32_t dither[NB_SUBBANDS];
86
87 QMFAnalysis qmf;
88 Quantize quantize[NB_SUBBANDS];
89 InvertQuantize invert_quantize[NB_SUBBANDS];
90 Prediction prediction[NB_SUBBANDS];
91 } Channel;
92
93 typedef struct {
94 int hd;
95 int block_size;
96 int32_t sync_idx;
97 Channel channels[NB_CHANNELS];
98 AudioFrameQueue afq;
99 } AptXContext;
100
101 typedef const struct {
102 const int32_t *quantize_intervals;
103 const int32_t *invert_quantize_dither_factors;
104 const int32_t *quantize_dither_factors;
105 const int16_t *quantize_factor_select_offset;
106 int tables_size;
107 int32_t factor_max;
108 int32_t prediction_order;
109 } ConstTables;
110
111 extern ConstTables ff_aptx_quant_tables[2][NB_SUBBANDS];
112
113 /* Rounded right shift with optionnal clipping */
114 #define RSHIFT_SIZE(size) \
115 av_always_inline \
116 static int##size##_t rshift##size(int##size##_t value, int shift) \
117 { \
118 int##size##_t rounding = (int##size##_t)1 << (shift - 1); \
119 int##size##_t mask = ((int##size##_t)1 << (shift + 1)) - 1; \
120 return ((value + rounding) >> shift) - ((value & mask) == rounding); \
121 } \
122 av_always_inline \
123 static int##size##_t rshift##size##_clip24(int##size##_t value, int shift) \
124 { \
125 return av_clip_intp2(rshift##size(value, shift), 23); \
126 }
127 RSHIFT_SIZE(32)
128 RSHIFT_SIZE(64)
129
130 /*
131 * Convolution filter coefficients for the outer QMF of the QMF tree.
132 * The 2 sets are a mirror of each other.
133 */
134 static const int32_t aptx_qmf_outer_coeffs[NB_FILTERS][FILTER_TAPS] = {
135 {
136 730, -413, -9611, 43626, -121026, 269973, -585547, 2801966,
137 697128, -160481, 27611, 8478, -10043, 3511, 688, -897,
138 },
139 {
140 -897, 688, 3511, -10043, 8478, 27611, -160481, 697128,
141 2801966, -585547, 269973, -121026, 43626, -9611, -413, 730,
142 },
143 };
144
145 /*
146 * Convolution filter coefficients for the inner QMF of the QMF tree.
147 * The 2 sets are a mirror of each other.
148 */
149 static const int32_t aptx_qmf_inner_coeffs[NB_FILTERS][FILTER_TAPS] = {
150 {
151 1033, -584, -13592, 61697, -171156, 381799, -828088, 3962579,
152 985888, -226954, 39048, 11990, -14203, 4966, 973, -1268,
153 },
154 {
155 -1268, 973, 4966, -14203, 11990, 39048, -226954, 985888,
156 3962579, -828088, 381799, -171156, 61697, -13592, -584, 1033,
157 },
158 };
159
160 /*
161 * Push one sample into a circular signal buffer.
162 */
163 av_always_inline
164 static void aptx_qmf_filter_signal_push(FilterSignal *signal, int32_t sample)
165 {
166 signal->buffer[signal->pos ] = sample;
167 signal->buffer[signal->pos+FILTER_TAPS] = sample;
168 signal->pos = (signal->pos + 1) & (FILTER_TAPS - 1);
169 }
170
171 /*
172 * Compute the convolution of the signal with the coefficients, and reduce
173 * to 24 bits by applying the specified right shifting.
174 */
175 av_always_inline
176 static int32_t aptx_qmf_convolution(FilterSignal *signal,
177 const int32_t coeffs[FILTER_TAPS],
178 int shift)
179 {
180 int32_t *sig = &signal->buffer[signal->pos];
181 int64_t e = 0;
182 int i;
183
184 for (i = 0; i < FILTER_TAPS; i++)
185 e += MUL64(sig[i], coeffs[i]);
186
187 return rshift64_clip24(e, shift);
188 }
189
190 static inline int32_t aptx_quantized_parity(Channel *channel)
191 {
192 int32_t parity = channel->dither_parity;
193 int subband;
194
195 for (subband = 0; subband < NB_SUBBANDS; subband++)
196 parity ^= channel->quantize[subband].quantized_sample;
197
198 return parity & 1;
199 }
200
201 /* For each sample, ensure that the parity of all subbands of all channels
202 * is 0 except once every 8 samples where the parity is forced to 1. */
203 static inline int aptx_check_parity(Channel channels[NB_CHANNELS], int32_t *idx)
204 {
205 int32_t parity = aptx_quantized_parity(&channels[LEFT])
206 ^ aptx_quantized_parity(&channels[RIGHT]);
207
208 int eighth = *idx == 7;
209 *idx = (*idx + 1) & 7;
210
211 return parity ^ eighth;
212 }
213
214 void ff_aptx_invert_quantize_and_prediction(Channel *channel, int hd);
215 void ff_aptx_generate_dither(Channel *channel);
216
217 int ff_aptx_init(AVCodecContext *avctx);
218
219 #endif /* AVCODEC_APTX_H */
220