/src/ffmpeg/libavcodec/sbc.c

Source
/*
 * Bluetooth low-complexity, subband codec (SBC)
 *
 * Copyright (C) 2017  Aurelien Jacobs <aurel@gnuage.org>
 * Copyright (C) 2012-2013  Intel Corporation
 * Copyright (C) 2008-2010  Nokia Corporation
 * Copyright (C) 2004-2010  Marcel Holtmann <marcel@holtmann.org>
 * Copyright (C) 2004-2005  Henryk Ploetz <henryk@ploetzli.ch>
 * Copyright (C) 2005-2008  Brad Midgley <bmidgley@xmission.com>
 *
 * 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
 */

/**
 * @file
 * SBC common functions for the encoder and decoder
 */

#include "sbc.h"

/* A2DP specification: Appendix B, page 69 */
static const int sbc_offset4[4][4] = {
    { -1, 0, 0, 0 },
    { -2, 0, 0, 1 },
    { -2, 0, 0, 1 },
    { -2, 0, 0, 1 }
};

/* A2DP specification: Appendix B, page 69 */
static const int sbc_offset8[4][8] = {
    { -2, 0, 0, 0, 0, 0, 0, 1 },
    { -3, 0, 0, 0, 0, 0, 1, 2 },
    { -4, 0, 0, 0, 0, 0, 1, 2 },
    { -4, 0, 0, 0, 0, 0, 1, 2 }
};

/*
 * Calculates the CRC-8 of the first len bits in data
 */
uint8_t ff_sbc_crc8(const AVCRC *ctx, const uint8_t *data, size_t len)
{
    size_t byte_length = len >> 3;
    int bit_length = len & 7;
    uint8_t crc;

    crc = av_crc(ctx, 0x0F, data, byte_length);

    if (bit_length) {
        uint8_t bits = data[byte_length];
        while (bit_length--) {
            int8_t mask = bits ^ crc;
            crc = (crc << 1) ^ ((mask >> 7) & 0x1D);
            bits <<= 1;
        }
    }

    return crc;
}

/*
 * Code straight from the spec to calculate the bits array
 * Takes a pointer to the frame in question and a pointer to the bits array
 */
void ff_sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8])
{
    int subbands = frame->subbands;
    uint8_t sf = frame->frequency;

    if (frame->mode == MONO || frame->mode == DUAL_CHANNEL) {
        int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
        int ch, sb;

        for (ch = 0; ch < frame->channels; ch++) {
            max_bitneed = 0;
            if (frame->allocation == SNR) {
                for (sb = 0; sb < subbands; sb++) {
                    bitneed[ch][sb] = frame->scale_factor[ch][sb];
                    if (bitneed[ch][sb] > max_bitneed)
                        max_bitneed = bitneed[ch][sb];
                }
            } else {
                for (sb = 0; sb < subbands; sb++) {
                    if (frame->scale_factor[ch][sb] == 0)
                        bitneed[ch][sb] = -5;
                    else {
                        if (subbands == 4)
                            loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
                        else
                            loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
                        if (loudness > 0)
                            bitneed[ch][sb] = loudness / 2;
                        else
                            bitneed[ch][sb] = loudness;
                    }
                    if (bitneed[ch][sb] > max_bitneed)
                        max_bitneed = bitneed[ch][sb];
                }
            }

            bitcount = 0;
            slicecount = 0;
            bitslice = max_bitneed + 1;
            do {
                bitslice--;
                bitcount += slicecount;
                slicecount = 0;
                for (sb = 0; sb < subbands; sb++) {
                    if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
                        slicecount++;
                    else if (bitneed[ch][sb] == bitslice + 1)
                        slicecount += 2;
                }
            } while (bitcount + slicecount < frame->bitpool);

            if (bitcount + slicecount == frame->bitpool) {
                bitcount += slicecount;
                bitslice--;
            }

            for (sb = 0; sb < subbands; sb++) {
                if (bitneed[ch][sb] < bitslice + 2)
                    bits[ch][sb] = 0;
                else {
                    bits[ch][sb] = bitneed[ch][sb] - bitslice;
                    if (bits[ch][sb] > 16)
                        bits[ch][sb] = 16;
                }
            }

            for (sb = 0; bitcount < frame->bitpool &&
                            sb < subbands; sb++) {
                if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
                    bits[ch][sb]++;
                    bitcount++;
                } else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
                    bits[ch][sb] = 2;
                    bitcount += 2;
                }
            }

            for (sb = 0; bitcount < frame->bitpool &&
                            sb < subbands; sb++) {
                if (bits[ch][sb] < 16) {
                    bits[ch][sb]++;
                    bitcount++;
                }
            }

        }

    } else if (frame->mode == STEREO || frame->mode == JOINT_STEREO) {
        int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
        int ch, sb;

        max_bitneed = 0;
        if (frame->allocation == SNR) {
            for (ch = 0; ch < 2; ch++) {
                for (sb = 0; sb < subbands; sb++) {
                    bitneed[ch][sb] = frame->scale_factor[ch][sb];
                    if (bitneed[ch][sb] > max_bitneed)
                        max_bitneed = bitneed[ch][sb];
                }
            }
        } else {
            for (ch = 0; ch < 2; ch++) {
                for (sb = 0; sb < subbands; sb++) {
                    if (frame->scale_factor[ch][sb] == 0)
                        bitneed[ch][sb] = -5;
                    else {
                        if (subbands == 4)
                            loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
                        else
                            loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
                        if (loudness > 0)
                            bitneed[ch][sb] = loudness / 2;
                        else
                            bitneed[ch][sb] = loudness;
                    }
                    if (bitneed[ch][sb] > max_bitneed)
                        max_bitneed = bitneed[ch][sb];
                }
            }
        }

        bitcount = 0;
        slicecount = 0;
        bitslice = max_bitneed + 1;
        do {
            bitslice--;
            bitcount += slicecount;
            slicecount = 0;
            for (ch = 0; ch < 2; ch++) {
                for (sb = 0; sb < subbands; sb++) {
                    if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
                        slicecount++;
                    else if (bitneed[ch][sb] == bitslice + 1)
                        slicecount += 2;
                }
            }
        } while (bitcount + slicecount < frame->bitpool);

        if (bitcount + slicecount == frame->bitpool) {
            bitcount += slicecount;
            bitslice--;
        }

        for (ch = 0; ch < 2; ch++) {
            for (sb = 0; sb < subbands; sb++) {
                if (bitneed[ch][sb] < bitslice + 2) {
                    bits[ch][sb] = 0;
                } else {
                    bits[ch][sb] = bitneed[ch][sb] - bitslice;
                    if (bits[ch][sb] > 16)
                        bits[ch][sb] = 16;
                }
            }
        }

        ch = 0;
        sb = 0;
        while (bitcount < frame->bitpool) {
            if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
                bits[ch][sb]++;
                bitcount++;
            } else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
                bits[ch][sb] = 2;
                bitcount += 2;
            }
            if (ch == 1) {
                ch = 0;
                sb++;
                if (sb >= subbands)
                    break;
            } else
                ch = 1;
        }

        ch = 0;
        sb = 0;
        while (bitcount < frame->bitpool) {
            if (bits[ch][sb] < 16) {
                bits[ch][sb]++;
                bitcount++;
            }
            if (ch == 1) {
                ch = 0;
                sb++;
                if (sb >= subbands)
                    break;
            } else
                ch = 1;
        }

    }

}

Coverage Report

Created: 2025-11-16 07:20

Line	Count	Source
1		/*
2		* Bluetooth low-complexity, subband codec (SBC)
3		*
4		* Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
5		* Copyright (C) 2012-2013 Intel Corporation
6		* Copyright (C) 2008-2010 Nokia Corporation
7		* Copyright (C) 2004-2010 Marcel Holtmann <marcel@holtmann.org>
8		* Copyright (C) 2004-2005 Henryk Ploetz <henryk@ploetzli.ch>
9		* Copyright (C) 2005-2008 Brad Midgley <bmidgley@xmission.com>
10		*
11		* This file is part of FFmpeg.
12		*
13		* FFmpeg is free software; you can redistribute it and/or
14		* modify it under the terms of the GNU Lesser General Public
15		* License as published by the Free Software Foundation; either
16		* version 2.1 of the License, or (at your option) any later version.
17		*
18		* FFmpeg is distributed in the hope that it will be useful,
19		* but WITHOUT ANY WARRANTY; without even the implied warranty of
20		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21		* Lesser General Public License for more details.
22		*
23		* You should have received a copy of the GNU Lesser General Public
24		* License along with FFmpeg; if not, write to the Free Software
25		* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26		*/
27
28		/**
29		* @file
30		* SBC common functions for the encoder and decoder
31		*/
32
33		#include "sbc.h"
34
35		/* A2DP specification: Appendix B, page 69 */
36		static const int sbc_offset4[4][4] = {
37		{ -1, 0, 0, 0 },
38		{ -2, 0, 0, 1 },
39		{ -2, 0, 0, 1 },
40		{ -2, 0, 0, 1 }
41		};
42
43		/* A2DP specification: Appendix B, page 69 */
44		static const int sbc_offset8[4][8] = {
45		{ -2, 0, 0, 0, 0, 0, 0, 1 },
46		{ -3, 0, 0, 0, 0, 0, 1, 2 },
47		{ -4, 0, 0, 0, 0, 0, 1, 2 },
48		{ -4, 0, 0, 0, 0, 0, 1, 2 }
49		};
50
51		/*
52		* Calculates the CRC-8 of the first len bits in data
53		*/
54		uint8_t ff_sbc_crc8(const AVCRC ctx, const uint8_t data, size_t len)
55	43.6k	{
56	43.6k	size_t byte_length = len >> 3;
57	43.6k	int bit_length = len & 7;
58	43.6k	uint8_t crc;
59
60	43.6k	crc = av_crc(ctx, 0x0F, data, byte_length);
61
62	43.6k	if (bit_length) {
63	3.94k	uint8_t bits = data[byte_length];
64	19.7k	while (bit_length--) {
65	15.7k	int8_t mask = bits ^ crc;
66	15.7k	crc = (crc << 1) ^ ((mask >> 7) & 0x1D);
67	15.7k	bits <<= 1;
68	15.7k	}
69	3.94k	}
70
71	43.6k	return crc;
72	43.6k	}
73
74		/*
75		* Code straight from the spec to calculate the bits array
76		* Takes a pointer to the frame in question and a pointer to the bits array
77		*/
78		void ff_sbc_calculate_bits(const struct sbc_frame frame, int (bits)[8])
79	18.3k	{
80	18.3k	int subbands = frame->subbands;
81	18.3k	uint8_t sf = frame->frequency;
82
83	18.3k	if (frame->mode == MONO \|\| frame->mode == DUAL_CHANNEL) {
84	6.94k	int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
85	6.94k	int ch, sb;
86
87	13.9k	for (ch = 0; ch < frame->channels; ch++) {
88	6.98k	max_bitneed = 0;
89	6.98k	if (frame->allocation == SNR) {
90	7.55k	for (sb = 0; sb < subbands; sb++) {
91	6.71k	bitneed[ch][sb] = frame->scale_factor[ch][sb];
92	6.71k	if (bitneed[ch][sb] > max_bitneed)
93	1.62k	max_bitneed = bitneed[ch][sb];
94	6.71k	}
95	6.13k	} else {
96	34.8k	for (sb = 0; sb < subbands; sb++) {
97	28.6k	if (frame->scale_factor[ch][sb] == 0)
98	63	bitneed[ch][sb] = -5;
99	28.6k	else {
100	28.6k	if (subbands == 4)
101	20.3k	loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
102	8.23k	else
103	8.23k	loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
104	28.6k	if (loudness > 0)
105	28.6k	bitneed[ch][sb] = loudness / 2;
106	0	else
107	0	bitneed[ch][sb] = loudness;
108	28.6k	}
109	28.6k	if (bitneed[ch][sb] > max_bitneed)
110	16.3k	max_bitneed = bitneed[ch][sb];
111	28.6k	}
112	6.13k	}
113
114	6.98k	bitcount = 0;
115	6.98k	slicecount = 0;
116	6.98k	bitslice = max_bitneed + 1;
117	24.7k	do {
118	24.7k	bitslice--;
119	24.7k	bitcount += slicecount;
120	24.7k	slicecount = 0;
121	180k	for (sb = 0; sb < subbands; sb++) {
122	156k	if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
123	54.7k	slicecount++;
124	101k	else if (bitneed[ch][sb] == bitslice + 1)
125	18.0k	slicecount += 2;
126	156k	}
127	24.7k	} while (bitcount + slicecount < frame->bitpool);
128
129	6.98k	if (bitcount + slicecount == frame->bitpool) {
130	54	bitcount += slicecount;
131	54	bitslice--;
132	54	}
133
134	42.3k	for (sb = 0; sb < subbands; sb++) {
135	35.4k	if (bitneed[ch][sb] < bitslice + 2)
136	24.6k	bits[ch][sb] = 0;
137	10.7k	else {
138	10.7k	bits[ch][sb] = bitneed[ch][sb] - bitslice;
139	10.7k	if (bits[ch][sb] > 16)
140	39	bits[ch][sb] = 16;
141	10.7k	}
142	35.4k	}
143
144	36.3k	for (sb = 0; bitcount < frame->bitpool &&
145	34.4k	sb < subbands; sb++) {
146	29.3k	if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
147	7.74k	bits[ch][sb]++;
148	7.74k	bitcount++;
149	21.6k	} else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
150	1.21k	bits[ch][sb] = 2;
151	1.21k	bitcount += 2;
152	1.21k	}
153	29.3k	}
154
155	12.1k	for (sb = 0; bitcount < frame->bitpool &&
156	5.12k	sb < subbands; sb++) {
157	5.12k	if (bits[ch][sb] < 16) {
158	5.12k	bits[ch][sb]++;
159	5.12k	bitcount++;
160	5.12k	}
161	5.12k	}
162
163	6.98k	}
164
165	11.3k	} else if (frame->mode == STEREO \|\| frame->mode == JOINT_STEREO) {
166	11.3k	int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
167	11.3k	int ch, sb;
168
169	11.3k	max_bitneed = 0;
170	11.3k	if (frame->allocation == SNR) {
171	24.1k	for (ch = 0; ch < 2; ch++) {
172	144k	for (sb = 0; sb < subbands; sb++) {
173	128k	bitneed[ch][sb] = frame->scale_factor[ch][sb];
174	128k	if (bitneed[ch][sb] > max_bitneed)
175	185	max_bitneed = bitneed[ch][sb];
176	128k	}
177	16.1k	}
178	8.05k	} else {
179	10.0k	for (ch = 0; ch < 2; ch++) {
180	33.6k	for (sb = 0; sb < subbands; sb++) {
181	26.9k	if (frame->scale_factor[ch][sb] == 0)
182	231	bitneed[ch][sb] = -5;
183	26.6k	else {
184	26.6k	if (subbands == 4)
185	26.4k	loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
186	223	else
187	223	loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
188	26.6k	if (loudness > 0)
189	23.4k	bitneed[ch][sb] = loudness / 2;
190	3.28k	else
191	3.28k	bitneed[ch][sb] = loudness;
192	26.6k	}
193	26.9k	if (bitneed[ch][sb] > max_bitneed)
194	3.38k	max_bitneed = bitneed[ch][sb];
195	26.9k	}
196	6.68k	}
197	3.34k	}
198
199	11.3k	bitcount = 0;
200	11.3k	slicecount = 0;
201	11.3k	bitslice = max_bitneed + 1;
202	29.5k	do {
203	29.5k	bitslice--;
204	29.5k	bitcount += slicecount;
205	29.5k	slicecount = 0;
206	88.6k	for (ch = 0; ch < 2; ch++) {
207	366k	for (sb = 0; sb < subbands; sb++) {
208	307k	if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
209	49.3k	slicecount++;
210	257k	else if (bitneed[ch][sb] == bitslice + 1)
211	20.9k	slicecount += 2;
212	307k	}
213	59.0k	}
214	29.5k	} while (bitcount + slicecount < frame->bitpool);
215
216	11.3k	if (bitcount + slicecount == frame->bitpool) {
217	7.99k	bitcount += slicecount;
218	7.99k	bitslice--;
219	7.99k	}
220
221	34.1k	for (ch = 0; ch < 2; ch++) {
222	178k	for (sb = 0; sb < subbands; sb++) {
223	155k	if (bitneed[ch][sb] < bitslice + 2) {
224	137k	bits[ch][sb] = 0;
225	137k	} else {
226	17.6k	bits[ch][sb] = bitneed[ch][sb] - bitslice;
227	17.6k	if (bits[ch][sb] > 16)
228	123	bits[ch][sb] = 16;
229	17.6k	}
230	155k	}
231	22.7k	}
232
233	11.3k	ch = 0;
234	11.3k	sb = 0;
235	18.6k	while (bitcount < frame->bitpool) {
236	7.26k	if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
237	7.00k	bits[ch][sb]++;
238	7.00k	bitcount++;
239	7.00k	} else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
240	44	bits[ch][sb] = 2;
241	44	bitcount += 2;
242	44	}
243	7.26k	if (ch == 1) {
244	3.58k	ch = 0;
245	3.58k	sb++;
246	3.58k	if (sb >= subbands)
247	5	break;
248	3.58k	} else
249	3.67k	ch = 1;
250	7.26k	}
251
252	11.3k	ch = 0;
253	11.3k	sb = 0;
254	11.4k	while (bitcount < frame->bitpool) {
255	5	if (bits[ch][sb] < 16) {
256	5	bits[ch][sb]++;
257	5	bitcount++;
258	5	}
259	5	if (ch == 1) {
260	0	ch = 0;
261	0	sb++;
262	0	if (sb >= subbands)
263	0	break;
264	0	} else
265	5	ch = 1;
266	5	}
267
268	11.3k	}
269
270	18.3k	}