summaryrefslogtreecommitdiffstats
path: root/libavcodec/sbcdec.c
blob: d8ea6855fe7aad88be40bc140ff53125ca87b137 (plain)
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
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
/*
 * 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 decoder implementation
 */

#include <stdbool.h>
#include "avcodec.h"
#include "internal.h"
#include "libavutil/intreadwrite.h"
#include "sbc.h"
#include "sbcdec_data.h"

struct sbc_decoder_state {
    int32_t V[2][170];
    int offset[2][16];
};

typedef struct SBCDecContext {
    AVClass *class;
    DECLARE_ALIGNED(SBC_ALIGN, struct sbc_frame, frame);
    DECLARE_ALIGNED(SBC_ALIGN, struct sbc_decoder_state, dsp);
} SBCDecContext;

/*
 * Unpacks a SBC frame at the beginning of the stream in data,
 * which has at most len bytes into frame.
 * Returns the length in bytes of the packed frame, or a negative
 * value on error. The error codes are:
 *
 *  -1   Data stream too short
 *  -2   Sync byte incorrect
 *  -3   CRC8 incorrect
 *  -4   Bitpool value out of bounds
 */
static int sbc_unpack_frame(const uint8_t *data, struct sbc_frame *frame,
                            size_t len)
{
    unsigned int consumed;
    /* Will copy the parts of the header that are relevant to crc
     * calculation here */
    uint8_t crc_header[11] = { 0 };
    int crc_pos;
    int32_t temp;

    uint32_t audio_sample;
    int ch, sb, blk, bit;   /* channel, subband, block and bit standard
                               counters */
    int bits[2][8];         /* bits distribution */
    uint32_t levels[2][8];  /* levels derived from that */

    if (len < 4)
        return -1;

    if (data[0] == MSBC_SYNCWORD) {
        if (data[1] != 0)
            return -2;
        if (data[2] != 0)
            return -2;

        frame->frequency = SBC_FREQ_16000;
        frame->blocks = MSBC_BLOCKS;
        frame->allocation = LOUDNESS;
        frame->mode = MONO;
        frame->channels = 1;
        frame->subbands = 8;
        frame->bitpool = 26;
    } else if (data[0] == SBC_SYNCWORD) {
        frame->frequency  = (data[1] >> 6) & 0x03;
        frame->blocks = 4 * ((data[1] >> 4) & 0x03) + 4;
        frame->mode = (data[1] >> 2) & 0x03;
        frame->channels = frame->mode == MONO ? 1 : 2;
        frame->allocation = (data[1] >> 1) & 0x01;
        frame->subbands = data[1] & 0x01 ? 8 : 4;
        frame->bitpool = data[2];

        if ((frame->mode == MONO || frame->mode == DUAL_CHANNEL) &&
            frame->bitpool > 16 * frame->subbands)
            return -4;

        if ((frame->mode == STEREO || frame->mode == JOINT_STEREO) &&
            frame->bitpool > 32 * frame->subbands)
            return -4;
    } else
        return -2;

    consumed = 32;
    crc_header[0] = data[1];
    crc_header[1] = data[2];
    crc_pos = 16;

    if (frame->mode == JOINT_STEREO) {
        if (len * 8 < consumed + frame->subbands)
            return -1;

        frame->joint = 0x00;
        for (sb = 0; sb < frame->subbands - 1; sb++)
            frame->joint |= ((data[4] >> (7 - sb)) & 0x01) << sb;
        if (frame->subbands == 4)
            crc_header[crc_pos / 8] = data[4] & 0xf0;
        else
            crc_header[crc_pos / 8] = data[4];

        consumed += frame->subbands;
        crc_pos += frame->subbands;
    }

    if (len * 8 < consumed + (4 * frame->subbands * frame->channels))
        return -1;

    for (ch = 0; ch < frame->channels; ch++) {
        for (sb = 0; sb < frame->subbands; sb++) {
            /* FIXME assert(consumed % 4 == 0); */
            frame->scale_factor[ch][sb] =
                (data[consumed >> 3] >> (4 - (consumed & 0x7))) & 0x0F;
            crc_header[crc_pos >> 3] |=
                frame->scale_factor[ch][sb] << (4 - (crc_pos & 0x7));

            consumed += 4;
            crc_pos += 4;
        }
    }

    if (data[3] != ff_sbc_crc8(frame->crc_ctx, crc_header, crc_pos))
        return -3;

    ff_sbc_calculate_bits(frame, bits);

    for (ch = 0; ch < frame->channels; ch++) {
        for (sb = 0; sb < frame->subbands; sb++)
            levels[ch][sb] = (1 << bits[ch][sb]) - 1;
    }

    for (blk = 0; blk < frame->blocks; blk++) {
        for (ch = 0; ch < frame->channels; ch++) {
            for (sb = 0; sb < frame->subbands; sb++) {
                uint32_t shift;

                if (levels[ch][sb] == 0) {
                    frame->sb_sample[blk][ch][sb] = 0;
                    continue;
                }

                shift = frame->scale_factor[ch][sb] +
                        1 + SBCDEC_FIXED_EXTRA_BITS;

                audio_sample = 0;
                for (bit = 0; bit < bits[ch][sb]; bit++) {
                    if (consumed > len * 8)
                        return -1;

                    if ((data[consumed >> 3] >> (7 - (consumed & 0x7))) & 0x01)
                        audio_sample |= 1 << (bits[ch][sb] - bit - 1);

                    consumed++;
                }

                frame->sb_sample[blk][ch][sb] = (int32_t)
                    (((((uint64_t) audio_sample << 1) | 1) << shift) /
                    levels[ch][sb]) - (1 << shift);
            }
        }
    }

    if (frame->mode == JOINT_STEREO) {
        for (blk = 0; blk < frame->blocks; blk++) {
            for (sb = 0; sb < frame->subbands; sb++) {
                if (frame->joint & (0x01 << sb)) {
                    temp = frame->sb_sample[blk][0][sb] +
                           frame->sb_sample[blk][1][sb];
                    frame->sb_sample[blk][1][sb] =
                        frame->sb_sample[blk][0][sb] -
                        frame->sb_sample[blk][1][sb];
                    frame->sb_sample[blk][0][sb] = temp;
                }
            }
        }
    }

    if ((consumed & 0x7) != 0)
        consumed += 8 - (consumed & 0x7);

    return consumed >> 3;
}

static inline void sbc_synthesize_four(struct sbc_decoder_state *state,
                                       struct sbc_frame *frame,
                                       int ch, int blk, AVFrame *output_frame)
{
    int i, k, idx;
    int32_t *v = state->V[ch];
    int *offset = state->offset[ch];

    for (i = 0; i < 8; i++) {
        /* Shifting */
        offset[i]--;
        if (offset[i] < 0) {
            offset[i] = 79;
            memcpy(v + 80, v, 9 * sizeof(*v));
        }

        /* Distribute the new matrix value to the shifted position */
        v[offset[i]] =
            (int)( (unsigned)ff_synmatrix4[i][0] * frame->sb_sample[blk][ch][0] +
                   (unsigned)ff_synmatrix4[i][1] * frame->sb_sample[blk][ch][1] +
                   (unsigned)ff_synmatrix4[i][2] * frame->sb_sample[blk][ch][2] +
                   (unsigned)ff_synmatrix4[i][3] * frame->sb_sample[blk][ch][3] ) >> 15;
    }

    /* Compute the samples */
    for (idx = 0, i = 0; i < 4; i++, idx += 5) {
        k = (i + 4) & 0xf;

        /* Store in output, Q0 */
        AV_WN16A(&output_frame->data[ch][blk * 8 + i * 2], av_clip_int16(
         (int)( (unsigned)v[offset[i] + 0] * ff_sbc_proto_4_40m0[idx + 0] +
                (unsigned)v[offset[k] + 1] * ff_sbc_proto_4_40m1[idx + 0] +
                (unsigned)v[offset[i] + 2] * ff_sbc_proto_4_40m0[idx + 1] +
                (unsigned)v[offset[k] + 3] * ff_sbc_proto_4_40m1[idx + 1] +
                (unsigned)v[offset[i] + 4] * ff_sbc_proto_4_40m0[idx + 2] +
                (unsigned)v[offset[k] + 5] * ff_sbc_proto_4_40m1[idx + 2] +
                (unsigned)v[offset[i] + 6] * ff_sbc_proto_4_40m0[idx + 3] +
                (unsigned)v[offset[k] + 7] * ff_sbc_proto_4_40m1[idx + 3] +
                (unsigned)v[offset[i] + 8] * ff_sbc_proto_4_40m0[idx + 4] +
                (unsigned)v[offset[k] + 9] * ff_sbc_proto_4_40m1[idx + 4] ) >> 15));
    }
}

static inline void sbc_synthesize_eight(struct sbc_decoder_state *state,
                                        struct sbc_frame *frame,
                                        int ch, int blk, AVFrame *output_frame)
{
    int i, k, idx;
    int32_t *v = state->V[ch];
    int *offset = state->offset[ch];

    for (i = 0; i < 16; i++) {
        /* Shifting */
        offset[i]--;
        if (offset[i] < 0) {
            offset[i] = 159;
            memcpy(v + 160, v, 9 * sizeof(*v));
        }

        /* Distribute the new matrix value to the shifted position */
        v[offset[i]] =
             (int)( (unsigned)ff_synmatrix8[i][0] * frame->sb_sample[blk][ch][0] +
                    (unsigned)ff_synmatrix8[i][1] * frame->sb_sample[blk][ch][1] +
                    (unsigned)ff_synmatrix8[i][2] * frame->sb_sample[blk][ch][2] +
                    (unsigned)ff_synmatrix8[i][3] * frame->sb_sample[blk][ch][3] +
                    (unsigned)ff_synmatrix8[i][4] * frame->sb_sample[blk][ch][4] +
                    (unsigned)ff_synmatrix8[i][5] * frame->sb_sample[blk][ch][5] +
                    (unsigned)ff_synmatrix8[i][6] * frame->sb_sample[blk][ch][6] +
                    (unsigned)ff_synmatrix8[i][7] * frame->sb_sample[blk][ch][7] ) >> 15;
    }

    /* Compute the samples */
    for (idx = 0, i = 0; i < 8; i++, idx += 5) {
        k = (i + 8) & 0xf;

        /* Store in output, Q0 */
        AV_WN16A(&output_frame->data[ch][blk * 16 + i * 2], av_clip_int16(
         (int)( (unsigned)v[offset[i] + 0] * ff_sbc_proto_8_80m0[idx + 0] +
                (unsigned)v[offset[k] + 1] * ff_sbc_proto_8_80m1[idx + 0] +
                (unsigned)v[offset[i] + 2] * ff_sbc_proto_8_80m0[idx + 1] +
                (unsigned)v[offset[k] + 3] * ff_sbc_proto_8_80m1[idx + 1] +
                (unsigned)v[offset[i] + 4] * ff_sbc_proto_8_80m0[idx + 2] +
                (unsigned)v[offset[k] + 5] * ff_sbc_proto_8_80m1[idx + 2] +
                (unsigned)v[offset[i] + 6] * ff_sbc_proto_8_80m0[idx + 3] +
                (unsigned)v[offset[k] + 7] * ff_sbc_proto_8_80m1[idx + 3] +
                (unsigned)v[offset[i] + 8] * ff_sbc_proto_8_80m0[idx + 4] +
                (unsigned)v[offset[k] + 9] * ff_sbc_proto_8_80m1[idx + 4] ) >> 15));
    }
}

static void sbc_synthesize_audio(struct sbc_decoder_state *state,
                                 struct sbc_frame *frame, AVFrame *output_frame)
{
    int ch, blk;

    switch (frame->subbands) {
    case 4:
        for (ch = 0; ch < frame->channels; ch++)
            for (blk = 0; blk < frame->blocks; blk++)
                sbc_synthesize_four(state, frame, ch, blk, output_frame);
        break;

    case 8:
        for (ch = 0; ch < frame->channels; ch++)
            for (blk = 0; blk < frame->blocks; blk++)
                sbc_synthesize_eight(state, frame, ch, blk, output_frame);
        break;
    }
}

static int sbc_decode_init(AVCodecContext *avctx)
{
    SBCDecContext *sbc = avctx->priv_data;
    int i, ch;

    sbc->frame.crc_ctx = av_crc_get_table(AV_CRC_8_EBU);

    memset(sbc->dsp.V, 0, sizeof(sbc->dsp.V));
    for (ch = 0; ch < 2; ch++)
        for (i = 0; i < FF_ARRAY_ELEMS(sbc->dsp.offset[0]); i++)
            sbc->dsp.offset[ch][i] = (10 * i + 10);
    return 0;
}

static int sbc_decode_frame(AVCodecContext *avctx,
                            void *data, int *got_frame_ptr,
                            AVPacket *avpkt)
{
    SBCDecContext *sbc = avctx->priv_data;
    AVFrame *frame = data;
    int ret, frame_length;

    if (!sbc)
        return AVERROR(EIO);

    frame_length = sbc_unpack_frame(avpkt->data, &sbc->frame, avpkt->size);
    if (frame_length <= 0)
        return frame_length;

    avctx->channels =
    frame->channels = sbc->frame.channels;
    frame->format = AV_SAMPLE_FMT_S16P;
    frame->nb_samples = sbc->frame.blocks * sbc->frame.subbands;
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;

    sbc_synthesize_audio(&sbc->dsp, &sbc->frame, frame);

    *got_frame_ptr = 1;

    return frame_length;
}

AVCodec ff_sbc_decoder = {
    .name                  = "sbc",
    .long_name             = NULL_IF_CONFIG_SMALL("SBC (low-complexity subband codec)"),
    .type                  = AVMEDIA_TYPE_AUDIO,
    .id                    = AV_CODEC_ID_SBC,
    .priv_data_size        = sizeof(SBCDecContext),
    .init                  = sbc_decode_init,
    .decode                = sbc_decode_frame,
    .capabilities          = AV_CODEC_CAP_DR1,
    .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,
    .channel_layouts       = (const uint64_t[]) { AV_CH_LAYOUT_MONO,
                                                  AV_CH_LAYOUT_STEREO, 0},
    .sample_fmts           = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
                                                             AV_SAMPLE_FMT_NONE },
    .supported_samplerates = (const int[]) { 16000, 32000, 44100, 48000, 0 },
};
OpenPOWER on IntegriCloud