alac.c 21.7 KB
Newer Older
1 2 3 4
/*
 * ALAC (Apple Lossless Audio Codec) decoder
 * Copyright (c) 2005 David Hammerton
 *
5 6 7
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
8 9
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
10
 * version 2.1 of the License, or (at your option) any later version.
11
 *
12
 * FFmpeg is distributed in the hope that it will be useful,
13 14 15 16 17
 * 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
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
20 21 22
 */

/**
23
 * @file
24 25
 * ALAC (Apple Lossless Audio Codec) decoder
 * @author 2005 David Hammerton
26
 * @see http://crazney.net/programs/itunes/alac.html
27
 *
28
 * Note: This decoder expects a 36-byte QuickTime atom to be
29 30
 * passed through the extradata[_size] fields. This atom is tacked onto
 * the end of an 'alac' stsd atom and has the following format:
31
 *
32 33 34 35 36
 * 32bit  atom size
 * 32bit  tag                  ("alac")
 * 32bit  tag version          (0)
 * 32bit  samples per frame    (used when not set explicitly in the frames)
 *  8bit  compatible version   (0)
37
 *  8bit  sample size
38
 *  8bit  history mult         (40)
39 40
 *  8bit  initial history      (10)
 *  8bit  rice param limit     (14)
41 42 43 44
 *  8bit  channels
 * 16bit  maxRun               (255)
 * 32bit  max coded frame size (0 means unknown)
 * 32bit  average bitrate      (0 means unknown)
45
 * 32bit  samplerate
46 47
 */

48 49
#include <inttypes.h>

50
#include "libavutil/channel_layout.h"
51
#include "libavutil/opt.h"
52
#include "avcodec.h"
53
#include "get_bits.h"
54
#include "bytestream.h"
55
#include "internal.h"
56
#include "thread.h"
57
#include "unary.h"
58
#include "mathops.h"
59
#include "alac_data.h"
60 61 62

#define ALAC_EXTRADATA_SIZE 36

63
typedef struct {
64
    AVClass *class;
65 66
    AVCodecContext *avctx;
    GetBitContext gb;
67
    int channels;
68

69 70 71
    int32_t *predict_error_buffer[2];
    int32_t *output_samples_buffer[2];
    int32_t *extra_bits_buffer[2];
72

73 74 75 76 77
    uint32_t max_samples_per_frame;
    uint8_t  sample_size;
    uint8_t  rice_history_mult;
    uint8_t  rice_initial_history;
    uint8_t  rice_limit;
78

79 80
    int extra_bits;     /**< number of extra bits beyond 16-bit */
    int nb_samples;     /**< number of samples in the current frame */
81 82

    int direct_output;
83
    int extra_bit_bug;
84 85
} ALACContext;

86
static inline unsigned int decode_scalar(GetBitContext *gb, int k, int bps)
87
{
88
    unsigned int x = get_unary_0_9(gb);
89 90 91

    if (x > 8) { /* RICE THRESHOLD */
        /* use alternative encoding */
92
        x = get_bits_long(gb, bps);
93
    } else if (k != 1) {
94
        int extrabits = show_bits(gb, k);
95

96 97
        /* multiply x by 2^k - 1, as part of their strange algorithm */
        x = (x << k) - x;
98

99 100 101 102 103
        if (extrabits > 1) {
            x += extrabits - 1;
            skip_bits(gb, k);
        } else
            skip_bits(gb, k - 1);
104
    }
105 106 107
    return x;
}

108
static int rice_decompress(ALACContext *alac, int32_t *output_buffer,
109
                            int nb_samples, int bps, int rice_history_mult)
110
{
111
    int i;
112
    unsigned int history = alac->rice_initial_history;
113 114
    int sign_modifier = 0;

115
    for (i = 0; i < nb_samples; i++) {
116 117
        int k;
        unsigned int x;
118

119 120 121
        if(get_bits_left(&alac->gb) <= 0)
            return -1;

122
        /* calculate rice param and decode next value */
123
        k = av_log2((history >> 9) + 3);
124
        k = FFMIN(k, alac->rice_limit);
125
        x = decode_scalar(&alac->gb, k, bps);
126
        x += sign_modifier;
127
        sign_modifier = 0;
128
        output_buffer[i] = (x >> 1) ^ -(x & 1);
129

130
        /* update the history */
131
        if (x > 0xffff)
132
            history = 0xffff;
133
        else
134 135
            history +=         x * rice_history_mult -
                       ((history * rice_history_mult) >> 9);
136 137

        /* special case: there may be compressed blocks of 0 */
138
        if ((history < 128) && (i + 1 < nb_samples)) {
139
            int block_size;
140

141 142
            /* calculate rice param and decode block size */
            k = 7 - av_log2(history) + ((history + 16) >> 6);
143 144
            k = FFMIN(k, alac->rice_limit);
            block_size = decode_scalar(&alac->gb, k, 16);
145 146

            if (block_size > 0) {
147 148 149 150 151
                if (block_size >= nb_samples - i) {
                    av_log(alac->avctx, AV_LOG_ERROR,
                           "invalid zero block size of %d %d %d\n", block_size,
                           nb_samples, i);
                    block_size = nb_samples - i - 1;
152
                }
153
                memset(&output_buffer[i + 1], 0,
154
                       block_size * sizeof(*output_buffer));
155
                i += block_size;
156
            }
157 158
            if (block_size <= 0xffff)
                sign_modifier = 1;
159 160 161
            history = 0;
        }
    }
162
    return 0;
163 164
}

165 166 167 168
static inline int sign_only(int v)
{
    return v ? FFSIGN(v) : 0;
}
169

170 171 172
static void lpc_prediction(int32_t *error_buffer, int32_t *buffer_out,
                           int nb_samples, int bps, int16_t *lpc_coefs,
                           int lpc_order, int lpc_quant)
173 174
{
    int i;
175
    int32_t *pred = buffer_out;
176 177 178 179

    /* first sample always copies */
    *buffer_out = *error_buffer;

180
    if (nb_samples <= 1)
181
        return;
Vitor Sessak's avatar
Vitor Sessak committed
182

183
    if (!lpc_order) {
184
        memcpy(&buffer_out[1], &error_buffer[1],
185
               (nb_samples - 1) * sizeof(*buffer_out));
186 187 188
        return;
    }

189
    if (lpc_order == 31) {
190
        /* simple 1st-order prediction */
191
        for (i = 1; i < nb_samples; i++) {
192
            buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i],
193
                                        bps);
194 195 196 197 198
        }
        return;
    }

    /* read warm-up samples */
199
    for (i = 1; i <= lpc_order && i < nb_samples; i++)
200
        buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i], bps);
201

202
    /* NOTE: 4 and 8 are very common cases that could be optimized. */
203

204
    for (; i < nb_samples; i++) {
205
        int j;
206
        int val = 0;
207
        int error_val = error_buffer[i];
208
        int error_sign;
209
        int d = *pred++;
210

211 212
        /* LPC prediction */
        for (j = 0; j < lpc_order; j++)
213
            val += (pred[j] - d) * lpc_coefs[j];
214
        val = (val + (1 << (lpc_quant - 1))) >> lpc_quant;
215
        val += d + error_val;
216
        buffer_out[i] = sign_extend(val, bps);
217

218 219 220
        /* adapt LPC coefficients */
        error_sign = sign_only(error_val);
        if (error_sign) {
221
            for (j = 0; j < lpc_order && error_val * error_sign > 0; j++) {
222
                int sign;
223
                val  = d - pred[j];
224
                sign = sign_only(val) * error_sign;
225
                lpc_coefs[j] -= sign;
226
                val *= sign;
227
                error_val -= (val >> lpc_quant) * (j + 1);
228 229 230 231 232
            }
        }
    }
}

233 234
static void decorrelate_stereo(int32_t *buffer[2], int nb_samples,
                               int decorr_shift, int decorr_left_weight)
235
{
236 237
    int i;

238
    for (i = 0; i < nb_samples; i++) {
239
        int32_t a, b;
240

241 242
        a = buffer[0][i];
        b = buffer[1][i];
243

244
        a -= (b * decorr_left_weight) >> decorr_shift;
245
        b += a;
246

247 248
        buffer[0][i] = b;
        buffer[1][i] = a;
249
    }
250
}
251

252
static void append_extra_bits(int32_t *buffer[2], int32_t *extra_bits_buffer[2],
253
                              int extra_bits, int channels, int nb_samples)
254 255
{
    int i, ch;
256

257 258
    for (ch = 0; ch < channels; ch++)
        for (i = 0; i < nb_samples; i++)
259
            buffer[ch][i] = (buffer[ch][i] << extra_bits) | extra_bits_buffer[ch][i];
260 261
}

262
static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,
263
                          int channels)
264
{
265
    ALACContext *alac = avctx->priv_data;
266
    int has_size, bps, is_compressed, decorr_shift, decorr_left_weight, ret;
267
    uint32_t output_samples;
268
    int i, ch;
269

270 271
    skip_bits(&alac->gb, 4);  /* element instance tag */
    skip_bits(&alac->gb, 12); /* unused header bits */
272

273
    /* the number of output samples is stored in the frame */
274
    has_size = get_bits1(&alac->gb);
275

276
    alac->extra_bits = get_bits(&alac->gb, 2) << 3;
277
    bps = alac->sample_size - alac->extra_bits + channels - 1;
278
    if (bps > 32U) {
279
        av_log(avctx, AV_LOG_ERROR, "bps is unsupported: %d\n", bps);
280 281
        return AVERROR_PATCHWELCOME;
    }
282

Vitor Sessak's avatar
Vitor Sessak committed
283
    /* whether the frame is compressed */
284
    is_compressed = !get_bits1(&alac->gb);
285

286
    if (has_size)
287 288 289 290
        output_samples = get_bits_long(&alac->gb, 32);
    else
        output_samples = alac->max_samples_per_frame;
    if (!output_samples || output_samples > alac->max_samples_per_frame) {
291
        av_log(avctx, AV_LOG_ERROR, "invalid samples per frame: %"PRIu32"\n",
292
               output_samples);
293 294
        return AVERROR_INVALIDDATA;
    }
295
    if (!alac->nb_samples) {
296
        ThreadFrame tframe = { .f = frame };
297
        /* get output buffer */
298
        frame->nb_samples = output_samples;
299
        if ((ret = ff_thread_get_buffer(avctx, &tframe, 0)) < 0)
300 301
            return ret;
    } else if (output_samples != alac->nb_samples) {
302
        av_log(avctx, AV_LOG_ERROR, "sample count mismatch: %"PRIu32" != %d\n",
303 304
               output_samples, alac->nb_samples);
        return AVERROR_INVALIDDATA;
305
    }
306
    alac->nb_samples = output_samples;
307
    if (alac->direct_output) {
308
        for (ch = 0; ch < channels; ch++)
309
            alac->output_samples_buffer[ch] = (int32_t *)frame->extended_data[ch_index + ch];
310
    }
311

312
    if (is_compressed) {
313 314
        int16_t lpc_coefs[2][32];
        int lpc_order[2];
315
        int prediction_type[2];
316 317
        int lpc_quant[2];
        int rice_history_mult[2];
318

319 320
        decorr_shift       = get_bits(&alac->gb, 8);
        decorr_left_weight = get_bits(&alac->gb, 8);
321

322
        for (ch = 0; ch < channels; ch++) {
323 324 325 326
            prediction_type[ch]   = get_bits(&alac->gb, 4);
            lpc_quant[ch]         = get_bits(&alac->gb, 4);
            rice_history_mult[ch] = get_bits(&alac->gb, 3);
            lpc_order[ch]         = get_bits(&alac->gb, 5);
327

328 329 330
            if (lpc_order[ch] >= alac->max_samples_per_frame)
                return AVERROR_INVALIDDATA;

331
            /* read the predictor table */
332
            for (i = lpc_order[ch] - 1; i >= 0; i--)
333
                lpc_coefs[ch][i] = get_sbits(&alac->gb, 16);
Vitor Sessak's avatar
Vitor Sessak committed
334
        }
335

336
        if (alac->extra_bits) {
337
            for (i = 0; i < alac->nb_samples; i++) {
338 339
                if(get_bits_left(&alac->gb) <= 0)
                    return -1;
340
                for (ch = 0; ch < channels; ch++)
341
                    alac->extra_bits_buffer[ch][i] = get_bits(&alac->gb, alac->extra_bits);
342 343
            }
        }
344
        for (ch = 0; ch < channels; ch++) {
345
            int ret=rice_decompress(alac, alac->predict_error_buffer[ch],
346 347
                            alac->nb_samples, bps,
                            rice_history_mult[ch] * alac->rice_history_mult / 4);
348 349
            if(ret<0)
                return ret;
350

351 352 353 354 355 356 357 358
            /* adaptive FIR filter */
            if (prediction_type[ch] == 15) {
                /* Prediction type 15 runs the adaptive FIR twice.
                 * The first pass uses the special-case coef_num = 31, while
                 * the second pass uses the coefs from the bitstream.
                 *
                 * However, this prediction type is not currently used by the
                 * reference encoder.
359
                 */
360 361 362
                lpc_prediction(alac->predict_error_buffer[ch],
                               alac->predict_error_buffer[ch],
                               alac->nb_samples, bps, NULL, 31, 0);
363 364 365
            } else if (prediction_type[ch] > 0) {
                av_log(avctx, AV_LOG_WARNING, "unknown prediction type: %i\n",
                       prediction_type[ch]);
366
            }
367 368 369
            lpc_prediction(alac->predict_error_buffer[ch],
                           alac->output_samples_buffer[ch], alac->nb_samples,
                           bps, lpc_coefs[ch], lpc_order[ch], lpc_quant[ch]);
Vitor Sessak's avatar
Vitor Sessak committed
370 371 372
        }
    } else {
        /* not compressed, easy case */
373
        for (i = 0; i < alac->nb_samples; i++) {
374 375
            if(get_bits_left(&alac->gb) <= 0)
                return -1;
376
            for (ch = 0; ch < channels; ch++) {
377 378
                alac->output_samples_buffer[ch][i] =
                         get_sbits_long(&alac->gb, alac->sample_size);
379 380
            }
        }
381
        alac->extra_bits   = 0;
382 383
        decorr_shift       = 0;
        decorr_left_weight = 0;
Vitor Sessak's avatar
Vitor Sessak committed
384
    }
385

386 387 388 389 390
    if (alac->extra_bits && alac->extra_bit_bug) {
        append_extra_bits(alac->output_samples_buffer, alac->extra_bits_buffer,
                          alac->extra_bits, channels, alac->nb_samples);
    }

391
    if (channels == 2 && decorr_left_weight) {
392
        decorrelate_stereo(alac->output_samples_buffer, alac->nb_samples,
393
                           decorr_shift, decorr_left_weight);
394 395
    }

396
    if (alac->extra_bits && !alac->extra_bit_bug) {
397
        append_extra_bits(alac->output_samples_buffer, alac->extra_bits_buffer,
398
                          alac->extra_bits, channels, alac->nb_samples);
399 400
    }

401
    if(av_sample_fmt_is_planar(avctx->sample_fmt)) {
402
    switch(alac->sample_size) {
403
    case 16: {
404
        for (ch = 0; ch < channels; ch++) {
405
            int16_t *outbuffer = (int16_t *)frame->extended_data[ch_index + ch];
406 407
            for (i = 0; i < alac->nb_samples; i++)
                *outbuffer++ = alac->output_samples_buffer[ch][i];
408
        }}
Vitor Sessak's avatar
Vitor Sessak committed
409
        break;
410
    case 24: {
411
        for (ch = 0; ch < channels; ch++) {
412 413
            for (i = 0; i < alac->nb_samples; i++)
                alac->output_samples_buffer[ch][i] <<= 8;
414
        }}
Vitor Sessak's avatar
Vitor Sessak committed
415 416
        break;
    }
417 418 419
    }else{
        switch(alac->sample_size) {
        case 16: {
420
            int16_t *outbuffer = ((int16_t *)frame->extended_data[0]) + ch_index;
421
            for (i = 0; i < alac->nb_samples; i++) {
422 423
                for (ch = 0; ch < channels; ch++)
                    *outbuffer++ = alac->output_samples_buffer[ch][i];
424 425
                outbuffer += alac->channels - channels;
            }
426 427 428
            }
            break;
        case 24: {
429
            int32_t *outbuffer = ((int32_t *)frame->extended_data[0]) + ch_index;
430
            for (i = 0; i < alac->nb_samples; i++) {
431 432
                for (ch = 0; ch < channels; ch++)
                    *outbuffer++ = alac->output_samples_buffer[ch][i] << 8;
433 434
                outbuffer += alac->channels - channels;
            }
435 436 437
            }
            break;
        case 32: {
438
            int32_t *outbuffer = ((int32_t *)frame->extended_data[0]) + ch_index;
439
            for (i = 0; i < alac->nb_samples; i++) {
440 441
                for (ch = 0; ch < channels; ch++)
                    *outbuffer++ = alac->output_samples_buffer[ch][i];
442 443
                outbuffer += alac->channels - channels;
            }
444 445 446 447
            }
            break;
        }
    }
448

449 450 451 452 453 454 455
    return 0;
}

static int alac_decode_frame(AVCodecContext *avctx, void *data,
                             int *got_frame_ptr, AVPacket *avpkt)
{
    ALACContext *alac = avctx->priv_data;
456
    AVFrame *frame    = data;
457
    enum AlacRawDataBlockType element;
458
    int channels;
459
    int ch, ret, got_end;
460

461 462
    if ((ret = init_get_bits8(&alac->gb, avpkt->data, avpkt->size)) < 0)
        return ret;
463

464
    got_end = 0;
465 466
    alac->nb_samples = 0;
    ch = 0;
467
    while (get_bits_left(&alac->gb) >= 3) {
468
        element = get_bits(&alac->gb, 3);
469 470
        if (element == TYPE_END) {
            got_end = 1;
471
            break;
472
        }
473
        if (element > TYPE_CPE && element != TYPE_LFE) {
474
            av_log(avctx, AV_LOG_ERROR, "syntax element unsupported: %d\n", element);
475
            return AVERROR_PATCHWELCOME;
476
        }
477 478

        channels = (element == TYPE_CPE) ? 2 : 1;
479 480
        if (ch + channels > alac->channels ||
            ff_alac_channel_layout_offsets[alac->channels - 1][ch] + channels > alac->channels) {
481 482 483 484
            av_log(avctx, AV_LOG_ERROR, "invalid element channel count\n");
            return AVERROR_INVALIDDATA;
        }

485
        ret = decode_element(avctx, frame,
486
                             ff_alac_channel_layout_offsets[alac->channels - 1][ch],
487
                             channels);
488
        if (ret < 0 && get_bits_left(&alac->gb))
489 490 491
            return ret;

        ch += channels;
Vitor Sessak's avatar
Vitor Sessak committed
492
    }
493 494 495 496
    if (!got_end) {
        av_log(avctx, AV_LOG_ERROR, "no end tag found. incomplete packet.\n");
        return AVERROR_INVALIDDATA;
    }
497

498
    if (avpkt->size * 8 - get_bits_count(&alac->gb) > 8) {
499 500
        av_log(avctx, AV_LOG_ERROR, "Error : %d bits left\n",
               avpkt->size * 8 - get_bits_count(&alac->gb));
501
    }
Matthieu Castet's avatar
Matthieu Castet committed
502

503 504
    if (alac->channels == ch)
        *got_frame_ptr = 1;
505 506
    else
        av_log(avctx, AV_LOG_WARNING, "Failed to decode all channels\n");
507

508
    return avpkt->size;
509 510
}

511 512 513 514
static av_cold int alac_decode_close(AVCodecContext *avctx)
{
    ALACContext *alac = avctx->priv_data;

515
    int ch;
516
    for (ch = 0; ch < FFMIN(alac->channels, 2); ch++) {
517
        av_freep(&alac->predict_error_buffer[ch]);
518
        if (!alac->direct_output)
519
            av_freep(&alac->output_samples_buffer[ch]);
520
        av_freep(&alac->extra_bits_buffer[ch]);
521 522 523 524 525 526 527
    }

    return 0;
}

static int allocate_buffers(ALACContext *alac)
{
528
    int ch;
529
    int buf_size = alac->max_samples_per_frame * sizeof(int32_t);
530

531
    for (ch = 0; ch < FFMIN(alac->channels, 2); ch++) {
532
        FF_ALLOC_OR_GOTO(alac->avctx, alac->predict_error_buffer[ch],
533
                         buf_size, buf_alloc_fail);
534

535 536
        alac->direct_output = alac->sample_size > 16 && av_sample_fmt_is_planar(alac->avctx->sample_fmt);
        if (!alac->direct_output) {
537 538 539
            FF_ALLOC_OR_GOTO(alac->avctx, alac->output_samples_buffer[ch],
                             buf_size, buf_alloc_fail);
        }
540

541 542
        FF_ALLOC_OR_GOTO(alac->avctx, alac->extra_bits_buffer[ch],
                         buf_size, buf_alloc_fail);
543 544
    }
    return 0;
545 546 547
buf_alloc_fail:
    alac_decode_close(alac->avctx);
    return AVERROR(ENOMEM);
548 549 550 551
}

static int alac_set_info(ALACContext *alac)
{
552
    GetByteContext gb;
553

554 555
    bytestream2_init(&gb, alac->avctx->extradata,
                     alac->avctx->extradata_size);
556

557
    bytestream2_skipu(&gb, 12); // size:4, alac:4, version:4
558

559
    alac->max_samples_per_frame = bytestream2_get_be32u(&gb);
560 561
    if (!alac->max_samples_per_frame ||
        alac->max_samples_per_frame > INT_MAX / sizeof(int32_t)) {
562 563
        av_log(alac->avctx, AV_LOG_ERROR,
               "max samples per frame invalid: %"PRIu32"\n",
564
               alac->max_samples_per_frame);
565 566 567
        return AVERROR_INVALIDDATA;
    }
    bytestream2_skipu(&gb, 1);  // compatible version
568 569 570 571 572
    alac->sample_size          = bytestream2_get_byteu(&gb);
    alac->rice_history_mult    = bytestream2_get_byteu(&gb);
    alac->rice_initial_history = bytestream2_get_byteu(&gb);
    alac->rice_limit           = bytestream2_get_byteu(&gb);
    alac->channels             = bytestream2_get_byteu(&gb);
573 574 575 576
    bytestream2_get_be16u(&gb); // maxRun
    bytestream2_get_be32u(&gb); // max coded frame size
    bytestream2_get_be32u(&gb); // average bitrate
    bytestream2_get_be32u(&gb); // samplerate
577 578 579 580

    return 0;
}

581
static av_cold int alac_decode_init(AVCodecContext * avctx)
582
{
583
    int ret;
584
    int req_packed;
585 586
    ALACContext *alac = avctx->priv_data;
    alac->avctx = avctx;
587

Jason Garrett-Glaser's avatar
Jason Garrett-Glaser committed
588
    /* initialize from the extradata */
589
    if (alac->avctx->extradata_size < ALAC_EXTRADATA_SIZE) {
590
        av_log(avctx, AV_LOG_ERROR, "extradata is too small\n");
591
        return AVERROR_INVALIDDATA;
Jason Garrett-Glaser's avatar
Jason Garrett-Glaser committed
592 593
    }
    if (alac_set_info(alac)) {
594
        av_log(avctx, AV_LOG_ERROR, "set_info failed\n");
Jason Garrett-Glaser's avatar
Jason Garrett-Glaser committed
595 596 597
        return -1;
    }

598
    req_packed = LIBAVCODEC_VERSION_MAJOR < 55 && !av_sample_fmt_is_planar(avctx->request_sample_fmt);
599
    switch (alac->sample_size) {
600
    case 16: avctx->sample_fmt = req_packed ? AV_SAMPLE_FMT_S16 : AV_SAMPLE_FMT_S16P;
601
             break;
602
    case 24:
603
    case 32: avctx->sample_fmt = req_packed ? AV_SAMPLE_FMT_S32 : AV_SAMPLE_FMT_S32P;
604
             break;
605
    default: avpriv_request_sample(avctx, "Sample depth %d", alac->sample_size);
606
             return AVERROR_PATCHWELCOME;
607
    }
608
    avctx->bits_per_raw_sample = alac->sample_size;
609

610
    if (alac->channels < 1) {
611
        av_log(avctx, AV_LOG_WARNING, "Invalid channel count\n");
612
        alac->channels = avctx->channels;
613
    } else {
614
        if (alac->channels > ALAC_MAX_CHANNELS)
615
            alac->channels = avctx->channels;
616
        else
617
            avctx->channels = alac->channels;
618
    }
619
    if (avctx->channels > ALAC_MAX_CHANNELS || avctx->channels <= 0 ) {
620 621 622 623
        av_log(avctx, AV_LOG_ERROR, "Unsupported channel count: %d\n",
               avctx->channels);
        return AVERROR_PATCHWELCOME;
    }
624
    avctx->channel_layout = ff_alac_channel_layouts[alac->channels - 1];
625

626 627 628
    if ((ret = allocate_buffers(alac)) < 0) {
        av_log(avctx, AV_LOG_ERROR, "Error allocating buffers\n");
        return ret;
629
    }
630 631 632 633

    return 0;
}

634 635 636
static int init_thread_copy(AVCodecContext *avctx)
{
    ALACContext *alac = avctx->priv_data;
637
    alac->avctx = avctx;
638 639 640
    return allocate_buffers(alac);
}

641 642 643 644 645 646 647 648 649 650 651 652 653 654
static const AVOption options[] = {
    { "extra_bits_bug", "Force non-standard decoding process",
      offsetof(ALACContext, extra_bit_bug), AV_OPT_TYPE_INT, { .i64 = 0 },
      0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM },
    { NULL },
};

static const AVClass alac_class = {
    .class_name = "alac",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

655
AVCodec ff_alac_decoder = {
656
    .name           = "alac",
657
    .long_name      = NULL_IF_CONFIG_SMALL("ALAC (Apple Lossless Audio Codec)"),
658
    .type           = AVMEDIA_TYPE_AUDIO,
659
    .id             = AV_CODEC_ID_ALAC,
660 661 662 663
    .priv_data_size = sizeof(ALACContext),
    .init           = alac_decode_init,
    .close          = alac_decode_close,
    .decode         = alac_decode_frame,
664
    .init_thread_copy = ONLY_IF_THREADS_ENABLED(init_thread_copy),
665
    .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
666
    .priv_class     = &alac_class
667
};