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1
/*
2
 * Monkey's Audio lossless audio decoder
3
 * Copyright (c) 2007 Benjamin Zores <ben@geexbox.org>
4
 *  based upon libdemac from Dave Chapman.
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
9
 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
22

    
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#define ALT_BITSTREAM_READER_LE
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#include "avcodec.h"
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#include "dsputil.h"
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#include "get_bits.h"
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#include "bytestream.h"
28

    
29
/**
30
 * @file libavcodec/apedec.c
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 * Monkey's Audio lossless audio decoder
32
 */
33

    
34
#define BLOCKS_PER_LOOP     4608
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#define MAX_CHANNELS        2
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#define MAX_BYTESPERSAMPLE  3
37

    
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#define APE_FRAMECODE_MONO_SILENCE    1
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#define APE_FRAMECODE_STEREO_SILENCE  3
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#define APE_FRAMECODE_PSEUDO_STEREO   4
41

    
42
#define HISTORY_SIZE 512
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#define PREDICTOR_ORDER 8
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/** Total size of all predictor histories */
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#define PREDICTOR_SIZE 50
46

    
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#define YDELAYA (18 + PREDICTOR_ORDER*4)
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#define YDELAYB (18 + PREDICTOR_ORDER*3)
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#define XDELAYA (18 + PREDICTOR_ORDER*2)
50
#define XDELAYB (18 + PREDICTOR_ORDER)
51

    
52
#define YADAPTCOEFFSA 18
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#define XADAPTCOEFFSA 14
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#define YADAPTCOEFFSB 10
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#define XADAPTCOEFFSB 5
56

    
57
/**
58
 * Possible compression levels
59
 * @{
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 */
61
enum APECompressionLevel {
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    COMPRESSION_LEVEL_FAST       = 1000,
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    COMPRESSION_LEVEL_NORMAL     = 2000,
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    COMPRESSION_LEVEL_HIGH       = 3000,
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    COMPRESSION_LEVEL_EXTRA_HIGH = 4000,
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    COMPRESSION_LEVEL_INSANE     = 5000
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};
68
/** @} */
69

    
70
#define APE_FILTER_LEVELS 3
71

    
72
/** Filter orders depending on compression level */
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static const uint16_t ape_filter_orders[5][APE_FILTER_LEVELS] = {
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    {  0,   0,    0 },
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    { 16,   0,    0 },
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    { 64,   0,    0 },
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    { 32, 256,    0 },
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    { 16, 256, 1280 }
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};
80

    
81
/** Filter fraction bits depending on compression level */
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static const uint8_t ape_filter_fracbits[5][APE_FILTER_LEVELS] = {
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    {  0,  0,  0 },
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    { 11,  0,  0 },
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    { 11,  0,  0 },
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    { 10, 13,  0 },
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    { 11, 13, 15 }
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};
89

    
90

    
91
/** Filters applied to the decoded data */
92
typedef struct APEFilter {
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    int16_t *coeffs;        ///< actual coefficients used in filtering
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    int16_t *adaptcoeffs;   ///< adaptive filter coefficients used for correcting of actual filter coefficients
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    int16_t *historybuffer; ///< filter memory
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    int16_t *delay;         ///< filtered values
97

    
98
    int avg;
99
} APEFilter;
100

    
101
typedef struct APERice {
102
    uint32_t k;
103
    uint32_t ksum;
104
} APERice;
105

    
106
typedef struct APERangecoder {
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    uint32_t low;           ///< low end of interval
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    uint32_t range;         ///< length of interval
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    uint32_t help;          ///< bytes_to_follow resp. intermediate value
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    unsigned int buffer;    ///< buffer for input/output
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} APERangecoder;
112

    
113
/** Filter histories */
114
typedef struct APEPredictor {
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    int32_t *buf;
116

    
117
    int32_t lastA[2];
118

    
119
    int32_t filterA[2];
120
    int32_t filterB[2];
121

    
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    int32_t coeffsA[2][4];  ///< adaption coefficients
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    int32_t coeffsB[2][5];  ///< adaption coefficients
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    int32_t historybuffer[HISTORY_SIZE + PREDICTOR_SIZE];
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} APEPredictor;
126

    
127
/** Decoder context */
128
typedef struct APEContext {
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    AVCodecContext *avctx;
130
    DSPContext dsp;
131
    int channels;
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    int samples;                             ///< samples left to decode in current frame
133

    
134
    int fileversion;                         ///< codec version, very important in decoding process
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    int compression_level;                   ///< compression levels
136
    int fset;                                ///< which filter set to use (calculated from compression level)
137
    int flags;                               ///< global decoder flags
138

    
139
    uint32_t CRC;                            ///< frame CRC
140
    int frameflags;                          ///< frame flags
141
    int currentframeblocks;                  ///< samples (per channel) in current frame
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    int blocksdecoded;                       ///< count of decoded samples in current frame
143
    APEPredictor predictor;                  ///< predictor used for final reconstruction
144

    
145
    int32_t decoded0[BLOCKS_PER_LOOP];       ///< decoded data for the first channel
146
    int32_t decoded1[BLOCKS_PER_LOOP];       ///< decoded data for the second channel
147

    
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    int16_t* filterbuf[APE_FILTER_LEVELS];   ///< filter memory
149

    
150
    APERangecoder rc;                        ///< rangecoder used to decode actual values
151
    APERice riceX;                           ///< rice code parameters for the second channel
152
    APERice riceY;                           ///< rice code parameters for the first channel
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    APEFilter filters[APE_FILTER_LEVELS][2]; ///< filters used for reconstruction
154

    
155
    uint8_t *data;                           ///< current frame data
156
    uint8_t *data_end;                       ///< frame data end
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    const uint8_t *ptr;                      ///< current position in frame data
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    const uint8_t *last_ptr;                 ///< position where last 4608-sample block ended
159

    
160
    int error;
161
} APEContext;
162

    
163
// TODO: dsputilize
164

    
165
static av_cold int ape_decode_init(AVCodecContext * avctx)
166
{
167
    APEContext *s = avctx->priv_data;
168
    int i;
169

    
170
    if (avctx->extradata_size != 6) {
171
        av_log(avctx, AV_LOG_ERROR, "Incorrect extradata\n");
172
        return -1;
173
    }
174
    if (avctx->bits_per_coded_sample != 16) {
175
        av_log(avctx, AV_LOG_ERROR, "Only 16-bit samples are supported\n");
176
        return -1;
177
    }
178
    if (avctx->channels > 2) {
179
        av_log(avctx, AV_LOG_ERROR, "Only mono and stereo is supported\n");
180
        return -1;
181
    }
182
    s->avctx             = avctx;
183
    s->channels          = avctx->channels;
184
    s->fileversion       = AV_RL16(avctx->extradata);
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    s->compression_level = AV_RL16(avctx->extradata + 2);
186
    s->flags             = AV_RL16(avctx->extradata + 4);
187

    
188
    av_log(avctx, AV_LOG_DEBUG, "Compression Level: %d - Flags: %d\n", s->compression_level, s->flags);
189
    if (s->compression_level % 1000 || s->compression_level > COMPRESSION_LEVEL_INSANE) {
190
        av_log(avctx, AV_LOG_ERROR, "Incorrect compression level %d\n", s->compression_level);
191
        return -1;
192
    }
193
    s->fset = s->compression_level / 1000 - 1;
194
    for (i = 0; i < APE_FILTER_LEVELS; i++) {
195
        if (!ape_filter_orders[s->fset][i])
196
            break;
197
        s->filterbuf[i] = av_malloc((ape_filter_orders[s->fset][i] * 3 + HISTORY_SIZE) * 4);
198
    }
199

    
200
    dsputil_init(&s->dsp, avctx);
201
    avctx->sample_fmt = SAMPLE_FMT_S16;
202
    avctx->channel_layout = (avctx->channels==2) ? CH_LAYOUT_STEREO : CH_LAYOUT_MONO;
203
    return 0;
204
}
205

    
206
static av_cold int ape_decode_close(AVCodecContext * avctx)
207
{
208
    APEContext *s = avctx->priv_data;
209
    int i;
210

    
211
    for (i = 0; i < APE_FILTER_LEVELS; i++)
212
        av_freep(&s->filterbuf[i]);
213

    
214
    return 0;
215
}
216

    
217
/**
218
 * @defgroup rangecoder APE range decoder
219
 * @{
220
 */
221

    
222
#define CODE_BITS    32
223
#define TOP_VALUE    ((unsigned int)1 << (CODE_BITS-1))
224
#define SHIFT_BITS   (CODE_BITS - 9)
225
#define EXTRA_BITS   ((CODE_BITS-2) % 8 + 1)
226
#define BOTTOM_VALUE (TOP_VALUE >> 8)
227

    
228
/** Start the decoder */
229
static inline void range_start_decoding(APEContext * ctx)
230
{
231
    ctx->rc.buffer = bytestream_get_byte(&ctx->ptr);
232
    ctx->rc.low    = ctx->rc.buffer >> (8 - EXTRA_BITS);
233
    ctx->rc.range  = (uint32_t) 1 << EXTRA_BITS;
234
}
235

    
236
/** Perform normalization */
237
static inline void range_dec_normalize(APEContext * ctx)
238
{
239
    while (ctx->rc.range <= BOTTOM_VALUE) {
240
        ctx->rc.buffer <<= 8;
241
        if(ctx->ptr < ctx->data_end)
242
            ctx->rc.buffer += *ctx->ptr;
243
        ctx->ptr++;
244
        ctx->rc.low    = (ctx->rc.low << 8)    | ((ctx->rc.buffer >> 1) & 0xFF);
245
        ctx->rc.range  <<= 8;
246
    }
247
}
248

    
249
/**
250
 * Calculate culmulative frequency for next symbol. Does NO update!
251
 * @param ctx decoder context
252
 * @param tot_f is the total frequency or (code_value)1<<shift
253
 * @return the culmulative frequency
254
 */
255
static inline int range_decode_culfreq(APEContext * ctx, int tot_f)
256
{
257
    range_dec_normalize(ctx);
258
    ctx->rc.help = ctx->rc.range / tot_f;
259
    return ctx->rc.low / ctx->rc.help;
260
}
261

    
262
/**
263
 * Decode value with given size in bits
264
 * @param ctx decoder context
265
 * @param shift number of bits to decode
266
 */
267
static inline int range_decode_culshift(APEContext * ctx, int shift)
268
{
269
    range_dec_normalize(ctx);
270
    ctx->rc.help = ctx->rc.range >> shift;
271
    return ctx->rc.low / ctx->rc.help;
272
}
273

    
274

    
275
/**
276
 * Update decoding state
277
 * @param ctx decoder context
278
 * @param sy_f the interval length (frequency of the symbol)
279
 * @param lt_f the lower end (frequency sum of < symbols)
280
 */
281
static inline void range_decode_update(APEContext * ctx, int sy_f, int lt_f)
282
{
283
    ctx->rc.low  -= ctx->rc.help * lt_f;
284
    ctx->rc.range = ctx->rc.help * sy_f;
285
}
286

    
287
/** Decode n bits (n <= 16) without modelling */
288
static inline int range_decode_bits(APEContext * ctx, int n)
289
{
290
    int sym = range_decode_culshift(ctx, n);
291
    range_decode_update(ctx, 1, sym);
292
    return sym;
293
}
294

    
295

    
296
#define MODEL_ELEMENTS 64
297

    
298
/**
299
 * Fixed probabilities for symbols in Monkey Audio version 3.97
300
 */
301
static const uint16_t counts_3970[22] = {
302
        0, 14824, 28224, 39348, 47855, 53994, 58171, 60926,
303
    62682, 63786, 64463, 64878, 65126, 65276, 65365, 65419,
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    65450, 65469, 65480, 65487, 65491, 65493,
305
};
306

    
307
/**
308
 * Probability ranges for symbols in Monkey Audio version 3.97
309
 */
310
static const uint16_t counts_diff_3970[21] = {
311
    14824, 13400, 11124, 8507, 6139, 4177, 2755, 1756,
312
    1104, 677, 415, 248, 150, 89, 54, 31,
313
    19, 11, 7, 4, 2,
314
};
315

    
316
/**
317
 * Fixed probabilities for symbols in Monkey Audio version 3.98
318
 */
319
static const uint16_t counts_3980[22] = {
320
        0, 19578, 36160, 48417, 56323, 60899, 63265, 64435,
321
    64971, 65232, 65351, 65416, 65447, 65466, 65476, 65482,
322
    65485, 65488, 65490, 65491, 65492, 65493,
323
};
324

    
325
/**
326
 * Probability ranges for symbols in Monkey Audio version 3.98
327
 */
328
static const uint16_t counts_diff_3980[21] = {
329
    19578, 16582, 12257, 7906, 4576, 2366, 1170, 536,
330
    261, 119, 65, 31, 19, 10, 6, 3,
331
    3, 2, 1, 1, 1,
332
};
333

    
334
/**
335
 * Decode symbol
336
 * @param ctx decoder context
337
 * @param counts probability range start position
338
 * @param counts_diff probability range widths
339
 */
340
static inline int range_get_symbol(APEContext * ctx,
341
                                   const uint16_t counts[],
342
                                   const uint16_t counts_diff[])
343
{
344
    int symbol, cf;
345

    
346
    cf = range_decode_culshift(ctx, 16);
347

    
348
    if(cf > 65492){
349
        symbol= cf - 65535 + 63;
350
        range_decode_update(ctx, 1, cf);
351
        if(cf > 65535)
352
            ctx->error=1;
353
        return symbol;
354
    }
355
    /* figure out the symbol inefficiently; a binary search would be much better */
356
    for (symbol = 0; counts[symbol + 1] <= cf; symbol++);
357

    
358
    range_decode_update(ctx, counts_diff[symbol], counts[symbol]);
359

    
360
    return symbol;
361
}
362
/** @} */ // group rangecoder
363

    
364
static inline void update_rice(APERice *rice, int x)
365
{
366
    int lim = rice->k ? (1 << (rice->k + 4)) : 0;
367
    rice->ksum += ((x + 1) / 2) - ((rice->ksum + 16) >> 5);
368

    
369
    if (rice->ksum < lim)
370
        rice->k--;
371
    else if (rice->ksum >= (1 << (rice->k + 5)))
372
        rice->k++;
373
}
374

    
375
static inline int ape_decode_value(APEContext * ctx, APERice *rice)
376
{
377
    int x, overflow;
378

    
379
    if (ctx->fileversion < 3990) {
380
        int tmpk;
381

    
382
        overflow = range_get_symbol(ctx, counts_3970, counts_diff_3970);
383

    
384
        if (overflow == (MODEL_ELEMENTS - 1)) {
385
            tmpk = range_decode_bits(ctx, 5);
386
            overflow = 0;
387
        } else
388
            tmpk = (rice->k < 1) ? 0 : rice->k - 1;
389

    
390
        if (tmpk <= 16)
391
            x = range_decode_bits(ctx, tmpk);
392
        else {
393
            x = range_decode_bits(ctx, 16);
394
            x |= (range_decode_bits(ctx, tmpk - 16) << 16);
395
        }
396
        x += overflow << tmpk;
397
    } else {
398
        int base, pivot;
399

    
400
        pivot = rice->ksum >> 5;
401
        if (pivot == 0)
402
            pivot = 1;
403

    
404
        overflow = range_get_symbol(ctx, counts_3980, counts_diff_3980);
405

    
406
        if (overflow == (MODEL_ELEMENTS - 1)) {
407
            overflow  = range_decode_bits(ctx, 16) << 16;
408
            overflow |= range_decode_bits(ctx, 16);
409
        }
410

    
411
        if (pivot < 0x10000) {
412
            base = range_decode_culfreq(ctx, pivot);
413
            range_decode_update(ctx, 1, base);
414
        } else {
415
            int base_hi = pivot, base_lo;
416
            int bbits = 0;
417

    
418
            while (base_hi & ~0xFFFF) {
419
                base_hi >>= 1;
420
                bbits++;
421
            }
422
            base_hi = range_decode_culfreq(ctx, base_hi + 1);
423
            range_decode_update(ctx, 1, base_hi);
424
            base_lo = range_decode_culfreq(ctx, 1 << bbits);
425
            range_decode_update(ctx, 1, base_lo);
426

    
427
            base = (base_hi << bbits) + base_lo;
428
        }
429

    
430
        x = base + overflow * pivot;
431
    }
432

    
433
    update_rice(rice, x);
434

    
435
    /* Convert to signed */
436
    if (x & 1)
437
        return (x >> 1) + 1;
438
    else
439
        return -(x >> 1);
440
}
441

    
442
static void entropy_decode(APEContext * ctx, int blockstodecode, int stereo)
443
{
444
    int32_t *decoded0 = ctx->decoded0;
445
    int32_t *decoded1 = ctx->decoded1;
446

    
447
    ctx->blocksdecoded = blockstodecode;
448

    
449
    if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
450
        /* We are pure silence, just memset the output buffer. */
451
        memset(decoded0, 0, blockstodecode * sizeof(int32_t));
452
        memset(decoded1, 0, blockstodecode * sizeof(int32_t));
453
    } else {
454
        while (blockstodecode--) {
455
            *decoded0++ = ape_decode_value(ctx, &ctx->riceY);
456
            if (stereo)
457
                *decoded1++ = ape_decode_value(ctx, &ctx->riceX);
458
        }
459
    }
460

    
461
    if (ctx->blocksdecoded == ctx->currentframeblocks)
462
        range_dec_normalize(ctx);   /* normalize to use up all bytes */
463
}
464

    
465
static void init_entropy_decoder(APEContext * ctx)
466
{
467
    /* Read the CRC */
468
    ctx->CRC = bytestream_get_be32(&ctx->ptr);
469

    
470
    /* Read the frame flags if they exist */
471
    ctx->frameflags = 0;
472
    if ((ctx->fileversion > 3820) && (ctx->CRC & 0x80000000)) {
473
        ctx->CRC &= ~0x80000000;
474

    
475
        ctx->frameflags = bytestream_get_be32(&ctx->ptr);
476
    }
477

    
478
    /* Keep a count of the blocks decoded in this frame */
479
    ctx->blocksdecoded = 0;
480

    
481
    /* Initialize the rice structs */
482
    ctx->riceX.k = 10;
483
    ctx->riceX.ksum = (1 << ctx->riceX.k) * 16;
484
    ctx->riceY.k = 10;
485
    ctx->riceY.ksum = (1 << ctx->riceY.k) * 16;
486

    
487
    /* The first 8 bits of input are ignored. */
488
    ctx->ptr++;
489

    
490
    range_start_decoding(ctx);
491
}
492

    
493
static const int32_t initial_coeffs[4] = {
494
    360, 317, -109, 98
495
};
496

    
497
static void init_predictor_decoder(APEContext * ctx)
498
{
499
    APEPredictor *p = &ctx->predictor;
500

    
501
    /* Zero the history buffers */
502
    memset(p->historybuffer, 0, PREDICTOR_SIZE * sizeof(int32_t));
503
    p->buf = p->historybuffer;
504

    
505
    /* Initialize and zero the coefficients */
506
    memcpy(p->coeffsA[0], initial_coeffs, sizeof(initial_coeffs));
507
    memcpy(p->coeffsA[1], initial_coeffs, sizeof(initial_coeffs));
508
    memset(p->coeffsB, 0, sizeof(p->coeffsB));
509

    
510
    p->filterA[0] = p->filterA[1] = 0;
511
    p->filterB[0] = p->filterB[1] = 0;
512
    p->lastA[0]   = p->lastA[1]   = 0;
513
}
514

    
515
/** Get inverse sign of integer (-1 for positive, 1 for negative and 0 for zero) */
516
static inline int APESIGN(int32_t x) {
517
    return (x < 0) - (x > 0);
518
}
519

    
520
static av_always_inline int predictor_update_filter(APEPredictor *p, const int decoded, const int filter, const int delayA, const int delayB, const int adaptA, const int adaptB)
521
{
522
    int32_t predictionA, predictionB, sign;
523

    
524
    p->buf[delayA]     = p->lastA[filter];
525
    p->buf[adaptA]     = APESIGN(p->buf[delayA]);
526
    p->buf[delayA - 1] = p->buf[delayA] - p->buf[delayA - 1];
527
    p->buf[adaptA - 1] = APESIGN(p->buf[delayA - 1]);
528

    
529
    predictionA = p->buf[delayA    ] * p->coeffsA[filter][0] +
530
                  p->buf[delayA - 1] * p->coeffsA[filter][1] +
531
                  p->buf[delayA - 2] * p->coeffsA[filter][2] +
532
                  p->buf[delayA - 3] * p->coeffsA[filter][3];
533

    
534
    /*  Apply a scaled first-order filter compression */
535
    p->buf[delayB]     = p->filterA[filter ^ 1] - ((p->filterB[filter] * 31) >> 5);
536
    p->buf[adaptB]     = APESIGN(p->buf[delayB]);
537
    p->buf[delayB - 1] = p->buf[delayB] - p->buf[delayB - 1];
538
    p->buf[adaptB - 1] = APESIGN(p->buf[delayB - 1]);
539
    p->filterB[filter] = p->filterA[filter ^ 1];
540

    
541
    predictionB = p->buf[delayB    ] * p->coeffsB[filter][0] +
542
                  p->buf[delayB - 1] * p->coeffsB[filter][1] +
543
                  p->buf[delayB - 2] * p->coeffsB[filter][2] +
544
                  p->buf[delayB - 3] * p->coeffsB[filter][3] +
545
                  p->buf[delayB - 4] * p->coeffsB[filter][4];
546

    
547
    p->lastA[filter] = decoded + ((predictionA + (predictionB >> 1)) >> 10);
548
    p->filterA[filter] = p->lastA[filter] + ((p->filterA[filter] * 31) >> 5);
549

    
550
    sign = APESIGN(decoded);
551
    p->coeffsA[filter][0] += p->buf[adaptA    ] * sign;
552
    p->coeffsA[filter][1] += p->buf[adaptA - 1] * sign;
553
    p->coeffsA[filter][2] += p->buf[adaptA - 2] * sign;
554
    p->coeffsA[filter][3] += p->buf[adaptA - 3] * sign;
555
    p->coeffsB[filter][0] += p->buf[adaptB    ] * sign;
556
    p->coeffsB[filter][1] += p->buf[adaptB - 1] * sign;
557
    p->coeffsB[filter][2] += p->buf[adaptB - 2] * sign;
558
    p->coeffsB[filter][3] += p->buf[adaptB - 3] * sign;
559
    p->coeffsB[filter][4] += p->buf[adaptB - 4] * sign;
560

    
561
    return p->filterA[filter];
562
}
563

    
564
static void predictor_decode_stereo(APEContext * ctx, int count)
565
{
566
    APEPredictor *p = &ctx->predictor;
567
    int32_t *decoded0 = ctx->decoded0;
568
    int32_t *decoded1 = ctx->decoded1;
569

    
570
    while (count--) {
571
        /* Predictor Y */
572
        *decoded0 = predictor_update_filter(p, *decoded0, 0, YDELAYA, YDELAYB, YADAPTCOEFFSA, YADAPTCOEFFSB);
573
        decoded0++;
574
        *decoded1 = predictor_update_filter(p, *decoded1, 1, XDELAYA, XDELAYB, XADAPTCOEFFSA, XADAPTCOEFFSB);
575
        decoded1++;
576

    
577
        /* Combined */
578
        p->buf++;
579

    
580
        /* Have we filled the history buffer? */
581
        if (p->buf == p->historybuffer + HISTORY_SIZE) {
582
            memmove(p->historybuffer, p->buf, PREDICTOR_SIZE * sizeof(int32_t));
583
            p->buf = p->historybuffer;
584
        }
585
    }
586
}
587

    
588
static void predictor_decode_mono(APEContext * ctx, int count)
589
{
590
    APEPredictor *p = &ctx->predictor;
591
    int32_t *decoded0 = ctx->decoded0;
592
    int32_t predictionA, currentA, A, sign;
593

    
594
    currentA = p->lastA[0];
595

    
596
    while (count--) {
597
        A = *decoded0;
598

    
599
        p->buf[YDELAYA] = currentA;
600
        p->buf[YDELAYA - 1] = p->buf[YDELAYA] - p->buf[YDELAYA - 1];
601

    
602
        predictionA = p->buf[YDELAYA    ] * p->coeffsA[0][0] +
603
                      p->buf[YDELAYA - 1] * p->coeffsA[0][1] +
604
                      p->buf[YDELAYA - 2] * p->coeffsA[0][2] +
605
                      p->buf[YDELAYA - 3] * p->coeffsA[0][3];
606

    
607
        currentA = A + (predictionA >> 10);
608

    
609
        p->buf[YADAPTCOEFFSA]     = APESIGN(p->buf[YDELAYA    ]);
610
        p->buf[YADAPTCOEFFSA - 1] = APESIGN(p->buf[YDELAYA - 1]);
611

    
612
        sign = APESIGN(A);
613
        p->coeffsA[0][0] += p->buf[YADAPTCOEFFSA    ] * sign;
614
        p->coeffsA[0][1] += p->buf[YADAPTCOEFFSA - 1] * sign;
615
        p->coeffsA[0][2] += p->buf[YADAPTCOEFFSA - 2] * sign;
616
        p->coeffsA[0][3] += p->buf[YADAPTCOEFFSA - 3] * sign;
617

    
618
        p->buf++;
619

    
620
        /* Have we filled the history buffer? */
621
        if (p->buf == p->historybuffer + HISTORY_SIZE) {
622
            memmove(p->historybuffer, p->buf, PREDICTOR_SIZE * sizeof(int32_t));
623
            p->buf = p->historybuffer;
624
        }
625

    
626
        p->filterA[0] = currentA + ((p->filterA[0] * 31) >> 5);
627
        *(decoded0++) = p->filterA[0];
628
    }
629

    
630
    p->lastA[0] = currentA;
631
}
632

    
633
static void do_init_filter(APEFilter *f, int16_t * buf, int order)
634
{
635
    f->coeffs = buf;
636
    f->historybuffer = buf + order;
637
    f->delay       = f->historybuffer + order * 2;
638
    f->adaptcoeffs = f->historybuffer + order;
639

    
640
    memset(f->historybuffer, 0, (order * 2) * sizeof(int16_t));
641
    memset(f->coeffs, 0, order * sizeof(int16_t));
642
    f->avg = 0;
643
}
644

    
645
static void init_filter(APEContext * ctx, APEFilter *f, int16_t * buf, int order)
646
{
647
    do_init_filter(&f[0], buf, order);
648
    do_init_filter(&f[1], buf + order * 3 + HISTORY_SIZE, order);
649
}
650

    
651
static inline void do_apply_filter(APEContext * ctx, int version, APEFilter *f, int32_t *data, int count, int order, int fracbits)
652
{
653
    int res;
654
    int absres;
655

    
656
    while (count--) {
657
        /* round fixedpoint scalar product */
658
        res = (ctx->dsp.scalarproduct_int16(f->delay - order, f->coeffs, order, 0) + (1 << (fracbits - 1))) >> fracbits;
659

    
660
        if (*data < 0)
661
            ctx->dsp.add_int16(f->coeffs, f->adaptcoeffs - order, order);
662
        else if (*data > 0)
663
            ctx->dsp.sub_int16(f->coeffs, f->adaptcoeffs - order, order);
664

    
665
        res += *data;
666

    
667
        *data++ = res;
668

    
669
        /* Update the output history */
670
        *f->delay++ = av_clip_int16(res);
671

    
672
        if (version < 3980) {
673
            /* Version ??? to < 3.98 files (untested) */
674
            f->adaptcoeffs[0]  = (res == 0) ? 0 : ((res >> 28) & 8) - 4;
675
            f->adaptcoeffs[-4] >>= 1;
676
            f->adaptcoeffs[-8] >>= 1;
677
        } else {
678
            /* Version 3.98 and later files */
679

    
680
            /* Update the adaption coefficients */
681
            absres = (res < 0 ? -res : res);
682

    
683
            if (absres > (f->avg * 3))
684
                *f->adaptcoeffs = ((res >> 25) & 64) - 32;
685
            else if (absres > (f->avg * 4) / 3)
686
                *f->adaptcoeffs = ((res >> 26) & 32) - 16;
687
            else if (absres > 0)
688
                *f->adaptcoeffs = ((res >> 27) & 16) - 8;
689
            else
690
                *f->adaptcoeffs = 0;
691

    
692
            f->avg += (absres - f->avg) / 16;
693

    
694
            f->adaptcoeffs[-1] >>= 1;
695
            f->adaptcoeffs[-2] >>= 1;
696
            f->adaptcoeffs[-8] >>= 1;
697
        }
698

    
699
        f->adaptcoeffs++;
700

    
701
        /* Have we filled the history buffer? */
702
        if (f->delay == f->historybuffer + HISTORY_SIZE + (order * 2)) {
703
            memmove(f->historybuffer, f->delay - (order * 2),
704
                    (order * 2) * sizeof(int16_t));
705
            f->delay = f->historybuffer + order * 2;
706
            f->adaptcoeffs = f->historybuffer + order;
707
        }
708
    }
709
}
710

    
711
static void apply_filter(APEContext * ctx, APEFilter *f,
712
                         int32_t * data0, int32_t * data1,
713
                         int count, int order, int fracbits)
714
{
715
    do_apply_filter(ctx, ctx->fileversion, &f[0], data0, count, order, fracbits);
716
    if (data1)
717
        do_apply_filter(ctx, ctx->fileversion, &f[1], data1, count, order, fracbits);
718
}
719

    
720
static void ape_apply_filters(APEContext * ctx, int32_t * decoded0,
721
                              int32_t * decoded1, int count)
722
{
723
    int i;
724

    
725
    for (i = 0; i < APE_FILTER_LEVELS; i++) {
726
        if (!ape_filter_orders[ctx->fset][i])
727
            break;
728
        apply_filter(ctx, ctx->filters[i], decoded0, decoded1, count, ape_filter_orders[ctx->fset][i], ape_filter_fracbits[ctx->fset][i]);
729
    }
730
}
731

    
732
static void init_frame_decoder(APEContext * ctx)
733
{
734
    int i;
735
    init_entropy_decoder(ctx);
736
    init_predictor_decoder(ctx);
737

    
738
    for (i = 0; i < APE_FILTER_LEVELS; i++) {
739
        if (!ape_filter_orders[ctx->fset][i])
740
            break;
741
        init_filter(ctx, ctx->filters[i], ctx->filterbuf[i], ape_filter_orders[ctx->fset][i]);
742
    }
743
}
744

    
745
static void ape_unpack_mono(APEContext * ctx, int count)
746
{
747
    int32_t left;
748
    int32_t *decoded0 = ctx->decoded0;
749
    int32_t *decoded1 = ctx->decoded1;
750

    
751
    if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
752
        entropy_decode(ctx, count, 0);
753
        /* We are pure silence, so we're done. */
754
        av_log(ctx->avctx, AV_LOG_DEBUG, "pure silence mono\n");
755
        return;
756
    }
757

    
758
    entropy_decode(ctx, count, 0);
759
    ape_apply_filters(ctx, decoded0, NULL, count);
760

    
761
    /* Now apply the predictor decoding */
762
    predictor_decode_mono(ctx, count);
763

    
764
    /* Pseudo-stereo - just copy left channel to right channel */
765
    if (ctx->channels == 2) {
766
        while (count--) {
767
            left = *decoded0;
768
            *(decoded1++) = *(decoded0++) = left;
769
        }
770
    }
771
}
772

    
773
static void ape_unpack_stereo(APEContext * ctx, int count)
774
{
775
    int32_t left, right;
776
    int32_t *decoded0 = ctx->decoded0;
777
    int32_t *decoded1 = ctx->decoded1;
778

    
779
    if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
780
        /* We are pure silence, so we're done. */
781
        av_log(ctx->avctx, AV_LOG_DEBUG, "pure silence stereo\n");
782
        return;
783
    }
784

    
785
    entropy_decode(ctx, count, 1);
786
    ape_apply_filters(ctx, decoded0, decoded1, count);
787

    
788
    /* Now apply the predictor decoding */
789
    predictor_decode_stereo(ctx, count);
790

    
791
    /* Decorrelate and scale to output depth */
792
    while (count--) {
793
        left = *decoded1 - (*decoded0 / 2);
794
        right = left + *decoded0;
795

    
796
        *(decoded0++) = left;
797
        *(decoded1++) = right;
798
    }
799
}
800

    
801
static int ape_decode_frame(AVCodecContext * avctx,
802
                            void *data, int *data_size,
803
                            AVPacket *avpkt)
804
{
805
    const uint8_t *buf = avpkt->data;
806
    int buf_size = avpkt->size;
807
    APEContext *s = avctx->priv_data;
808
    int16_t *samples = data;
809
    int nblocks;
810
    int i, n;
811
    int blockstodecode;
812
    int bytes_used;
813

    
814
    if (buf_size == 0 && !s->samples) {
815
        *data_size = 0;
816
        return 0;
817
    }
818

    
819
    /* should not happen but who knows */
820
    if (BLOCKS_PER_LOOP * 2 * avctx->channels > *data_size) {
821
        av_log (avctx, AV_LOG_ERROR, "Packet size is too big to be handled in lavc! (max is %d where you have %d)\n", *data_size, s->samples * 2 * avctx->channels);
822
        return -1;
823
    }
824

    
825
    if(!s->samples){
826
        s->data = av_realloc(s->data, (buf_size + 3) & ~3);
827
        s->dsp.bswap_buf((uint32_t*)s->data, (const uint32_t*)buf, buf_size >> 2);
828
        s->ptr = s->last_ptr = s->data;
829
        s->data_end = s->data + buf_size;
830

    
831
        nblocks = s->samples = bytestream_get_be32(&s->ptr);
832
        n =  bytestream_get_be32(&s->ptr);
833
        if(n < 0 || n > 3){
834
            av_log(avctx, AV_LOG_ERROR, "Incorrect offset passed\n");
835
            s->data = NULL;
836
            return -1;
837
        }
838
        s->ptr += n;
839

    
840
        s->currentframeblocks = nblocks;
841
        buf += 4;
842
        if (s->samples <= 0) {
843
            *data_size = 0;
844
            return buf_size;
845
        }
846

    
847
        memset(s->decoded0,  0, sizeof(s->decoded0));
848
        memset(s->decoded1,  0, sizeof(s->decoded1));
849

    
850
        /* Initialize the frame decoder */
851
        init_frame_decoder(s);
852
    }
853

    
854
    if (!s->data) {
855
        *data_size = 0;
856
        return buf_size;
857
    }
858

    
859
    nblocks = s->samples;
860
    blockstodecode = FFMIN(BLOCKS_PER_LOOP, nblocks);
861

    
862
    s->error=0;
863

    
864
    if ((s->channels == 1) || (s->frameflags & APE_FRAMECODE_PSEUDO_STEREO))
865
        ape_unpack_mono(s, blockstodecode);
866
    else
867
        ape_unpack_stereo(s, blockstodecode);
868
    emms_c();
869

    
870
    if(s->error || s->ptr > s->data_end){
871
        s->samples=0;
872
        av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
873
        return -1;
874
    }
875

    
876
    for (i = 0; i < blockstodecode; i++) {
877
        *samples++ = s->decoded0[i];
878
        if(s->channels == 2)
879
            *samples++ = s->decoded1[i];
880
    }
881

    
882
    s->samples -= blockstodecode;
883

    
884
    *data_size = blockstodecode * 2 * s->channels;
885
    bytes_used = s->samples ? s->ptr - s->last_ptr : buf_size;
886
    s->last_ptr = s->ptr;
887
    return bytes_used;
888
}
889

    
890
AVCodec ape_decoder = {
891
    "ape",
892
    CODEC_TYPE_AUDIO,
893
    CODEC_ID_APE,
894
    sizeof(APEContext),
895
    ape_decode_init,
896
    NULL,
897
    ape_decode_close,
898
    ape_decode_frame,
899
    .capabilities = CODEC_CAP_SUBFRAMES,
900
    .long_name = NULL_IF_CONFIG_SMALL("Monkey's Audio"),
901
};