Revision d267b339

View differences:

Changelog
71 71
- FFmpeg metadata format muxer and demuxer
72 72
- SubRip (srt) subtitle decoder
73 73
- floating-point AC-3 encoder added
74
- Lagarith decoder
74 75

  
75 76

  
76 77
version 0.6:
doc/general.texi
424 424
    @tab Codec used in Worms games.
425 425
@item Kega Game Video (KGV1) @tab      @tab  X
426 426
    @tab Kega emulator screen capture codec.
427
@item Lagarith               @tab     @tab  X
427 428
@item LCL (LossLess Codec Library) MSZH  @tab     @tab  X
428 429
@item LCL (LossLess Codec Library) ZLIB  @tab  E  @tab  E
429 430
@item LOCO                   @tab     @tab  X
libavcodec/Makefile
185 185
OBJS-$(CONFIG_JPEGLS_ENCODER)          += jpeglsenc.o jpegls.o
186 186
OBJS-$(CONFIG_KGV1_DECODER)            += kgv1dec.o
187 187
OBJS-$(CONFIG_KMVC_DECODER)            += kmvc.o
188
OBJS-$(CONFIG_LAGARITH_DECODER)        += lagarith.o lagarithrac.o
188 189
OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpegenc.o mjpeg.o \
189 190
                                          mpegvideo_enc.o motion_est.o  \
190 191
                                          ratecontrol.o mpeg12data.o    \
libavcodec/allcodecs.c
128 128
    REGISTER_ENCDEC  (JPEGLS, jpegls);
129 129
    REGISTER_DECODER (KGV1, kgv1);
130 130
    REGISTER_DECODER (KMVC, kmvc);
131
    REGISTER_DECODER (LAGARITH, lagarith);
131 132
    REGISTER_ENCODER (LJPEG, ljpeg);
132 133
    REGISTER_DECODER (LOCO, loco);
133 134
    REGISTER_DECODER (MDEC, mdec);
libavcodec/avcodec.h
32 32
#include "libavutil/cpu.h"
33 33

  
34 34
#define LIBAVCODEC_VERSION_MAJOR 52
35
#define LIBAVCODEC_VERSION_MINOR 107
35
#define LIBAVCODEC_VERSION_MINOR 108
36 36
#define LIBAVCODEC_VERSION_MICRO  0
37 37

  
38 38
#define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
......
259 259
    CODEC_ID_A64_MULTI5,
260 260
    CODEC_ID_R10K,
261 261
    CODEC_ID_MXPEG,
262
    CODEC_ID_LAGARITH,
262 263

  
263 264
    /* various PCM "codecs" */
264 265
    CODEC_ID_PCM_S16LE= 0x10000,
libavcodec/lagarith.c
1
/*
2
 * Lagarith lossless decoder
3
 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
4
 *
5
 * This file is part of FFmpeg.
6
 *
7
 * FFmpeg is free software; you can redistribute it and/or
8
 * modify it under the terms of the GNU Lesser General Public
9
 * 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
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * Lesser General Public License for more details.
16
 *
17
 * 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 libavcodec/lagarith.c
24
 * Lagarith lossless decoder
25
 * @author Nathan Caldwell
26
 */
27

  
28
#include "avcodec.h"
29
#include "get_bits.h"
30
#include "mathops.h"
31
#include "dsputil.h"
32
#include "lagarithrac.h"
33

  
34
enum LagarithFrameType {
35
    FRAME_RAW           = 1,    /*!< uncompressed */
36
    FRAME_U_RGB24       = 2,    /*!< unaligned RGB24 */
37
    FRAME_ARITH_YUY2    = 3,    /*!< arithmetic coded YUY2 */
38
    FRAME_ARITH_RGB24   = 4,    /*!< arithmetic coded RGB24 */
39
    FRAME_SOLID_GRAY    = 5,    /*!< solid grayscale color frame */
40
    FRAME_SOLID_COLOR   = 6,    /*!< solid non-grayscale color frame */
41
    FRAME_OLD_ARITH_RGB = 7,    /*!< obsolete arithmetic coded RGB (no longer encoded by upstream since version 1.1.0) */
42
    FRAME_ARITH_RGBA    = 8,    /*!< arithmetic coded RGBA */
43
    FRAME_SOLID_RGBA    = 9,    /*!< solid RGBA color frame */
44
    FRAME_ARITH_YV12    = 10,   /*!< arithmetic coded YV12 */
45
    FRAME_REDUCED_RES   = 11,   /*!< reduced resolution YV12 frame */
46
};
47

  
48
typedef struct LagarithContext {
49
    AVCodecContext *avctx;
50
    AVFrame picture;
51
    DSPContext dsp;
52
    int zeros;                  /*!< number of consecutive zero bytes encountered */
53
    int zeros_rem;              /*!< number of zero bytes remaining to output */
54
} LagarithContext;
55

  
56
/**
57
 * Compute the 52bit mantissa of 1/(double)denom.
58
 * This crazy format uses floats in an entropy coder and we have to match x86
59
 * rounding exactly, thus ordinary floats aren't portable enough.
60
 * @param denom denominator
61
 * @return 52bit mantissa
62
 * @see softfloat_mul
63
 */
64
static uint64_t softfloat_reciprocal(uint32_t denom)
65
{
66
    int shift = av_log2(denom - 1) + 1;
67
    uint64_t ret = (1ULL << 52) / denom;
68
    uint64_t err = (1ULL << 52) - ret * denom;
69
    ret <<= shift;
70
    err <<= shift;
71
    err +=  denom / 2;
72
    return ret + err / denom;
73
}
74

  
75
/**
76
 * (uint32_t)(x*f), where f has the given mantissa, and exponent 0
77
 * Used in combination with softfloat_reciprocal computes x/(double)denom.
78
 * @param x 32bit integer factor
79
 * @param mantissa mantissa of f with exponent 0
80
 * @return 32bit integer value (x*f)
81
 * @see softfloat_reciprocal
82
 */
83
static uint32_t softfloat_mul(uint32_t x, uint64_t mantissa)
84
{
85
    uint64_t l = x * (mantissa & 0xffffffff);
86
    uint64_t h = x * (mantissa >> 32);
87
    h += l >> 32;
88
    l &= 0xffffffff;
89
    l += 1 << av_log2(h >> 21);
90
    h += l >> 32;
91
    return h >> 20;
92
}
93

  
94
static uint8_t lag_calc_zero_run(int8_t x)
95
{
96
    return (x << 1) ^ (x >> 7);
97
}
98

  
99
static int lag_decode_prob(GetBitContext *gb, uint32_t *value)
100
{
101
    static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21 };
102
    int i;
103
    int bit     = 0;
104
    int bits    = 0;
105
    int prevbit = 0;
106
    unsigned val;
107

  
108
    for (i = 0; i < 7; i++) {
109
        if (prevbit && bit)
110
            break;
111
        prevbit = bit;
112
        bit = get_bits1(gb);
113
        if (bit && !prevbit)
114
            bits += series[i];
115
    }
116
    bits--;
117
    if (bits < 0 || bits > 31) {
118
        *value = 0;
119
        return -1;
120
    } else if (bits == 0) {
121
        *value = 0;
122
        return 0;
123
    }
124

  
125
    val  = get_bits_long(gb, bits);
126
    val |= 1 << bits;
127

  
128
    *value = val - 1;
129

  
130
    return 0;
131
}
132

  
133
static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
134
{
135
    int i, j, scale_factor;
136
    unsigned prob, cumulative_target;
137
    unsigned cumul_prob = 0;
138
    unsigned scaled_cumul_prob = 0;
139

  
140
    rac->prob[0] = 0;
141
    rac->prob[257] = UINT_MAX;
142
    /* Read probabilities from bitstream */
143
    for (i = 1; i < 257; i++) {
144
        if (lag_decode_prob(gb, &rac->prob[i]) < 0) {
145
            av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability encountered.\n");
146
            return -1;
147
        }
148
        if ((uint64_t)cumul_prob + rac->prob[i] > UINT_MAX) {
149
            av_log(rac->avctx, AV_LOG_ERROR, "Integer overflow encountered in cumulative probability calculation.\n");
150
            return -1;
151
        }
152
        cumul_prob += rac->prob[i];
153
        if (!rac->prob[i]) {
154
            if (lag_decode_prob(gb, &prob)) {
155
                av_log(rac->avctx, AV_LOG_ERROR, "Invalid probability run encountered.\n");
156
                return -1;
157
            }
158
            if (prob > 257 - i)
159
                prob = 257 - i;
160
            for (j = 0; j < prob; j++)
161
                rac->prob[++i] = 0;
162
        }
163
    }
164

  
165
    if (!cumul_prob) {
166
        av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
167
        return -1;
168
    }
169

  
170
    /* Scale probabilities so cumulative probability is an even power of 2. */
171
    scale_factor = av_log2(cumul_prob);
172

  
173
    if (cumul_prob & (cumul_prob - 1)) {
174
        uint64_t mul = softfloat_reciprocal(cumul_prob);
175
        for (i = 1; i < 257; i++) {
176
            rac->prob[i] = softfloat_mul(rac->prob[i], mul);
177
            scaled_cumul_prob += rac->prob[i];
178
        }
179

  
180
        scale_factor++;
181
        cumulative_target = 1 << scale_factor;
182

  
183
        if (scaled_cumul_prob > cumulative_target) {
184
            av_log(rac->avctx, AV_LOG_ERROR,
185
                   "Scaled probabilities are larger than target!\n");
186
            return -1;
187
        }
188

  
189
        scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
190

  
191
        for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
192
            if (rac->prob[i]) {
193
                rac->prob[i]++;
194
                scaled_cumul_prob--;
195
            }
196
            /* Comment from reference source:
197
             * if (b & 0x80 == 0) {     // order of operations is 'wrong'; it has been left this way
198
             *                          // since the compression change is negligable and fixing it
199
             *                          // breaks backwards compatibilty
200
             *      b =- (signed int)b;
201
             *      b &= 0xFF;
202
             * } else {
203
             *      b++;
204
             *      b &= 0x7f;
205
             * }
206
             */
207
        }
208
    }
209

  
210
    rac->scale = scale_factor;
211

  
212
    /* Fill probability array with cumulative probability for each symbol. */
213
    for (i = 1; i < 257; i++)
214
        rac->prob[i] += rac->prob[i - 1];
215

  
216
    return 0;
217
}
218

  
219
static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
220
                                      uint8_t *diff, int w, int *left,
221
                                      int *left_top)
222
{
223
    /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
224
     * However the &0xFF on the gradient predictor yealds incorrect output
225
     * for lagarith.
226
     */
227
    int i;
228
    uint8_t l, lt;
229

  
230
    l  = *left;
231
    lt = *left_top;
232

  
233
    for (i = 0; i < w; i++) {
234
        l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
235
        lt = src1[i];
236
        dst[i] = l;
237
    }
238

  
239
    *left     = l;
240
    *left_top = lt;
241
}
242

  
243
static void lag_pred_line(LagarithContext *l, uint8_t *buf,
244
                          int width, int stride, int line)
245
{
246
    int L, TL;
247

  
248
    if (!line) {
249
        /* Left prediction only for first line */
250
        L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
251
                                            width - 1, buf[0]);
252
        return;
253
    } else if (line == 1) {
254
        /* Second line, left predict first pixel, the rest of the line is median predicted */
255
        /* FIXME: In the case of RGB this pixel is top predicted */
256
        TL = buf[-stride];
257
    } else {
258
        /* Top left is 2 rows back, last pixel */
259
        TL = buf[width - (2 * stride) - 1];
260
    }
261
    /* Left pixel is actually prev_row[width] */
262
    L = buf[width - stride - 1];
263

  
264
    add_lag_median_prediction(buf, buf - stride, buf,
265
                              width, &L, &TL);
266
}
267

  
268
static int lag_decode_line(LagarithContext *l, lag_rac *rac,
269
                           uint8_t *dst, int width, int stride,
270
                           int esc_count)
271
{
272
    int i = 0;
273
    int ret = 0;
274

  
275
    if (!esc_count)
276
        esc_count = -1;
277

  
278
    /* Output any zeros remaining from the previous run */
279
handle_zeros:
280
    if (l->zeros_rem) {
281
        int count = FFMIN(l->zeros_rem, width - i);
282
        memset(dst + i, 0, count);
283
        i += count;
284
        l->zeros_rem -= count;
285
    }
286

  
287
    while (i < width) {
288
        dst[i] = lag_get_rac(rac);
289
        ret++;
290

  
291
        if (dst[i])
292
            l->zeros = 0;
293
        else
294
            l->zeros++;
295

  
296
        i++;
297
        if (l->zeros == esc_count) {
298
            int index = lag_get_rac(rac);
299
            ret++;
300

  
301
            l->zeros = 0;
302

  
303
            l->zeros_rem = lag_calc_zero_run(index);
304
            goto handle_zeros;
305
        }
306
    }
307
    return ret;
308
}
309

  
310
static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
311
                                    const uint8_t *src, int width,
312
                                    int esc_count)
313
{
314
    int i = 0;
315
    int count;
316
    uint8_t zero_run = 0;
317
    const uint8_t *start = src;
318
    uint8_t mask1 = -(esc_count < 2);
319
    uint8_t mask2 = -(esc_count < 3);
320
    uint8_t *end = dst + (width - 2);
321

  
322
output_zeros:
323
    if (l->zeros_rem) {
324
        count = FFMIN(l->zeros_rem, width - i);
325
        memset(dst, 0, count);
326
        l->zeros_rem -= count;
327
        dst += count;
328
    }
329

  
330
    while (dst < end) {
331
        i = 0;
332
        while (!zero_run && dst + i < end) {
333
            i++;
334
            zero_run =
335
                !(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
336
        }
337
        if (zero_run) {
338
            zero_run = 0;
339
            i += esc_count;
340
            memcpy(dst, src, i);
341
            dst += i;
342
            l->zeros_rem = lag_calc_zero_run(src[i]);
343

  
344
            src += i + 1;
345
            goto output_zeros;
346
        } else {
347
            memcpy(dst, src, i);
348
            src += i;
349
        }
350
    }
351
    return start - src;
352
}
353

  
354

  
355

  
356
static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
357
                                  int width, int height, int stride,
358
                                  const uint8_t *src, int src_size)
359
{
360
    int i = 0;
361
    int read = 0;
362
    uint32_t length;
363
    uint32_t offset = 1;
364
    int esc_count = src[0];
365
    GetBitContext gb;
366
    lag_rac rac;
367

  
368
    rac.avctx = l->avctx;
369
    l->zeros = 0;
370

  
371
    if (esc_count < 4) {
372
        length = width * height;
373
        if (esc_count && AV_RL32(src + 1) < length) {
374
            length = AV_RL32(src + 1);
375
            offset += 4;
376
        }
377

  
378
        init_get_bits(&gb, src + offset, src_size * 8);
379

  
380
        if (lag_read_prob_header(&rac, &gb) < 0)
381
            return -1;
382

  
383
        lag_rac_init(&rac, &gb, length - stride);
384

  
385
        for (i = 0; i < height; i++)
386
            read += lag_decode_line(l, &rac, dst + (i * stride), width,
387
                                    stride, esc_count);
388

  
389
        if (read > length)
390
            av_log(l->avctx, AV_LOG_WARNING,
391
                   "Output more bytes than length (%d of %d)\n", read,
392
                   length);
393
    } else if (esc_count < 8) {
394
        esc_count -= 4;
395
        if (esc_count > 0) {
396
            /* Zero run coding only, no range coding. */
397
            for (i = 0; i < height; i++)
398
                src += lag_decode_zero_run_line(l, dst + (i * stride), src,
399
                                                width, esc_count);
400
        } else {
401
            /* Plane is stored uncompressed */
402
            for (i = 0; i < height; i++) {
403
                memcpy(dst + (i * stride), src, width);
404
                src += width;
405
            }
406
        }
407
    } else if (esc_count == 0xff) {
408
        /* Plane is a solid run of 0 bytes */
409
        for (i = 0; i < height; i++)
410
            memset(dst + i * stride, 0, width);
411
    } else {
412
        av_log(l->avctx, AV_LOG_ERROR,
413
               "Invalid zero run escape code! (%#x)\n", esc_count);
414
        return -1;
415
    }
416

  
417
    for (i = 0; i < height; i++) {
418
        lag_pred_line(l, dst, width, stride, i);
419
        dst += stride;
420
    }
421

  
422
    return 0;
423
}
424

  
425
/**
426
 * Decode a frame.
427
 * @param avctx codec context
428
 * @param data output AVFrame
429
 * @param data_size size of output data or 0 if no picture is returned
430
 * @param avpkt input packet
431
 * @return number of consumed bytes on success or negative if decode fails
432
 */
433
static int lag_decode_frame(AVCodecContext *avctx,
434
                            void *data, int *data_size, AVPacket *avpkt)
435
{
436
    const uint8_t *buf = avpkt->data;
437
    int buf_size = avpkt->size;
438
    LagarithContext *l = avctx->priv_data;
439
    AVFrame *const p = &l->picture;
440
    uint8_t frametype = 0;
441
    uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
442

  
443
    AVFrame *picture = data;
444

  
445
    if (p->data[0])
446
        avctx->release_buffer(avctx, p);
447

  
448
    p->reference = 0;
449
    p->key_frame = 1;
450

  
451
    frametype = buf[0];
452

  
453
    offset_gu = AV_RL32(buf + 1);
454
    offset_bv = AV_RL32(buf + 5);
455

  
456
    switch (frametype) {
457
    case FRAME_ARITH_YV12:
458
        avctx->pix_fmt = PIX_FMT_YUV420P;
459

  
460
        if (avctx->get_buffer(avctx, p) < 0) {
461
            av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
462
            return -1;
463
        }
464

  
465
        lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
466
                               p->linesize[0], buf + offset_ry,
467
                               buf_size);
468
        lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
469
                               avctx->height / 2, p->linesize[2],
470
                               buf + offset_gu, buf_size);
471
        lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
472
                               avctx->height / 2, p->linesize[1],
473
                               buf + offset_bv, buf_size);
474
        break;
475
    default:
476
        av_log(avctx, AV_LOG_ERROR,
477
               "Unsupported Lagarith frame type: %#x\n", frametype);
478
        return -1;
479
    }
480

  
481
    *picture = *p;
482
    *data_size = sizeof(AVFrame);
483

  
484
    return buf_size;
485
}
486

  
487
static av_cold int lag_decode_init(AVCodecContext *avctx)
488
{
489
    LagarithContext *l = avctx->priv_data;
490
    l->avctx = avctx;
491

  
492
    dsputil_init(&l->dsp, avctx);
493

  
494
    return 0;
495
}
496

  
497
static av_cold int lag_decode_end(AVCodecContext *avctx)
498
{
499
    LagarithContext *l = avctx->priv_data;
500

  
501
    if (l->picture.data[0])
502
        avctx->release_buffer(avctx, &l->picture);
503

  
504
    return 0;
505
}
506

  
507
AVCodec lagarith_decoder = {
508
    "lagarith",
509
    CODEC_TYPE_VIDEO,
510
    CODEC_ID_LAGARITH,
511
    sizeof(LagarithContext),
512
    lag_decode_init,
513
    NULL,
514
    lag_decode_end,
515
    lag_decode_frame,
516
    CODEC_CAP_DR1,
517
    .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
518
};
libavcodec/lagarithrac.c
1
/*
2
 * Lagarith range decoder
3
 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
4
 * Copyright (c) 2009 David Conrad
5
 *
6
 * This file is part of FFmpeg.
7
 *
8
 * FFmpeg is free software; you can redistribute it and/or
9
 * modify it under the terms of the GNU Lesser General Public
10
 * License as published by the Free Software Foundation; either
11
 * version 2.1 of the License, or (at your option) any later version.
12
 *
13
 * FFmpeg is distributed in the hope that it will be useful,
14
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16
 * Lesser General Public License for more details.
17
 *
18
 * You should have received a copy of the GNU Lesser General Public
19
 * License along with FFmpeg; if not, write to the Free Software
20
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21
 */
22

  
23
/**
24
 * @file libavcodec/lagarithrac.c
25
 * Lagarith range decoder
26
 * @author Nathan Caldwell
27
 * @author David Conrad
28
 */
29

  
30
#include "get_bits.h"
31
#include "lagarithrac.h"
32

  
33
void lag_rac_init(lag_rac *l, GetBitContext *gb, int length)
34
{
35
    int i, j;
36

  
37
    /* According to reference decoder "1st byte is garbage",
38
     * however, it gets skipped by the call to align_get_bits()
39
     */
40
    align_get_bits(gb);
41
    l->bytestream_start =
42
    l->bytestream       = gb->buffer + get_bits_count(gb) / 8;
43
    l->bytestream_end   = l->bytestream_start + length;
44

  
45
    l->range        = 0x80;
46
    l->low          = *l->bytestream >> 1;
47
    l->hash_shift   = FFMAX(l->scale - 8, 0);
48

  
49
    for (i = j = 0; i < 256; i++) {
50
        unsigned r = i << l->hash_shift;
51
        while (l->prob[j + 1] <= r)
52
            j++;
53
        l->range_hash[i] = j;
54
    }
55

  
56
    /* Add conversion factor to hash_shift so we don't have to in lag_get_rac. */
57
    l->hash_shift += 23;
58
}
libavcodec/lagarithrac.h
1
/*
2
 * Lagarith range decoder
3
 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
4
 * Copyright (c) 2009 David Conrad
5
 *
6
 * This file is part of FFmpeg.
7
 *
8
 * FFmpeg is free software; you can redistribute it and/or
9
 * modify it under the terms of the GNU Lesser General Public
10
 * License as published by the Free Software Foundation; either
11
 * version 2.1 of the License, or (at your option) any later version.
12
 *
13
 * FFmpeg is distributed in the hope that it will be useful,
14
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16
 * Lesser General Public License for more details.
17
 *
18
 * You should have received a copy of the GNU Lesser General Public
19
 * License along with FFmpeg; if not, write to the Free Software
20
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21
 */
22

  
23
/**
24
 * @file libavcodec/lagarithrac.h
25
 * Lagarith range decoder
26
 * @author Nathan Caldwell
27
 * @author David Conrad
28
 */
29

  
30
#ifndef AVCODEC_LAGARITHRAC_H
31
#define AVCODEC_LAGARITHRAC_H
32

  
33
#include <stdint.h>
34
#include "libavutil/common.h"
35
#include "libavutil/intreadwrite.h"
36
#include "avcodec.h"
37
#include "get_bits.h"
38

  
39
typedef struct lag_rac {
40
    AVCodecContext *avctx;
41
    unsigned low;
42
    unsigned range;
43
    unsigned scale;             /*!< Number of bits of precision in range. */
44
    unsigned hash_shift;        /*!< Number of bits to shift to calculate hash for radix search. */
45

  
46
    const uint8_t *bytestream_start;  /*!< Start of input bytestream. */
47
    const uint8_t *bytestream;        /*!< Current position in input bytestream. */
48
    const uint8_t *bytestream_end;    /*!< End position of input bytestream. */
49

  
50
    uint32_t prob[258];         /*!< Table of cumulative probability for each symbol. */
51
    uint8_t  range_hash[256];   /*!< Hash table mapping upper byte to approximate symbol. */
52
} lag_rac;
53

  
54
void lag_rac_init(lag_rac *l, GetBitContext *gb, int length);
55

  
56
/* TODO: Optimize */
57
static inline void lag_rac_refill(lag_rac *l)
58
{
59
    while (l->range <= 0x800000) {
60
        l->low   <<= 8;
61
        l->range <<= 8;
62
        l->low |= 0xff & (AV_RB16(l->bytestream) >> 1);
63
        if (l->bytestream < l->bytestream_end)
64
            l->bytestream++;
65
    }
66
}
67

  
68
/**
69
 * Decode a single byte from the compressed plane described by *l.
70
 * @param l pointer to lag_rac for the current plane
71
 * @return next byte of decoded data
72
 */
73
static inline uint8_t lag_get_rac(lag_rac *l)
74
{
75
    unsigned range_scaled, low_scaled, div;
76
    int val;
77
    uint8_t shift;
78

  
79
    lag_rac_refill(l);
80

  
81
    range_scaled = l->range >> l->scale;
82

  
83
    if (l->low < range_scaled * l->prob[255]) {
84
        /* val = 0 is frequent enough to deserve a shortcut */
85
        if (l->low < range_scaled * l->prob[1]) {
86
            val = 0;
87
        } else {
88
            /* FIXME __builtin_clz is ~20% faster here, but not allowed in generic code. */
89
            shift = 30 - av_log2(range_scaled);
90
            div = ((range_scaled << shift) + (1 << 23) - 1) >> 23;
91
            /* low>>24 ensures that any cases too big for exact FASTDIV are
92
             * under- rather than over-estimated
93
             */
94
            low_scaled = FASTDIV(l->low - (l->low >> 24), div);
95
            shift -= l->hash_shift;
96
            shift &= 31;
97
            low_scaled = (low_scaled << shift) | (low_scaled >> (32 - shift));
98
            /* low_scaled is now a lower bound of low/range_scaled */
99
            val = l->range_hash[(uint8_t) low_scaled];
100
            while (l->low >= range_scaled * l->prob[val + 1])
101
                val++;
102
        }
103

  
104
        l->range = range_scaled * (l->prob[val + 1] - l->prob[val]);
105
    } else {
106
        val = 255;
107
        l->range -= range_scaled * l->prob[255];
108
    }
109

  
110
    l->low -= range_scaled * l->prob[val];
111

  
112
    return val;
113
}
114

  
115

  
116
#endif /* AVCODEC_LAGARITHRAC_H */
libavformat/riff.c
257 257
    { CODEC_ID_AURA2,        MKTAG('A', 'U', 'R', '2') },
258 258
    { CODEC_ID_DPX,          MKTAG('d', 'p', 'x', ' ') },
259 259
    { CODEC_ID_KGV1,         MKTAG('K', 'G', 'V', '1') },
260
    { CODEC_ID_LAGARITH,     MKTAG('L', 'A', 'G', 'S') },
260 261
    { CODEC_ID_NONE,         0 }
261 262
};
262 263

  

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