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
  29 #include "avcodec.h"
  30 #include "get_bits.h"
  31 #include "mathops.h"
  32 #include "lagarith.h"
  33 #include "lagarithrac.h"
  34
  35 typedef struct LagarithContext {
  36     AVCodecContext *avctx;
  37     AVFrame picture;
  38     int zeros;                  /*!< number of consecutave zero bytes encountered */
  39     int zeros_rem;              /*!< number of zero bytes remaining to output */
  40 } LagarithContext;
  41
  42 static void lag_memset(uint8_t *s, uint8_t c, size_t n, int step)
  43 {
  44     int i;
  45     if (step == 1) {
  46         memset(s, c, n);
  47         return;
  48     }
  49
  50     for (i = 0; i < n * step; i += step)
  51         s[i] = c;
  52 }
  53
  54 static uint8_t *lag_memcpy(uint8_t *dest, const uint8_t *src, size_t n,
  55                            int step)
  56 {
  57     int i, j;
  58     if (step == 1)
  59         return memcpy(dest, src, n);
  60
  61     for (i = j = 0; i < n ; i++) {
  62         dest[j] = src[i];
  63         j += step;
  64     }
  65     return dest;
  66 }
  67
  68 static uint8_t lag_calc_zero_run(int8_t x)
  69 {
  70     return (x << 1) ^ (x >> 7);
  71 }
  72
  73 static uint32_t lag_decode_prob(GetBitContext *gb)
  74 {
  75     static const uint8_t series[] = { 1, 2, 3, 5, 8, 13, 21, 34 };
  76     int i = 0;
  77     int bit     = 0;
  78     int bits    = 0;
  79     int prevbit = 0;
  80     unsigned value = 1;
  81
  82     for (i = 0; i < 7; i++) {
  83         if (prevbit && bit)
  84             break;
  85         prevbit = bit;
  86         bit = get_bits1(gb);
  87         if (bit && !prevbit)
  88             bits += series[i];
  89     }
  90     bits--;
  91     if (bits <= 0)
  92         return 0;
  93     if (bits > 31) {
  94         /* This is most likely an error, just use the first 32 bits */
  95         bits = 31;
  96     }
  97
  98     value  = get_bits_long(gb, bits);
  99     value |= 1 << bits;
 100
 101     return value - 1;
 102 }
 103
 104 static int lag_read_prob_header(lag_rac *rac, GetBitContext *gb)
 105 {
 106     int i, j;
 107     int prob = 0;
 108     int scale_factor = 0;
 109     unsigned cumul_prob = 0;
 110     unsigned cumulative_target = 1;
 111     unsigned scaled_cumul_prob = 0;
 112
 113     rac->prob[0] = 0;
 114     rac->prob[257] = UINT_MAX;
 115     /* Read probabilities from bitstream */
 116     for (i = 1; i < 257; i++) {
 117         rac->prob[i] = lag_decode_prob(gb);
 118         cumul_prob += rac->prob[i];
 119         if (!rac->prob[i]) {
 120             prob = lag_decode_prob(gb);
 121             if (i + prob >= 258)
 122                 prob = 257 - i;
 123             for (j = 0; j < prob; j++)
 124                 rac->prob[++i] = 0;
 125         }
 126     }
 127
 128     if (!cumul_prob) {
 129         av_log(rac->avctx, AV_LOG_ERROR, "All probabilities are 0!\n");
 130         return -1;
 131     }
 132
 133     /* Scale probabilities so cumulative probability is an even power of 2. */
 134     scale_factor = av_log2(cumul_prob);
 135
 136     if (cumul_prob & (cumul_prob - 1)) {
 137         scale_factor++;
 138         for (i = 1; i < 257; i++) {
 139             rac->prob[i] =
 140                 ((uint64_t) rac->prob[i] << scale_factor) / cumul_prob;
 141             scaled_cumul_prob += rac->prob[i];
 142         }
 143
 144         cumulative_target = 1 << scale_factor;
 145
 146         if (scaled_cumul_prob > cumulative_target) {
 147             av_log(rac->avctx, AV_LOG_ERROR,
 148                    "Scaled probabilities are larger than target!\n");
 149             return -1;
 150         }
 151
 152         scaled_cumul_prob = cumulative_target - scaled_cumul_prob;
 153
 154         for (i = 1; scaled_cumul_prob; i = (i & 0x7f) + 1) {
 155             if (rac->prob[i]) {
 156                 rac->prob[i]++;
 157                 scaled_cumul_prob--;
 158             }
 159             /* Comment from reference source:
 160              * if (b & 0x80 == 0) {     // order of operations is 'wrong'; it has been left this way
 161              *                          // since the compression change is negligable and fixing it
 162              *                          // breaks backwards compatibilty
 163              *      b =- (signed int)b;
 164              *      b &= 0xFF;
 165              * } else {
 166              *      b++;
 167              *      b &= 0x7f;
 168              * }
 169              */
 170         }
 171     }
 172
 173     rac->scale = scale_factor;
 174
 175     /* Fill probability array with cumulative probability for each symbol. */
 176     for (i = 1; i < 257; i++)
 177         rac->prob[i] += rac->prob[i - 1];
 178
 179     return 0;
 180 }
 181
 182 static void add_lag_median_prediction(uint8_t *dst, uint8_t *src1,
 183                                       uint8_t *diff, int w, int *left,
 184                                       int *left_top)
 185 {
 186     /* This is almost identical to add_hfyu_median_prediction in dsputil.h.
 187      * However the &0xFF on the gradient predictor yealds incorrect output
 188      * for lagarith.
 189      */
 190     int i;
 191     uint8_t l, lt;
 192
 193     l  = *left;
 194     lt = *left_top;
 195
 196     for (i = 0; i < w; i++) {
 197         l = mid_pred(l, src1[i], l + src1[i] - lt) + diff[i];
 198         lt = src1[i];
 199         dst[i] = l;
 200     }
 201
 202     *left     = l;
 203     *left_top = lt;
 204 }
 205
 206 static inline int add_left_prediction(uint8_t *dst, uint8_t *src, int w,
 207                                       int acc)
 208 {
 209     int i;
 210
 211     for (i = 0; i < w - 1; i++) {
 212         acc += src[i];
 213         dst[i] = acc;
 214         i++;
 215         acc += src[i];
 216         dst[i] = acc;
 217     }
 218
 219     for (; i < w; i++) {
 220         acc += src[i];
 221         dst[i] = acc;
 222     }
 223
 224     return acc;
 225 }
 226
 227 static void lag_pred_line(LagarithContext *l, uint8_t *buf,
 228                           int width, int stride, int step, int line)
 229 {
 230     int i = 0;
 231     int L, TL;
 232     int width_scaled = width * step;
 233
 234     if (!line) {
 235         /* Left prediction only for first line */
 236         L = add_left_prediction(buf + step, buf + step, width - step,
 237                                 buf[0]);
 238         return;
 239     } else if (line == 1) {
 240         /* Second line, left predict first pixel, the rest of the line is median predicted */
 241         /* FIXME: In the case of RGB this pixel is top predicted */
 242         TL = buf[-stride];
 243         L = add_left_prediction(buf, buf, 1,
 244                                 buf[width_scaled - stride - step]);
 245         i += step;
 246     } else {
 247         /* Left pixel is actually prev_row[width] */
 248         L = buf[width_scaled - stride - step];
 249         /* Top left is 2 rows back, last pixel */
 250         TL = buf[width_scaled - (2 * stride) - step];
 251     }
 252
 253     if (i < width_scaled)
 254         add_lag_median_prediction(buf + i, buf - stride + i, buf + i,
 255                                   width_scaled - i, &L, &TL);
 256 }
 257
 258 static int lag_decode_line(LagarithContext *l, lag_rac *rac,
 259                            uint8_t *dst, int width, int stride,
 260                            int step, int esc_count)
 261 {
 262     int i = 0;
 263     int ret = 0;
 264
 265     /* Output any zeros remaining from the previous run */
 266     if (l->zeros_rem) {
 267         int count = FFMIN(l->zeros_rem, width);
 268         lag_memset(dst + i * step, 0, count, step);
 269         i += count;
 270         l->zeros_rem -= count;
 271     }
 272
 273     while (i < width) {
 274
 275         dst[i * step] = lag_get_rac(rac);
 276         ret++;
 277
 278         if (dst[i * step])
 279             l->zeros = 0;
 280         else
 281             l->zeros++;
 282
 283         i++;
 284         if (esc_count && (l->zeros == esc_count)) {
 285             int count;
 286             int index = lag_get_rac(rac);
 287             ret++;
 288
 289             l->zeros = 0;
 290
 291             l->zeros_rem =
 292             count        = lag_calc_zero_run(index);
 293
 294             if (i + count > width)
 295                 count = width - i;
 296             if (!count)
 297                 continue;
 298
 299             lag_memset(dst + i * step, 0, count, step);
 300
 301             i += count;
 302             l->zeros_rem -= count;
 303         }
 304     }
 305     return ret;
 306 }
 307
 308 static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
 309                                     const uint8_t *src, int width,
 310                                     int step, int esc_count)
 311 {
 312     int i = 0;
 313     int count;
 314     uint8_t zero_run = 1;
 315     const uint8_t *start = src;
 316     uint8_t mask1 = -(esc_count < 2);
 317     uint8_t mask2 = -(esc_count < 3);
 318     uint8_t *end = dst + (width - 2) * step;
 319
 320     if (l->zeros_rem) {
 321         count = FFMIN(l->zeros_rem, width);
 322         lag_memset(dst, 0, count, step);
 323         l->zeros_rem -= count;
 324         dst += count;
 325     }
 326
 327     while (dst < end) {
 328         i = 0;
 329         while (!zero_run && dst + i * step < end) {
 330             i++;
 331             zero_run =
 332                 (src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
 333         }
 334         if (!zero_run) {
 335             i += esc_count;
 336             lag_memcpy(dst, src, i, step);
 337             dst += i;
 338             l->zeros_rem =
 339             count        = lag_calc_zero_run(src[i]);
 340
 341             if (dst + l->zeros_rem * step > end)
 342                 count = (end - dst) / step;
 343
 344             lag_memset(dst, 0, count, step);
 345             dst += count;
 346             src += i + 1;
 347             l->zeros_rem -= count;
 348         } else {
 349             lag_memcpy(dst, src, i, step);
 350             src += i;
 351         }
 352     }
 353     return start - src;
 354 }
 355
 356
 357
 358 static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
 359                                   int width, int height, int stride,
 360                                   int step, const uint8_t *src,
 361                                   int src_size)
 362 {
 363     int i = 0;
 364     int read = 0;
 365     uint32_t length;
 366     uint32_t offset = 1;
 367     int esc_count = src[0];
 368     GetBitContext gb;
 369     lag_rac rac;
 370
 371     rac.avctx = l->avctx;
 372
 373     if (esc_count < 4) {
 374         length = width * height;
 375         if (esc_count && AV_RL32(src + 1) < length) {
 376             length = AV_RL32(src + 1);
 377             offset += 4;
 378         }
 379
 380         init_get_bits(&gb, src + offset, src_size * 8);
 381
 382         if (lag_read_prob_header(&rac, &gb) < 0)
 383             return -1;
 384
 385         lag_rac_init(&rac, &gb, length - stride);
 386
 387         for (i = 0; i < height; i++)
 388             read +=
 389                 lag_decode_line(l, &rac, dst + (i * stride), width,
 390                                 stride, step, esc_count);
 391
 392         if (read > length)
 393             av_log(l->avctx, AV_LOG_WARNING,
 394                    "Output more bytes than length (%d of %d)\n", read,
 395                    length);
 396     } else if (esc_count < 8) {
 397         esc_count -= 4;
 398         if (esc_count > 0) {
 399             /* Zero run coding only, no range coding. */
 400             for (i = 0; i < height; i++)
 401                 src +=
 402                     lag_decode_zero_run_line(l, dst + (i * stride),
 403                                              src, width, step, esc_count);
 404         } else {
 405             /* Plane is stored uncompressed */
 406             for (i = 0; i < height; i++) {
 407                 lag_memcpy(dst + (i * stride), src, width, step);
 408                 src += width;
 409             }
 410         }
 411     } else if (esc_count == 0xff) {
 412         /* Plane is a solid run of 0 bytes */
 413         for(i = 0; i < height; i++)
 414             lag_memset(dst + i * stride, 0, width, step);
 415     } else {
 416         av_log(l->avctx, AV_LOG_ERROR,
 417                "Invalid zero run escape code! (%#x)\n", esc_count);
 418         return -1;
 419     }
 420
 421     for (i = 0; i < height; i++) {
 422         lag_pred_line(l, dst, width, stride, step, i);
 423         dst += stride;
 424     }
 425
 426     return 0;
 427 }
 428
 429 /**
 430 * Decode a frame.
 431 * @param avctx codec context
 432 * @param data output AVFrame
 433 * @param data_size size of output data or 0 if no picture is returned
 434 * @param avpkt input packet
 435 * @return number of consumed bytes on success or negative if decode fails
 436 */
 437 static int lag_decode_frame(AVCodecContext *avctx,
 438                             void *data, int *data_size, AVPacket *avpkt)
 439 {
 440     const uint8_t *buf = avpkt->data;
 441     int buf_size = avpkt->size;
 442     LagarithContext *l = avctx->priv_data;
 443     AVFrame *const p = &l->picture;
 444     uint8_t frametype = 0;
 445     uint32_t offset_gu = 0, offset_bv = 0, offset_ry = 9;
 446
 447     AVFrame *picture = data;
 448
 449     if (!l->avctx)
 450         l->avctx = avctx;
 451
 452     if (p->data[0])
 453         avctx->release_buffer(avctx, p);
 454
 455     p->reference = 0;
 456     p->key_frame = 1;
 457
 458     frametype = buf[0];
 459
 460     offset_gu = AV_RL32(buf + 1);
 461     offset_bv = AV_RL32(buf + 5);
 462
 463     switch (frametype) {
 464     case FRAME_ARITH_YV12:
 465         avctx->pix_fmt = PIX_FMT_YUV420P;
 466
 467         if (avctx->get_buffer(avctx, p) < 0) {
 468             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 469             return -1;
 470         }
 471
 472         lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
 473                                p->linesize[0], 1, buf + offset_ry,
 474                                buf_size);
 475         lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
 476                                avctx->height / 2, p->linesize[2], 1,
 477                                buf + offset_gu, buf_size);
 478         lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
 479                                avctx->height / 2, p->linesize[1], 1,
 480                                buf + offset_bv, buf_size);
 481         break;
 482     default:
 483         av_log(avctx, AV_LOG_ERROR,
 484                "Unsupported Lagarith frame type: %#x\n", frametype);
 485         return -1;
 486     }
 487
 488     *picture = *p;
 489     *data_size = sizeof(AVFrame);
 490
 491     return buf_size;
 492 }
 493
 494 AVCodec lagarith_decoder = {
 495     "lagarith",
 496     CODEC_TYPE_VIDEO,
 497     CODEC_ID_LAGARITH,
 498     sizeof(LagarithContext),
 499     NULL,
 500     NULL,
 501     NULL,
 502     lag_decode_frame,
 503     CODEC_CAP_DR1,
 504     .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
 505 };