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 given value */
 409         for (i = 0; i < height; i++)
 410             memset(dst + i * stride, src[1], width);
 411         /* Do not apply prediction.
 412            Note: memset to 0 above, setting first value to src[1]
 413            and applying prediction gives the same result. */
 414         return 0;
 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, 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 (p->data[0])
 450         avctx->release_buffer(avctx, p);
 451
 452     p->reference = 0;
 453     p->key_frame = 1;
 454
 455     frametype = buf[0];
 456
 457     offset_gu = AV_RL32(buf + 1);
 458     offset_bv = AV_RL32(buf + 5);
 459
 460     switch (frametype) {
 461     case FRAME_ARITH_YV12:
 462         avctx->pix_fmt = PIX_FMT_YUV420P;
 463
 464         if (avctx->get_buffer(avctx, p) < 0) {
 465             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 466             return -1;
 467         }
 468
 469         lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
 470                                p->linesize[0], buf + offset_ry,
 471                                buf_size);
 472         lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
 473                                avctx->height / 2, p->linesize[2],
 474                                buf + offset_gu, buf_size);
 475         lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
 476                                avctx->height / 2, p->linesize[1],
 477                                buf + offset_bv, buf_size);
 478         break;
 479     default:
 480         av_log(avctx, AV_LOG_ERROR,
 481                "Unsupported Lagarith frame type: %#x\n", frametype);
 482         return -1;
 483     }
 484
 485     *picture = *p;
 486     *data_size = sizeof(AVFrame);
 487
 488     return buf_size;
 489 }
 490
 491 static av_cold int lag_decode_init(AVCodecContext *avctx)
 492 {
 493     LagarithContext *l = avctx->priv_data;
 494     l->avctx = avctx;
 495
 496     dsputil_init(&l->dsp, avctx);
 497
 498     return 0;
 499 }
 500
 501 static av_cold int lag_decode_end(AVCodecContext *avctx)
 502 {
 503     LagarithContext *l = avctx->priv_data;
 504
 505     if (l->picture.data[0])
 506         avctx->release_buffer(avctx, &l->picture);
 507
 508     return 0;
 509 }
 510
 511 AVCodec lagarith_decoder = {
 512     "lagarith",
 513     CODEC_TYPE_VIDEO,
 514     CODEC_ID_LAGARITH,
 515     sizeof(LagarithContext),
 516     lag_decode_init,
 517     NULL,
 518     lag_decode_end,
 519     lag_decode_frame,
 520     CODEC_CAP_DR1,
 521     .long_name = NULL_IF_CONFIG_SMALL("Lagarith lossless"),
 522 };