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| 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 | +}; |