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FFmpeg/libavcodec/webp.c

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  1. /*

  2.  * WebP (.webp) image decoder

  3.  * Copyright (c) 2013 Aneesh Dogra <aneesh@sugarlabs.org>

  4.  * Copyright (c) 2013 Justin Ruggles <justin.ruggles@gmail.com>

  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

  25.  * WebP image decoder

  26.  *

  27.  * @author Aneesh Dogra <aneesh@sugarlabs.org>

  28.  * Container and Lossy decoding

  29.  *

  30.  * @author Justin Ruggles <justin.ruggles@gmail.com>

  31.  * Lossless decoder

  32.  * Compressed alpha for lossy

  33.  *

  34.  * @author James Almer <jamrial@gmail.com>

  35.  * Exif metadata

  36.  *

  37.  * Unimplemented:

  38.  *   - Animation

  39.  *   - ICC profile

  40.  *   - XMP metadata

  41.  */

  42. 

  43. #define BITSTREAM_READER_LE

  44. #include "libavutil/imgutils.h"

  45. #include "avcodec.h"

  46. #include "bytestream.h"

  47. #include "exif.h"

  48. #include "internal.h"

  49. #include "get_bits.h"

  50. #include "thread.h"

  51. #include "vp8.h"

  52. 

  53. #define VP8X_FLAG_ANIMATION             0x02

  54. #define VP8X_FLAG_XMP_METADATA          0x04

  55. #define VP8X_FLAG_EXIF_METADATA         0x08

  56. #define VP8X_FLAG_ALPHA                 0x10

  57. #define VP8X_FLAG_ICC                   0x20

  58. 

  59. #define MAX_PALETTE_SIZE                256

  60. #define MAX_CACHE_BITS                  11

  61. #define NUM_CODE_LENGTH_CODES           19

  62. #define HUFFMAN_CODES_PER_META_CODE     5

  63. #define NUM_LITERAL_CODES               256

  64. #define NUM_LENGTH_CODES                24

  65. #define NUM_DISTANCE_CODES              40

  66. #define NUM_SHORT_DISTANCES             120

  67. #define MAX_HUFFMAN_CODE_LENGTH         15

  68. 

  69. static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {

  70.     NUM_LITERAL_CODES + NUM_LENGTH_CODES,

  71.     NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,

  72.     NUM_DISTANCE_CODES

  73. };

  74. 

  75. static const uint8_t code_length_code_order[NUM_CODE_LENGTH_CODES] = {

  76.     17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15

  77. };

  78. 

  79. static const int8_t lz77_distance_offsets[NUM_SHORT_DISTANCES][2] = {

  80.     {  0, 1 }, {  1, 0 }, {  1, 1 }, { -1, 1 }, {  0, 2 }, {  2, 0 }, {  1, 2 }, { -1, 2 },

  81.     {  2, 1 }, { -2, 1 }, {  2, 2 }, { -2, 2 }, {  0, 3 }, {  3, 0 }, {  1, 3 }, { -1, 3 },

  82.     {  3, 1 }, { -3, 1 }, {  2, 3 }, { -2, 3 }, {  3, 2 }, { -3, 2 }, {  0, 4 }, {  4, 0 },

  83.     {  1, 4 }, { -1, 4 }, {  4, 1 }, { -4, 1 }, {  3, 3 }, { -3, 3 }, {  2, 4 }, { -2, 4 },

  84.     {  4, 2 }, { -4, 2 }, {  0, 5 }, {  3, 4 }, { -3, 4 }, {  4, 3 }, { -4, 3 }, {  5, 0 },

  85.     {  1, 5 }, { -1, 5 }, {  5, 1 }, { -5, 1 }, {  2, 5 }, { -2, 5 }, {  5, 2 }, { -5, 2 },

  86.     {  4, 4 }, { -4, 4 }, {  3, 5 }, { -3, 5 }, {  5, 3 }, { -5, 3 }, {  0, 6 }, {  6, 0 },

  87.     {  1, 6 }, { -1, 6 }, {  6, 1 }, { -6, 1 }, {  2, 6 }, { -2, 6 }, {  6, 2 }, { -6, 2 },

  88.     {  4, 5 }, { -4, 5 }, {  5, 4 }, { -5, 4 }, {  3, 6 }, { -3, 6 }, {  6, 3 }, { -6, 3 },

  89.     {  0, 7 }, {  7, 0 }, {  1, 7 }, { -1, 7 }, {  5, 5 }, { -5, 5 }, {  7, 1 }, { -7, 1 },

  90.     {  4, 6 }, { -4, 6 }, {  6, 4 }, { -6, 4 }, {  2, 7 }, { -2, 7 }, {  7, 2 }, { -7, 2 },

  91.     {  3, 7 }, { -3, 7 }, {  7, 3 }, { -7, 3 }, {  5, 6 }, { -5, 6 }, {  6, 5 }, { -6, 5 },

  92.     {  8, 0 }, {  4, 7 }, { -4, 7 }, {  7, 4 }, { -7, 4 }, {  8, 1 }, {  8, 2 }, {  6, 6 },

  93.     { -6, 6 }, {  8, 3 }, {  5, 7 }, { -5, 7 }, {  7, 5 }, { -7, 5 }, {  8, 4 }, {  6, 7 },

  94.     { -6, 7 }, {  7, 6 }, { -7, 6 }, {  8, 5 }, {  7, 7 }, { -7, 7 }, {  8, 6 }, {  8, 7 }

  95. };

  96. 

  97. enum AlphaCompression {

  98.     ALPHA_COMPRESSION_NONE,

  99.     ALPHA_COMPRESSION_VP8L,

  100. };

  101. 

  102. enum AlphaFilter {

  103.     ALPHA_FILTER_NONE,

  104.     ALPHA_FILTER_HORIZONTAL,

  105.     ALPHA_FILTER_VERTICAL,

  106.     ALPHA_FILTER_GRADIENT,

  107. };

  108. 

  109. enum TransformType {

  110.     PREDICTOR_TRANSFORM      = 0,

  111.     COLOR_TRANSFORM          = 1,

  112.     SUBTRACT_GREEN           = 2,

  113.     COLOR_INDEXING_TRANSFORM = 3,

  114. };

  115. 

  116. enum PredictionMode {

  117.     PRED_MODE_BLACK,

  118.     PRED_MODE_L,

  119.     PRED_MODE_T,

  120.     PRED_MODE_TR,

  121.     PRED_MODE_TL,

  122.     PRED_MODE_AVG_T_AVG_L_TR,

  123.     PRED_MODE_AVG_L_TL,

  124.     PRED_MODE_AVG_L_T,

  125.     PRED_MODE_AVG_TL_T,

  126.     PRED_MODE_AVG_T_TR,

  127.     PRED_MODE_AVG_AVG_L_TL_AVG_T_TR,

  128.     PRED_MODE_SELECT,

  129.     PRED_MODE_ADD_SUBTRACT_FULL,

  130.     PRED_MODE_ADD_SUBTRACT_HALF,

  131. };

  132. 

  133. enum HuffmanIndex {

  134.     HUFF_IDX_GREEN = 0,

  135.     HUFF_IDX_RED   = 1,

  136.     HUFF_IDX_BLUE  = 2,

  137.     HUFF_IDX_ALPHA = 3,

  138.     HUFF_IDX_DIST  = 4

  139. };

  140. 

  141. /* The structure of WebP lossless is an optional series of transformation data,

  142.  * followed by the primary image. The primary image also optionally contains

  143.  * an entropy group mapping if there are multiple entropy groups. There is a

  144.  * basic image type called an "entropy coded image" that is used for all of

  145.  * these. The type of each entropy coded image is referred to by the

  146.  * specification as its role. */

  147. enum ImageRole {

  148.     /* Primary Image: Stores the actual pixels of the image. */

  149.     IMAGE_ROLE_ARGB,

  150. 

  151.     /* Entropy Image: Defines which Huffman group to use for different areas of

  152.      *                the primary image. */

  153.     IMAGE_ROLE_ENTROPY,

  154. 

  155.     /* Predictors: Defines which predictor type to use for different areas of

  156.      *             the primary image. */

  157.     IMAGE_ROLE_PREDICTOR,

  158. 

  159.     /* Color Transform Data: Defines the color transformation for different

  160.      *                       areas of the primary image. */

  161.     IMAGE_ROLE_COLOR_TRANSFORM,

  162. 

  163.     /* Color Index: Stored as an image of height == 1. */

  164.     IMAGE_ROLE_COLOR_INDEXING,

  165. 

  166.     IMAGE_ROLE_NB,

  167. };

  168. 

  169. typedef struct HuffReader {

  170.     VLC vlc;                            /* Huffman decoder context */

  171.     int simple;                         /* whether to use simple mode */

  172.     int nb_symbols;                     /* number of coded symbols */

  173.     uint16_t simple_symbols[2];         /* symbols for simple mode */

  174. } HuffReader;

  175. 

  176. typedef struct ImageContext {

  177.     enum ImageRole role;                /* role of this image */

  178.     AVFrame *frame;                     /* AVFrame for data */

  179.     int color_cache_bits;               /* color cache size, log2 */

  180.     uint32_t *color_cache;              /* color cache data */

  181.     int nb_huffman_groups;              /* number of huffman groups */

  182.     HuffReader *huffman_groups;         /* reader for each huffman group */

  183.     int size_reduction;                 /* relative size compared to primary image, log2 */

  184.     int is_alpha_primary;

  185. } ImageContext;

  186. 

  187. typedef struct WebPContext {

  188.     VP8Context v;                       /* VP8 Context used for lossy decoding */

  189.     GetBitContext gb;                   /* bitstream reader for main image chunk */

  190.     AVFrame *alpha_frame;               /* AVFrame for alpha data decompressed from VP8L */

  191.     AVCodecContext *avctx;              /* parent AVCodecContext */

  192.     int initialized;                    /* set once the VP8 context is initialized */

  193.     int has_alpha;                      /* has a separate alpha chunk */

  194.     enum AlphaCompression alpha_compression; /* compression type for alpha chunk */

  195.     enum AlphaFilter alpha_filter;      /* filtering method for alpha chunk */

  196.     uint8_t *alpha_data;                /* alpha chunk data */

  197.     int alpha_data_size;                /* alpha chunk data size */

  198.     int has_exif;                       /* set after an EXIF chunk has been processed */

  199.     AVDictionary *exif_metadata;        /* EXIF chunk data */

  200.     int width;                          /* image width */

  201.     int height;                         /* image height */

  202.     int lossless;                       /* indicates lossless or lossy */

  203. 

  204.     int nb_transforms;                  /* number of transforms */

  205.     enum TransformType transforms[4];   /* transformations used in the image, in order */

  206.     int reduced_width;                  /* reduced width for index image, if applicable */

  207.     int nb_huffman_groups;              /* number of huffman groups in the primary image */

  208.     ImageContext image[IMAGE_ROLE_NB];  /* image context for each role */

  209. } WebPContext;

  210. 

  211. #define GET_PIXEL(frame, x, y) \

  212.     ((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x))

  213. 

  214. #define GET_PIXEL_COMP(frame, x, y, c) \

  215.     (*((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x) + c))

  216. 

  217. static void image_ctx_free(ImageContext *img)

  218. {

  219.     int i, j;

  220. 

  221.     av_free(img->color_cache);

  222.     if (img->role != IMAGE_ROLE_ARGB && !img->is_alpha_primary)

  223.         av_frame_free(&img->frame);

  224.     if (img->huffman_groups) {

  225.         for (i = 0; i < img->nb_huffman_groups; i++) {

  226.             for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++)

  227.                 ff_free_vlc(&img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE + j].vlc);

  228.         }

  229.         av_free(img->huffman_groups);

  230.     }

  231.     memset(img, 0, sizeof(*img));

  232. }

  233. 

  234. 

  235. /* Differs from get_vlc2() in the following ways:

  236.  *   - codes are bit-reversed

  237.  *   - assumes 8-bit table to make reversal simpler

  238.  *   - assumes max depth of 2 since the max code length for WebP is 15

  239.  */

  240. static av_always_inline int webp_get_vlc(GetBitContext *gb, VLC_TYPE (*table)[2])

  241. {

  242.     int n, nb_bits;

  243.     unsigned int index;

  244.     int code;

  245. 

  246.     OPEN_READER(re, gb);

  247.     UPDATE_CACHE(re, gb);

  248. 

  249.     index = SHOW_UBITS(re, gb, 8);

  250.     index = ff_reverse[index];

  251.     code  = table[index][0];

  252.     n     = table[index][1];

  253. 

  254.     if (n < 0) {

  255.         LAST_SKIP_BITS(re, gb, 8);

  256.         UPDATE_CACHE(re, gb);

  257. 

  258.         nb_bits = -n;

  259. 

  260.         index = SHOW_UBITS(re, gb, nb_bits);

  261.         index = (ff_reverse[index] >> (8 - nb_bits)) + code;

  262.         code  = table[index][0];

  263.         n     = table[index][1];

  264.     }

  265.     SKIP_BITS(re, gb, n);

  266. 

  267.     CLOSE_READER(re, gb);

  268. 

  269.     return code;

  270. }

  271. 

  272. static int huff_reader_get_symbol(HuffReader *r, GetBitContext *gb)

  273. {

  274.     if (r->simple) {

  275.         if (r->nb_symbols == 1)

  276.             return r->simple_symbols[0];

  277.         else

  278.             return r->simple_symbols[get_bits1(gb)];

  279.     } else

  280.         return webp_get_vlc(gb, r->vlc.table);

  281. }

  282. 

  283. static int huff_reader_build_canonical(HuffReader *r, int *code_lengths,

  284.                                        int alphabet_size)

  285. {

  286.     int len = 0, sym, code = 0, ret;

  287.     int max_code_length = 0;

  288.     uint16_t *codes;

  289. 

  290.     /* special-case 1 symbol since the vlc reader cannot handle it */

  291.     for (sym = 0; sym < alphabet_size; sym++) {

  292.         if (code_lengths[sym] > 0) {

  293.             len++;

  294.             code = sym;

  295.             if (len > 1)

  296.                 break;

  297.         }

  298.     }

  299.     if (len == 1) {

  300.         r->nb_symbols = 1;

  301.         r->simple_symbols[0] = code;

  302.         r->simple = 1;

  303.         return 0;

  304.     }

  305. 

  306.     for (sym = 0; sym < alphabet_size; sym++)

  307.         max_code_length = FFMAX(max_code_length, code_lengths[sym]);

  308. 

  309.     if (max_code_length == 0 || max_code_length > MAX_HUFFMAN_CODE_LENGTH)

  310.         return AVERROR(EINVAL);

  311. 

  312.     codes = av_malloc_array(alphabet_size, sizeof(*codes));

  313.     if (!codes)

  314.         return AVERROR(ENOMEM);

  315. 

  316.     code = 0;

  317.     r->nb_symbols = 0;

  318.     for (len = 1; len <= max_code_length; len++) {

  319.         for (sym = 0; sym < alphabet_size; sym++) {

  320.             if (code_lengths[sym] != len)

  321.                 continue;

  322.             codes[sym] = code++;

  323.             r->nb_symbols++;

  324.         }

  325.         code <<= 1;

  326.     }

  327.     if (!r->nb_symbols) {

  328.         av_free(codes);

  329.         return AVERROR_INVALIDDATA;

  330.     }

  331. 

  332.     ret = init_vlc(&r->vlc, 8, alphabet_size,

  333.                    code_lengths, sizeof(*code_lengths), sizeof(*code_lengths),

  334.                    codes, sizeof(*codes), sizeof(*codes), 0);

  335.     if (ret < 0) {

  336.         av_free(codes);

  337.         return ret;

  338.     }

  339.     r->simple = 0;

  340. 

  341.     av_free(codes);

  342.     return 0;

  343. }

  344. 

  345. static void read_huffman_code_simple(WebPContext *s, HuffReader *hc)

  346. {

  347.     hc->nb_symbols = get_bits1(&s->gb) + 1;

  348. 

  349.     if (get_bits1(&s->gb))

  350.         hc->simple_symbols[0] = get_bits(&s->gb, 8);

  351.     else

  352.         hc->simple_symbols[0] = get_bits1(&s->gb);

  353. 

  354.     if (hc->nb_symbols == 2)

  355.         hc->simple_symbols[1] = get_bits(&s->gb, 8);

  356. 

  357.     hc->simple = 1;

  358. }

  359. 

  360. static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,

  361.                                     int alphabet_size)

  362. {

  363.     HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } };

  364.     int *code_lengths = NULL;

  365.     int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };

  366.     int i, symbol, max_symbol, prev_code_len, ret;

  367.     int num_codes = 4 + get_bits(&s->gb, 4);

  368. 

  369.     if (num_codes > NUM_CODE_LENGTH_CODES)

  370.         return AVERROR_INVALIDDATA;

  371. 

  372.     for (i = 0; i < num_codes; i++)

  373.         code_length_code_lengths[code_length_code_order[i]] = get_bits(&s->gb, 3);

  374. 

  375.     ret = huff_reader_build_canonical(&code_len_hc, code_length_code_lengths,

  376.                                       NUM_CODE_LENGTH_CODES);

  377.     if (ret < 0)

  378.         goto finish;

  379. 

  380.     code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths));

  381.     if (!code_lengths) {

  382.         ret = AVERROR(ENOMEM);

  383.         goto finish;

  384.     }

  385. 

  386.     if (get_bits1(&s->gb)) {

  387.         int bits   = 2 + 2 * get_bits(&s->gb, 3);

  388.         max_symbol = 2 + get_bits(&s->gb, bits);

  389.         if (max_symbol > alphabet_size) {

  390.             av_log(s->avctx, AV_LOG_ERROR, "max symbol %d > alphabet size %d\n",

  391.                    max_symbol, alphabet_size);

  392.             ret = AVERROR_INVALIDDATA;

  393.             goto finish;

  394.         }

  395.     } else {

  396.         max_symbol = alphabet_size;

  397.     }

  398. 

  399.     prev_code_len = 8;

  400.     symbol        = 0;

  401.     while (symbol < alphabet_size) {

  402.         int code_len;

  403. 

  404.         if (!max_symbol--)

  405.             break;

  406.         code_len = huff_reader_get_symbol(&code_len_hc, &s->gb);

  407.         if (code_len < 16) {

  408.             /* Code length code [0..15] indicates literal code lengths. */

  409.             code_lengths[symbol++] = code_len;

  410.             if (code_len)

  411.                 prev_code_len = code_len;

  412.         } else {

  413.             int repeat = 0, length = 0;

  414.             switch (code_len) {

  415.             case 16:

  416.                 /* Code 16 repeats the previous non-zero value [3..6] times,

  417.                  * i.e., 3 + ReadBits(2) times. If code 16 is used before a

  418.                  * non-zero value has been emitted, a value of 8 is repeated. */

  419.                 repeat = 3 + get_bits(&s->gb, 2);

  420.                 length = prev_code_len;

  421.                 break;

  422.             case 17:

  423.                 /* Code 17 emits a streak of zeros [3..10], i.e.,

  424.                  * 3 + ReadBits(3) times. */

  425.                 repeat = 3 + get_bits(&s->gb, 3);

  426.                 break;

  427.             case 18:

  428.                 /* Code 18 emits a streak of zeros of length [11..138], i.e.,

  429.                  * 11 + ReadBits(7) times. */

  430.                 repeat = 11 + get_bits(&s->gb, 7);

  431.                 break;

  432.             }

  433.             if (symbol + repeat > alphabet_size) {

  434.                 av_log(s->avctx, AV_LOG_ERROR,

  435.                        "invalid symbol %d + repeat %d > alphabet size %d\n",

  436.                        symbol, repeat, alphabet_size);

  437.                 ret = AVERROR_INVALIDDATA;

  438.                 goto finish;

  439.             }

  440.             while (repeat-- > 0)

  441.                 code_lengths[symbol++] = length;

  442.         }

  443.     }

  444. 

  445.     ret = huff_reader_build_canonical(hc, code_lengths, alphabet_size);

  446. 

  447. finish:

  448.     ff_free_vlc(&code_len_hc.vlc);

  449.     av_free(code_lengths);

  450.     return ret;

  451. }

  452. 

  453. static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,

  454.                                       int w, int h);

  455. 

  456. #define PARSE_BLOCK_SIZE(w, h) do {                                         \

  457.     block_bits = get_bits(&s->gb, 3) + 2;                                   \

  458.     blocks_w   = FFALIGN((w), 1 << block_bits) >> block_bits;               \

  459.     blocks_h   = FFALIGN((h), 1 << block_bits) >> block_bits;               \

  460. } while (0)

  461. 

  462. static int decode_entropy_image(WebPContext *s)

  463. {

  464.     ImageContext *img;

  465.     int ret, block_bits, width, blocks_w, blocks_h, x, y, max;

  466. 

  467.     width = s->width;

  468.     if (s->reduced_width > 0)

  469.         width = s->reduced_width;

  470. 

  471.     PARSE_BLOCK_SIZE(width, s->height);

  472. 

  473.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_ENTROPY, blocks_w, blocks_h);

  474.     if (ret < 0)

  475.         return ret;

  476. 

  477.     img = &s->image[IMAGE_ROLE_ENTROPY];

  478.     img->size_reduction = block_bits;

  479. 

  480.     /* the number of huffman groups is determined by the maximum group number

  481.      * coded in the entropy image */

  482.     max = 0;

  483.     for (y = 0; y < img->frame->height; y++) {

  484.         for (x = 0; x < img->frame->width; x++) {

  485.             int p = GET_PIXEL_COMP(img->frame, x, y, 2);

  486.             max = FFMAX(max, p);

  487.         }

  488.     }

  489.     s->nb_huffman_groups = max + 1;

  490. 

  491.     return 0;

  492. }

  493. 

  494. static int parse_transform_predictor(WebPContext *s)

  495. {

  496.     int block_bits, blocks_w, blocks_h, ret;

  497. 

  498.     PARSE_BLOCK_SIZE(s->width, s->height);

  499. 

  500.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_PREDICTOR, blocks_w,

  501.                                      blocks_h);

  502.     if (ret < 0)

  503.         return ret;

  504. 

  505.     s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits;

  506. 

  507.     return 0;

  508. }

  509. 

  510. static int parse_transform_color(WebPContext *s)

  511. {

  512.     int block_bits, blocks_w, blocks_h, ret;

  513. 

  514.     PARSE_BLOCK_SIZE(s->width, s->height);

  515. 

  516.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_TRANSFORM, blocks_w,

  517.                                      blocks_h);

  518.     if (ret < 0)

  519.         return ret;

  520. 

  521.     s->image[IMAGE_ROLE_COLOR_TRANSFORM].size_reduction = block_bits;

  522. 

  523.     return 0;

  524. }

  525. 

  526. static int parse_transform_color_indexing(WebPContext *s)

  527. {

  528.     ImageContext *img;

  529.     int width_bits, index_size, ret, x;

  530.     uint8_t *ct;

  531. 

  532.     index_size = get_bits(&s->gb, 8) + 1;

  533. 

  534.     if (index_size <= 2)

  535.         width_bits = 3;

  536.     else if (index_size <= 4)

  537.         width_bits = 2;

  538.     else if (index_size <= 16)

  539.         width_bits = 1;

  540.     else

  541.         width_bits = 0;

  542. 

  543.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING,

  544.                                      index_size, 1);

  545.     if (ret < 0)

  546.         return ret;

  547. 

  548.     img = &s->image[IMAGE_ROLE_COLOR_INDEXING];

  549.     img->size_reduction = width_bits;

  550.     if (width_bits > 0)

  551.         s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits;

  552. 

  553.     /* color index values are delta-coded */

  554.     ct  = img->frame->data[0] + 4;

  555.     for (x = 4; x < img->frame->width * 4; x++, ct++)

  556.         ct[0] += ct[-4];

  557. 

  558.     return 0;

  559. }

  560. 

  561. static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img,

  562.                                      int x, int y)

  563. {

  564.     ImageContext *gimg = &s->image[IMAGE_ROLE_ENTROPY];

  565.     int group = 0;

  566. 

  567.     if (gimg->size_reduction > 0) {

  568.         int group_x = x >> gimg->size_reduction;

  569.         int group_y = y >> gimg->size_reduction;

  570.         group       = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);

  571.     }

  572. 

  573.     return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];

  574. }

  575. 

  576. static av_always_inline void color_cache_put(ImageContext *img, uint32_t c)

  577. {

  578.     uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits);

  579.     img->color_cache[cache_idx] = c;

  580. }

  581. 

  582. static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,

  583.                                       int w, int h)

  584. {

  585.     ImageContext *img;

  586.     HuffReader *hg;

  587.     int i, j, ret, x, y, width;

  588. 

  589.     img       = &s->image[role];

  590.     img->role = role;

  591. 

  592.     if (!img->frame) {

  593.         img->frame = av_frame_alloc();

  594.         if (!img->frame)

  595.             return AVERROR(ENOMEM);

  596.     }

  597. 

  598.     img->frame->format = AV_PIX_FMT_ARGB;

  599.     img->frame->width  = w;

  600.     img->frame->height = h;

  601. 

  602.     if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {

  603.         ThreadFrame pt = { .f = img->frame };

  604.         ret = ff_thread_get_buffer(s->avctx, &pt, 0);

  605.     } else

  606.         ret = av_frame_get_buffer(img->frame, 1);

  607.     if (ret < 0)

  608.         return ret;

  609. 

  610.     if (get_bits1(&s->gb)) {

  611.         img->color_cache_bits = get_bits(&s->gb, 4);

  612.         if (img->color_cache_bits < 1 || img->color_cache_bits > 11) {

  613.             av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n",

  614.                    img->color_cache_bits);

  615.             return AVERROR_INVALIDDATA;

  616.         }

  617.         img->color_cache = av_mallocz_array(1 << img->color_cache_bits,

  618.                                             sizeof(*img->color_cache));

  619.         if (!img->color_cache)

  620.             return AVERROR(ENOMEM);

  621.     } else {

  622.         img->color_cache_bits = 0;

  623.     }

  624. 

  625.     img->nb_huffman_groups = 1;

  626.     if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) {

  627.         ret = decode_entropy_image(s);

  628.         if (ret < 0)

  629.             return ret;

  630.         img->nb_huffman_groups = s->nb_huffman_groups;

  631.     }

  632.     img->huffman_groups = av_mallocz_array(img->nb_huffman_groups *

  633.                                            HUFFMAN_CODES_PER_META_CODE,

  634.                                            sizeof(*img->huffman_groups));

  635.     if (!img->huffman_groups)

  636.         return AVERROR(ENOMEM);

  637. 

  638.     for (i = 0; i < img->nb_huffman_groups; i++) {

  639.         hg = &img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE];

  640.         for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) {

  641.             int alphabet_size = alphabet_sizes[j];

  642.             if (!j && img->color_cache_bits > 0)

  643.                 alphabet_size += 1 << img->color_cache_bits;

  644. 

  645.             if (get_bits1(&s->gb)) {

  646.                 read_huffman_code_simple(s, &hg[j]);

  647.             } else {

  648.                 ret = read_huffman_code_normal(s, &hg[j], alphabet_size);

  649.                 if (ret < 0)

  650.                     return ret;

  651.             }

  652.         }

  653.     }

  654. 

  655.     width = img->frame->width;

  656.     if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0)

  657.         width = s->reduced_width;

  658. 

  659.     x = 0; y = 0;

  660.     while (y < img->frame->height) {

  661.         int v;

  662. 

  663.         hg = get_huffman_group(s, img, x, y);

  664.         v = huff_reader_get_symbol(&hg[HUFF_IDX_GREEN], &s->gb);

  665.         if (v < NUM_LITERAL_CODES) {

  666.             /* literal pixel values */

  667.             uint8_t *p = GET_PIXEL(img->frame, x, y);

  668.             p[2] = v;

  669.             p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED],   &s->gb);

  670.             p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE],  &s->gb);

  671.             p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb);

  672.             if (img->color_cache_bits)

  673.                 color_cache_put(img, AV_RB32(p));

  674.             x++;

  675.             if (x == width) {

  676.                 x = 0;

  677.                 y++;

  678.             }

  679.         } else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) {

  680.             /* LZ77 backwards mapping */

  681.             int prefix_code, length, distance, ref_x, ref_y;

  682. 

  683.             /* parse length and distance */

  684.             prefix_code = v - NUM_LITERAL_CODES;

  685.             if (prefix_code < 4) {

  686.                 length = prefix_code + 1;

  687.             } else {

  688.                 int extra_bits = (prefix_code - 2) >> 1;

  689.                 int offset     = 2 + (prefix_code & 1) << extra_bits;

  690.                 length = offset + get_bits(&s->gb, extra_bits) + 1;

  691.             }

  692.             prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb);

  693.             if (prefix_code < 4) {

  694.                 distance = prefix_code + 1;

  695.             } else {

  696.                 int extra_bits = prefix_code - 2 >> 1;

  697.                 int offset     = 2 + (prefix_code & 1) << extra_bits;

  698.                 distance = offset + get_bits(&s->gb, extra_bits) + 1;

  699.             }

  700. 

  701.             /* find reference location */

  702.             if (distance <= NUM_SHORT_DISTANCES) {

  703.                 int xi = lz77_distance_offsets[distance - 1][0];

  704.                 int yi = lz77_distance_offsets[distance - 1][1];

  705.                 distance = FFMAX(1, xi + yi * width);

  706.             } else {

  707.                 distance -= NUM_SHORT_DISTANCES;

  708.             }

  709.             ref_x = x;

  710.             ref_y = y;

  711.             if (distance <= x) {

  712.                 ref_x -= distance;

  713.                 distance = 0;

  714.             } else {

  715.                 ref_x = 0;

  716.                 distance -= x;

  717.             }

  718.             while (distance >= width) {

  719.                 ref_y--;

  720.                 distance -= width;

  721.             }

  722.             if (distance > 0) {

  723.                 ref_x = width - distance;

  724.                 ref_y--;

  725.             }

  726.             ref_x = FFMAX(0, ref_x);

  727.             ref_y = FFMAX(0, ref_y);

  728. 

  729.             /* copy pixels

  730.              * source and dest regions can overlap and wrap lines, so just

  731.              * copy per-pixel */

  732.             for (i = 0; i < length; i++) {

  733.                 uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y);

  734.                 uint8_t *p     = GET_PIXEL(img->frame,     x,     y);

  735. 

  736.                 AV_COPY32(p, p_ref);

  737.                 if (img->color_cache_bits)

  738.                     color_cache_put(img, AV_RB32(p));

  739.                 x++;

  740.                 ref_x++;

  741.                 if (x == width) {

  742.                     x = 0;

  743.                     y++;

  744.                 }

  745.                 if (ref_x == width) {

  746.                     ref_x = 0;

  747.                     ref_y++;

  748.                 }

  749.                 if (y == img->frame->height || ref_y == img->frame->height)

  750.                     break;

  751.             }

  752.         } else {

  753.             /* read from color cache */

  754.             uint8_t *p = GET_PIXEL(img->frame, x, y);

  755.             int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES);

  756. 

  757.             if (!img->color_cache_bits) {

  758.                 av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n");

  759.                 return AVERROR_INVALIDDATA;

  760.             }

  761.             if (cache_idx >= 1 << img->color_cache_bits) {

  762.                 av_log(s->avctx, AV_LOG_ERROR,

  763.                        "color cache index out-of-bounds\n");

  764.                 return AVERROR_INVALIDDATA;

  765.             }

  766.             AV_WB32(p, img->color_cache[cache_idx]);

  767.             x++;

  768.             if (x == width) {

  769.                 x = 0;

  770.                 y++;

  771.             }

  772.         }

  773.     }

  774. 

  775.     return 0;

  776. }

  777. 

  778. /* PRED_MODE_BLACK */

  779. static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  780.                           const uint8_t *p_t, const uint8_t *p_tr)

  781. {

  782.     AV_WB32(p, 0xFF000000);

  783. }

  784. 

  785. /* PRED_MODE_L */

  786. static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  787.                           const uint8_t *p_t, const uint8_t *p_tr)

  788. {

  789.     AV_COPY32(p, p_l);

  790. }

  791. 

  792. /* PRED_MODE_T */

  793. static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  794.                           const uint8_t *p_t, const uint8_t *p_tr)

  795. {

  796.     AV_COPY32(p, p_t);

  797. }

  798. 

  799. /* PRED_MODE_TR */

  800. static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  801.                           const uint8_t *p_t, const uint8_t *p_tr)

  802. {

  803.     AV_COPY32(p, p_tr);

  804. }

  805. 

  806. /* PRED_MODE_TL */

  807. static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  808.                           const uint8_t *p_t, const uint8_t *p_tr)

  809. {

  810.     AV_COPY32(p, p_tl);

  811. }

  812. 

  813. /* PRED_MODE_AVG_T_AVG_L_TR */

  814. static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  815.                           const uint8_t *p_t, const uint8_t *p_tr)

  816. {

  817.     p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1;

  818.     p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1;

  819.     p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1;

  820.     p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1;

  821. }

  822. 

  823. /* PRED_MODE_AVG_L_TL */

  824. static void inv_predict_6(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  825.                           const uint8_t *p_t, const uint8_t *p_tr)

  826. {

  827.     p[0] = p_l[0] + p_tl[0] >> 1;

  828.     p[1] = p_l[1] + p_tl[1] >> 1;

  829.     p[2] = p_l[2] + p_tl[2] >> 1;

  830.     p[3] = p_l[3] + p_tl[3] >> 1;

  831. }

  832. 

  833. /* PRED_MODE_AVG_L_T */

  834. static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  835.                           const uint8_t *p_t, const uint8_t *p_tr)

  836. {

  837.     p[0] = p_l[0] + p_t[0] >> 1;

  838.     p[1] = p_l[1] + p_t[1] >> 1;

  839.     p[2] = p_l[2] + p_t[2] >> 1;

  840.     p[3] = p_l[3] + p_t[3] >> 1;

  841. }

  842. 

  843. /* PRED_MODE_AVG_TL_T */

  844. static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  845.                           const uint8_t *p_t, const uint8_t *p_tr)

  846. {

  847.     p[0] = p_tl[0] + p_t[0] >> 1;

  848.     p[1] = p_tl[1] + p_t[1] >> 1;

  849.     p[2] = p_tl[2] + p_t[2] >> 1;

  850.     p[3] = p_tl[3] + p_t[3] >> 1;

  851. }

  852. 

  853. /* PRED_MODE_AVG_T_TR */

  854. static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  855.                           const uint8_t *p_t, const uint8_t *p_tr)

  856. {

  857.     p[0] = p_t[0] + p_tr[0] >> 1;

  858.     p[1] = p_t[1] + p_tr[1] >> 1;

  859.     p[2] = p_t[2] + p_tr[2] >> 1;

  860.     p[3] = p_t[3] + p_tr[3] >> 1;

  861. }

  862. 

  863. /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */

  864. static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  865.                            const uint8_t *p_t, const uint8_t *p_tr)

  866. {

  867.     p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1;

  868.     p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1;

  869.     p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1;

  870.     p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1;

  871. }

  872. 

  873. /* PRED_MODE_SELECT */

  874. static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  875.                            const uint8_t *p_t, const uint8_t *p_tr)

  876. {

  877.     int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) +

  878.                (FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) +

  879.                (FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) +

  880.                (FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3]));

  881.     if (diff <= 0)

  882.         AV_COPY32(p, p_t);

  883.     else

  884.         AV_COPY32(p, p_l);

  885. }

  886. 

  887. /* PRED_MODE_ADD_SUBTRACT_FULL */

  888. static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  889.                            const uint8_t *p_t, const uint8_t *p_tr)

  890. {

  891.     p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]);

  892.     p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]);

  893.     p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]);

  894.     p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]);

  895. }

  896. 

  897. static av_always_inline uint8_t clamp_add_subtract_half(int a, int b, int c)

  898. {

  899.     int d = a + b >> 1;

  900.     return av_clip_uint8(d + (d - c) / 2);

  901. }

  902. 

  903. /* PRED_MODE_ADD_SUBTRACT_HALF */

  904. static void inv_predict_13(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,

  905.                            const uint8_t *p_t, const uint8_t *p_tr)

  906. {

  907.     p[0] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]);

  908.     p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]);

  909.     p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]);

  910.     p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]);

  911. }

  912. 

  913. typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l,

  914.                                  const uint8_t *p_tl, const uint8_t *p_t,

  915.                                  const uint8_t *p_tr);

  916. 

  917. static const inv_predict_func inverse_predict[14] = {

  918.     inv_predict_0,  inv_predict_1,  inv_predict_2,  inv_predict_3,

  919.     inv_predict_4,  inv_predict_5,  inv_predict_6,  inv_predict_7,

  920.     inv_predict_8,  inv_predict_9,  inv_predict_10, inv_predict_11,

  921.     inv_predict_12, inv_predict_13,

  922. };

  923. 

  924. static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y)

  925. {

  926.     uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr;

  927.     uint8_t p[4];

  928. 

  929.     dec  = GET_PIXEL(frame, x,     y);

  930.     p_l  = GET_PIXEL(frame, x - 1, y);

  931.     p_tl = GET_PIXEL(frame, x - 1, y - 1);

  932.     p_t  = GET_PIXEL(frame, x,     y - 1);

  933.     if (x == frame->width - 1)

  934.         p_tr = GET_PIXEL(frame, 0, y);

  935.     else

  936.         p_tr = GET_PIXEL(frame, x + 1, y - 1);

  937. 

  938.     inverse_predict[m](p, p_l, p_tl, p_t, p_tr);

  939. 

  940.     dec[0] += p[0];

  941.     dec[1] += p[1];

  942.     dec[2] += p[2];

  943.     dec[3] += p[3];

  944. }

  945. 

  946. static int apply_predictor_transform(WebPContext *s)

  947. {

  948.     ImageContext *img  = &s->image[IMAGE_ROLE_ARGB];

  949.     ImageContext *pimg = &s->image[IMAGE_ROLE_PREDICTOR];

  950.     int x, y;

  951. 

  952.     for (y = 0; y < img->frame->height; y++) {

  953.         for (x = 0; x < img->frame->width; x++) {

  954.             int tx = x >> pimg->size_reduction;

  955.             int ty = y >> pimg->size_reduction;

  956.             enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2);

  957. 

  958.             if (x == 0) {

  959.                 if (y == 0)

  960.                     m = PRED_MODE_BLACK;

  961.                 else

  962.                     m = PRED_MODE_T;

  963.             } else if (y == 0)

  964.                 m = PRED_MODE_L;

  965. 

  966.             if (m > 13) {

  967.                 av_log(s->avctx, AV_LOG_ERROR,

  968.                        "invalid predictor mode: %d\n", m);

  969.                 return AVERROR_INVALIDDATA;

  970.             }

  971.             inverse_prediction(img->frame, m, x, y);

  972.         }

  973.     }

  974.     return 0;

  975. }

  976. 

  977. static av_always_inline uint8_t color_transform_delta(uint8_t color_pred,

  978.                                                       uint8_t color)

  979. {

  980.     return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5;

  981. }

  982. 

  983. static int apply_color_transform(WebPContext *s)

  984. {

  985.     ImageContext *img, *cimg;

  986.     int x, y, cx, cy;

  987.     uint8_t *p, *cp;

  988. 

  989.     img  = &s->image[IMAGE_ROLE_ARGB];

  990.     cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM];

  991. 

  992.     for (y = 0; y < img->frame->height; y++) {

  993.         for (x = 0; x < img->frame->width; x++) {

  994.             cx = x >> cimg->size_reduction;

  995.             cy = y >> cimg->size_reduction;

  996.             cp = GET_PIXEL(cimg->frame, cx, cy);

  997.             p  = GET_PIXEL(img->frame,   x,  y);

  998. 

  999.             p[1] += color_transform_delta(cp[3], p[2]);

  1000.             p[3] += color_transform_delta(cp[2], p[2]) +

  1001.                     color_transform_delta(cp[1], p[1]);

  1002.         }

  1003.     }

  1004.     return 0;

  1005. }

  1006. 

  1007. static int apply_subtract_green_transform(WebPContext *s)

  1008. {

  1009.     int x, y;

  1010.     ImageContext *img = &s->image[IMAGE_ROLE_ARGB];

  1011. 

  1012.     for (y = 0; y < img->frame->height; y++) {

  1013.         for (x = 0; x < img->frame->width; x++) {

  1014.             uint8_t *p = GET_PIXEL(img->frame, x, y);

  1015.             p[1] += p[2];

  1016.             p[3] += p[2];

  1017.         }

  1018.     }

  1019.     return 0;

  1020. }

  1021. 

  1022. static int apply_color_indexing_transform(WebPContext *s)

  1023. {

  1024.     ImageContext *img;

  1025.     ImageContext *pal;

  1026.     int i, x, y;

  1027.     uint8_t *p, *pi;

  1028. 

  1029.     img = &s->image[IMAGE_ROLE_ARGB];

  1030.     pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];

  1031. 

  1032.     if (pal->size_reduction > 0) {

  1033.         GetBitContext gb_g;

  1034.         uint8_t *line;

  1035.         int pixel_bits = 8 >> pal->size_reduction;

  1036. 

  1037.         line = av_malloc(img->frame->linesize[0]);

  1038.         if (!line)

  1039.             return AVERROR(ENOMEM);

  1040. 

  1041.         for (y = 0; y < img->frame->height; y++) {

  1042.             p = GET_PIXEL(img->frame, 0, y);

  1043.             memcpy(line, p, img->frame->linesize[0]);

  1044.             init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);

  1045.             skip_bits(&gb_g, 16);

  1046.             i = 0;

  1047.             for (x = 0; x < img->frame->width; x++) {

  1048.                 p    = GET_PIXEL(img->frame, x, y);

  1049.                 p[2] = get_bits(&gb_g, pixel_bits);

  1050.                 i++;

  1051.                 if (i == 1 << pal->size_reduction) {

  1052.                     skip_bits(&gb_g, 24);

  1053.                     i = 0;

  1054.                 }

  1055.             }

  1056.         }

  1057.         av_free(line);

  1058.     }

  1059. 

  1060.     for (y = 0; y < img->frame->height; y++) {

  1061.         for (x = 0; x < img->frame->width; x++) {

  1062.             p = GET_PIXEL(img->frame, x, y);

  1063.             i = p[2];

  1064.             if (i >= pal->frame->width) {

  1065.                 av_log(s->avctx, AV_LOG_ERROR, "invalid palette index %d\n", i);

  1066.                 return AVERROR_INVALIDDATA;

  1067.             }

  1068.             pi = GET_PIXEL(pal->frame, i, 0);

  1069.             AV_COPY32(p, pi);

  1070.         }

  1071.     }

  1072. 

  1073.     return 0;

  1074. }

  1075. 

  1076. static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,

  1077.                                      int *got_frame, uint8_t *data_start,

  1078.                                      unsigned int data_size, int is_alpha_chunk)

  1079. {

  1080.     WebPContext *s = avctx->priv_data;

  1081.     int w, h, ret, i;

  1082. 

  1083.     if (!is_alpha_chunk) {

  1084.         s->lossless = 1;

  1085.         avctx->pix_fmt = AV_PIX_FMT_ARGB;

  1086.     }

  1087. 

  1088.     ret = init_get_bits(&s->gb, data_start, data_size * 8);

  1089.     if (ret < 0)

  1090.         return ret;

  1091. 

  1092.     if (!is_alpha_chunk) {

  1093.         if (get_bits(&s->gb, 8) != 0x2F) {

  1094.             av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");

  1095.             return AVERROR_INVALIDDATA;

  1096.         }

  1097. 

  1098.         w = get_bits(&s->gb, 14) + 1;

  1099.         h = get_bits(&s->gb, 14) + 1;

  1100.         if (s->width && s->width != w) {

  1101.             av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",

  1102.                    s->width, w);

  1103.         }

  1104.         s->width = w;

  1105.         if (s->height && s->height != h) {

  1106.             av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",

  1107.                    s->width, w);

  1108.         }

  1109.         s->height = h;

  1110. 

  1111.         ret = ff_set_dimensions(avctx, s->width, s->height);

  1112.         if (ret < 0)

  1113.             return ret;

  1114. 

  1115.         s->has_alpha = get_bits1(&s->gb);

  1116. 

  1117.         if (get_bits(&s->gb, 3) != 0x0) {

  1118.             av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");

  1119.             return AVERROR_INVALIDDATA;

  1120.         }

  1121.     } else {

  1122.         if (!s->width || !s->height)

  1123.             return AVERROR_BUG;

  1124.         w = s->width;

  1125.         h = s->height;

  1126.     }

  1127. 

  1128.     /* parse transformations */

  1129.     s->nb_transforms = 0;

  1130.     s->reduced_width = 0;

  1131.     while (get_bits1(&s->gb)) {

  1132.         enum TransformType transform = get_bits(&s->gb, 2);

  1133.         s->transforms[s->nb_transforms++] = transform;

  1134.         switch (transform) {

  1135.         case PREDICTOR_TRANSFORM:

  1136.             ret = parse_transform_predictor(s);

  1137.             break;

  1138.         case COLOR_TRANSFORM:

  1139.             ret = parse_transform_color(s);

  1140.             break;

  1141.         case COLOR_INDEXING_TRANSFORM:

  1142.             ret = parse_transform_color_indexing(s);

  1143.             break;

  1144.         }

  1145.         if (ret < 0)

  1146.             goto free_and_return;

  1147.     }

  1148. 

  1149.     /* decode primary image */

  1150.     s->image[IMAGE_ROLE_ARGB].frame = p;

  1151.     if (is_alpha_chunk)

  1152.         s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;

  1153.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);

  1154.     if (ret < 0)

  1155.         goto free_and_return;

  1156. 

  1157.     /* apply transformations */

  1158.     for (i = s->nb_transforms - 1; i >= 0; i--) {

  1159.         switch (s->transforms[i]) {

  1160.         case PREDICTOR_TRANSFORM:

  1161.             ret = apply_predictor_transform(s);

  1162.             break;

  1163.         case COLOR_TRANSFORM:

  1164.             ret = apply_color_transform(s);

  1165.             break;

  1166.         case SUBTRACT_GREEN:

  1167.             ret = apply_subtract_green_transform(s);

  1168.             break;

  1169.         case COLOR_INDEXING_TRANSFORM:

  1170.             ret = apply_color_indexing_transform(s);

  1171.             break;

  1172.         }

  1173.         if (ret < 0)

  1174.             goto free_and_return;

  1175.     }

  1176. 

  1177.     *got_frame   = 1;

  1178.     p->pict_type = AV_PICTURE_TYPE_I;

  1179.     p->key_frame = 1;

  1180.     ret          = data_size;

  1181. 

  1182. free_and_return:

  1183.     for (i = 0; i < IMAGE_ROLE_NB; i++)

  1184.         image_ctx_free(&s->image[i]);

  1185. 

  1186.     return ret;

  1187. }

  1188. 

  1189. static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)

  1190. {

  1191.     int x, y, ls;

  1192.     uint8_t *dec;

  1193. 

  1194.     ls = frame->linesize[3];

  1195. 

  1196.     /* filter first row using horizontal filter */

  1197.     dec = frame->data[3] + 1;

  1198.     for (x = 1; x < frame->width; x++, dec++)

  1199.         *dec += *(dec - 1);

  1200. 

  1201.     /* filter first column using vertical filter */

  1202.     dec = frame->data[3] + ls;

  1203.     for (y = 1; y < frame->height; y++, dec += ls)

  1204.         *dec += *(dec - ls);

  1205. 

  1206.     /* filter the rest using the specified filter */

  1207.     switch (m) {

  1208.     case ALPHA_FILTER_HORIZONTAL:

  1209.         for (y = 1; y < frame->height; y++) {

  1210.             dec = frame->data[3] + y * ls + 1;

  1211.             for (x = 1; x < frame->width; x++, dec++)

  1212.                 *dec += *(dec - 1);

  1213.         }

  1214.         break;

  1215.     case ALPHA_FILTER_VERTICAL:

  1216.         for (y = 1; y < frame->height; y++) {

  1217.             dec = frame->data[3] + y * ls + 1;

  1218.             for (x = 1; x < frame->width; x++, dec++)

  1219.                 *dec += *(dec - ls);

  1220.         }

  1221.         break;

  1222.     case ALPHA_FILTER_GRADIENT:

  1223.         for (y = 1; y < frame->height; y++) {

  1224.             dec = frame->data[3] + y * ls + 1;

  1225.             for (x = 1; x < frame->width; x++, dec++)

  1226.                 dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));

  1227.         }

  1228.         break;

  1229.     }

  1230. }

  1231. 

  1232. static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,

  1233.                                   uint8_t *data_start,

  1234.                                   unsigned int data_size)

  1235. {

  1236.     WebPContext *s = avctx->priv_data;

  1237.     int x, y, ret;

  1238. 

  1239.     if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {

  1240.         GetByteContext gb;

  1241. 

  1242.         bytestream2_init(&gb, data_start, data_size);

  1243.         for (y = 0; y < s->height; y++)

  1244.             bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,

  1245.                                    s->width);

  1246.     } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {

  1247.         uint8_t *ap, *pp;

  1248.         int alpha_got_frame = 0;

  1249. 

  1250.         s->alpha_frame = av_frame_alloc();

  1251.         if (!s->alpha_frame)

  1252.             return AVERROR(ENOMEM);

  1253. 

  1254.         ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,

  1255.                                         data_start, data_size, 1);

  1256.         if (ret < 0) {

  1257.             av_frame_free(&s->alpha_frame);

  1258.             return ret;

  1259.         }

  1260.         if (!alpha_got_frame) {

  1261.             av_frame_free(&s->alpha_frame);

  1262.             return AVERROR_INVALIDDATA;

  1263.         }

  1264. 

  1265.         /* copy green component of alpha image to alpha plane of primary image */

  1266.         for (y = 0; y < s->height; y++) {

  1267.             ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;

  1268.             pp = p->data[3] + p->linesize[3] * y;

  1269.             for (x = 0; x < s->width; x++) {

  1270.                 *pp = *ap;

  1271.                 pp++;

  1272.                 ap += 4;

  1273.             }

  1274.         }

  1275.         av_frame_free(&s->alpha_frame);

  1276.     }

  1277. 

  1278.     /* apply alpha filtering */

  1279.     if (s->alpha_filter)

  1280.         alpha_inverse_prediction(p, s->alpha_filter);

  1281. 

  1282.     return 0;

  1283. }

  1284. 

  1285. static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,

  1286.                                   int *got_frame, uint8_t *data_start,

  1287.                                   unsigned int data_size)

  1288. {

  1289.     WebPContext *s = avctx->priv_data;

  1290.     AVPacket pkt;

  1291.     int ret;

  1292. 

  1293.     if (!s->initialized) {

  1294.         ff_vp8_decode_init(avctx);

  1295.         s->initialized = 1;

  1296.         if (s->has_alpha)

  1297.             avctx->pix_fmt = AV_PIX_FMT_YUVA420P;

  1298.     }

  1299.     s->lossless = 0;

  1300. 

  1301.     if (data_size > INT_MAX) {

  1302.         av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");

  1303.         return AVERROR_PATCHWELCOME;

  1304.     }

  1305. 

  1306.     av_init_packet(&pkt);

  1307.     pkt.data = data_start;

  1308.     pkt.size = data_size;

  1309. 

  1310.     ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);

  1311.     if (s->has_alpha) {

  1312.         ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,

  1313.                                      s->alpha_data_size);

  1314.         if (ret < 0)

  1315.             return ret;

  1316.     }

  1317.     return ret;

  1318. }

  1319. 

  1320. static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

  1321.                              AVPacket *avpkt)

  1322. {

  1323.     AVFrame * const p = data;

  1324.     WebPContext *s = avctx->priv_data;

  1325.     GetByteContext gb;

  1326.     int ret;

  1327.     uint32_t chunk_type, chunk_size;

  1328.     int vp8x_flags = 0;

  1329. 

  1330.     s->avctx     = avctx;

  1331.     s->width     = 0;

  1332.     s->height    = 0;

  1333.     *got_frame   = 0;

  1334.     s->has_alpha = 0;

  1335.     s->has_exif  = 0;

  1336.     bytestream2_init(&gb, avpkt->data, avpkt->size);

  1337. 

  1338.     if (bytestream2_get_bytes_left(&gb) < 12)

  1339.         return AVERROR_INVALIDDATA;

  1340. 

  1341.     if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {

  1342.         av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");

  1343.         return AVERROR_INVALIDDATA;

  1344.     }

  1345. 

  1346.     chunk_size = bytestream2_get_le32(&gb);

  1347.     if (bytestream2_get_bytes_left(&gb) < chunk_size)

  1348.         return AVERROR_INVALIDDATA;

  1349. 

  1350.     if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {

  1351.         av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");

  1352.         return AVERROR_INVALIDDATA;

  1353.     }

  1354. 

  1355.     av_dict_free(&s->exif_metadata);

  1356.     while (bytestream2_get_bytes_left(&gb) > 0) {

  1357.         char chunk_str[5] = { 0 };

  1358. 

  1359.         chunk_type = bytestream2_get_le32(&gb);

  1360.         chunk_size = bytestream2_get_le32(&gb);

  1361.         if (chunk_size == UINT32_MAX)

  1362.             return AVERROR_INVALIDDATA;

  1363.         chunk_size += chunk_size & 1;

  1364. 

  1365.         if (bytestream2_get_bytes_left(&gb) < chunk_size)

  1366.             return AVERROR_INVALIDDATA;

  1367. 

  1368.         switch (chunk_type) {

  1369.         case MKTAG('V', 'P', '8', ' '):

  1370.             if (!*got_frame) {

  1371.                 ret = vp8_lossy_decode_frame(avctx, p, got_frame,

  1372.                                              avpkt->data + bytestream2_tell(&gb),

  1373.                                              chunk_size);

  1374.                 if (ret < 0)

  1375.                     return ret;

  1376.             }

  1377.             bytestream2_skip(&gb, chunk_size);

  1378.             break;

  1379.         case MKTAG('V', 'P', '8', 'L'):

  1380.             if (!*got_frame) {

  1381.                 ret = vp8_lossless_decode_frame(avctx, p, got_frame,

  1382.                                                 avpkt->data + bytestream2_tell(&gb),

  1383.                                                 chunk_size, 0);

  1384.                 if (ret < 0)

  1385.                     return ret;

  1386.             }

  1387.             bytestream2_skip(&gb, chunk_size);

  1388.             break;

  1389.         case MKTAG('V', 'P', '8', 'X'):

  1390.             vp8x_flags = bytestream2_get_byte(&gb);

  1391.             bytestream2_skip(&gb, 3);

  1392.             s->width  = bytestream2_get_le24(&gb) + 1;

  1393.             s->height = bytestream2_get_le24(&gb) + 1;

  1394.             ret = av_image_check_size(s->width, s->height, 0, avctx);

  1395.             if (ret < 0)

  1396.                 return ret;

  1397.             break;

  1398.         case MKTAG('A', 'L', 'P', 'H'): {

  1399.             int alpha_header, filter_m, compression;

  1400. 

  1401.             if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {

  1402.                 av_log(avctx, AV_LOG_WARNING,

  1403.                        "ALPHA chunk present, but alpha bit not set in the "

  1404.                        "VP8X header\n");

  1405.             }

  1406.             if (chunk_size == 0) {

  1407.                 av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");

  1408.                 return AVERROR_INVALIDDATA;

  1409.             }

  1410.             alpha_header       = bytestream2_get_byte(&gb);

  1411.             s->alpha_data      = avpkt->data + bytestream2_tell(&gb);

  1412.             s->alpha_data_size = chunk_size - 1;

  1413.             bytestream2_skip(&gb, s->alpha_data_size);

  1414. 

  1415.             filter_m    = (alpha_header >> 2) & 0x03;

  1416.             compression =  alpha_header       & 0x03;

  1417. 

  1418.             if (compression > ALPHA_COMPRESSION_VP8L) {

  1419.                 av_log(avctx, AV_LOG_VERBOSE,

  1420.                        "skipping unsupported ALPHA chunk\n");

  1421.             } else {

  1422.                 s->has_alpha         = 1;

  1423.                 s->alpha_compression = compression;

  1424.                 s->alpha_filter      = filter_m;

  1425.             }

  1426. 

  1427.             break;

  1428.         }

  1429.         case MKTAG('E', 'X', 'I', 'F'): {

  1430.             int le, ifd_offset, exif_offset = bytestream2_tell(&gb);

  1431.             GetByteContext exif_gb;

  1432. 

  1433.             if (s->has_exif) {

  1434.                 av_log(avctx, AV_LOG_VERBOSE, "Ignoring extra EXIF chunk\n");

  1435.                 goto exif_end;

  1436.             }

  1437.             if (!(vp8x_flags & VP8X_FLAG_EXIF_METADATA))

  1438.                 av_log(avctx, AV_LOG_WARNING,

  1439.                        "EXIF chunk present, but Exif bit not set in the "

  1440.                        "VP8X header\n");

  1441. 

  1442.             s->has_exif = 1;

  1443.             bytestream2_init(&exif_gb, avpkt->data + exif_offset,

  1444.                              avpkt->size - exif_offset);

  1445.             if (ff_tdecode_header(&exif_gb, &le, &ifd_offset) < 0) {

  1446.                 av_log(avctx, AV_LOG_ERROR, "invalid TIFF header "

  1447.                        "in Exif data\n");

  1448.                 goto exif_end;

  1449.             }

  1450. 

  1451.             bytestream2_seek(&exif_gb, ifd_offset, SEEK_SET);

  1452.             if (avpriv_exif_decode_ifd(avctx, &exif_gb, le, 0, &s->exif_metadata) < 0) {

  1453.                 av_log(avctx, AV_LOG_ERROR, "error decoding Exif data\n");

  1454.                 goto exif_end;

  1455.             }

  1456. 

  1457.             av_dict_copy(avpriv_frame_get_metadatap(data), s->exif_metadata, 0);

  1458. 

  1459. exif_end:

  1460.             av_dict_free(&s->exif_metadata);

  1461.             bytestream2_skip(&gb, chunk_size);

  1462.             break;

  1463.         }

  1464.         case MKTAG('I', 'C', 'C', 'P'):

  1465.         case MKTAG('A', 'N', 'I', 'M'):

  1466.         case MKTAG('A', 'N', 'M', 'F'):

  1467.         case MKTAG('X', 'M', 'P', ' '):

  1468.             AV_WL32(chunk_str, chunk_type);

  1469.             av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",

  1470.                    chunk_str);

  1471.             bytestream2_skip(&gb, chunk_size);

  1472.             break;

  1473.         default:

  1474.             AV_WL32(chunk_str, chunk_type);

  1475.             av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",

  1476.                    chunk_str);

  1477.             bytestream2_skip(&gb, chunk_size);

  1478.             break;

  1479.         }

  1480.     }

  1481. 

  1482.     if (!*got_frame) {

  1483.         av_log(avctx, AV_LOG_ERROR, "image data not found\n");

  1484.         return AVERROR_INVALIDDATA;

  1485.     }

  1486. 

  1487.     return avpkt->size;

  1488. }

  1489. 

  1490. static av_cold int webp_decode_close(AVCodecContext *avctx)

  1491. {

  1492.     WebPContext *s = avctx->priv_data;

  1493. 

  1494.     if (s->initialized)

  1495.         return ff_vp8_decode_free(avctx);

  1496. 

  1497.     return 0;

  1498. }

  1499. 

  1500. AVCodec ff_webp_decoder = {

  1501.     .name           = "webp",

  1502.     .long_name      = NULL_IF_CONFIG_SMALL("WebP image"),

  1503.     .type           = AVMEDIA_TYPE_VIDEO,

  1504.     .id             = AV_CODEC_ID_WEBP,

  1505.     .priv_data_size = sizeof(WebPContext),

  1506.     .decode         = webp_decode_frame,

  1507.     .close          = webp_decode_close,

  1508.     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,

  1509. };