falkTX
/
FFmpeg
mirror of https://github.com/falkTX/FFmpeg.git
1
0
Fork 0
Code Issues 0 Releases 338 Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
74465 Commits
32 Branches
290MB
Tree: 1907e19d0c
Branches Tags
${ item.name }
Create branch ${ searchTerm }
from '1907e19d0c'
${ noResults }
FFmpeg/libavcodec/webp.c

1545 lines
50KB
Raw Blame History 

  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 p0 = GET_PIXEL_COMP(img->frame, x, y, 1);

  486.             int p1 = GET_PIXEL_COMP(img->frame, x, y, 2);

  487.             int p  = p0 << 8 | p1;

  488.             max = FFMAX(max, p);

  489.         }

  490.     }

  491.     s->nb_huffman_groups = max + 1;

  492. 

  493.     return 0;

  494. }

  495. 

  496. static int parse_transform_predictor(WebPContext *s)

  497. {

  498.     int block_bits, blocks_w, blocks_h, ret;

  499. 

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

  501. 

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

  503.                                      blocks_h);

  504.     if (ret < 0)

  505.         return ret;

  506. 

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

  508. 

  509.     return 0;

  510. }

  511. 

  512. static int parse_transform_color(WebPContext *s)

  513. {

  514.     int block_bits, blocks_w, blocks_h, ret;

  515. 

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

  517. 

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

  519.                                      blocks_h);

  520.     if (ret < 0)

  521.         return ret;

  522. 

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

  524. 

  525.     return 0;

  526. }

  527. 

  528. static int parse_transform_color_indexing(WebPContext *s)

  529. {

  530.     ImageContext *img;

  531.     int width_bits, index_size, ret, x;

  532.     uint8_t *ct;

  533. 

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

  535. 

  536.     if (index_size <= 2)

  537.         width_bits = 3;

  538.     else if (index_size <= 4)

  539.         width_bits = 2;

  540.     else if (index_size <= 16)

  541.         width_bits = 1;

  542.     else

  543.         width_bits = 0;

  544. 

  545.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING,

  546.                                      index_size, 1);

  547.     if (ret < 0)

  548.         return ret;

  549. 

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

  551.     img->size_reduction = width_bits;

  552.     if (width_bits > 0)

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

  554. 

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

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

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

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

  559. 

  560.     return 0;

  561. }

  562. 

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

  564.                                      int x, int y)

  565. {

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

  567.     int group = 0;

  568. 

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

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

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

  572.         int g0      = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 1);

  573.         int g1      = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);

  574.         group       = g0 << 8 | g1;

  575.     }

  576. 

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

  578. }

  579. 

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

  581. {

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

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

  584. }

  585. 

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

  587.                                       int w, int h)

  588. {

  589.     ImageContext *img;

  590.     HuffReader *hg;

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

  592. 

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

  594.     img->role = role;

  595. 

  596.     if (!img->frame) {

  597.         img->frame = av_frame_alloc();

  598.         if (!img->frame)

  599.             return AVERROR(ENOMEM);

  600.     }

  601. 

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

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

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

  605. 

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

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

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

  609.     } else

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

  611.     if (ret < 0)

  612.         return ret;

  613. 

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

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

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

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

  618.                    img->color_cache_bits);

  619.             return AVERROR_INVALIDDATA;

  620.         }

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

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

  623.         if (!img->color_cache)

  624.             return AVERROR(ENOMEM);

  625.     } else {

  626.         img->color_cache_bits = 0;

  627.     }

  628. 

  629.     img->nb_huffman_groups = 1;

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

  631.         ret = decode_entropy_image(s);

  632.         if (ret < 0)

  633.             return ret;

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

  635.     }

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

  637.                                            HUFFMAN_CODES_PER_META_CODE,

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

  639.     if (!img->huffman_groups)

  640.         return AVERROR(ENOMEM);

  641. 

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

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

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

  645.             int alphabet_size = alphabet_sizes[j];

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

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

  648. 

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

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

  651.             } else {

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

  653.                 if (ret < 0)

  654.                     return ret;

  655.             }

  656.         }

  657.     }

  658. 

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

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

  661.         width = s->reduced_width;

  662. 

  663.     x = 0; y = 0;

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

  665.         int v;

  666. 

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

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

  669.         if (v < NUM_LITERAL_CODES) {

  670.             /* literal pixel values */

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

  672.             p[2] = v;

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

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

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

  676.             if (img->color_cache_bits)

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

  678.             x++;

  679.             if (x == width) {

  680.                 x = 0;

  681.                 y++;

  682.             }

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

  684.             /* LZ77 backwards mapping */

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

  686. 

  687.             /* parse length and distance */

  688.             prefix_code = v - NUM_LITERAL_CODES;

  689.             if (prefix_code < 4) {

  690.                 length = prefix_code + 1;

  691.             } else {

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

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

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

  695.             }

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

  697.             if (prefix_code > 39) {

  698.                 av_log(s->avctx, AV_LOG_ERROR,

  699.                        "distance prefix code too large: %d\n", prefix_code);

  700.                 return AVERROR_INVALIDDATA;

  701.             }

  702.             if (prefix_code < 4) {

  703.                 distance = prefix_code + 1;

  704.             } else {

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

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

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

  708.             }

  709. 

  710.             /* find reference location */

  711.             if (distance <= NUM_SHORT_DISTANCES) {

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

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

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

  715.             } else {

  716.                 distance -= NUM_SHORT_DISTANCES;

  717.             }

  718.             ref_x = x;

  719.             ref_y = y;

  720.             if (distance <= x) {

  721.                 ref_x -= distance;

  722.                 distance = 0;

  723.             } else {

  724.                 ref_x = 0;

  725.                 distance -= x;

  726.             }

  727.             while (distance >= width) {

  728.                 ref_y--;

  729.                 distance -= width;

  730.             }

  731.             if (distance > 0) {

  732.                 ref_x = width - distance;

  733.                 ref_y--;

  734.             }

  735.             ref_x = FFMAX(0, ref_x);

  736.             ref_y = FFMAX(0, ref_y);

  737. 

  738.             /* copy pixels

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

  740.              * copy per-pixel */

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

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

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

  744. 

  745.                 AV_COPY32(p, p_ref);

  746.                 if (img->color_cache_bits)

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

  748.                 x++;

  749.                 ref_x++;

  750.                 if (x == width) {

  751.                     x = 0;

  752.                     y++;

  753.                 }

  754.                 if (ref_x == width) {

  755.                     ref_x = 0;

  756.                     ref_y++;

  757.                 }

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

  759.                     break;

  760.             }

  761.         } else {

  762.             /* read from color cache */

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

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

  765. 

  766.             if (!img->color_cache_bits) {

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

  768.                 return AVERROR_INVALIDDATA;

  769.             }

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

  771.                 av_log(s->avctx, AV_LOG_ERROR,

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

  773.                 return AVERROR_INVALIDDATA;

  774.             }

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

  776.             x++;

  777.             if (x == width) {

  778.                 x = 0;

  779.                 y++;

  780.             }

  781.         }

  782.     }

  783. 

  784.     return 0;

  785. }

  786. 

  787. /* PRED_MODE_BLACK */

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

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

  790. {

  791.     AV_WB32(p, 0xFF000000);

  792. }

  793. 

  794. /* PRED_MODE_L */

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

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

  797. {

  798.     AV_COPY32(p, p_l);

  799. }

  800. 

  801. /* PRED_MODE_T */

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

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

  804. {

  805.     AV_COPY32(p, p_t);

  806. }

  807. 

  808. /* PRED_MODE_TR */

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

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

  811. {

  812.     AV_COPY32(p, p_tr);

  813. }

  814. 

  815. /* PRED_MODE_TL */

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

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

  818. {

  819.     AV_COPY32(p, p_tl);

  820. }

  821. 

  822. /* PRED_MODE_AVG_T_AVG_L_TR */

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

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

  825. {

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

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

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

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

  830. }

  831. 

  832. /* PRED_MODE_AVG_L_TL */

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

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

  835. {

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

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

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

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

  840. }

  841. 

  842. /* PRED_MODE_AVG_L_T */

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

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

  845. {

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

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

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

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

  850. }

  851. 

  852. /* PRED_MODE_AVG_TL_T */

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

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

  855. {

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

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

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

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

  860. }

  861. 

  862. /* PRED_MODE_AVG_T_TR */

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

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

  865. {

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

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

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

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

  870. }

  871. 

  872. /* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */

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

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

  875. {

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

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

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

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

  880. }

  881. 

  882. /* PRED_MODE_SELECT */

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

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

  885. {

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

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

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

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

  890.     if (diff <= 0)

  891.         AV_COPY32(p, p_t);

  892.     else

  893.         AV_COPY32(p, p_l);

  894. }

  895. 

  896. /* PRED_MODE_ADD_SUBTRACT_FULL */

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

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

  899. {

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

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

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

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

  904. }

  905. 

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

  907. {

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

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

  910. }

  911. 

  912. /* PRED_MODE_ADD_SUBTRACT_HALF */

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

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

  915. {

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

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

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

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

  920. }

  921. 

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

  923.                                  const uint8_t *p_tl, const uint8_t *p_t,

  924.                                  const uint8_t *p_tr);

  925. 

  926. static const inv_predict_func inverse_predict[14] = {

  927.     inv_predict_0,  inv_predict_1,  inv_predict_2,  inv_predict_3,

  928.     inv_predict_4,  inv_predict_5,  inv_predict_6,  inv_predict_7,

  929.     inv_predict_8,  inv_predict_9,  inv_predict_10, inv_predict_11,

  930.     inv_predict_12, inv_predict_13,

  931. };

  932. 

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

  934. {

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

  936.     uint8_t p[4];

  937. 

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

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

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

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

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

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

  944.     else

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

  946. 

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

  948. 

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

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

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

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

  953. }

  954. 

  955. static int apply_predictor_transform(WebPContext *s)

  956. {

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

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

  959.     int x, y;

  960. 

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

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

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

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

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

  966. 

  967.             if (x == 0) {

  968.                 if (y == 0)

  969.                     m = PRED_MODE_BLACK;

  970.                 else

  971.                     m = PRED_MODE_T;

  972.             } else if (y == 0)

  973.                 m = PRED_MODE_L;

  974. 

  975.             if (m > 13) {

  976.                 av_log(s->avctx, AV_LOG_ERROR,

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

  978.                 return AVERROR_INVALIDDATA;

  979.             }

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

  981.         }

  982.     }

  983.     return 0;

  984. }

  985. 

  986. static av_always_inline uint8_t color_transform_delta(uint8_t color_pred,

  987.                                                       uint8_t color)

  988. {

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

  990. }

  991. 

  992. static int apply_color_transform(WebPContext *s)

  993. {

  994.     ImageContext *img, *cimg;

  995.     int x, y, cx, cy;

  996.     uint8_t *p, *cp;

  997. 

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

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

  1000. 

  1001.     for (y = 0; y < img->frame->height; y++) {

  1002.         for (x = 0; x < img->frame->width; x++) {

  1003.             cx = x >> cimg->size_reduction;

  1004.             cy = y >> cimg->size_reduction;

  1005.             cp = GET_PIXEL(cimg->frame, cx, cy);

  1006.             p  = GET_PIXEL(img->frame,   x,  y);

  1007. 

  1008.             p[1] += color_transform_delta(cp[3], p[2]);

  1009.             p[3] += color_transform_delta(cp[2], p[2]) +

  1010.                     color_transform_delta(cp[1], p[1]);

  1011.         }

  1012.     }

  1013.     return 0;

  1014. }

  1015. 

  1016. static int apply_subtract_green_transform(WebPContext *s)

  1017. {

  1018.     int x, y;

  1019.     ImageContext *img = &s->image[IMAGE_ROLE_ARGB];

  1020. 

  1021.     for (y = 0; y < img->frame->height; y++) {

  1022.         for (x = 0; x < img->frame->width; x++) {

  1023.             uint8_t *p = GET_PIXEL(img->frame, x, y);

  1024.             p[1] += p[2];

  1025.             p[3] += p[2];

  1026.         }

  1027.     }

  1028.     return 0;

  1029. }

  1030. 

  1031. static int apply_color_indexing_transform(WebPContext *s)

  1032. {

  1033.     ImageContext *img;

  1034.     ImageContext *pal;

  1035.     int i, x, y;

  1036.     uint8_t *p;

  1037. 

  1038.     img = &s->image[IMAGE_ROLE_ARGB];

  1039.     pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];

  1040. 

  1041.     if (pal->size_reduction > 0) {

  1042.         GetBitContext gb_g;

  1043.         uint8_t *line;

  1044.         int pixel_bits = 8 >> pal->size_reduction;

  1045. 

  1046.         line = av_malloc(img->frame->linesize[0]);

  1047.         if (!line)

  1048.             return AVERROR(ENOMEM);

  1049. 

  1050.         for (y = 0; y < img->frame->height; y++) {

  1051.             p = GET_PIXEL(img->frame, 0, y);

  1052.             memcpy(line, p, img->frame->linesize[0]);

  1053.             init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);

  1054.             skip_bits(&gb_g, 16);

  1055.             i = 0;

  1056.             for (x = 0; x < img->frame->width; x++) {

  1057.                 p    = GET_PIXEL(img->frame, x, y);

  1058.                 p[2] = get_bits(&gb_g, pixel_bits);

  1059.                 i++;

  1060.                 if (i == 1 << pal->size_reduction) {

  1061.                     skip_bits(&gb_g, 24);

  1062.                     i = 0;

  1063.                 }

  1064.             }

  1065.         }

  1066.         av_free(line);

  1067.     }

  1068. 

  1069.     // switch to local palette if it's worth initializing it

  1070.     if (img->frame->height * img->frame->width > 300) {

  1071.         uint8_t palette[256 * 4];

  1072.         const int size = pal->frame->width * 4;

  1073.         av_assert0(size <= 1024U);

  1074.         memcpy(palette, GET_PIXEL(pal->frame, 0, 0), size);   // copy palette

  1075.         // set extra entries to transparent black

  1076.         memset(palette + size, 0, 256 * 4 - size);

  1077.         for (y = 0; y < img->frame->height; y++) {

  1078.             for (x = 0; x < img->frame->width; x++) {

  1079.                 p = GET_PIXEL(img->frame, x, y);

  1080.                 i = p[2];

  1081.                 AV_COPY32(p, &palette[i * 4]);

  1082.             }

  1083.         }

  1084.     } else {

  1085.         for (y = 0; y < img->frame->height; y++) {

  1086.             for (x = 0; x < img->frame->width; x++) {

  1087.                 p = GET_PIXEL(img->frame, x, y);

  1088.                 i = p[2];

  1089.                 if (i >= pal->frame->width) {

  1090.                     AV_WB32(p, 0x00000000);

  1091.                 } else {

  1092.                     const uint8_t *pi = GET_PIXEL(pal->frame, i, 0);

  1093.                     AV_COPY32(p, pi);

  1094.                 }

  1095.             }

  1096.         }

  1097.     }

  1098. 

  1099.     return 0;

  1100. }

  1101. 

  1102. static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,

  1103.                                      int *got_frame, uint8_t *data_start,

  1104.                                      unsigned int data_size, int is_alpha_chunk)

  1105. {

  1106.     WebPContext *s = avctx->priv_data;

  1107.     int w, h, ret, i, used;

  1108. 

  1109.     if (!is_alpha_chunk) {

  1110.         s->lossless = 1;

  1111.         avctx->pix_fmt = AV_PIX_FMT_ARGB;

  1112.     }

  1113. 

  1114.     ret = init_get_bits8(&s->gb, data_start, data_size);

  1115.     if (ret < 0)

  1116.         return ret;

  1117. 

  1118.     if (!is_alpha_chunk) {

  1119.         if (get_bits(&s->gb, 8) != 0x2F) {

  1120.             av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");

  1121.             return AVERROR_INVALIDDATA;

  1122.         }

  1123. 

  1124.         w = get_bits(&s->gb, 14) + 1;

  1125.         h = get_bits(&s->gb, 14) + 1;

  1126.         if (s->width && s->width != w) {

  1127.             av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",

  1128.                    s->width, w);

  1129.         }

  1130.         s->width = w;

  1131.         if (s->height && s->height != h) {

  1132.             av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",

  1133.                    s->width, w);

  1134.         }

  1135.         s->height = h;

  1136. 

  1137.         ret = ff_set_dimensions(avctx, s->width, s->height);

  1138.         if (ret < 0)

  1139.             return ret;

  1140. 

  1141.         s->has_alpha = get_bits1(&s->gb);

  1142. 

  1143.         if (get_bits(&s->gb, 3) != 0x0) {

  1144.             av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");

  1145.             return AVERROR_INVALIDDATA;

  1146.         }

  1147.     } else {

  1148.         if (!s->width || !s->height)

  1149.             return AVERROR_BUG;

  1150.         w = s->width;

  1151.         h = s->height;

  1152.     }

  1153. 

  1154.     /* parse transformations */

  1155.     s->nb_transforms = 0;

  1156.     s->reduced_width = 0;

  1157.     used = 0;

  1158.     while (get_bits1(&s->gb)) {

  1159.         enum TransformType transform = get_bits(&s->gb, 2);

  1160.         if (used & (1 << transform)) {

  1161.             av_log(avctx, AV_LOG_ERROR, "Transform %d used more than once\n",

  1162.                    transform);

  1163.             ret = AVERROR_INVALIDDATA;

  1164.             goto free_and_return;

  1165.         }

  1166.         used |= (1 << transform);

  1167.         s->transforms[s->nb_transforms++] = transform;

  1168.         switch (transform) {

  1169.         case PREDICTOR_TRANSFORM:

  1170.             ret = parse_transform_predictor(s);

  1171.             break;

  1172.         case COLOR_TRANSFORM:

  1173.             ret = parse_transform_color(s);

  1174.             break;

  1175.         case COLOR_INDEXING_TRANSFORM:

  1176.             ret = parse_transform_color_indexing(s);

  1177.             break;

  1178.         }

  1179.         if (ret < 0)

  1180.             goto free_and_return;

  1181.     }

  1182. 

  1183.     /* decode primary image */

  1184.     s->image[IMAGE_ROLE_ARGB].frame = p;

  1185.     if (is_alpha_chunk)

  1186.         s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;

  1187.     ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);

  1188.     if (ret < 0)

  1189.         goto free_and_return;

  1190. 

  1191.     /* apply transformations */

  1192.     for (i = s->nb_transforms - 1; i >= 0; i--) {

  1193.         switch (s->transforms[i]) {

  1194.         case PREDICTOR_TRANSFORM:

  1195.             ret = apply_predictor_transform(s);

  1196.             break;

  1197.         case COLOR_TRANSFORM:

  1198.             ret = apply_color_transform(s);

  1199.             break;

  1200.         case SUBTRACT_GREEN:

  1201.             ret = apply_subtract_green_transform(s);

  1202.             break;

  1203.         case COLOR_INDEXING_TRANSFORM:

  1204.             ret = apply_color_indexing_transform(s);

  1205.             break;

  1206.         }

  1207.         if (ret < 0)

  1208.             goto free_and_return;

  1209.     }

  1210. 

  1211.     *got_frame   = 1;

  1212.     p->pict_type = AV_PICTURE_TYPE_I;

  1213.     p->key_frame = 1;

  1214.     ret          = data_size;

  1215. 

  1216. free_and_return:

  1217.     for (i = 0; i < IMAGE_ROLE_NB; i++)

  1218.         image_ctx_free(&s->image[i]);

  1219. 

  1220.     return ret;

  1221. }

  1222. 

  1223. static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)

  1224. {

  1225.     int x, y, ls;

  1226.     uint8_t *dec;

  1227. 

  1228.     ls = frame->linesize[3];

  1229. 

  1230.     /* filter first row using horizontal filter */

  1231.     dec = frame->data[3] + 1;

  1232.     for (x = 1; x < frame->width; x++, dec++)

  1233.         *dec += *(dec - 1);

  1234. 

  1235.     /* filter first column using vertical filter */

  1236.     dec = frame->data[3] + ls;

  1237.     for (y = 1; y < frame->height; y++, dec += ls)

  1238.         *dec += *(dec - ls);

  1239. 

  1240.     /* filter the rest using the specified filter */

  1241.     switch (m) {

  1242.     case ALPHA_FILTER_HORIZONTAL:

  1243.         for (y = 1; y < frame->height; y++) {

  1244.             dec = frame->data[3] + y * ls + 1;

  1245.             for (x = 1; x < frame->width; x++, dec++)

  1246.                 *dec += *(dec - 1);

  1247.         }

  1248.         break;

  1249.     case ALPHA_FILTER_VERTICAL:

  1250.         for (y = 1; y < frame->height; y++) {

  1251.             dec = frame->data[3] + y * ls + 1;

  1252.             for (x = 1; x < frame->width; x++, dec++)

  1253.                 *dec += *(dec - ls);

  1254.         }

  1255.         break;

  1256.     case ALPHA_FILTER_GRADIENT:

  1257.         for (y = 1; y < frame->height; y++) {

  1258.             dec = frame->data[3] + y * ls + 1;

  1259.             for (x = 1; x < frame->width; x++, dec++)

  1260.                 dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));

  1261.         }

  1262.         break;

  1263.     }

  1264. }

  1265. 

  1266. static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,

  1267.                                   uint8_t *data_start,

  1268.                                   unsigned int data_size)

  1269. {

  1270.     WebPContext *s = avctx->priv_data;

  1271.     int x, y, ret;

  1272. 

  1273.     if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {

  1274.         GetByteContext gb;

  1275. 

  1276.         bytestream2_init(&gb, data_start, data_size);

  1277.         for (y = 0; y < s->height; y++)

  1278.             bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,

  1279.                                    s->width);

  1280.     } else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {

  1281.         uint8_t *ap, *pp;

  1282.         int alpha_got_frame = 0;

  1283. 

  1284.         s->alpha_frame = av_frame_alloc();

  1285.         if (!s->alpha_frame)

  1286.             return AVERROR(ENOMEM);

  1287. 

  1288.         ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,

  1289.                                         data_start, data_size, 1);

  1290.         if (ret < 0) {

  1291.             av_frame_free(&s->alpha_frame);

  1292.             return ret;

  1293.         }

  1294.         if (!alpha_got_frame) {

  1295.             av_frame_free(&s->alpha_frame);

  1296.             return AVERROR_INVALIDDATA;

  1297.         }

  1298. 

  1299.         /* copy green component of alpha image to alpha plane of primary image */

  1300.         for (y = 0; y < s->height; y++) {

  1301.             ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;

  1302.             pp = p->data[3] + p->linesize[3] * y;

  1303.             for (x = 0; x < s->width; x++) {

  1304.                 *pp = *ap;

  1305.                 pp++;

  1306.                 ap += 4;

  1307.             }

  1308.         }

  1309.         av_frame_free(&s->alpha_frame);

  1310.     }

  1311. 

  1312.     /* apply alpha filtering */

  1313.     if (s->alpha_filter)

  1314.         alpha_inverse_prediction(p, s->alpha_filter);

  1315. 

  1316.     return 0;

  1317. }

  1318. 

  1319. static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,

  1320.                                   int *got_frame, uint8_t *data_start,

  1321.                                   unsigned int data_size)

  1322. {

  1323.     WebPContext *s = avctx->priv_data;

  1324.     AVPacket pkt;

  1325.     int ret;

  1326. 

  1327.     if (!s->initialized) {

  1328.         ff_vp8_decode_init(avctx);

  1329.         s->initialized = 1;

  1330.         if (s->has_alpha)

  1331.             avctx->pix_fmt = AV_PIX_FMT_YUVA420P;

  1332.     }

  1333.     s->lossless = 0;

  1334. 

  1335.     if (data_size > INT_MAX) {

  1336.         av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");

  1337.         return AVERROR_PATCHWELCOME;

  1338.     }

  1339. 

  1340.     av_init_packet(&pkt);

  1341.     pkt.data = data_start;

  1342.     pkt.size = data_size;

  1343. 

  1344.     ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);

  1345.     if (s->has_alpha) {

  1346.         ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,

  1347.                                      s->alpha_data_size);

  1348.         if (ret < 0)

  1349.             return ret;

  1350.     }

  1351.     return ret;

  1352. }

  1353. 

  1354. static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,

  1355.                              AVPacket *avpkt)

  1356. {

  1357.     AVFrame * const p = data;

  1358.     WebPContext *s = avctx->priv_data;

  1359.     GetByteContext gb;

  1360.     int ret;

  1361.     uint32_t chunk_type, chunk_size;

  1362.     int vp8x_flags = 0;

  1363. 

  1364.     s->avctx     = avctx;

  1365.     s->width     = 0;

  1366.     s->height    = 0;

  1367.     *got_frame   = 0;

  1368.     s->has_alpha = 0;

  1369.     s->has_exif  = 0;

  1370.     bytestream2_init(&gb, avpkt->data, avpkt->size);

  1371. 

  1372.     if (bytestream2_get_bytes_left(&gb) < 12)

  1373.         return AVERROR_INVALIDDATA;

  1374. 

  1375.     if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {

  1376.         av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");

  1377.         return AVERROR_INVALIDDATA;

  1378.     }

  1379. 

  1380.     chunk_size = bytestream2_get_le32(&gb);

  1381.     if (bytestream2_get_bytes_left(&gb) < chunk_size)

  1382.         return AVERROR_INVALIDDATA;

  1383. 

  1384.     if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {

  1385.         av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");

  1386.         return AVERROR_INVALIDDATA;

  1387.     }

  1388. 

  1389.     av_dict_free(&s->exif_metadata);

  1390.     while (bytestream2_get_bytes_left(&gb) > 8) {

  1391.         char chunk_str[5] = { 0 };

  1392. 

  1393.         chunk_type = bytestream2_get_le32(&gb);

  1394.         chunk_size = bytestream2_get_le32(&gb);

  1395.         if (chunk_size == UINT32_MAX)

  1396.             return AVERROR_INVALIDDATA;

  1397.         chunk_size += chunk_size & 1;

  1398. 

  1399.         if (bytestream2_get_bytes_left(&gb) < chunk_size)

  1400.             return AVERROR_INVALIDDATA;

  1401. 

  1402.         switch (chunk_type) {

  1403.         case MKTAG('V', 'P', '8', ' '):

  1404.             if (!*got_frame) {

  1405.                 ret = vp8_lossy_decode_frame(avctx, p, got_frame,

  1406.                                              avpkt->data + bytestream2_tell(&gb),

  1407.                                              chunk_size);

  1408.                 if (ret < 0)

  1409.                     return ret;

  1410.             }

  1411.             bytestream2_skip(&gb, chunk_size);

  1412.             break;

  1413.         case MKTAG('V', 'P', '8', 'L'):

  1414.             if (!*got_frame) {

  1415.                 ret = vp8_lossless_decode_frame(avctx, p, got_frame,

  1416.                                                 avpkt->data + bytestream2_tell(&gb),

  1417.                                                 chunk_size, 0);

  1418.                 if (ret < 0)

  1419.                     return ret;

  1420.                 avctx->properties |= FF_CODEC_PROPERTY_LOSSLESS;

  1421.             }

  1422.             bytestream2_skip(&gb, chunk_size);

  1423.             break;

  1424.         case MKTAG('V', 'P', '8', 'X'):

  1425.             vp8x_flags = bytestream2_get_byte(&gb);

  1426.             bytestream2_skip(&gb, 3);

  1427.             s->width  = bytestream2_get_le24(&gb) + 1;

  1428.             s->height = bytestream2_get_le24(&gb) + 1;

  1429.             ret = av_image_check_size(s->width, s->height, 0, avctx);

  1430.             if (ret < 0)

  1431.                 return ret;

  1432.             break;

  1433.         case MKTAG('A', 'L', 'P', 'H'): {

  1434.             int alpha_header, filter_m, compression;

  1435. 

  1436.             if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {

  1437.                 av_log(avctx, AV_LOG_WARNING,

  1438.                        "ALPHA chunk present, but alpha bit not set in the "

  1439.                        "VP8X header\n");

  1440.             }

  1441.             if (chunk_size == 0) {

  1442.                 av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");

  1443.                 return AVERROR_INVALIDDATA;

  1444.             }

  1445.             alpha_header       = bytestream2_get_byte(&gb);

  1446.             s->alpha_data      = avpkt->data + bytestream2_tell(&gb);

  1447.             s->alpha_data_size = chunk_size - 1;

  1448.             bytestream2_skip(&gb, s->alpha_data_size);

  1449. 

  1450.             filter_m    = (alpha_header >> 2) & 0x03;

  1451.             compression =  alpha_header       & 0x03;

  1452. 

  1453.             if (compression > ALPHA_COMPRESSION_VP8L) {

  1454.                 av_log(avctx, AV_LOG_VERBOSE,

  1455.                        "skipping unsupported ALPHA chunk\n");

  1456.             } else {

  1457.                 s->has_alpha         = 1;

  1458.                 s->alpha_compression = compression;

  1459.                 s->alpha_filter      = filter_m;

  1460.             }

  1461. 

  1462.             break;

  1463.         }

  1464.         case MKTAG('E', 'X', 'I', 'F'): {

  1465.             int le, ifd_offset, exif_offset = bytestream2_tell(&gb);

  1466.             GetByteContext exif_gb;

  1467. 

  1468.             if (s->has_exif) {

  1469.                 av_log(avctx, AV_LOG_VERBOSE, "Ignoring extra EXIF chunk\n");

  1470.                 goto exif_end;

  1471.             }

  1472.             if (!(vp8x_flags & VP8X_FLAG_EXIF_METADATA))

  1473.                 av_log(avctx, AV_LOG_WARNING,

  1474.                        "EXIF chunk present, but Exif bit not set in the "

  1475.                        "VP8X header\n");

  1476. 

  1477.             s->has_exif = 1;

  1478.             bytestream2_init(&exif_gb, avpkt->data + exif_offset,

  1479.                              avpkt->size - exif_offset);

  1480.             if (ff_tdecode_header(&exif_gb, &le, &ifd_offset) < 0) {

  1481.                 av_log(avctx, AV_LOG_ERROR, "invalid TIFF header "

  1482.                        "in Exif data\n");

  1483.                 goto exif_end;

  1484.             }

  1485. 

  1486.             bytestream2_seek(&exif_gb, ifd_offset, SEEK_SET);

  1487.             if (avpriv_exif_decode_ifd(avctx, &exif_gb, le, 0, &s->exif_metadata) < 0) {

  1488.                 av_log(avctx, AV_LOG_ERROR, "error decoding Exif data\n");

  1489.                 goto exif_end;

  1490.             }

  1491. 

  1492.             av_dict_copy(avpriv_frame_get_metadatap(data), s->exif_metadata, 0);

  1493. 

  1494. exif_end:

  1495.             av_dict_free(&s->exif_metadata);

  1496.             bytestream2_skip(&gb, chunk_size);

  1497.             break;

  1498.         }

  1499.         case MKTAG('I', 'C', 'C', 'P'):

  1500.         case MKTAG('A', 'N', 'I', 'M'):

  1501.         case MKTAG('A', 'N', 'M', 'F'):

  1502.         case MKTAG('X', 'M', 'P', ' '):

  1503.             AV_WL32(chunk_str, chunk_type);

  1504.             av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",

  1505.                    chunk_str);

  1506.             bytestream2_skip(&gb, chunk_size);

  1507.             break;

  1508.         default:

  1509.             AV_WL32(chunk_str, chunk_type);

  1510.             av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",

  1511.                    chunk_str);

  1512.             bytestream2_skip(&gb, chunk_size);

  1513.             break;

  1514.         }

  1515.     }

  1516. 

  1517.     if (!*got_frame) {

  1518.         av_log(avctx, AV_LOG_ERROR, "image data not found\n");

  1519.         return AVERROR_INVALIDDATA;

  1520.     }

  1521. 

  1522.     return avpkt->size;

  1523. }

  1524. 

  1525. static av_cold int webp_decode_close(AVCodecContext *avctx)

  1526. {

  1527.     WebPContext *s = avctx->priv_data;

  1528. 

  1529.     if (s->initialized)

  1530.         return ff_vp8_decode_free(avctx);

  1531. 

  1532.     return 0;

  1533. }

  1534. 

  1535. AVCodec ff_webp_decoder = {

  1536.     .name           = "webp",

  1537.     .long_name      = NULL_IF_CONFIG_SMALL("WebP image"),

  1538.     .type           = AVMEDIA_TYPE_VIDEO,

  1539.     .id             = AV_CODEC_ID_WEBP,

  1540.     .priv_data_size = sizeof(WebPContext),

  1541.     .decode         = webp_decode_frame,

  1542.     .close          = webp_decode_close,

  1543.     .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,

  1544. };