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third_party_ffmpeg/libavcodec/webp.c
Justin Ruggles d085f80fa1 webp: add a special case for a huffman table with only 1 symbol 
The vlc reader cannot handle 0-bit huffman codes. For most
situations WebP uses the "simple" huffman coding for this case,
but that will only handle symbols up to 255. For the LZ77 distance
codes, larger symbol values are needed, so it can happen in rare
cases that a normal huffman table is used that only has a single
symbol.
2013-12-05 20:37:06 -05:00

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/*
* WebP (.webp) image decoder
* Copyright (c) 2013 Aneesh Dogra <aneesh@sugarlabs.org>
* Copyright (c) 2013 Justin Ruggles <justin.ruggles@gmail.com>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* WebP image decoder
*
* @author Aneesh Dogra <aneesh@sugarlabs.org>
* Container and Lossy decoding
*
* @author Justin Ruggles <justin.ruggles@gmail.com>
* Lossless decoder
* Compressed alpha for lossy
*
* Unimplemented:
* - Animation
* - ICC profile
* - Exif and XMP metadata
*/
#define BITSTREAM_READER_LE
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "get_bits.h"
#include "thread.h"
#include "vp8.h"
#define VP8X_FLAG_ANIMATION 0x02
#define VP8X_FLAG_XMP_METADATA 0x04
#define VP8X_FLAG_EXIF_METADATA 0x08
#define VP8X_FLAG_ALPHA 0x10
#define VP8X_FLAG_ICC 0x20
#define MAX_PALETTE_SIZE 256
#define MAX_CACHE_BITS 11
#define NUM_CODE_LENGTH_CODES 19
#define HUFFMAN_CODES_PER_META_CODE 5
#define NUM_LITERAL_CODES 256
#define NUM_LENGTH_CODES 24
#define NUM_DISTANCE_CODES 40
#define NUM_SHORT_DISTANCES 120
#define MAX_HUFFMAN_CODE_LENGTH 15
static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {
NUM_LITERAL_CODES + NUM_LENGTH_CODES,
NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
NUM_DISTANCE_CODES
};
static const uint8_t code_length_code_order[NUM_CODE_LENGTH_CODES] = {
17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
};
static const int8_t lz77_distance_offsets[NUM_SHORT_DISTANCES][2] = {
{ 0, 1 }, { 1, 0 }, { 1, 1 }, { -1, 1 }, { 0, 2 }, { 2, 0 }, { 1, 2 }, { -1, 2 },
{ 2, 1 }, { -2, 1 }, { 2, 2 }, { -2, 2 }, { 0, 3 }, { 3, 0 }, { 1, 3 }, { -1, 3 },
{ 3, 1 }, { -3, 1 }, { 2, 3 }, { -2, 3 }, { 3, 2 }, { -3, 2 }, { 0, 4 }, { 4, 0 },
{ 1, 4 }, { -1, 4 }, { 4, 1 }, { -4, 1 }, { 3, 3 }, { -3, 3 }, { 2, 4 }, { -2, 4 },
{ 4, 2 }, { -4, 2 }, { 0, 5 }, { 3, 4 }, { -3, 4 }, { 4, 3 }, { -4, 3 }, { 5, 0 },
{ 1, 5 }, { -1, 5 }, { 5, 1 }, { -5, 1 }, { 2, 5 }, { -2, 5 }, { 5, 2 }, { -5, 2 },
{ 4, 4 }, { -4, 4 }, { 3, 5 }, { -3, 5 }, { 5, 3 }, { -5, 3 }, { 0, 6 }, { 6, 0 },
{ 1, 6 }, { -1, 6 }, { 6, 1 }, { -6, 1 }, { 2, 6 }, { -2, 6 }, { 6, 2 }, { -6, 2 },
{ 4, 5 }, { -4, 5 }, { 5, 4 }, { -5, 4 }, { 3, 6 }, { -3, 6 }, { 6, 3 }, { -6, 3 },
{ 0, 7 }, { 7, 0 }, { 1, 7 }, { -1, 7 }, { 5, 5 }, { -5, 5 }, { 7, 1 }, { -7, 1 },
{ 4, 6 }, { -4, 6 }, { 6, 4 }, { -6, 4 }, { 2, 7 }, { -2, 7 }, { 7, 2 }, { -7, 2 },
{ 3, 7 }, { -3, 7 }, { 7, 3 }, { -7, 3 }, { 5, 6 }, { -5, 6 }, { 6, 5 }, { -6, 5 },
{ 8, 0 }, { 4, 7 }, { -4, 7 }, { 7, 4 }, { -7, 4 }, { 8, 1 }, { 8, 2 }, { 6, 6 },
{ -6, 6 }, { 8, 3 }, { 5, 7 }, { -5, 7 }, { 7, 5 }, { -7, 5 }, { 8, 4 }, { 6, 7 },
{ -6, 7 }, { 7, 6 }, { -7, 6 }, { 8, 5 }, { 7, 7 }, { -7, 7 }, { 8, 6 }, { 8, 7 }
};
enum AlphaCompression {
ALPHA_COMPRESSION_NONE,
ALPHA_COMPRESSION_VP8L,
};
enum AlphaFilter {
ALPHA_FILTER_NONE,
ALPHA_FILTER_HORIZONTAL,
ALPHA_FILTER_VERTICAL,
ALPHA_FILTER_GRADIENT,
};
enum TransformType {
PREDICTOR_TRANSFORM = 0,
COLOR_TRANSFORM = 1,
SUBTRACT_GREEN = 2,
COLOR_INDEXING_TRANSFORM = 3,
};
enum PredictionMode {
PRED_MODE_BLACK,
PRED_MODE_L,
PRED_MODE_T,
PRED_MODE_TR,
PRED_MODE_TL,
PRED_MODE_AVG_T_AVG_L_TR,
PRED_MODE_AVG_L_TL,
PRED_MODE_AVG_L_T,
PRED_MODE_AVG_TL_T,
PRED_MODE_AVG_T_TR,
PRED_MODE_AVG_AVG_L_TL_AVG_T_TR,
PRED_MODE_SELECT,
PRED_MODE_ADD_SUBTRACT_FULL,
PRED_MODE_ADD_SUBTRACT_HALF,
};
enum HuffmanIndex {
HUFF_IDX_GREEN = 0,
HUFF_IDX_RED = 1,
HUFF_IDX_BLUE = 2,
HUFF_IDX_ALPHA = 3,
HUFF_IDX_DIST = 4
};
/* The structure of WebP lossless is an optional series of transformation data,
* followed by the primary image. The primary image also optionally contains
* an entropy group mapping if there are multiple entropy groups. There is a
* basic image type called an "entropy coded image" that is used for all of
* these. The type of each entropy coded image is referred to by the
* specification as its role. */
enum ImageRole {
/* Primary Image: Stores the actual pixels of the image. */
IMAGE_ROLE_ARGB,
/* Entropy Image: Defines which Huffman group to use for different areas of
* the primary image. */
IMAGE_ROLE_ENTROPY,
/* Predictors: Defines which predictor type to use for different areas of
* the primary image. */
IMAGE_ROLE_PREDICTOR,
/* Color Transform Data: Defines the color transformation for different
* areas of the primary image. */
IMAGE_ROLE_COLOR_TRANSFORM,
/* Color Index: Stored as an image of height == 1. */
IMAGE_ROLE_COLOR_INDEXING,
IMAGE_ROLE_NB,
};
typedef struct HuffReader {
VLC vlc; /* Huffman decoder context */
int simple; /* whether to use simple mode */
int nb_symbols; /* number of coded symbols */
uint16_t simple_symbols[2]; /* symbols for simple mode */
} HuffReader;
typedef struct ImageContext {
enum ImageRole role; /* role of this image */
AVFrame *frame; /* AVFrame for data */
int color_cache_bits; /* color cache size, log2 */
uint32_t *color_cache; /* color cache data */
int nb_huffman_groups; /* number of huffman groups */
HuffReader *huffman_groups; /* reader for each huffman group */
int size_reduction; /* relative size compared to primary image, log2 */
int is_alpha_primary;
} ImageContext;
typedef struct WebPContext {
VP8Context v; /* VP8 Context used for lossy decoding */
GetBitContext gb; /* bitstream reader for main image chunk */
AVFrame *alpha_frame; /* AVFrame for alpha data decompressed from VP8L */
AVCodecContext *avctx; /* parent AVCodecContext */
int initialized; /* set once the VP8 context is initialized */
int has_alpha; /* has a separate alpha chunk */
enum AlphaCompression alpha_compression; /* compression type for alpha chunk */
enum AlphaFilter alpha_filter; /* filtering method for alpha chunk */
uint8_t *alpha_data; /* alpha chunk data */
int alpha_data_size; /* alpha chunk data size */
int width; /* image width */
int height; /* image height */
int lossless; /* indicates lossless or lossy */
int nb_transforms; /* number of transforms */
enum TransformType transforms[4]; /* transformations used in the image, in order */
int reduced_width; /* reduced width for index image, if applicable */
int nb_huffman_groups; /* number of huffman groups in the primary image */
ImageContext image[IMAGE_ROLE_NB]; /* image context for each role */
} WebPContext;
#define GET_PIXEL(frame, x, y) \
((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x))
#define GET_PIXEL_COMP(frame, x, y, c) \
(*((frame)->data[0] + (y) * frame->linesize[0] + 4 * (x) + c))
static void image_ctx_free(ImageContext *img)
{
int i, j;
av_free(img->color_cache);
if (img->role != IMAGE_ROLE_ARGB && !img->is_alpha_primary)
av_frame_free(&img->frame);
if (img->huffman_groups) {
for (i = 0; i < img->nb_huffman_groups; i++) {
for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++)
ff_free_vlc(&img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE + j].vlc);
}
av_free(img->huffman_groups);
}
memset(img, 0, sizeof(*img));
}
/* Differs from get_vlc2() in the following ways:
* - codes are bit-reversed
* - assumes 8-bit table to make reversal simpler
* - assumes max depth of 2 since the max code length for WebP is 15
*/
static av_always_inline int webp_get_vlc(GetBitContext *gb, VLC_TYPE (*table)[2])
{
int n, nb_bits;
unsigned int index;
int code;
OPEN_READER(re, gb);
UPDATE_CACHE(re, gb);
index = SHOW_UBITS(re, gb, 8);
index = ff_reverse[index];
code = table[index][0];
n = table[index][1];
if (n < 0) {
LAST_SKIP_BITS(re, gb, 8);
UPDATE_CACHE(re, gb);
nb_bits = -n;
index = SHOW_UBITS(re, gb, nb_bits);
index = (ff_reverse[index] >> (8 - nb_bits)) + code;
code = table[index][0];
n = table[index][1];
}
SKIP_BITS(re, gb, n);
CLOSE_READER(re, gb);
return code;
}
static int huff_reader_get_symbol(HuffReader *r, GetBitContext *gb)
{
if (r->simple) {
if (r->nb_symbols == 1)
return r->simple_symbols[0];
else
return r->simple_symbols[get_bits1(gb)];
} else
return webp_get_vlc(gb, r->vlc.table);
}
static int huff_reader_build_canonical(HuffReader *r, int *code_lengths,
int alphabet_size)
{
int len = 0, sym, code = 0, ret;
int max_code_length = 0;
uint16_t *codes;
/* special-case 1 symbol since the vlc reader cannot handle it */
for (sym = 0; sym < alphabet_size; sym++) {
if (code_lengths[sym] > 0) {
len++;
code = sym;
if (len > 1)
break;
}
}
if (len == 1) {
r->nb_symbols = 1;
r->simple_symbols[0] = code;
r->simple = 1;
return 0;
}
for (sym = 0; sym < alphabet_size; sym++)
max_code_length = FFMAX(max_code_length, code_lengths[sym]);
if (max_code_length == 0 || max_code_length > MAX_HUFFMAN_CODE_LENGTH)
return AVERROR(EINVAL);
codes = av_malloc(alphabet_size * sizeof(*codes));
if (!codes)
return AVERROR(ENOMEM);
code = 0;
r->nb_symbols = 0;
for (len = 1; len <= max_code_length; len++) {
for (sym = 0; sym < alphabet_size; sym++) {
if (code_lengths[sym] != len)
continue;
codes[sym] = code++;
r->nb_symbols++;
}
code <<= 1;
}
if (!r->nb_symbols) {
av_free(codes);
return AVERROR_INVALIDDATA;
}
ret = init_vlc(&r->vlc, 8, alphabet_size,
code_lengths, sizeof(*code_lengths), sizeof(*code_lengths),
codes, sizeof(*codes), sizeof(*codes), 0);
if (ret < 0) {
av_free(codes);
return ret;
}
r->simple = 0;
av_free(codes);
return 0;
}
static void read_huffman_code_simple(WebPContext *s, HuffReader *hc)
{
hc->nb_symbols = get_bits1(&s->gb) + 1;
if (get_bits1(&s->gb))
hc->simple_symbols[0] = get_bits(&s->gb, 8);
else
hc->simple_symbols[0] = get_bits1(&s->gb);
if (hc->nb_symbols == 2)
hc->simple_symbols[1] = get_bits(&s->gb, 8);
hc->simple = 1;
}
static int read_huffman_code_normal(WebPContext *s, HuffReader *hc,
int alphabet_size)
{
HuffReader code_len_hc = { { 0 }, 0, 0, { 0 } };
int *code_lengths = NULL;
int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
int i, symbol, max_symbol, prev_code_len, ret;
int num_codes = 4 + get_bits(&s->gb, 4);
if (num_codes > NUM_CODE_LENGTH_CODES)
return AVERROR_INVALIDDATA;
for (i = 0; i < num_codes; i++)
code_length_code_lengths[code_length_code_order[i]] = get_bits(&s->gb, 3);
ret = huff_reader_build_canonical(&code_len_hc, code_length_code_lengths,
NUM_CODE_LENGTH_CODES);
if (ret < 0)
goto finish;
code_lengths = av_mallocz_array(alphabet_size, sizeof(*code_lengths));
if (!code_lengths) {
ret = AVERROR(ENOMEM);
goto finish;
}
if (get_bits1(&s->gb)) {
int bits = 2 + 2 * get_bits(&s->gb, 3);
max_symbol = 2 + get_bits(&s->gb, bits);
if (max_symbol > alphabet_size) {
av_log(s->avctx, AV_LOG_ERROR, "max symbol %d > alphabet size %d\n",
max_symbol, alphabet_size);
ret = AVERROR_INVALIDDATA;
goto finish;
}
} else {
max_symbol = alphabet_size;
}
prev_code_len = 8;
symbol = 0;
while (symbol < alphabet_size) {
int code_len;
if (!max_symbol--)
break;
code_len = huff_reader_get_symbol(&code_len_hc, &s->gb);
if (code_len < 16) {
/* Code length code [0..15] indicates literal code lengths. */
code_lengths[symbol++] = code_len;
if (code_len)
prev_code_len = code_len;
} else {
int repeat = 0, length = 0;
switch (code_len) {
case 16:
/* Code 16 repeats the previous non-zero value [3..6] times,
* i.e., 3 + ReadBits(2) times. If code 16 is used before a
* non-zero value has been emitted, a value of 8 is repeated. */
repeat = 3 + get_bits(&s->gb, 2);
length = prev_code_len;
break;
case 17:
/* Code 17 emits a streak of zeros [3..10], i.e.,
* 3 + ReadBits(3) times. */
repeat = 3 + get_bits(&s->gb, 3);
break;
case 18:
/* Code 18 emits a streak of zeros of length [11..138], i.e.,
* 11 + ReadBits(7) times. */
repeat = 11 + get_bits(&s->gb, 7);
break;
}
if (symbol + repeat > alphabet_size) {
av_log(s->avctx, AV_LOG_ERROR,
"invalid symbol %d + repeat %d > alphabet size %d\n",
symbol, repeat, alphabet_size);
ret = AVERROR_INVALIDDATA;
goto finish;
}
while (repeat-- > 0)
code_lengths[symbol++] = length;
}
}
ret = huff_reader_build_canonical(hc, code_lengths, alphabet_size);
finish:
ff_free_vlc(&code_len_hc.vlc);
av_free(code_lengths);
return ret;
}
static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
int w, int h);
#define PARSE_BLOCK_SIZE(w, h) do { \
block_bits = get_bits(&s->gb, 3) + 2; \
blocks_w = FFALIGN((w), 1 << block_bits) >> block_bits; \
blocks_h = FFALIGN((h), 1 << block_bits) >> block_bits; \
} while (0)
static int decode_entropy_image(WebPContext *s)
{
ImageContext *img;
int ret, block_bits, width, blocks_w, blocks_h, x, y, max;
width = s->width;
if (s->reduced_width > 0)
width = s->reduced_width;
PARSE_BLOCK_SIZE(width, s->height);
ret = decode_entropy_coded_image(s, IMAGE_ROLE_ENTROPY, blocks_w, blocks_h);
if (ret < 0)
return ret;
img = &s->image[IMAGE_ROLE_ENTROPY];
img->size_reduction = block_bits;
/* the number of huffman groups is determined by the maximum group number
* coded in the entropy image */
max = 0;
for (y = 0; y < img->frame->height; y++) {
for (x = 0; x < img->frame->width; x++) {
int p = GET_PIXEL_COMP(img->frame, x, y, 2);
max = FFMAX(max, p);
}
}
s->nb_huffman_groups = max + 1;
return 0;
}
static int parse_transform_predictor(WebPContext *s)
{
int block_bits, blocks_w, blocks_h, ret;
PARSE_BLOCK_SIZE(s->width, s->height);
ret = decode_entropy_coded_image(s, IMAGE_ROLE_PREDICTOR, blocks_w,
blocks_h);
if (ret < 0)
return ret;
s->image[IMAGE_ROLE_PREDICTOR].size_reduction = block_bits;
return 0;
}
static int parse_transform_color(WebPContext *s)
{
int block_bits, blocks_w, blocks_h, ret;
PARSE_BLOCK_SIZE(s->width, s->height);
ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_TRANSFORM, blocks_w,
blocks_h);
if (ret < 0)
return ret;
s->image[IMAGE_ROLE_COLOR_TRANSFORM].size_reduction = block_bits;
return 0;
}
static int parse_transform_color_indexing(WebPContext *s)
{
ImageContext *img;
int width_bits, index_size, ret, x;
uint8_t *ct;
index_size = get_bits(&s->gb, 8) + 1;
if (index_size <= 2)
width_bits = 3;
else if (index_size <= 4)
width_bits = 2;
else if (index_size <= 16)
width_bits = 1;
else
width_bits = 0;
ret = decode_entropy_coded_image(s, IMAGE_ROLE_COLOR_INDEXING,
index_size, 1);
if (ret < 0)
return ret;
img = &s->image[IMAGE_ROLE_COLOR_INDEXING];
img->size_reduction = width_bits;
if (width_bits > 0)
s->reduced_width = (s->width + ((1 << width_bits) - 1)) >> width_bits;
/* color index values are delta-coded */
ct = img->frame->data[0] + 4;
for (x = 4; x < img->frame->width * 4; x++, ct++)
ct[0] += ct[-4];
return 0;
}
static HuffReader *get_huffman_group(WebPContext *s, ImageContext *img,
int x, int y)
{
ImageContext *gimg = &s->image[IMAGE_ROLE_ENTROPY];
int group = 0;
if (gimg->size_reduction > 0) {
int group_x = x >> gimg->size_reduction;
int group_y = y >> gimg->size_reduction;
group = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
}
return &img->huffman_groups[group * HUFFMAN_CODES_PER_META_CODE];
}
static av_always_inline void color_cache_put(ImageContext *img, uint32_t c)
{
uint32_t cache_idx = (0x1E35A7BD * c) >> (32 - img->color_cache_bits);
img->color_cache[cache_idx] = c;
}
static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
int w, int h)
{
ImageContext *img;
HuffReader *hg;
int i, j, ret, x, y, width;
img = &s->image[role];
img->role = role;
if (!img->frame) {
img->frame = av_frame_alloc();
if (!img->frame)
return AVERROR(ENOMEM);
}
img->frame->format = AV_PIX_FMT_ARGB;
img->frame->width = w;
img->frame->height = h;
if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {
ThreadFrame pt = { .f = img->frame };
ret = ff_thread_get_buffer(s->avctx, &pt, 0);
} else
ret = av_frame_get_buffer(img->frame, 1);
if (ret < 0)
return ret;
if (get_bits1(&s->gb)) {
img->color_cache_bits = get_bits(&s->gb, 4);
if (img->color_cache_bits < 1 || img->color_cache_bits > 11) {
av_log(s->avctx, AV_LOG_ERROR, "invalid color cache bits: %d\n",
img->color_cache_bits);
return AVERROR_INVALIDDATA;
}
img->color_cache = av_mallocz_array(1 << img->color_cache_bits,
sizeof(*img->color_cache));
if (!img->color_cache)
return AVERROR(ENOMEM);
} else {
img->color_cache_bits = 0;
}
img->nb_huffman_groups = 1;
if (role == IMAGE_ROLE_ARGB && get_bits1(&s->gb)) {
ret = decode_entropy_image(s);
if (ret < 0)
return ret;
img->nb_huffman_groups = s->nb_huffman_groups;
}
img->huffman_groups = av_mallocz_array(img->nb_huffman_groups *
HUFFMAN_CODES_PER_META_CODE,
sizeof(*img->huffman_groups));
if (!img->huffman_groups)
return AVERROR(ENOMEM);
for (i = 0; i < img->nb_huffman_groups; i++) {
hg = &img->huffman_groups[i * HUFFMAN_CODES_PER_META_CODE];
for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; j++) {
int alphabet_size = alphabet_sizes[j];
if (!j && img->color_cache_bits > 0)
alphabet_size += 1 << img->color_cache_bits;
if (get_bits1(&s->gb)) {
read_huffman_code_simple(s, &hg[j]);
} else {
ret = read_huffman_code_normal(s, &hg[j], alphabet_size);
if (ret < 0)
return ret;
}
}
}
width = img->frame->width;
if (role == IMAGE_ROLE_ARGB && s->reduced_width > 0)
width = s->reduced_width;
x = 0; y = 0;
while (y < img->frame->height) {
int v;
hg = get_huffman_group(s, img, x, y);
v = huff_reader_get_symbol(&hg[HUFF_IDX_GREEN], &s->gb);
if (v < NUM_LITERAL_CODES) {
/* literal pixel values */
uint8_t *p = GET_PIXEL(img->frame, x, y);
p[2] = v;
p[1] = huff_reader_get_symbol(&hg[HUFF_IDX_RED], &s->gb);
p[3] = huff_reader_get_symbol(&hg[HUFF_IDX_BLUE], &s->gb);
p[0] = huff_reader_get_symbol(&hg[HUFF_IDX_ALPHA], &s->gb);
if (img->color_cache_bits)
color_cache_put(img, AV_RB32(p));
x++;
if (x == width) {
x = 0;
y++;
}
} else if (v < NUM_LITERAL_CODES + NUM_LENGTH_CODES) {
/* LZ77 backwards mapping */
int prefix_code, length, distance, ref_x, ref_y;
/* parse length and distance */
prefix_code = v - NUM_LITERAL_CODES;
if (prefix_code < 4) {
length = prefix_code + 1;
} else {
int extra_bits = (prefix_code - 2) >> 1;
int offset = 2 + (prefix_code & 1) << extra_bits;
length = offset + get_bits(&s->gb, extra_bits) + 1;
}
prefix_code = huff_reader_get_symbol(&hg[HUFF_IDX_DIST], &s->gb);
if (prefix_code < 4) {
distance = prefix_code + 1;
} else {
int extra_bits = prefix_code - 2 >> 1;
int offset = 2 + (prefix_code & 1) << extra_bits;
distance = offset + get_bits(&s->gb, extra_bits) + 1;
}
/* find reference location */
if (distance <= NUM_SHORT_DISTANCES) {
int xi = lz77_distance_offsets[distance - 1][0];
int yi = lz77_distance_offsets[distance - 1][1];
distance = FFMAX(1, xi + yi * width);
} else {
distance -= NUM_SHORT_DISTANCES;
}
ref_x = x;
ref_y = y;
if (distance <= x) {
ref_x -= distance;
distance = 0;
} else {
ref_x = 0;
distance -= x;
}
while (distance >= width) {
ref_y--;
distance -= width;
}
if (distance > 0) {
ref_x = width - distance;
ref_y--;
}
ref_x = FFMAX(0, ref_x);
ref_y = FFMAX(0, ref_y);
/* copy pixels
* source and dest regions can overlap and wrap lines, so just
* copy per-pixel */
for (i = 0; i < length; i++) {
uint8_t *p_ref = GET_PIXEL(img->frame, ref_x, ref_y);
uint8_t *p = GET_PIXEL(img->frame, x, y);
AV_COPY32(p, p_ref);
if (img->color_cache_bits)
color_cache_put(img, AV_RB32(p));
x++;
ref_x++;
if (x == width) {
x = 0;
y++;
}
if (ref_x == width) {
ref_x = 0;
ref_y++;
}
if (y == img->frame->height || ref_y == img->frame->height)
break;
}
} else {
/* read from color cache */
uint8_t *p = GET_PIXEL(img->frame, x, y);
int cache_idx = v - (NUM_LITERAL_CODES + NUM_LENGTH_CODES);
if (!img->color_cache_bits) {
av_log(s->avctx, AV_LOG_ERROR, "color cache not found\n");
return AVERROR_INVALIDDATA;
}
if (cache_idx >= 1 << img->color_cache_bits) {
av_log(s->avctx, AV_LOG_ERROR,
"color cache index out-of-bounds\n");
return AVERROR_INVALIDDATA;
}
AV_WB32(p, img->color_cache[cache_idx]);
x++;
if (x == width) {
x = 0;
y++;
}
}
}
return 0;
}
/* PRED_MODE_BLACK */
static void inv_predict_0(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
AV_WB32(p, 0xFF000000);
}
/* PRED_MODE_L */
static void inv_predict_1(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
AV_COPY32(p, p_l);
}
/* PRED_MODE_T */
static void inv_predict_2(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
AV_COPY32(p, p_t);
}
/* PRED_MODE_TR */
static void inv_predict_3(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
AV_COPY32(p, p_tr);
}
/* PRED_MODE_TL */
static void inv_predict_4(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
AV_COPY32(p, p_tl);
}
/* PRED_MODE_AVG_T_AVG_L_TR */
static void inv_predict_5(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = p_t[0] + (p_l[0] + p_tr[0] >> 1) >> 1;
p[1] = p_t[1] + (p_l[1] + p_tr[1] >> 1) >> 1;
p[2] = p_t[2] + (p_l[2] + p_tr[2] >> 1) >> 1;
p[3] = p_t[3] + (p_l[3] + p_tr[3] >> 1) >> 1;
}
/* PRED_MODE_AVG_L_TL */
static void inv_predict_6(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = p_l[0] + p_tl[0] >> 1;
p[1] = p_l[1] + p_tl[1] >> 1;
p[2] = p_l[2] + p_tl[2] >> 1;
p[3] = p_l[3] + p_tl[3] >> 1;
}
/* PRED_MODE_AVG_L_T */
static void inv_predict_7(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = p_l[0] + p_t[0] >> 1;
p[1] = p_l[1] + p_t[1] >> 1;
p[2] = p_l[2] + p_t[2] >> 1;
p[3] = p_l[3] + p_t[3] >> 1;
}
/* PRED_MODE_AVG_TL_T */
static void inv_predict_8(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = p_tl[0] + p_t[0] >> 1;
p[1] = p_tl[1] + p_t[1] >> 1;
p[2] = p_tl[2] + p_t[2] >> 1;
p[3] = p_tl[3] + p_t[3] >> 1;
}
/* PRED_MODE_AVG_T_TR */
static void inv_predict_9(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = p_t[0] + p_tr[0] >> 1;
p[1] = p_t[1] + p_tr[1] >> 1;
p[2] = p_t[2] + p_tr[2] >> 1;
p[3] = p_t[3] + p_tr[3] >> 1;
}
/* PRED_MODE_AVG_AVG_L_TL_AVG_T_TR */
static void inv_predict_10(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = (p_l[0] + p_tl[0] >> 1) + (p_t[0] + p_tr[0] >> 1) >> 1;
p[1] = (p_l[1] + p_tl[1] >> 1) + (p_t[1] + p_tr[1] >> 1) >> 1;
p[2] = (p_l[2] + p_tl[2] >> 1) + (p_t[2] + p_tr[2] >> 1) >> 1;
p[3] = (p_l[3] + p_tl[3] >> 1) + (p_t[3] + p_tr[3] >> 1) >> 1;
}
/* PRED_MODE_SELECT */
static void inv_predict_11(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
int diff = (FFABS(p_l[0] - p_tl[0]) - FFABS(p_t[0] - p_tl[0])) +
(FFABS(p_l[1] - p_tl[1]) - FFABS(p_t[1] - p_tl[1])) +
(FFABS(p_l[2] - p_tl[2]) - FFABS(p_t[2] - p_tl[2])) +
(FFABS(p_l[3] - p_tl[3]) - FFABS(p_t[3] - p_tl[3]));
if (diff <= 0)
AV_COPY32(p, p_t);
else
AV_COPY32(p, p_l);
}
/* PRED_MODE_ADD_SUBTRACT_FULL */
static void inv_predict_12(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = av_clip_uint8(p_l[0] + p_t[0] - p_tl[0]);
p[1] = av_clip_uint8(p_l[1] + p_t[1] - p_tl[1]);
p[2] = av_clip_uint8(p_l[2] + p_t[2] - p_tl[2]);
p[3] = av_clip_uint8(p_l[3] + p_t[3] - p_tl[3]);
}
static av_always_inline uint8_t clamp_add_subtract_half(int a, int b, int c)
{
int d = a + b >> 1;
return av_clip_uint8(d + (d - c) / 2);
}
/* PRED_MODE_ADD_SUBTRACT_HALF */
static void inv_predict_13(uint8_t *p, const uint8_t *p_l, const uint8_t *p_tl,
const uint8_t *p_t, const uint8_t *p_tr)
{
p[0] = clamp_add_subtract_half(p_l[0], p_t[0], p_tl[0]);
p[1] = clamp_add_subtract_half(p_l[1], p_t[1], p_tl[1]);
p[2] = clamp_add_subtract_half(p_l[2], p_t[2], p_tl[2]);
p[3] = clamp_add_subtract_half(p_l[3], p_t[3], p_tl[3]);
}
typedef void (*inv_predict_func)(uint8_t *p, const uint8_t *p_l,
const uint8_t *p_tl, const uint8_t *p_t,
const uint8_t *p_tr);
static const inv_predict_func inverse_predict[14] = {
inv_predict_0, inv_predict_1, inv_predict_2, inv_predict_3,
inv_predict_4, inv_predict_5, inv_predict_6, inv_predict_7,
inv_predict_8, inv_predict_9, inv_predict_10, inv_predict_11,
inv_predict_12, inv_predict_13,
};
static void inverse_prediction(AVFrame *frame, enum PredictionMode m, int x, int y)
{
uint8_t *dec, *p_l, *p_tl, *p_t, *p_tr;
uint8_t p[4];
dec = GET_PIXEL(frame, x, y);
p_l = GET_PIXEL(frame, x - 1, y);
p_tl = GET_PIXEL(frame, x - 1, y - 1);
p_t = GET_PIXEL(frame, x, y - 1);
if (x == frame->width - 1)
p_tr = GET_PIXEL(frame, 0, y);
else
p_tr = GET_PIXEL(frame, x + 1, y - 1);
inverse_predict[m](p, p_l, p_tl, p_t, p_tr);
dec[0] += p[0];
dec[1] += p[1];
dec[2] += p[2];
dec[3] += p[3];
}
static int apply_predictor_transform(WebPContext *s)
{
ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
ImageContext *pimg = &s->image[IMAGE_ROLE_PREDICTOR];
int x, y;
for (y = 0; y < img->frame->height; y++) {
for (x = 0; x < img->frame->width; x++) {
int tx = x >> pimg->size_reduction;
int ty = y >> pimg->size_reduction;
enum PredictionMode m = GET_PIXEL_COMP(pimg->frame, tx, ty, 2);
if (x == 0) {
if (y == 0)
m = PRED_MODE_BLACK;
else
m = PRED_MODE_T;
} else if (y == 0)
m = PRED_MODE_L;
if (m > 13) {
av_log(s->avctx, AV_LOG_ERROR,
"invalid predictor mode: %d\n", m);
return AVERROR_INVALIDDATA;
}
inverse_prediction(img->frame, m, x, y);
}
}
return 0;
}
static av_always_inline uint8_t color_transform_delta(uint8_t color_pred,
uint8_t color)
{
return (int)ff_u8_to_s8(color_pred) * ff_u8_to_s8(color) >> 5;
}
static int apply_color_transform(WebPContext *s)
{
ImageContext *img, *cimg;
int x, y, cx, cy;
uint8_t *p, *cp;
img = &s->image[IMAGE_ROLE_ARGB];
cimg = &s->image[IMAGE_ROLE_COLOR_TRANSFORM];
for (y = 0; y < img->frame->height; y++) {
for (x = 0; x < img->frame->width; x++) {
cx = x >> cimg->size_reduction;
cy = y >> cimg->size_reduction;
cp = GET_PIXEL(cimg->frame, cx, cy);
p = GET_PIXEL(img->frame, x, y);
p[1] += color_transform_delta(cp[3], p[2]);
p[3] += color_transform_delta(cp[2], p[2]) +
color_transform_delta(cp[1], p[1]);
}
}
return 0;
}
static int apply_subtract_green_transform(WebPContext *s)
{
int x, y;
ImageContext *img = &s->image[IMAGE_ROLE_ARGB];
for (y = 0; y < img->frame->height; y++) {
for (x = 0; x < img->frame->width; x++) {
uint8_t *p = GET_PIXEL(img->frame, x, y);
p[1] += p[2];
p[3] += p[2];
}
}
return 0;
}
static int apply_color_indexing_transform(WebPContext *s)
{
ImageContext *img;
ImageContext *pal;
int i, x, y;
uint8_t *p, *pi;
img = &s->image[IMAGE_ROLE_ARGB];
pal = &s->image[IMAGE_ROLE_COLOR_INDEXING];
if (pal->size_reduction > 0) {
GetBitContext gb_g;
uint8_t *line;
int pixel_bits = 8 >> pal->size_reduction;
line = av_malloc(img->frame->linesize[0]);
if (!line)
return AVERROR(ENOMEM);
for (y = 0; y < img->frame->height; y++) {
p = GET_PIXEL(img->frame, 0, y);
memcpy(line, p, img->frame->linesize[0]);
init_get_bits(&gb_g, line, img->frame->linesize[0] * 8);
skip_bits(&gb_g, 16);
i = 0;
for (x = 0; x < img->frame->width; x++) {
p = GET_PIXEL(img->frame, x, y);
p[2] = get_bits(&gb_g, pixel_bits);
i++;
if (i == 1 << pal->size_reduction) {
skip_bits(&gb_g, 24);
i = 0;
}
}
}
av_free(line);
}
for (y = 0; y < img->frame->height; y++) {
for (x = 0; x < img->frame->width; x++) {
p = GET_PIXEL(img->frame, x, y);
i = p[2];
if (i >= pal->frame->width) {
av_log(s->avctx, AV_LOG_ERROR, "invalid palette index %d\n", i);
return AVERROR_INVALIDDATA;
}
pi = GET_PIXEL(pal->frame, i, 0);
AV_COPY32(p, pi);
}
}
return 0;
}
static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
int *got_frame, uint8_t *data_start,
unsigned int data_size, int is_alpha_chunk)
{
WebPContext *s = avctx->priv_data;
int w, h, ret, i;
if (!is_alpha_chunk) {
s->lossless = 1;
avctx->pix_fmt = AV_PIX_FMT_ARGB;
}
ret = init_get_bits(&s->gb, data_start, data_size * 8);
if (ret < 0)
return ret;
if (!is_alpha_chunk) {
if (get_bits(&s->gb, 8) != 0x2F) {
av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless signature\n");
return AVERROR_INVALIDDATA;
}
w = get_bits(&s->gb, 14) + 1;
h = get_bits(&s->gb, 14) + 1;
if (s->width && s->width != w) {
av_log(avctx, AV_LOG_WARNING, "Width mismatch. %d != %d\n",
s->width, w);
}
s->width = w;
if (s->height && s->height != h) {
av_log(avctx, AV_LOG_WARNING, "Height mismatch. %d != %d\n",
s->width, w);
}
s->height = h;
ret = ff_set_dimensions(avctx, s->width, s->height);
if (ret < 0)
return ret;
s->has_alpha = get_bits1(&s->gb);
if (get_bits(&s->gb, 3) != 0x0) {
av_log(avctx, AV_LOG_ERROR, "Invalid WebP Lossless version\n");
return AVERROR_INVALIDDATA;
}
} else {
if (!s->width || !s->height)
return AVERROR_BUG;
w = s->width;
h = s->height;
}
/* parse transformations */
s->nb_transforms = 0;
s->reduced_width = 0;
while (get_bits1(&s->gb)) {
enum TransformType transform = get_bits(&s->gb, 2);
s->transforms[s->nb_transforms++] = transform;
switch (transform) {
case PREDICTOR_TRANSFORM:
ret = parse_transform_predictor(s);
break;
case COLOR_TRANSFORM:
ret = parse_transform_color(s);
break;
case COLOR_INDEXING_TRANSFORM:
ret = parse_transform_color_indexing(s);
break;
}
if (ret < 0)
goto free_and_return;
}
/* decode primary image */
s->image[IMAGE_ROLE_ARGB].frame = p;
if (is_alpha_chunk)
s->image[IMAGE_ROLE_ARGB].is_alpha_primary = 1;
ret = decode_entropy_coded_image(s, IMAGE_ROLE_ARGB, w, h);
if (ret < 0)
goto free_and_return;
/* apply transformations */
for (i = s->nb_transforms - 1; i >= 0; i--) {
switch (s->transforms[i]) {
case PREDICTOR_TRANSFORM:
ret = apply_predictor_transform(s);
break;
case COLOR_TRANSFORM:
ret = apply_color_transform(s);
break;
case SUBTRACT_GREEN:
ret = apply_subtract_green_transform(s);
break;
case COLOR_INDEXING_TRANSFORM:
ret = apply_color_indexing_transform(s);
break;
}
if (ret < 0)
goto free_and_return;
}
*got_frame = 1;
p->pict_type = AV_PICTURE_TYPE_I;
p->key_frame = 1;
ret = data_size;
free_and_return:
for (i = 0; i < IMAGE_ROLE_NB; i++)
image_ctx_free(&s->image[i]);
return ret;
}
static void alpha_inverse_prediction(AVFrame *frame, enum AlphaFilter m)
{
int x, y, ls;
uint8_t *dec;
ls = frame->linesize[3];
/* filter first row using horizontal filter */
dec = frame->data[3] + 1;
for (x = 1; x < frame->width; x++, dec++)
*dec += *(dec - 1);
/* filter first column using vertical filter */
dec = frame->data[3] + ls;
for (y = 1; y < frame->height; y++, dec += ls)
*dec += *(dec - ls);
/* filter the rest using the specified filter */
switch (m) {
case ALPHA_FILTER_HORIZONTAL:
for (y = 1; y < frame->height; y++) {
dec = frame->data[3] + y * ls + 1;
for (x = 1; x < frame->width; x++, dec++)
*dec += *(dec - 1);
}
break;
case ALPHA_FILTER_VERTICAL:
for (y = 1; y < frame->height; y++) {
dec = frame->data[3] + y * ls + 1;
for (x = 1; x < frame->width; x++, dec++)
*dec += *(dec - ls);
}
break;
case ALPHA_FILTER_GRADIENT:
for (y = 1; y < frame->height; y++) {
dec = frame->data[3] + y * ls + 1;
for (x = 1; x < frame->width; x++, dec++)
dec[0] += av_clip_uint8(*(dec - 1) + *(dec - ls) - *(dec - ls - 1));
}
break;
}
}
static int vp8_lossy_decode_alpha(AVCodecContext *avctx, AVFrame *p,
uint8_t *data_start,
unsigned int data_size)
{
WebPContext *s = avctx->priv_data;
int x, y, ret;
if (s->alpha_compression == ALPHA_COMPRESSION_NONE) {
GetByteContext gb;
bytestream2_init(&gb, data_start, data_size);
for (y = 0; y < s->height; y++)
bytestream2_get_buffer(&gb, p->data[3] + p->linesize[3] * y,
s->width);
} else if (s->alpha_compression == ALPHA_COMPRESSION_VP8L) {
uint8_t *ap, *pp;
int alpha_got_frame = 0;
s->alpha_frame = av_frame_alloc();
if (!s->alpha_frame)
return AVERROR(ENOMEM);
ret = vp8_lossless_decode_frame(avctx, s->alpha_frame, &alpha_got_frame,
data_start, data_size, 1);
if (ret < 0) {
av_frame_free(&s->alpha_frame);
return ret;
}
if (!alpha_got_frame) {
av_frame_free(&s->alpha_frame);
return AVERROR_INVALIDDATA;
}
/* copy green component of alpha image to alpha plane of primary image */
for (y = 0; y < s->height; y++) {
ap = GET_PIXEL(s->alpha_frame, 0, y) + 2;
pp = p->data[3] + p->linesize[3] * y;
for (x = 0; x < s->width; x++) {
*pp = *ap;
pp++;
ap += 4;
}
}
av_frame_free(&s->alpha_frame);
}
/* apply alpha filtering */
if (s->alpha_filter)
alpha_inverse_prediction(p, s->alpha_filter);
return 0;
}
static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
int *got_frame, uint8_t *data_start,
unsigned int data_size)
{
WebPContext *s = avctx->priv_data;
AVPacket pkt;
int ret;
if (!s->initialized) {
ff_vp8_decode_init(avctx);
s->initialized = 1;
if (s->has_alpha)
avctx->pix_fmt = AV_PIX_FMT_YUVA420P;
}
s->lossless = 0;
if (data_size > INT_MAX) {
av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");
return AVERROR_PATCHWELCOME;
}
av_init_packet(&pkt);
pkt.data = data_start;
pkt.size = data_size;
ret = ff_vp8_decode_frame(avctx, p, got_frame, &pkt);
if (s->has_alpha) {
ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,
s->alpha_data_size);
if (ret < 0)
return ret;
}
return ret;
}
static int webp_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
AVPacket *avpkt)
{
AVFrame * const p = data;
WebPContext *s = avctx->priv_data;
GetByteContext gb;
int ret;
uint32_t chunk_type, chunk_size;
int vp8x_flags = 0;
s->avctx = avctx;
s->width = 0;
s->height = 0;
*got_frame = 0;
s->has_alpha = 0;
bytestream2_init(&gb, avpkt->data, avpkt->size);
if (bytestream2_get_bytes_left(&gb) < 12)
return AVERROR_INVALIDDATA;
if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
return AVERROR_INVALIDDATA;
}
chunk_size = bytestream2_get_le32(&gb);
if (bytestream2_get_bytes_left(&gb) < chunk_size)
return AVERROR_INVALIDDATA;
if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
return AVERROR_INVALIDDATA;
}
while (bytestream2_get_bytes_left(&gb) > 0) {
char chunk_str[5] = { 0 };
chunk_type = bytestream2_get_le32(&gb);
chunk_size = bytestream2_get_le32(&gb);
if (chunk_size == UINT32_MAX)
return AVERROR_INVALIDDATA;
chunk_size += chunk_size & 1;
if (bytestream2_get_bytes_left(&gb) < chunk_size)
return AVERROR_INVALIDDATA;
switch (chunk_type) {
case MKTAG('V', 'P', '8', ' '):
if (!*got_frame) {
ret = vp8_lossy_decode_frame(avctx, p, got_frame,
avpkt->data + bytestream2_tell(&gb),
chunk_size);
if (ret < 0)
return ret;
}
bytestream2_skip(&gb, chunk_size);
break;
case MKTAG('V', 'P', '8', 'L'):
if (!*got_frame) {
ret = vp8_lossless_decode_frame(avctx, p, got_frame,
avpkt->data + bytestream2_tell(&gb),
chunk_size, 0);
if (ret < 0)
return ret;
}
bytestream2_skip(&gb, chunk_size);
break;
case MKTAG('V', 'P', '8', 'X'):
vp8x_flags = bytestream2_get_byte(&gb);
bytestream2_skip(&gb, 3);
s->width = bytestream2_get_le24(&gb) + 1;
s->height = bytestream2_get_le24(&gb) + 1;
ret = av_image_check_size(s->width, s->height, 0, avctx);
if (ret < 0)
return ret;
break;
case MKTAG('A', 'L', 'P', 'H'): {
int alpha_header, filter_m, compression;
if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {
av_log(avctx, AV_LOG_WARNING,
"ALPHA chunk present, but alpha bit not set in the "
"VP8X header\n");
}
if (chunk_size == 0) {
av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");
return AVERROR_INVALIDDATA;
}
alpha_header = bytestream2_get_byte(&gb);
s->alpha_data = avpkt->data + bytestream2_tell(&gb);
s->alpha_data_size = chunk_size - 1;
bytestream2_skip(&gb, s->alpha_data_size);
filter_m = (alpha_header >> 2) & 0x03;
compression = alpha_header & 0x03;
if (compression > ALPHA_COMPRESSION_VP8L) {
av_log(avctx, AV_LOG_VERBOSE,
"skipping unsupported ALPHA chunk\n");
} else {
s->has_alpha = 1;
s->alpha_compression = compression;
s->alpha_filter = filter_m;
}
break;
}
case MKTAG('I', 'C', 'C', 'P'):
case MKTAG('A', 'N', 'I', 'M'):
case MKTAG('A', 'N', 'M', 'F'):
case MKTAG('E', 'X', 'I', 'F'):
case MKTAG('X', 'M', 'P', ' '):
AV_WL32(chunk_str, chunk_type);
av_log(avctx, AV_LOG_VERBOSE, "skipping unsupported chunk: %s\n",
chunk_str);
bytestream2_skip(&gb, chunk_size);
break;
default:
AV_WL32(chunk_str, chunk_type);
av_log(avctx, AV_LOG_VERBOSE, "skipping unknown chunk: %s\n",
chunk_str);
bytestream2_skip(&gb, chunk_size);
break;
}
}
if (!*got_frame) {
av_log(avctx, AV_LOG_ERROR, "image data not found\n");
return AVERROR_INVALIDDATA;
}
return avpkt->size;
}
static av_cold int webp_decode_close(AVCodecContext *avctx)
{
WebPContext *s = avctx->priv_data;
if (s->initialized)
return ff_vp8_decode_free(avctx);
return 0;
}
AVCodec ff_webp_decoder = {
.name = "webp",
.long_name = NULL_IF_CONFIG_SMALL("WebP image"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_WEBP,
.priv_data_size = sizeof(WebPContext),
.decode = webp_decode_frame,
.close = webp_decode_close,
.capabilities = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,
};
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