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FFmpeg/libavcodec/webp.c
Vittorio Giovara def97856de lavc: AV-prefix all codec capabilities 
Express bitfields more simply.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
2015-07-27 15:24:58 +01:00

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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 p0 = GET_PIXEL_COMP(img->frame, x, y, 1);
int p1 = GET_PIXEL_COMP(img->frame, x, y, 2);
int p = p0 << 8 | p1;
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;
int g0 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 1);
int g1 = GET_PIXEL_COMP(gimg->frame, group_x, group_y, 2);
group = g0 << 8 | g1;
}
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 > 39) {
av_log(s->avctx, AV_LOG_ERROR,
"distance prefix code too large: %d\n", prefix_code);
return AVERROR_INVALIDDATA;
}
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, used;
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;
used = 0;
while (get_bits1(&s->gb)) {
enum TransformType transform = get_bits(&s->gb, 2);
s->transforms[s->nb_transforms++] = transform;
if (used & (1 << transform)) {
av_log(avctx, AV_LOG_ERROR, "Transform %d used more than once\n",
transform);
ret = AVERROR_INVALIDDATA;
goto free_and_return;
}
used |= (1 << 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) > 8) {
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 = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
};
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