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FFmpeg/libavcodec/webp.c
Andreas Rheinhardt 00772ef4f7 avcodec/webp: Use LE VLC table for LE bitstream reader 
The WebP format uses Huffman tables and the decoder therefore uses
VLC tables. Given that WebP is a LE format, a LE bitreader is used;
yet the VLC table is not created for a LE reader (the process used to
create the tables puts the last bit to be read in the lowest bit) and
therefore custom code for reading the VLCs that reverses the bits
read is used instead of get_vlc2(). This commit changes this to use
a table designed for LE bitreader which allows to use get_vlc2() directly.
The necessary reversing of the codes is delegated to
ff_init_vlc_sparse() (and is therefore only done during init and not
when actually reading the VLCs).

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-10-12 22:40:00 +02:00

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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 FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; 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
*
* @author James Almer <jamrial@gmail.com>
* Exif metadata
* ICC profile
*
* Unimplemented:
* - Animation
* - XMP metadata
*/
#include "libavutil/imgutils.h"
#define BITSTREAM_READER_LE
#include "avcodec.h"
#include "bytestream.h"
#include "exif.h"
#include "get_bits.h"
#include "internal.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 has_exif; /* set after an EXIF chunk has been processed */
int has_iccp; /* set after an ICCP chunk has been processed */
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));
}
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 get_vlc2(gb, r->vlc.table, 8, 2);
}
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_array(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), INIT_VLC_OUTPUT_LE);
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 > 39U) {
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;
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] + AV_INPUT_BUFFER_PADDING_SIZE);
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);
}
// switch to local palette if it's worth initializing it
if (img->frame->height * img->frame->width > 300) {
uint8_t palette[256 * 4];
const int size = pal->frame->width * 4;
av_assert0(size <= 1024U);
memcpy(palette, GET_PIXEL(pal->frame, 0, 0), size); // copy palette
// set extra entries to transparent black
memset(palette + size, 0, 256 * 4 - size);
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];
AV_COPY32(p, &palette[i * 4]);
}
}
} else {
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_WB32(p, 0x00000000);
} else {
const uint8_t *pi = GET_PIXEL(pal->frame, i, 0);
AV_COPY32(p, pi);
}
}
}
}
return 0;
}
static void update_canvas_size(AVCodecContext *avctx, int w, int h)
{
WebPContext *s = avctx->priv_data;
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->height, h);
}
s->height = h;
}
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_bits8(&s->gb, data_start, data_size);
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;
update_canvas_size(avctx, w, 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);
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);
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;
s->v.actually_webp = 1;
}
avctx->pix_fmt = s->has_alpha ? AV_PIX_FMT_YUVA420P : AV_PIX_FMT_YUV420P;
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 (ret < 0)
return ret;
if (!*got_frame)
return AVERROR_INVALIDDATA;
update_canvas_size(avctx, avctx->width, avctx->height);
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;
s->has_exif = 0;
s->has_iccp = 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) {
/* we seem to be running out of data, but it could also be that the
bitstream has trailing junk leading to bogus chunk_size. */
break;
}
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;
avctx->properties |= FF_CODEC_PROPERTY_LOSSLESS;
}
bytestream2_skip(&gb, chunk_size);
break;
case MKTAG('V', 'P', '8', 'X'):
if (s->width || s->height || *got_frame) {
av_log(avctx, AV_LOG_ERROR, "Canvas dimensions are already set\n");
return AVERROR_INVALIDDATA;
}
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('E', 'X', 'I', 'F'): {
int le, ifd_offset, exif_offset = bytestream2_tell(&gb);
AVDictionary *exif_metadata = NULL;
GetByteContext exif_gb;
if (s->has_exif) {
av_log(avctx, AV_LOG_VERBOSE, "Ignoring extra EXIF chunk\n");
goto exif_end;
}
if (!(vp8x_flags & VP8X_FLAG_EXIF_METADATA))
av_log(avctx, AV_LOG_WARNING,
"EXIF chunk present, but Exif bit not set in the "
"VP8X header\n");
s->has_exif = 1;
bytestream2_init(&exif_gb, avpkt->data + exif_offset,
avpkt->size - exif_offset);
if (ff_tdecode_header(&exif_gb, &le, &ifd_offset) < 0) {
av_log(avctx, AV_LOG_ERROR, "invalid TIFF header "
"in Exif data\n");
goto exif_end;
}
bytestream2_seek(&exif_gb, ifd_offset, SEEK_SET);
if (ff_exif_decode_ifd(avctx, &exif_gb, le, 0, &exif_metadata) < 0) {
av_log(avctx, AV_LOG_ERROR, "error decoding Exif data\n");
goto exif_end;
}
av_dict_copy(&((AVFrame *) data)->metadata, exif_metadata, 0);
exif_end:
av_dict_free(&exif_metadata);
bytestream2_skip(&gb, chunk_size);
break;
}
case MKTAG('I', 'C', 'C', 'P'): {
AVFrameSideData *sd;
if (s->has_iccp) {
av_log(avctx, AV_LOG_VERBOSE, "Ignoring extra ICCP chunk\n");
bytestream2_skip(&gb, chunk_size);
break;
}
if (!(vp8x_flags & VP8X_FLAG_ICC))
av_log(avctx, AV_LOG_WARNING,
"ICCP chunk present, but ICC Profile bit not set in the "
"VP8X header\n");
s->has_iccp = 1;
sd = av_frame_new_side_data(p, AV_FRAME_DATA_ICC_PROFILE, chunk_size);
if (!sd)
return AVERROR(ENOMEM);
bytestream2_get_buffer(&gb, sd->data, chunk_size);
break;
}
case MKTAG('A', 'N', 'I', 'M'):
case MKTAG('A', 'N', 'M', 'F'):
case MKTAG('X', 'M', 'P', ' '):
AV_WL32(chunk_str, chunk_type);
av_log(avctx, AV_LOG_WARNING, "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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