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pngdec.c
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pngdec.c
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/*
* PNG image format
* Copyright (c) 2003 Fabrice Bellard
*
* 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
*/
//#define DEBUG
#include "libavutil/bprint.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "apng.h"
#include "png.h"
#include "pngdsp.h"
#include "thread.h"
#include <zlib.h>
typedef struct PNGDecContext {
PNGDSPContext dsp;
AVCodecContext *avctx;
GetByteContext gb;
ThreadFrame previous_picture;
ThreadFrame last_picture;
ThreadFrame picture;
int state;
int width, height;
int cur_w, cur_h;
int last_w, last_h;
int x_offset, y_offset;
int last_x_offset, last_y_offset;
uint8_t dispose_op, blend_op;
uint8_t last_dispose_op;
int bit_depth;
int color_type;
int compression_type;
int interlace_type;
int filter_type;
int channels;
int bits_per_pixel;
int bpp;
int has_trns;
uint8_t *image_buf;
int image_linesize;
uint32_t palette[256];
uint8_t *crow_buf;
uint8_t *last_row;
unsigned int last_row_size;
uint8_t *tmp_row;
unsigned int tmp_row_size;
uint8_t *buffer;
int buffer_size;
int pass;
int crow_size; /* compressed row size (include filter type) */
int row_size; /* decompressed row size */
int pass_row_size; /* decompress row size of the current pass */
int y;
z_stream zstream;
} PNGDecContext;
/* Mask to determine which pixels are valid in a pass */
static const uint8_t png_pass_mask[NB_PASSES] = {
0x01, 0x01, 0x11, 0x11, 0x55, 0x55, 0xff,
};
/* Mask to determine which y pixels can be written in a pass */
static const uint8_t png_pass_dsp_ymask[NB_PASSES] = {
0xff, 0xff, 0x0f, 0xff, 0x33, 0xff, 0x55,
};
/* Mask to determine which pixels to overwrite while displaying */
static const uint8_t png_pass_dsp_mask[NB_PASSES] = {
0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff
};
/* NOTE: we try to construct a good looking image at each pass. width
* is the original image width. We also do pixel format conversion at
* this stage */
static void png_put_interlaced_row(uint8_t *dst, int width,
int bits_per_pixel, int pass,
int color_type, const uint8_t *src)
{
int x, mask, dsp_mask, j, src_x, b, bpp;
uint8_t *d;
const uint8_t *s;
mask = png_pass_mask[pass];
dsp_mask = png_pass_dsp_mask[pass];
switch (bits_per_pixel) {
case 1:
src_x = 0;
for (x = 0; x < width; x++) {
j = (x & 7);
if ((dsp_mask << j) & 0x80) {
b = (src[src_x >> 3] >> (7 - (src_x & 7))) & 1;
dst[x >> 3] &= 0xFF7F>>j;
dst[x >> 3] |= b << (7 - j);
}
if ((mask << j) & 0x80)
src_x++;
}
break;
case 2:
src_x = 0;
for (x = 0; x < width; x++) {
int j2 = 2 * (x & 3);
j = (x & 7);
if ((dsp_mask << j) & 0x80) {
b = (src[src_x >> 2] >> (6 - 2*(src_x & 3))) & 3;
dst[x >> 2] &= 0xFF3F>>j2;
dst[x >> 2] |= b << (6 - j2);
}
if ((mask << j) & 0x80)
src_x++;
}
break;
case 4:
src_x = 0;
for (x = 0; x < width; x++) {
int j2 = 4*(x&1);
j = (x & 7);
if ((dsp_mask << j) & 0x80) {
b = (src[src_x >> 1] >> (4 - 4*(src_x & 1))) & 15;
dst[x >> 1] &= 0xFF0F>>j2;
dst[x >> 1] |= b << (4 - j2);
}
if ((mask << j) & 0x80)
src_x++;
}
break;
default:
bpp = bits_per_pixel >> 3;
d = dst;
s = src;
for (x = 0; x < width; x++) {
j = x & 7;
if ((dsp_mask << j) & 0x80) {
memcpy(d, s, bpp);
}
d += bpp;
if ((mask << j) & 0x80)
s += bpp;
}
break;
}
}
void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top,
int w, int bpp)
{
int i;
for (i = 0; i < w; i++) {
int a, b, c, p, pa, pb, pc;
a = dst[i - bpp];
b = top[i];
c = top[i - bpp];
p = b - c;
pc = a - c;
pa = abs(p);
pb = abs(pc);
pc = abs(p + pc);
if (pa <= pb && pa <= pc)
p = a;
else if (pb <= pc)
p = b;
else
p = c;
dst[i] = p + src[i];
}
}
#define UNROLL1(bpp, op) \
{ \
r = dst[0]; \
if (bpp >= 2) \
g = dst[1]; \
if (bpp >= 3) \
b = dst[2]; \
if (bpp >= 4) \
a = dst[3]; \
for (; i <= size - bpp; i += bpp) { \
dst[i + 0] = r = op(r, src[i + 0], last[i + 0]); \
if (bpp == 1) \
continue; \
dst[i + 1] = g = op(g, src[i + 1], last[i + 1]); \
if (bpp == 2) \
continue; \
dst[i + 2] = b = op(b, src[i + 2], last[i + 2]); \
if (bpp == 3) \
continue; \
dst[i + 3] = a = op(a, src[i + 3], last[i + 3]); \
} \
}
#define UNROLL_FILTER(op) \
if (bpp == 1) { \
UNROLL1(1, op) \
} else if (bpp == 2) { \
UNROLL1(2, op) \
} else if (bpp == 3) { \
UNROLL1(3, op) \
} else if (bpp == 4) { \
UNROLL1(4, op) \
} \
for (; i < size; i++) { \
dst[i] = op(dst[i - bpp], src[i], last[i]); \
}
/* NOTE: 'dst' can be equal to 'last' */
static void png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
uint8_t *src, uint8_t *last, int size, int bpp)
{
int i, p, r, g, b, a;
switch (filter_type) {
case PNG_FILTER_VALUE_NONE:
memcpy(dst, src, size);
break;
case PNG_FILTER_VALUE_SUB:
for (i = 0; i < bpp; i++)
dst[i] = src[i];
if (bpp == 4) {
p = *(int *)dst;
for (; i < size; i += bpp) {
unsigned s = *(int *)(src + i);
p = ((s & 0x7f7f7f7f) + (p & 0x7f7f7f7f)) ^ ((s ^ p) & 0x80808080);
*(int *)(dst + i) = p;
}
} else {
#define OP_SUB(x, s, l) ((x) + (s))
UNROLL_FILTER(OP_SUB);
}
break;
case PNG_FILTER_VALUE_UP:
dsp->add_bytes_l2(dst, src, last, size);
break;
case PNG_FILTER_VALUE_AVG:
for (i = 0; i < bpp; i++) {
p = (last[i] >> 1);
dst[i] = p + src[i];
}
#define OP_AVG(x, s, l) (((((x) + (l)) >> 1) + (s)) & 0xff)
UNROLL_FILTER(OP_AVG);
break;
case PNG_FILTER_VALUE_PAETH:
for (i = 0; i < bpp; i++) {
p = last[i];
dst[i] = p + src[i];
}
if (bpp > 2 && size > 4) {
/* would write off the end of the array if we let it process
* the last pixel with bpp=3 */
int w = (bpp & 3) ? size - 3 : size;
if (w > i) {
dsp->add_paeth_prediction(dst + i, src + i, last + i, size - i, bpp);
i = w;
}
}
ff_add_png_paeth_prediction(dst + i, src + i, last + i, size - i, bpp);
break;
}
}
/* This used to be called "deloco" in FFmpeg
* and is actually an inverse reversible colorspace transformation */
#define YUV2RGB(NAME, TYPE) \
static void deloco_ ## NAME(TYPE *dst, int size, int alpha) \
{ \
int i; \
for (i = 0; i < size; i += 3 + alpha) { \
int g = dst [i + 1]; \
dst[i + 0] += g; \
dst[i + 2] += g; \
} \
}
YUV2RGB(rgb8, uint8_t)
YUV2RGB(rgb16, uint16_t)
/* process exactly one decompressed row */
static void png_handle_row(PNGDecContext *s)
{
uint8_t *ptr, *last_row;
int got_line;
if (!s->interlace_type) {
ptr = s->image_buf + s->image_linesize * (s->y + s->y_offset) + s->x_offset * s->bpp;
if (s->y == 0)
last_row = s->last_row;
else
last_row = ptr - s->image_linesize;
png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
last_row, s->row_size, s->bpp);
/* loco lags by 1 row so that it doesn't interfere with top prediction */
if (s->filter_type == PNG_FILTER_TYPE_LOCO && s->y > 0) {
if (s->bit_depth == 16) {
deloco_rgb16((uint16_t *)(ptr - s->image_linesize), s->row_size / 2,
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
} else {
deloco_rgb8(ptr - s->image_linesize, s->row_size,
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
}
}
s->y++;
if (s->y == s->cur_h) {
s->state |= PNG_ALLIMAGE;
if (s->filter_type == PNG_FILTER_TYPE_LOCO) {
if (s->bit_depth == 16) {
deloco_rgb16((uint16_t *)ptr, s->row_size / 2,
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
} else {
deloco_rgb8(ptr, s->row_size,
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA);
}
}
}
} else {
got_line = 0;
for (;;) {
ptr = s->image_buf + s->image_linesize * (s->y + s->y_offset) + s->x_offset * s->bpp;
if ((ff_png_pass_ymask[s->pass] << (s->y & 7)) & 0x80) {
/* if we already read one row, it is time to stop to
* wait for the next one */
if (got_line)
break;
png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
s->last_row, s->pass_row_size, s->bpp);
FFSWAP(uint8_t *, s->last_row, s->tmp_row);
FFSWAP(unsigned int, s->last_row_size, s->tmp_row_size);
got_line = 1;
}
if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
png_put_interlaced_row(ptr, s->cur_w, s->bits_per_pixel, s->pass,
s->color_type, s->last_row);
}
s->y++;
if (s->y == s->cur_h) {
memset(s->last_row, 0, s->row_size);
for (;;) {
if (s->pass == NB_PASSES - 1) {
s->state |= PNG_ALLIMAGE;
goto the_end;
} else {
s->pass++;
s->y = 0;
s->pass_row_size = ff_png_pass_row_size(s->pass,
s->bits_per_pixel,
s->cur_w);
s->crow_size = s->pass_row_size + 1;
if (s->pass_row_size != 0)
break;
/* skip pass if empty row */
}
}
}
}
the_end:;
}
}
static int png_decode_idat(PNGDecContext *s, int length)
{
int ret;
s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
s->zstream.next_in = (unsigned char *)s->gb.buffer;
bytestream2_skip(&s->gb, length);
/* decode one line if possible */
while (s->zstream.avail_in > 0) {
ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END) {
av_log(s->avctx, AV_LOG_ERROR, "inflate returned error %d\n", ret);
return AVERROR_EXTERNAL;
}
if (s->zstream.avail_out == 0) {
if (!(s->state & PNG_ALLIMAGE)) {
png_handle_row(s);
}
s->zstream.avail_out = s->crow_size;
s->zstream.next_out = s->crow_buf;
}
if (ret == Z_STREAM_END && s->zstream.avail_in > 0) {
av_log(NULL, AV_LOG_WARNING,
"%d undecompressed bytes left in buffer\n", s->zstream.avail_in);
return 0;
}
}
return 0;
}
static int decode_zbuf(AVBPrint *bp, const uint8_t *data,
const uint8_t *data_end)
{
z_stream zstream;
unsigned char *buf;
unsigned buf_size;
int ret;
zstream.zalloc = ff_png_zalloc;
zstream.zfree = ff_png_zfree;
zstream.opaque = NULL;
if (inflateInit(&zstream) != Z_OK)
return AVERROR_EXTERNAL;
zstream.next_in = (unsigned char *)data;
zstream.avail_in = data_end - data;
av_bprint_init(bp, 0, -1);
while (zstream.avail_in > 0) {
av_bprint_get_buffer(bp, 1, &buf, &buf_size);
if (!buf_size) {
ret = AVERROR(ENOMEM);
goto fail;
}
zstream.next_out = buf;
zstream.avail_out = buf_size;
ret = inflate(&zstream, Z_PARTIAL_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END) {
ret = AVERROR_EXTERNAL;
goto fail;
}
bp->len += zstream.next_out - buf;
if (ret == Z_STREAM_END)
break;
}
inflateEnd(&zstream);
bp->str[bp->len] = 0;
return 0;
fail:
inflateEnd(&zstream);
av_bprint_finalize(bp, NULL);
return ret;
}
static uint8_t *iso88591_to_utf8(const uint8_t *in, size_t size_in)
{
size_t extra = 0, i;
uint8_t *out, *q;
for (i = 0; i < size_in; i++)
extra += in[i] >= 0x80;
if (size_in == SIZE_MAX || extra > SIZE_MAX - size_in - 1)
return NULL;
q = out = av_malloc(size_in + extra + 1);
if (!out)
return NULL;
for (i = 0; i < size_in; i++) {
if (in[i] >= 0x80) {
*(q++) = 0xC0 | (in[i] >> 6);
*(q++) = 0x80 | (in[i] & 0x3F);
} else {
*(q++) = in[i];
}
}
*(q++) = 0;
return out;
}
static int decode_text_chunk(PNGDecContext *s, uint32_t length, int compressed,
AVDictionary **dict)
{
int ret, method;
const uint8_t *data = s->gb.buffer;
const uint8_t *data_end = data + length;
const uint8_t *keyword = data;
const uint8_t *keyword_end = memchr(keyword, 0, data_end - keyword);
uint8_t *kw_utf8 = NULL, *text, *txt_utf8 = NULL;
unsigned text_len;
AVBPrint bp;
if (!keyword_end)
return AVERROR_INVALIDDATA;
data = keyword_end + 1;
if (compressed) {
if (data == data_end)
return AVERROR_INVALIDDATA;
method = *(data++);
if (method)
return AVERROR_INVALIDDATA;
if ((ret = decode_zbuf(&bp, data, data_end)) < 0)
return ret;
text_len = bp.len;
av_bprint_finalize(&bp, (char **)&text);
if (!text)
return AVERROR(ENOMEM);
} else {
text = (uint8_t *)data;
text_len = data_end - text;
}
kw_utf8 = iso88591_to_utf8(keyword, keyword_end - keyword);
txt_utf8 = iso88591_to_utf8(text, text_len);
if (text != data)
av_free(text);
if (!(kw_utf8 && txt_utf8)) {
av_free(kw_utf8);
av_free(txt_utf8);
return AVERROR(ENOMEM);
}
av_dict_set(dict, kw_utf8, txt_utf8,
AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
return 0;
}
static int decode_ihdr_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length)
{
if (length != 13)
return AVERROR_INVALIDDATA;
if (s->state & PNG_IDAT) {
av_log(avctx, AV_LOG_ERROR, "IHDR after IDAT\n");
return AVERROR_INVALIDDATA;
}
s->width = bytestream2_get_be32(&s->gb);
s->height = bytestream2_get_be32(&s->gb);
if (av_image_check_size(s->width, s->height, 0, avctx)) {
s->width = s->height = 0;
av_log(avctx, AV_LOG_ERROR, "Invalid image size\n");
return AVERROR_INVALIDDATA;
}
if (s->cur_w == 0 && s->cur_h == 0) {
// Only set cur_w/h if update_thread_context() has not set it
s->cur_w = s->width;
s->cur_h = s->height;
}
s->bit_depth = bytestream2_get_byte(&s->gb);
s->color_type = bytestream2_get_byte(&s->gb);
s->compression_type = bytestream2_get_byte(&s->gb);
s->filter_type = bytestream2_get_byte(&s->gb);
s->interlace_type = bytestream2_get_byte(&s->gb);
bytestream2_skip(&s->gb, 4); /* crc */
s->state |= PNG_IHDR;
if (avctx->debug & FF_DEBUG_PICT_INFO)
av_log(avctx, AV_LOG_DEBUG, "width=%d height=%d depth=%d color_type=%d "
"compression_type=%d filter_type=%d interlace_type=%d\n",
s->width, s->height, s->bit_depth, s->color_type,
s->compression_type, s->filter_type, s->interlace_type);
return 0;
}
static int decode_phys_chunk(AVCodecContext *avctx, PNGDecContext *s)
{
if (s->state & PNG_IDAT) {
av_log(avctx, AV_LOG_ERROR, "pHYs after IDAT\n");
return AVERROR_INVALIDDATA;
}
avctx->sample_aspect_ratio.num = bytestream2_get_be32(&s->gb);
avctx->sample_aspect_ratio.den = bytestream2_get_be32(&s->gb);
if (avctx->sample_aspect_ratio.num < 0 || avctx->sample_aspect_ratio.den < 0)
avctx->sample_aspect_ratio = (AVRational){ 0, 1 };
bytestream2_skip(&s->gb, 1); /* unit specifier */
bytestream2_skip(&s->gb, 4); /* crc */
return 0;
}
static int decode_idat_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length, AVFrame *p)
{
int ret;
if (!(s->state & PNG_IHDR)) {
av_log(avctx, AV_LOG_ERROR, "IDAT without IHDR\n");
return AVERROR_INVALIDDATA;
}
if (!(s->state & PNG_IDAT)) {
/* init image info */
avctx->width = s->width;
avctx->height = s->height;
s->channels = ff_png_get_nb_channels(s->color_type);
s->bits_per_pixel = s->bit_depth * s->channels;
s->bpp = (s->bits_per_pixel + 7) >> 3;
s->row_size = (s->cur_w * s->bits_per_pixel + 7) >> 3;
if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
s->color_type == PNG_COLOR_TYPE_RGB) {
avctx->pix_fmt = AV_PIX_FMT_RGB24;
} else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
avctx->pix_fmt = AV_PIX_FMT_RGBA;
} else if ((s->bit_depth == 2 || s->bit_depth == 4 || s->bit_depth == 8) &&
s->color_type == PNG_COLOR_TYPE_GRAY) {
avctx->pix_fmt = AV_PIX_FMT_GRAY8;
} else if (s->bit_depth == 16 &&
s->color_type == PNG_COLOR_TYPE_GRAY) {
avctx->pix_fmt = AV_PIX_FMT_GRAY16BE;
} else if (s->bit_depth == 16 &&
s->color_type == PNG_COLOR_TYPE_RGB) {
avctx->pix_fmt = AV_PIX_FMT_RGB48BE;
} else if (s->bit_depth == 16 &&
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
avctx->pix_fmt = AV_PIX_FMT_RGBA64BE;
} else if ((s->bits_per_pixel == 1 || s->bits_per_pixel == 2 || s->bits_per_pixel == 4 || s->bits_per_pixel == 8) &&
s->color_type == PNG_COLOR_TYPE_PALETTE) {
avctx->pix_fmt = AV_PIX_FMT_PAL8;
} else if (s->bit_depth == 1 && s->bits_per_pixel == 1 && avctx->codec_id != AV_CODEC_ID_APNG) {
avctx->pix_fmt = AV_PIX_FMT_MONOBLACK;
} else if (s->bit_depth == 8 &&
s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
avctx->pix_fmt = AV_PIX_FMT_YA8;
} else if (s->bit_depth == 16 &&
s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
avctx->pix_fmt = AV_PIX_FMT_YA16BE;
} else {
av_log(avctx, AV_LOG_ERROR, "unsupported bit depth %d "
"and color type %d\n",
s->bit_depth, s->color_type);
return AVERROR_INVALIDDATA;
}
if ((ret = ff_thread_get_buffer(avctx, &s->picture, AV_GET_BUFFER_FLAG_REF)) < 0)
return ret;
ff_thread_finish_setup(avctx);
p->pict_type = AV_PICTURE_TYPE_I;
p->key_frame = 1;
p->interlaced_frame = !!s->interlace_type;
/* compute the compressed row size */
if (!s->interlace_type) {
s->crow_size = s->row_size + 1;
} else {
s->pass = 0;
s->pass_row_size = ff_png_pass_row_size(s->pass,
s->bits_per_pixel,
s->cur_w);
s->crow_size = s->pass_row_size + 1;
}
ff_dlog(avctx, "row_size=%d crow_size =%d\n",
s->row_size, s->crow_size);
s->image_buf = p->data[0];
s->image_linesize = p->linesize[0];
/* copy the palette if needed */
if (avctx->pix_fmt == AV_PIX_FMT_PAL8)
memcpy(p->data[1], s->palette, 256 * sizeof(uint32_t));
/* empty row is used if differencing to the first row */
av_fast_padded_mallocz(&s->last_row, &s->last_row_size, s->row_size);
if (!s->last_row)
return AVERROR_INVALIDDATA;
if (s->interlace_type ||
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
av_fast_padded_malloc(&s->tmp_row, &s->tmp_row_size, s->row_size);
if (!s->tmp_row)
return AVERROR_INVALIDDATA;
}
/* compressed row */
av_fast_padded_malloc(&s->buffer, &s->buffer_size, s->row_size + 16);
if (!s->buffer)
return AVERROR(ENOMEM);
/* we want crow_buf+1 to be 16-byte aligned */
s->crow_buf = s->buffer + 15;
s->zstream.avail_out = s->crow_size;
s->zstream.next_out = s->crow_buf;
}
s->state |= PNG_IDAT;
if ((ret = png_decode_idat(s, length)) < 0)
return ret;
bytestream2_skip(&s->gb, 4); /* crc */
return 0;
}
static int decode_plte_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length)
{
int n, i, r, g, b;
if ((length % 3) != 0 || length > 256 * 3)
return AVERROR_INVALIDDATA;
/* read the palette */
n = length / 3;
for (i = 0; i < n; i++) {
r = bytestream2_get_byte(&s->gb);
g = bytestream2_get_byte(&s->gb);
b = bytestream2_get_byte(&s->gb);
s->palette[i] = (0xFFU << 24) | (r << 16) | (g << 8) | b;
}
for (; i < 256; i++)
s->palette[i] = (0xFFU << 24);
s->state |= PNG_PLTE;
bytestream2_skip(&s->gb, 4); /* crc */
return 0;
}
static int decode_trns_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length)
{
int v, i;
/* read the transparency. XXX: Only palette mode supported */
if (s->color_type != PNG_COLOR_TYPE_PALETTE ||
length > 256 ||
!(s->state & PNG_PLTE))
return AVERROR_INVALIDDATA;
for (i = 0; i < length; i++) {
v = bytestream2_get_byte(&s->gb);
s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
}
bytestream2_skip(&s->gb, 4); /* crc */
s->has_trns = 1;
return 0;
}
static void handle_small_bpp(PNGDecContext *s, AVFrame *p)
{
if (s->bits_per_pixel == 1 && s->color_type == PNG_COLOR_TYPE_PALETTE) {
int i, j, k;
uint8_t *pd = p->data[0];
for (j = 0; j < s->height; j++) {
i = s->width / 8;
for (k = 7; k >= 1; k--)
if ((s->width&7) >= k)
pd[8*i + k - 1] = (pd[i]>>8-k) & 1;
for (i--; i >= 0; i--) {
pd[8*i + 7]= pd[i] & 1;
pd[8*i + 6]= (pd[i]>>1) & 1;
pd[8*i + 5]= (pd[i]>>2) & 1;
pd[8*i + 4]= (pd[i]>>3) & 1;
pd[8*i + 3]= (pd[i]>>4) & 1;
pd[8*i + 2]= (pd[i]>>5) & 1;
pd[8*i + 1]= (pd[i]>>6) & 1;
pd[8*i + 0]= pd[i]>>7;
}
pd += s->image_linesize;
}
} else if (s->bits_per_pixel == 2) {
int i, j;
uint8_t *pd = p->data[0];
for (j = 0; j < s->height; j++) {
i = s->width / 4;
if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
if ((s->width&3) >= 3) pd[4*i + 2]= (pd[i] >> 2) & 3;
if ((s->width&3) >= 2) pd[4*i + 1]= (pd[i] >> 4) & 3;
if ((s->width&3) >= 1) pd[4*i + 0]= pd[i] >> 6;
for (i--; i >= 0; i--) {
pd[4*i + 3]= pd[i] & 3;
pd[4*i + 2]= (pd[i]>>2) & 3;
pd[4*i + 1]= (pd[i]>>4) & 3;
pd[4*i + 0]= pd[i]>>6;
}
} else {
if ((s->width&3) >= 3) pd[4*i + 2]= ((pd[i]>>2) & 3)*0x55;
if ((s->width&3) >= 2) pd[4*i + 1]= ((pd[i]>>4) & 3)*0x55;
if ((s->width&3) >= 1) pd[4*i + 0]= ( pd[i]>>6 )*0x55;
for (i--; i >= 0; i--) {
pd[4*i + 3]= ( pd[i] & 3)*0x55;
pd[4*i + 2]= ((pd[i]>>2) & 3)*0x55;
pd[4*i + 1]= ((pd[i]>>4) & 3)*0x55;
pd[4*i + 0]= ( pd[i]>>6 )*0x55;
}
}
pd += s->image_linesize;
}
} else if (s->bits_per_pixel == 4) {
int i, j;
uint8_t *pd = p->data[0];
for (j = 0; j < s->height; j++) {
i = s->width/2;
if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
if (s->width&1) pd[2*i+0]= pd[i]>>4;
for (i--; i >= 0; i--) {
pd[2*i + 1] = pd[i] & 15;
pd[2*i + 0] = pd[i] >> 4;
}
} else {
if (s->width & 1) pd[2*i + 0]= (pd[i] >> 4) * 0x11;
for (i--; i >= 0; i--) {
pd[2*i + 1] = (pd[i] & 15) * 0x11;
pd[2*i + 0] = (pd[i] >> 4) * 0x11;
}
}
pd += s->image_linesize;
}
}
}
static int decode_fctl_chunk(AVCodecContext *avctx, PNGDecContext *s,
uint32_t length)
{
uint32_t sequence_number;
if (length != 26)
return AVERROR_INVALIDDATA;
s->last_w = s->cur_w;
s->last_h = s->cur_h;
s->last_x_offset = s->x_offset;
s->last_y_offset = s->y_offset;
s->last_dispose_op = s->dispose_op;
sequence_number = bytestream2_get_be32(&s->gb);
s->cur_w = bytestream2_get_be32(&s->gb);
s->cur_h = bytestream2_get_be32(&s->gb);
s->x_offset = bytestream2_get_be32(&s->gb);
s->y_offset = bytestream2_get_be32(&s->gb);
bytestream2_skip(&s->gb, 4); /* delay_num (2), delay_den (2) */
s->dispose_op = bytestream2_get_byte(&s->gb);
s->blend_op = bytestream2_get_byte(&s->gb);
bytestream2_skip(&s->gb, 4); /* crc */
if (sequence_number == 0 &&
(s->cur_w != s->width ||
s->cur_h != s->height ||
s->x_offset != 0 ||
s->y_offset != 0) ||
s->cur_w <= 0 || s->cur_h <= 0 ||
s->x_offset < 0 || s->y_offset < 0 ||
s->cur_w > s->width - s->x_offset|| s->cur_h > s->height - s->y_offset)
return AVERROR_INVALIDDATA;
if (sequence_number == 0 && s->dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
// No previous frame to revert to for the first frame
// Spec says to just treat it as a APNG_DISPOSE_OP_BACKGROUND
s->dispose_op = APNG_DISPOSE_OP_BACKGROUND;
}
if (s->dispose_op == APNG_BLEND_OP_OVER && !s->has_trns && (
avctx->pix_fmt == AV_PIX_FMT_RGB24 ||
avctx->pix_fmt == AV_PIX_FMT_RGB48BE ||
avctx->pix_fmt == AV_PIX_FMT_PAL8 ||
avctx->pix_fmt == AV_PIX_FMT_GRAY8 ||
avctx->pix_fmt == AV_PIX_FMT_GRAY16BE ||
avctx->pix_fmt == AV_PIX_FMT_MONOBLACK
)) {
// APNG_DISPOSE_OP_OVER is the same as APNG_DISPOSE_OP_SOURCE when there is no alpha channel
s->dispose_op = APNG_BLEND_OP_SOURCE;
}
return 0;
}
static void handle_p_frame_png(PNGDecContext *s, AVFrame *p)
{
int i, j;
uint8_t *pd = p->data[0];
uint8_t *pd_last = s->last_picture.f->data[0];
int ls = FFMIN(av_image_get_linesize(p->format, s->width, 0), s->width * s->bpp);
ff_thread_await_progress(&s->last_picture, INT_MAX, 0);
for (j = 0; j < s->height; j++) {
for (i = 0; i < ls; i++)
pd[i] += pd_last[i];
pd += s->image_linesize;
pd_last += s->image_linesize;
}
}
// divide by 255 and round to nearest
// apply a fast variant: (X+127)/255 = ((X+127)*257+257)>>16 = ((X+128)*257)>>16
#define FAST_DIV255(x) ((((x) + 128) * 257) >> 16)
static int handle_p_frame_apng(AVCodecContext *avctx, PNGDecContext *s,
AVFrame *p)
{
size_t x, y;
uint8_t *buffer = av_malloc(s->image_linesize * s->height);
if (!buffer)
return AVERROR(ENOMEM);
if (s->blend_op == APNG_BLEND_OP_OVER &&
avctx->pix_fmt != AV_PIX_FMT_RGBA &&
avctx->pix_fmt != AV_PIX_FMT_GRAY8A &&
avctx->pix_fmt != AV_PIX_FMT_PAL8) {
avpriv_request_sample(avctx, "Blending with pixel format %s",
av_get_pix_fmt_name(avctx->pix_fmt));
return AVERROR_PATCHWELCOME;
}
// Copy the previous frame to the buffer
ff_thread_await_progress(&s->last_picture, INT_MAX, 0);
memcpy(buffer, s->last_picture.f->data[0], s->image_linesize * s->height);
// Do the disposal operation specified by the last frame on the frame
if (s->last_dispose_op == APNG_DISPOSE_OP_BACKGROUND) {
for (y = s->last_y_offset; y < s->last_y_offset + s->last_h; ++y)
memset(buffer + s->image_linesize * y + s->bpp * s->last_x_offset, 0, s->bpp * s->last_w);
} else if (s->last_dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
ff_thread_await_progress(&s->previous_picture, INT_MAX, 0);
for (y = s->last_y_offset; y < s->last_y_offset + s->last_h; ++y) {
size_t row_start = s->image_linesize * y + s->bpp * s->last_x_offset;
memcpy(buffer + row_start, s->previous_picture.f->data[0] + row_start, s->bpp * s->last_w);
}
}
// Perform blending
if (s->blend_op == APNG_BLEND_OP_SOURCE) {
for (y = s->y_offset; y < s->y_offset + s->cur_h; ++y) {
size_t row_start = s->image_linesize * y + s->bpp * s->x_offset;
memcpy(buffer + row_start, p->data[0] + row_start, s->bpp * s->cur_w);
}
} else { // APNG_BLEND_OP_OVER
for (y = s->y_offset; y < s->y_offset + s->cur_h; ++y) {
uint8_t *foreground = p->data[0] + s->image_linesize * y + s->bpp * s->x_offset;
uint8_t *background = buffer + s->image_linesize * y + s->bpp * s->x_offset;
for (x = s->x_offset; x < s->x_offset + s->cur_w; ++x, foreground += s->bpp, background += s->bpp) {
size_t b;
uint8_t foreground_alpha, background_alpha, output_alpha;
uint8_t output[4];
// Since we might be blending alpha onto alpha, we use the following equations:
// output_alpha = foreground_alpha + (1 - foreground_alpha) * background_alpha
// output = (foreground_alpha * foreground + (1 - foreground_alpha) * background_alpha * background) / output_alpha
switch (avctx->pix_fmt) {
case AV_PIX_FMT_RGBA:
foreground_alpha = foreground[3];
background_alpha = background[3];
break;
case AV_PIX_FMT_GRAY8A:
foreground_alpha = foreground[1];
background_alpha = background[1];
break;
case AV_PIX_FMT_PAL8:
foreground_alpha = s->palette[foreground[0]] >> 24;
background_alpha = s->palette[background[0]] >> 24;
break;
}
if (foreground_alpha == 0)
continue;
if (foreground_alpha == 255) {
memcpy(background, foreground, s->bpp);
continue;
}
if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
// TODO: Alpha blending with PAL8 will likely need the entire image converted over to RGBA first
avpriv_request_sample(avctx, "Alpha blending palette samples");
background[0] = foreground[0];
continue;
}
output_alpha = foreground_alpha + FAST_DIV255((255 - foreground_alpha) * background_alpha);
for (b = 0; b < s->bpp - 1; ++b) {
if (output_alpha == 0) {
output[b] = 0;
} else if (background_alpha == 255) {
output[b] = FAST_DIV255(foreground_alpha * foreground[b] + (255 - foreground_alpha) * background[b]);
} else {
output[b] = (255 * foreground_alpha * foreground[b] + (255 - foreground_alpha) * background_alpha * background[b]) / (255 * output_alpha);
}
}
output[b] = output_alpha;
memcpy(background, output, s->bpp);
}
}
}
// Copy blended buffer into the frame and free
memcpy(p->data[0], buffer, s->image_linesize * s->height);
av_free(buffer);
return 0;
}
static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
AVFrame *p, AVPacket *avpkt)
{