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ffmpeg/libavcodec/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 "png.h"
#include "pngdsp.h"
/* TODO:
* - add 16 bit depth support
*/
#include <zlib.h>
typedef struct PNGDecContext {
PNGDSPContext dsp;
AVCodecContext *avctx;
GetByteContext gb;
AVFrame *prev;
int state;
int width, height;
int bit_depth;
int color_type;
int compression_type;
int interlace_type;
int filter_type;
int channels;
int bits_per_pixel;
int bpp;
uint8_t *image_buf;
int image_linesize;
uint32_t palette[256];
uint8_t *crow_buf;
uint8_t *last_row;
uint8_t *tmp_row;
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) {
int 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 == 4 ? size : size - 3;
dsp->add_paeth_prediction(dst + i, src + i, last + i, w - 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;
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->height) {
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;
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);
got_line = 1;
}
if ((png_pass_dsp_ymask[s->pass] << (s->y & 7)) & 0x80) {
png_put_interlaced_row(ptr, s->width, s->bits_per_pixel, s->pass,
s->color_type, s->last_row);
}
s->y++;
if (s->y == s->height) {
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->width);
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 %d\n", ret);
return -1;
}
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;
}
}
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_frame(AVCodecContext *avctx,
void *data, int *got_frame,
AVPacket *avpkt)
{
PNGDecContext * const s = avctx->priv_data;
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
AVFrame *p = data;
AVDictionary *metadata = NULL;
uint8_t *crow_buf_base = NULL;
uint32_t tag, length;
int64_t sig;
int ret;
bytestream2_init(&s->gb, buf, buf_size);
/* check signature */
sig = bytestream2_get_be64(&s->gb);
if (sig != PNGSIG &&
sig != MNGSIG) {
av_log(avctx, AV_LOG_ERROR, "Missing png signature\n");
return -1;
}
s->y = s->state = 0;
/* init the zlib */
s->zstream.zalloc = ff_png_zalloc;
s->zstream.zfree = ff_png_zfree;
s->zstream.opaque = NULL;
ret = inflateInit(&s->zstream);
if (ret != Z_OK) {
av_log(avctx, AV_LOG_ERROR, "inflateInit returned %d\n", ret);
return -1;
}
for (;;) {
if (bytestream2_get_bytes_left(&s->gb) <= 0) {
av_log(avctx, AV_LOG_ERROR, "No bytes left\n");
goto fail;
}
length = bytestream2_get_be32(&s->gb);
if (length > 0x7fffffff || length > bytestream2_get_bytes_left(&s->gb)) {
av_log(avctx, AV_LOG_ERROR, "chunk too big\n");
goto fail;
}
tag = bytestream2_get_le32(&s->gb);
if (avctx->debug & FF_DEBUG_STARTCODE)
av_log(avctx, AV_LOG_DEBUG, "png: tag=%c%c%c%c length=%u\n",
(tag & 0xff),
((tag >> 8) & 0xff),
((tag >> 16) & 0xff),
((tag >> 24) & 0xff), length);
switch (tag) {
case MKTAG('I', 'H', 'D', 'R'):
if (length != 13)
goto fail;
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");
goto fail;
}
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);
break;
case MKTAG('p', 'H', 'Y', 's'):
if (s->state & PNG_IDAT) {
av_log(avctx, AV_LOG_ERROR, "pHYs after IDAT\n");
goto fail;
}
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 */
break;
case MKTAG('I', 'D', 'A', 'T'):
if (!(s->state & PNG_IHDR)) {
av_log(avctx, AV_LOG_ERROR, "IDAT without IHDR\n");
goto fail;
}
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 = (avctx->width * 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) {
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_Y400A;
} else {
av_log(avctx, AV_LOG_ERROR, "unsupported bit depth %d "
"and color type %d\n",
s->bit_depth, s->color_type);
goto fail;
}
if (ff_get_buffer(avctx, p, AV_GET_BUFFER_FLAG_REF) < 0)
goto fail;
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->width);
s->crow_size = s->pass_row_size + 1;
}
av_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 */
s->last_row = av_mallocz(s->row_size);
if (!s->last_row)
goto fail;
if (s->interlace_type ||
s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
s->tmp_row = av_malloc(s->row_size);
if (!s->tmp_row)
goto fail;
}
/* compressed row */
crow_buf_base = av_malloc(s->row_size + 16);
if (!crow_buf_base)
goto fail;
/* we want crow_buf+1 to be 16-byte aligned */
s->crow_buf = crow_buf_base + 15;
s->zstream.avail_out = s->crow_size;
s->zstream.next_out = s->crow_buf;
}
s->state |= PNG_IDAT;
if (png_decode_idat(s, length) < 0)
goto fail;
bytestream2_skip(&s->gb, 4); /* crc */
break;
case MKTAG('P', 'L', 'T', 'E'):
{
int n, i, r, g, b;
if ((length % 3) != 0 || length > 256 * 3)
goto skip_tag;
/* 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 */
}
break;
case MKTAG('t', 'R', 'N', 'S'):
{
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))
goto skip_tag;
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 */
}
break;
case MKTAG('t', 'E', 'X', 't'):
if (decode_text_chunk(s, length, 0, &metadata) < 0)
av_log(avctx, AV_LOG_WARNING, "Broken tEXt chunk\n");
bytestream2_skip(&s->gb, length + 4);
break;
case MKTAG('z', 'T', 'X', 't'):
if (decode_text_chunk(s, length, 1, &metadata) < 0)
av_log(avctx, AV_LOG_WARNING, "Broken zTXt chunk\n");
bytestream2_skip(&s->gb, length + 4);
break;
case MKTAG('I', 'E', 'N', 'D'):
if (!(s->state & PNG_ALLIMAGE))
av_log(avctx, AV_LOG_ERROR, "IEND without all image\n");
if (!(s->state & (PNG_ALLIMAGE|PNG_IDAT))) {
goto fail;
}
bytestream2_skip(&s->gb, 4); /* crc */
goto exit_loop;
default:
/* skip tag */
skip_tag:
bytestream2_skip(&s->gb, length + 4);
break;
}
}
exit_loop:
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;
}
}
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;
}
}
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;
}
}
/* handle p-frames only if a predecessor frame is available */
if (s->prev->data[0]) {
if ( !(avpkt->flags & AV_PKT_FLAG_KEY) && avctx->codec_tag != AV_RL32("MPNG")
&& s->prev->width == p->width
&& s->prev->height== p->height
&& s->prev->format== p->format
) {
int i, j;
uint8_t *pd = p->data[0];
uint8_t *pd_last = s->prev->data[0];
for (j = 0; j < s->height; j++) {
for (i = 0; i < s->width * s->bpp; i++) {
pd[i] += pd_last[i];
}
pd += s->image_linesize;
pd_last += s->image_linesize;
}
}
}
av_frame_set_metadata(p, metadata);
metadata = NULL;
av_frame_unref(s->prev);
if ((ret = av_frame_ref(s->prev, p)) < 0)
goto fail;
*got_frame = 1;
ret = bytestream2_tell(&s->gb);
the_end:
inflateEnd(&s->zstream);
av_free(crow_buf_base);
s->crow_buf = NULL;
av_freep(&s->last_row);
av_freep(&s->tmp_row);
return ret;
fail:
av_dict_free(&metadata);
ret = -1;
goto the_end;
}
static av_cold int png_dec_init(AVCodecContext *avctx)
{
PNGDecContext *s = avctx->priv_data;
s->prev = av_frame_alloc();
if (!s->prev)
return AVERROR(ENOMEM);
ff_pngdsp_init(&s->dsp);
s->avctx = avctx;
return 0;
}
static av_cold int png_dec_end(AVCodecContext *avctx)
{
PNGDecContext *s = avctx->priv_data;
av_frame_free(&s->prev);
return 0;
}
AVCodec ff_png_decoder = {
.name = "png",
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_PNG,
.priv_data_size = sizeof(PNGDecContext),
.init = png_dec_init,
.close = png_dec_end,
.decode = decode_frame,
.capabilities = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
.long_name = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
};
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