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decode mng color decorrelation

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Originally committed as revision 12228 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Loren Merritt 2008-02-26 10:21:33 +00:00
parent d248905ba5
commit 042e0adda9
4 changed files with 37 additions and 3 deletions
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1
libavcodec/png.c
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@ -23,6 +23,7 @@
#include "png.h"
const uint8_t ff_pngsig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
const uint8_t ff_mngsig[8] = {138, 77, 78, 71, 13, 10, 26, 10};
/* Mask to determine which y pixels are valid in a pass */
const uint8_t ff_png_pass_ymask[NB_PASSES] = {

2
libavcodec/png.h
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@ -34,6 +34,7 @@
#define PNG_COLOR_TYPE_RGB_ALPHA (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
#define PNG_FILTER_TYPE_LOCO 64
#define PNG_FILTER_VALUE_NONE 0
#define PNG_FILTER_VALUE_SUB 1
#define PNG_FILTER_VALUE_UP 2
@ -49,6 +50,7 @@
#define NB_PASSES 7
extern const uint8_t ff_pngsig[8];
extern const uint8_t ff_mngsig[8];
/* Mask to determine which y pixels are valid in a pass */
extern const uint8_t ff_png_pass_ymask[NB_PASSES];

36
libavcodec/pngdec.c
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@ -234,7 +234,7 @@ static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
}
}
static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width)
static av_always_inline void convert_to_rgb32_loco(uint8_t *dst, const uint8_t *src, int width, int loco)
{
int j;
unsigned int r, g, b, a;
@ -244,12 +244,34 @@ static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width)
g = src[1];
b = src[2];
a = src[3];
if(loco) {
r = (r+g)&0xff;
b = (b+g)&0xff;
}
*(uint32_t *)dst = (a << 24) | (r << 16) | (g << 8) | b;
dst += 4;
src += 4;
}
}
static void convert_to_rgb32(uint8_t *dst, const uint8_t *src, int width, int loco)
{
if(loco)
convert_to_rgb32_loco(dst, src, width, 1);
else
convert_to_rgb32_loco(dst, src, width, 0);
}
static void deloco_rgb24(uint8_t *dst, int size)
{
int i;
for(i=0; i<size; i+=3) {
int g = dst[i+1];
dst[i+0] += g;
dst[i+2] += g;
}
}
/* process exactly one decompressed row */
static void png_handle_row(PNGDecContext *s)
{
@ -262,7 +284,7 @@ static void png_handle_row(PNGDecContext *s)
if (s->color_type == PNG_COLOR_TYPE_RGB_ALPHA) {
png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
s->last_row, s->row_size, s->bpp);
convert_to_rgb32(ptr, s->tmp_row, s->width);
convert_to_rgb32(ptr, s->tmp_row, s->width, s->filter_type == PNG_FILTER_TYPE_LOCO);
FFSWAP(uint8_t*, s->last_row, s->tmp_row);
} else {
/* in normal case, we avoid one copy */
@ -274,9 +296,16 @@ static void png_handle_row(PNGDecContext *s)
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->color_type == PNG_COLOR_TYPE_RGB && s->y > 0)
deloco_rgb24(ptr - s->image_linesize, s->row_size);
s->y++;
if (s->y == s->height) {
s->state |= PNG_ALLIMAGE;
if (s->filter_type == PNG_FILTER_TYPE_LOCO &&
s->color_type == PNG_COLOR_TYPE_RGB)
deloco_rgb24(ptr, s->row_size);
}
} else {
got_line = 0;
@ -363,7 +392,8 @@ static int decode_frame(AVCodecContext *avctx,
s->bytestream_end= buf + buf_size;
/* check signature */
if (memcmp(s->bytestream, ff_pngsig, 8) != 0)
if (memcmp(s->bytestream, ff_pngsig, 8) != 0 &&
memcmp(s->bytestream, ff_mngsig, 8) != 0)
return -1;
s->bytestream+= 8;
s->y=

1
libavformat/img2.c
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@ -41,6 +41,7 @@ static const IdStrMap img_tags[] = {
{ CODEC_ID_MJPEG , "jpg"},
{ CODEC_ID_LJPEG , "ljpg"},
{ CODEC_ID_PNG , "png"},
{ CODEC_ID_PNG , "mng"},
{ CODEC_ID_PPM , "ppm"},
{ CODEC_ID_PGM , "pgm"},
{ CODEC_ID_PGMYUV , "pgmyuv"},