FFmpeg
libavcodec
png.c
Go to the documentation of this file.
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/*
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* PNG image format
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* Copyright (c) 2003 Fabrice Bellard
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdint.h>
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#include "
libavutil/mem.h
"
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#include "
png.h
"
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/* Mask to determine which y pixels are valid in a pass */
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const
uint8_t
ff_png_pass_ymask
[
NB_PASSES
] = {
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0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55,
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};
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/* minimum x value */
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static
const
uint8_t
ff_png_pass_xmin
[
NB_PASSES
] = {
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0, 4, 0, 2, 0, 1, 0
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};
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/* x shift to get row width */
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static
const
uint8_t
ff_png_pass_xshift
[
NB_PASSES
] = {
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3, 3, 2, 2, 1, 1, 0
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};
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int
ff_png_get_nb_channels
(
int
color_type)
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{
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int
channels
;
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channels
= 1;
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if
((color_type & (
PNG_COLOR_MASK_COLOR
|
PNG_COLOR_MASK_PALETTE
)) ==
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PNG_COLOR_MASK_COLOR
)
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channels
= 3;
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if
(color_type &
PNG_COLOR_MASK_ALPHA
)
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channels
++;
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return
channels
;
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}
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/* compute the row size of an interleaved pass */
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int
ff_png_pass_row_size
(
int
pass
,
int
bits_per_pixel,
int
width
)
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{
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int
shift
, xmin, pass_width;
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xmin =
ff_png_pass_xmin
[
pass
];
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if
(
width
<= xmin)
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return
0;
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shift
=
ff_png_pass_xshift
[
pass
];
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pass_width = (
width
- xmin + (1 <<
shift
) - 1) >>
shift
;
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return
(pass_width * bits_per_pixel + 7) >> 3;
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}
ff_png_get_nb_channels
int ff_png_get_nb_channels(int color_type)
Definition:
png.c:41
ff_png_pass_xmin
static const uint8_t ff_png_pass_xmin[NB_PASSES]
Definition:
png.c:32
NB_PASSES
#define NB_PASSES
Definition:
png.h:47
ff_png_pass_row_size
int ff_png_pass_row_size(int pass, int bits_per_pixel, int width)
Definition:
png.c:54
width
#define width
channels
channels
Definition:
aptx.h:31
pass
#define pass
Definition:
fft_template.c:608
ff_png_pass_ymask
const uint8_t ff_png_pass_ymask[NB_PASSES]
Definition:
png.c:27
shift
static int shift(int a, int b)
Definition:
bonk.c:257
PNG_COLOR_MASK_COLOR
#define PNG_COLOR_MASK_COLOR
Definition:
png.h:30
PNG_COLOR_MASK_PALETTE
#define PNG_COLOR_MASK_PALETTE
Definition:
png.h:29
mem.h
png.h
PNG_COLOR_MASK_ALPHA
#define PNG_COLOR_MASK_ALPHA
Definition:
png.h:31
ff_png_pass_xshift
static const uint8_t ff_png_pass_xshift[NB_PASSES]
Definition:
png.c:37
Generated on Tue Feb 28 2023 21:33:34 for FFmpeg by
1.8.17