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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* |
| 2 | * PNG image format |
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| 3 | * Copyright (c) 2003 Fabrice Bellard |
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| 4 | * |
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| 5 | * This file is part of FFmpeg. |
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| 6 | * |
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| 7 | * FFmpeg is free software; you can redistribute it and/or |
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| 8 | * modify it under the terms of the GNU Lesser General Public |
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| 9 | * License as published by the Free Software Foundation; either |
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| 10 | * version 2.1 of the License, or (at your option) any later version. |
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| 11 | * |
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| 12 | * FFmpeg is distributed in the hope that it will be useful, |
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 15 | * Lesser General Public License for more details. |
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| 16 | * |
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| 17 | * You should have received a copy of the GNU Lesser General Public |
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| 18 | * License along with FFmpeg; if not, write to the Free Software |
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| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 20 | */ |
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| 21 | #include "avcodec.h" |
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| 22 | #include "png.h" |
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| 23 | |||
| 24 | /* Mask to determine which y pixels are valid in a pass */ |
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| 25 | const uint8_t ff_png_pass_ymask[NB_PASSES] = { |
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| 26 | 0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, |
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| 27 | }; |
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| 28 | |||
| 29 | /* minimum x value */ |
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| 30 | static const uint8_t ff_png_pass_xmin[NB_PASSES] = { |
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| 31 | 0, 4, 0, 2, 0, 1, 0 |
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| 32 | }; |
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| 33 | |||
| 34 | /* x shift to get row width */ |
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| 35 | static const uint8_t ff_png_pass_xshift[NB_PASSES] = { |
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| 36 | 3, 3, 2, 2, 1, 1, 0 |
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| 37 | }; |
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| 38 | |||
| 39 | void *ff_png_zalloc(void *opaque, unsigned int items, unsigned int size) |
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| 40 | { |
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| 41 | return av_mallocz_array(items, size); |
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| 42 | } |
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| 43 | |||
| 44 | void ff_png_zfree(void *opaque, void *ptr) |
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| 45 | { |
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| 46 | av_free(ptr); |
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| 47 | } |
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| 48 | |||
| 49 | int ff_png_get_nb_channels(int color_type) |
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| 50 | { |
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| 51 | int channels; |
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| 52 | channels = 1; |
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| 53 | if ((color_type & (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)) == |
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| 54 | PNG_COLOR_MASK_COLOR) |
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| 55 | channels = 3; |
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| 56 | if (color_type & PNG_COLOR_MASK_ALPHA) |
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| 57 | channels++; |
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| 58 | return channels; |
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| 59 | } |
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| 60 | |||
| 61 | /* compute the row size of an interleaved pass */ |
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| 62 | int ff_png_pass_row_size(int pass, int bits_per_pixel, int width) |
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| 63 | { |
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| 64 | int shift, xmin, pass_width; |
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| 65 | |||
| 66 | xmin = ff_png_pass_xmin[pass]; |
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| 67 | if (width <= xmin) |
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| 68 | return 0; |
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| 69 | shift = ff_png_pass_xshift[pass]; |
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| 70 | pass_width = (width - xmin + (1 << shift) - 1) >> shift; |
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| 71 | return (pass_width * bits_per_pixel + 7) >> 3; |
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| 72 | } |