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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 6147 | serge | 1 | /* |
| 2 | * RLE encoder |
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| 3 | * Copyright (c) 2007 Bobby Bingham |
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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 "rle.h" |
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| 23 | #include "libavutil/common.h" |
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| 24 | |||
| 25 | /** |
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| 26 | * Count up to 127 consecutive pixels which are either all the same or |
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| 27 | * all differ from the previous and next pixels. |
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| 28 | * @param start Pointer to the first pixel |
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| 29 | * @param len Maximum number of pixels |
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| 30 | * @param bpp Bytes per pixel |
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| 31 | * @param same 1 if searching for identical pixel values. 0 for differing |
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| 32 | * @return Number of matching consecutive pixels found |
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| 33 | */ |
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| 34 | static int count_pixels(const uint8_t *start, int len, int bpp, int same) |
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| 35 | { |
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| 36 | const uint8_t *pos; |
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| 37 | int count = 1; |
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| 38 | |||
| 39 | for(pos = start + bpp; count < FFMIN(127, len); pos += bpp, count ++) { |
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| 40 | if(same != !memcmp(pos-bpp, pos, bpp)) { |
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| 41 | if(!same) { |
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| 42 | /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a single |
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| 43 | * raw block of pixels. for larger bpp, RLE is as good or better */ |
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| 44 | if(bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos+1)) |
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| 45 | continue; |
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| 46 | |||
| 47 | /* if RLE can encode the next block better than as a raw block, |
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| 48 | * back up and leave _all_ the identical pixels for RLE */ |
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| 49 | count --; |
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| 50 | } |
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| 51 | break; |
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| 52 | } |
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| 53 | } |
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| 54 | |||
| 55 | return count; |
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| 56 | } |
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| 57 | |||
| 58 | int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr , int bpp, int w, |
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| 59 | int add_rep, int xor_rep, int add_raw, int xor_raw) |
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| 60 | { |
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| 61 | int count, x; |
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| 62 | uint8_t *out = outbuf; |
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| 63 | |||
| 64 | for(x = 0; x < w; x += count) { |
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| 65 | /* see if we can encode the next set of pixels with RLE */ |
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| 66 | if((count = count_pixels(ptr, w-x, bpp, 1)) > 1) { |
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| 67 | if(out + bpp + 1 > outbuf + out_size) return -1; |
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| 68 | *out++ = (count ^ xor_rep) + add_rep; |
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| 69 | memcpy(out, ptr, bpp); |
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| 70 | out += bpp; |
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| 71 | } else { |
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| 72 | /* fall back on uncompressed */ |
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| 73 | count = count_pixels(ptr, w-x, bpp, 0); |
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| 74 | if(out + bpp*count >= outbuf + out_size) return -1; |
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| 75 | *out++ = (count ^ xor_raw) + add_raw; |
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| 76 | |||
| 77 | memcpy(out, ptr, bpp * count); |
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| 78 | out += bpp * count; |
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| 79 | } |
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| 80 | |||
| 81 | ptr += count * bpp; |
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| 82 | } |
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| 83 | |||
| 84 | return out - outbuf; |
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| 85 | } |