blob: 792bc05e5d02f9f3a920d78a15d2842b01a6df55
| 1 | /* |
| 2 | * RLE encoder |
| 3 | * Copyright (c) 2007 Bobby Bingham |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | #include "libavutil/common.h" |
| 23 | |
| 24 | #include "avcodec.h" |
| 25 | #include "rle.h" |
| 26 | |
| 27 | int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same) |
| 28 | { |
| 29 | const uint8_t *pos; |
| 30 | int count = 1; |
| 31 | |
| 32 | for (pos = start + bpp; count < FFMIN(127, len); pos += bpp, count++) { |
| 33 | if (same != !memcmp(pos - bpp, pos, bpp)) { |
| 34 | if (!same) { |
| 35 | /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a |
| 36 | * single raw block of pixels. For larger bpp, RLE is as good |
| 37 | * or better */ |
| 38 | if (bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos + 1)) |
| 39 | continue; |
| 40 | |
| 41 | /* if RLE can encode the next block better than as a raw block, |
| 42 | * back up and leave _all_ the identical pixels for RLE */ |
| 43 | count--; |
| 44 | } |
| 45 | break; |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | return count; |
| 50 | } |
| 51 | |
| 52 | int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr, int bpp, |
| 53 | int w, int add_rep, int xor_rep, int add_raw, int xor_raw) |
| 54 | { |
| 55 | int count, x; |
| 56 | uint8_t *out = outbuf; |
| 57 | |
| 58 | for (x = 0; x < w; x += count) { |
| 59 | /* see if we can encode the next set of pixels with RLE */ |
| 60 | if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) { |
| 61 | if (out + bpp + 1 > outbuf + out_size) |
| 62 | return -1; |
| 63 | |
| 64 | *out++ = (count ^ xor_rep) + add_rep; |
| 65 | memcpy(out, ptr, bpp); |
| 66 | out += bpp; |
| 67 | } else { |
| 68 | /* fall back on uncompressed */ |
| 69 | count = ff_rle_count_pixels(ptr, w - x, bpp, 0); |
| 70 | if (out + bpp * count >= outbuf + out_size) |
| 71 | return -1; |
| 72 | |
| 73 | *out++ = (count ^ xor_raw) + add_raw; |
| 74 | memcpy(out, ptr, bpp * count); |
| 75 | out += bpp * count; |
| 76 | } |
| 77 | |
| 78 | ptr += count * bpp; |
| 79 | } |
| 80 | |
| 81 | return out - outbuf; |
| 82 | } |
| 83 |