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 <string.h> 23 24#include "libavutil/macros.h" 25 26#include "rle.h" 27 28int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same) 29{ 30 const uint8_t *pos; 31 int count = 1; 32 33 for (pos = start + bpp; count < FFMIN(127, len); pos += bpp, count++) { 34 if (same != !memcmp(pos - bpp, pos, bpp)) { 35 if (!same) { 36 /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a 37 * single raw block of pixels. For larger bpp, RLE is as good 38 * or better */ 39 if (bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos + 1)) 40 continue; 41 42 /* if RLE can encode the next block better than as a raw block, 43 * back up and leave _all_ the identical pixels for RLE */ 44 count--; 45 } 46 break; 47 } 48 } 49 50 return count; 51} 52 53int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr, int bpp, 54 int w, int add_rep, int xor_rep, int add_raw, int xor_raw) 55{ 56 int count, x; 57 uint8_t *out = outbuf; 58 59 for (x = 0; x < w; x += count) { 60 /* see if we can encode the next set of pixels with RLE */ 61 if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) { 62 if (out + bpp + 1 > outbuf + out_size) 63 return -1; 64 65 *out++ = (count ^ xor_rep) + add_rep; 66 memcpy(out, ptr, bpp); 67 out += bpp; 68 } else { 69 /* fall back on uncompressed */ 70 count = ff_rle_count_pixels(ptr, w - x, bpp, 0); 71 if (out + bpp * count >= outbuf + out_size) 72 return -1; 73 74 *out++ = (count ^ xor_raw) + add_raw; 75 memcpy(out, ptr, bpp * count); 76 out += bpp * count; 77 } 78 79 ptr += count * bpp; 80 } 81 82 return out - outbuf; 83} 84