3 * Copyright (c) 2007 Bobby Bingham
5 * This file is part of FFmpeg.
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.
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.
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
23 #include "libavutil/common.h"
25 int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same)
30 for(pos = start + bpp; count < FFMIN(127, len); pos += bpp, count ++) {
31 if(same != !memcmp(pos-bpp, pos, bpp)) {
33 /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a single
34 * raw block of pixels. for larger bpp, RLE is as good or better */
35 if(bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos+1))
38 /* if RLE can encode the next block better than as a raw block,
39 * back up and leave _all_ the identical pixels for RLE */
49 int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr , int bpp, int w,
50 int add_rep, int xor_rep, int add_raw, int xor_raw)
53 uint8_t *out = outbuf;
55 for(x = 0; x < w; x += count) {
56 /* see if we can encode the next set of pixels with RLE */
57 if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) {
58 if(out + bpp + 1 > outbuf + out_size) return -1;
59 *out++ = (count ^ xor_rep) + add_rep;
60 memcpy(out, ptr, bpp);
63 /* fall back on uncompressed */
64 count = ff_rle_count_pixels(ptr, w - x, bpp, 0);
65 if(out + bpp*count >= outbuf + out_size) return -1;
66 *out++ = (count ^ xor_raw) + add_raw;
68 memcpy(out, ptr, bpp * count);