| /* |
| * RLE encoder |
| * Copyright (c) 2007 Bobby Bingham |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/common.h" |
| |
| #include "avcodec.h" |
| #include "rle.h" |
| |
| int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same) |
| { |
| const uint8_t *pos; |
| int count = 1; |
| |
| for (pos = start + bpp; count < FFMIN(127, len); pos += bpp, count++) { |
| if (same != !memcmp(pos - bpp, pos, bpp)) { |
| if (!same) { |
| /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a |
| * single raw block of pixels. For larger bpp, RLE is as good |
| * or better */ |
| if (bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos + 1)) |
| continue; |
| |
| /* if RLE can encode the next block better than as a raw block, |
| * back up and leave _all_ the identical pixels for RLE */ |
| count--; |
| } |
| break; |
| } |
| } |
| |
| return count; |
| } |
| |
| int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr, int bpp, |
| int w, int add_rep, int xor_rep, int add_raw, int xor_raw) |
| { |
| int count, x; |
| uint8_t *out = outbuf; |
| |
| for (x = 0; x < w; x += count) { |
| /* see if we can encode the next set of pixels with RLE */ |
| if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) { |
| if (out + bpp + 1 > outbuf + out_size) |
| return -1; |
| |
| *out++ = (count ^ xor_rep) + add_rep; |
| memcpy(out, ptr, bpp); |
| out += bpp; |
| } else { |
| /* fall back on uncompressed */ |
| count = ff_rle_count_pixels(ptr, w - x, bpp, 0); |
| if (out + bpp * count >= outbuf + out_size) |
| return -1; |
| |
| *out++ = (count ^ xor_raw) + add_raw; |
| memcpy(out, ptr, bpp * count); |
| out += bpp * count; |
| } |
| |
| ptr += count * bpp; |
| } |
| |
| return out - outbuf; |
| } |