/* * 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 <string.h> #include "libavutil/macros.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; }