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59e3f4e598
SGI RLE encoding is slighlty different than the one provided by rle module (especially at high bit depth). The pixel count function however does not change, so it is simply made library-public.
77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
/*
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* RLE encoder
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* Copyright (c) 2007 Bobby Bingham
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avcodec.h"
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#include "rle.h"
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#include "libavutil/common.h"
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int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same)
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{
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const uint8_t *pos;
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int count = 1;
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for(pos = start + bpp; count < FFMIN(127, len); pos += bpp, count ++) {
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if(same != !memcmp(pos-bpp, pos, bpp)) {
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if(!same) {
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/* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a single
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* raw block of pixels. for larger bpp, RLE is as good or better */
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if(bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos+1))
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continue;
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/* if RLE can encode the next block better than as a raw block,
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* back up and leave _all_ the identical pixels for RLE */
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count --;
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}
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break;
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}
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}
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return count;
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}
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int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr , int bpp, int w,
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int add_rep, int xor_rep, int add_raw, int xor_raw)
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{
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int count, x;
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uint8_t *out = outbuf;
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for(x = 0; x < w; x += count) {
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/* see if we can encode the next set of pixels with RLE */
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if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) {
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if(out + bpp + 1 > outbuf + out_size) return -1;
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*out++ = (count ^ xor_rep) + add_rep;
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memcpy(out, ptr, bpp);
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out += bpp;
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} else {
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/* fall back on uncompressed */
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count = ff_rle_count_pixels(ptr, w - x, bpp, 0);
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if(out + bpp*count >= outbuf + out_size) return -1;
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*out++ = (count ^ xor_raw) + add_raw;
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memcpy(out, ptr, bpp * count);
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out += bpp * count;
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}
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ptr += count * bpp;
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}
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return out - outbuf;
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}
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