mirror of
https://github.com/KolibriOS/kolibrios.git
synced 2024-12-15 19:33:59 +03:00
86 lines
2.9 KiB
C
86 lines
2.9 KiB
C
/*
|
|
* 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 "avcodec.h"
|
|
#include "rle.h"
|
|
#include "libavutil/common.h"
|
|
|
|
/**
|
|
* Count up to 127 consecutive pixels which are either all the same or
|
|
* all differ from the previous and next pixels.
|
|
* @param start Pointer to the first pixel
|
|
* @param len Maximum number of pixels
|
|
* @param bpp Bytes per pixel
|
|
* @param same 1 if searching for identical pixel values. 0 for differing
|
|
* @return Number of matching consecutive pixels found
|
|
*/
|
|
static int 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 = 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 = 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;
|
|
}
|