mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-23 12:43:46 +02:00
83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
/*
|
|
* RLE encoder
|
|
* Copyright (c) 2007 Bobby Bingham
|
|
*
|
|
* This file is part of Libav.
|
|
*
|
|
* Libav 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.
|
|
*
|
|
* Libav 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 Libav; 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;
|
|
}
|