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/*
* Kega Game Video (KGV1) decoder
* Copyright (c) 2010 Daniel Verkamp
*
* 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
*/
/**
* @file
* Kega Game Video decoder
*/
#include "libavutil/intreadwrite.h"
#include "libavcore/imgutils.h"
#include "avcodec.h"
typedef struct {
AVCodecContext *avctx;
AVFrame pic;
uint16_t *prev, *cur;
} KgvContext;
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
const uint8_t *buf_end = buf + avpkt->size;
KgvContext * const c = avctx->priv_data;
int offsets[7];
uint16_t *out, *prev;
int outcnt = 0, maxcnt;
int w, h, i;
if (avpkt->size < 2)
return -1;
w = (buf[0] + 1) * 8;
h = (buf[1] + 1) * 8;
buf += 2;
if (av_check_image_size(w, h, 0, avctx))
return -1;
if (w != avctx->width || h != avctx->height)
avcodec_set_dimensions(avctx, w, h);
maxcnt = w * h;
out = av_realloc(c->cur, w * h * 2);
if (!out)
return -1;
c->cur = out;
prev = av_realloc(c->prev, w * h * 2);
if (!prev)
return -1;
c->prev = prev;
for (i = 0; i < 7; i++)
offsets[i] = -1;
while (outcnt < maxcnt && buf_end - 2 > buf) {
int code = AV_RL16(buf);
buf += 2;
if (!(code & 0x8000)) {
out[outcnt++] = code; // rgb555 pixel coded directly
} else {
int count;
uint16_t *inp;
if ((code & 0x6000) == 0x6000) {
// copy from previous frame
int oidx = (code >> 10) & 7;
int start;
count = (code & 0x3FF) + 3;
if (offsets[oidx] < 0) {
if (buf_end - 3 < buf)
break;
offsets[oidx] = AV_RL24(buf);
buf += 3;
}
start = (outcnt + offsets[oidx]) % maxcnt;
if (maxcnt - start < count)
break;
inp = prev + start;
} else {
// copy from earlier in this frame
int offset = (code & 0x1FFF) + 1;
if (!(code & 0x6000)) {
count = 2;
} else if ((code & 0x6000) == 0x2000) {
count = 3;
} else {
if (buf_end - 1 < buf)
break;
count = 4 + *buf++;
}
if (outcnt < offset)
break;
inp = out + outcnt - offset;
}
if (maxcnt - outcnt < count)
break;
for (i = 0; i < count; i++)
out[outcnt++] = inp[i];
}
}
if (outcnt - maxcnt)
av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
c->pic.data[0] = (uint8_t *)c->cur;
c->pic.linesize[0] = w * 2;
*data_size = sizeof(AVFrame);
*(AVFrame*)data = c->pic;
FFSWAP(uint16_t *, c->cur, c->prev);
return avpkt->size;
}
static av_cold int decode_init(AVCodecContext *avctx)
{
KgvContext * const c = avctx->priv_data;
c->avctx = avctx;
avctx->pix_fmt = PIX_FMT_RGB555;
return 0;
}
static av_cold int decode_end(AVCodecContext *avctx)
{
KgvContext * const c = avctx->priv_data;
av_freep(&c->cur);
av_freep(&c->prev);
return 0;
}
AVCodec kgv1_decoder = {
"kgv1",
AVMEDIA_TYPE_VIDEO,
CODEC_ID_KGV1,
sizeof(KgvContext),
decode_init,
NULL,
decode_end,
decode_frame,
.max_lowres = 1,
.long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
};
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