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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/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "internal.h"
typedef struct {
AVFrame *prev;
} KgvContext;
static void decode_flush(AVCodecContext *avctx)
{
KgvContext * const c = avctx->priv_data;
av_frame_free(&c->prev);
}
static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
AVPacket *avpkt)
{
AVFrame *frame = data;
const uint8_t *buf = avpkt->data;
const uint8_t *buf_end = buf + avpkt->size;
KgvContext * const c = avctx->priv_data;
int offsets[8];
uint8_t *out, *prev;
int outcnt = 0, maxcnt;
int w, h, i, res;
if (avpkt->size < 2)
return AVERROR_INVALIDDATA;
w = (buf[0] + 1) * 8;
h = (buf[1] + 1) * 8;
buf += 2;
if (w != avctx->width || h != avctx->height) {
av_frame_unref(c->prev);
if ((res = ff_set_dimensions(avctx, w, h)) < 0)
return res;
}
maxcnt = w * h;
if ((res = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
return res;
out = frame->data[0];
if (c->prev->data[0]) {
prev = c->prev->data[0];
} else {
prev = NULL;
}
for (i = 0; i < 8; i++)
offsets[i] = -1;
while (outcnt < maxcnt && buf_end - 2 >= buf) {
int code = AV_RL16(buf);
buf += 2;
if (!(code & 0x8000)) {
AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly
outcnt++;
} else {
int count;
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 || maxcnt - outcnt < count)
break;
if (!prev) {
av_log(avctx, AV_LOG_ERROR,
"Frame reference does not exist\n");
break;
}
memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count);
} 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 || maxcnt - outcnt < count)
break;
av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count);
}
outcnt += count;
}
}
if (outcnt - maxcnt)
av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
av_frame_unref(c->prev);
if ((res = av_frame_ref(c->prev, frame)) < 0)
return res;
*got_frame = 1;
return avpkt->size;
}
static av_cold int decode_init(AVCodecContext *avctx)
{
KgvContext * const c = avctx->priv_data;
c->prev = av_frame_alloc();
if (!c->prev)
return AVERROR(ENOMEM);
avctx->pix_fmt = AV_PIX_FMT_RGB555;
avctx->flags |= CODEC_FLAG_EMU_EDGE;
return 0;
}
static av_cold int decode_end(AVCodecContext *avctx)
{
KgvContext * const c = avctx->priv_data;
av_frame_free(&c->prev);
return 0;
}
AVCodec ff_kgv1_decoder = {
.name = "kgv1",
.long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_KGV1,
.priv_data_size = sizeof(KgvContext),
.init = decode_init,
.close = decode_end,
.decode = decode_frame,
.flush = decode_flush,
.capabilities = CODEC_CAP_DR1,
};
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