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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 |
*/ |
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/** |
* @file |
* Kega Game Video decoder |
*/ |
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#include "libavutil/common.h" |
#include "libavutil/intreadwrite.h" |
#include "libavutil/imgutils.h" |
#include "avcodec.h" |
#include "internal.h" |
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typedef struct KgvContext { |
uint16_t *frame_buffer; |
uint16_t *last_frame_buffer; |
} KgvContext; |
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static void decode_flush(AVCodecContext *avctx) |
{ |
KgvContext * const c = avctx->priv_data; |
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av_freep(&c->frame_buffer); |
av_freep(&c->last_frame_buffer); |
} |
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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; |
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if (avpkt->size < 2) |
return AVERROR_INVALIDDATA; |
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w = (buf[0] + 1) * 8; |
h = (buf[1] + 1) * 8; |
buf += 2; |
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if (w != avctx->width || h != avctx->height) { |
av_freep(&c->frame_buffer); |
av_freep(&c->last_frame_buffer); |
if ((res = ff_set_dimensions(avctx, w, h)) < 0) |
return res; |
} |
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if (!c->frame_buffer) { |
c->frame_buffer = av_mallocz(avctx->width * avctx->height * 2); |
c->last_frame_buffer = av_mallocz(avctx->width * avctx->height * 2); |
if (!c->frame_buffer || !c->last_frame_buffer) { |
decode_flush(avctx); |
return AVERROR(ENOMEM); |
} |
} |
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maxcnt = w * h; |
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if ((res = ff_get_buffer(avctx, frame, 0)) < 0) |
return res; |
out = (uint8_t*)c->frame_buffer; |
prev = (uint8_t*)c->last_frame_buffer; |
|
for (i = 0; i < 8; i++) |
offsets[i] = -1; |
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while (outcnt < maxcnt && buf_end - 2 >= buf) { |
int code = AV_RL16(buf); |
buf += 2; |
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if (!(code & 0x8000)) { |
AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly |
outcnt++; |
} else { |
int count; |
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if ((code & 0x6000) == 0x6000) { |
// copy from previous frame |
int oidx = (code >> 10) & 7; |
int start; |
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count = (code & 0x3FF) + 3; |
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if (offsets[oidx] < 0) { |
if (buf_end - 3 < buf) |
break; |
offsets[oidx] = AV_RL24(buf); |
buf += 3; |
} |
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start = (outcnt + offsets[oidx]) % maxcnt; |
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if (maxcnt - start < count || maxcnt - outcnt < count) |
break; |
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if (!prev) { |
av_log(avctx, AV_LOG_ERROR, |
"Frame reference does not exist\n"); |
break; |
} |
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memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count); |
} else { |
// copy from earlier in this frame |
int offset = (code & 0x1FFF) + 1; |
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if (!(code & 0x6000)) { |
count = 2; |
} else if ((code & 0x6000) == 0x2000) { |
count = 3; |
} else { |
if (buf_end - 1 < buf) |
break; |
count = 4 + *buf++; |
} |
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if (outcnt < offset || maxcnt - outcnt < count) |
break; |
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av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count); |
} |
outcnt += count; |
} |
} |
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if (outcnt - maxcnt) |
av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt); |
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av_image_copy_plane(frame->data[0], frame->linesize[0], |
(const uint8_t*)c->frame_buffer, avctx->width * 2, |
avctx->width * 2, avctx->height); |
FFSWAP(uint16_t *, c->frame_buffer, c->last_frame_buffer); |
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*got_frame = 1; |
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return avpkt->size; |
} |
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static av_cold int decode_init(AVCodecContext *avctx) |
{ |
avctx->pix_fmt = AV_PIX_FMT_RGB555; |
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return 0; |
} |
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static av_cold int decode_end(AVCodecContext *avctx) |
{ |
decode_flush(avctx); |
return 0; |
} |
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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 = AV_CODEC_CAP_DR1, |
}; |