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* Kega Game Video (KGV1) decoder
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* Copyright (c) 2010 Daniel Verkamp
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* This file is part of Libav.
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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* Kega Game Video decoder
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#include "libavutil/intreadwrite.h"
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#include "libavutil/imgutils.h"
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AVCodecContext *avctx;
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static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
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const uint8_t *buf = avpkt->data;
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const uint8_t *buf_end = buf + avpkt->size;
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KgvContext * const c = avctx->priv_data;
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int outcnt = 0, maxcnt;
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if (av_image_check_size(w, h, 0, avctx))
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if (w != avctx->width || h != avctx->height)
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avcodec_set_dimensions(avctx, w, h);
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out = av_realloc(c->cur, w * h * 2);
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prev = av_realloc(c->prev, w * h * 2);
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for (i = 0; i < 7; i++)
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while (outcnt < maxcnt && buf_end - 2 > buf) {
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int code = AV_RL16(buf);
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if (!(code & 0x8000)) {
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out[outcnt++] = code; // rgb555 pixel coded directly
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if ((code & 0x6000) == 0x6000) {
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// copy from previous frame
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int oidx = (code >> 10) & 7;
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count = (code & 0x3FF) + 3;
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if (offsets[oidx] < 0) {
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if (buf_end - 3 < buf)
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offsets[oidx] = AV_RL24(buf);
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start = (outcnt + offsets[oidx]) % maxcnt;
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if (maxcnt - start < count)
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// copy from earlier in this frame
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int offset = (code & 0x1FFF) + 1;
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if (!(code & 0x6000)) {
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} else if ((code & 0x6000) == 0x2000) {
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if (buf_end - 1 < buf)
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inp = out + outcnt - offset;
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if (maxcnt - outcnt < count)
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for (i = 0; i < count; i++)
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out[outcnt++] = inp[i];
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av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
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c->pic.data[0] = (uint8_t *)c->cur;
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c->pic.linesize[0] = w * 2;
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*data_size = sizeof(AVFrame);
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*(AVFrame*)data = c->pic;
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FFSWAP(uint16_t *, c->cur, c->prev);
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static av_cold int decode_init(AVCodecContext *avctx)
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KgvContext * const c = avctx->priv_data;
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avctx->pix_fmt = PIX_FMT_RGB555;
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static av_cold int decode_end(AVCodecContext *avctx)
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KgvContext * const c = avctx->priv_data;
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AVCodec ff_kgv1_decoder = {
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.long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),