2 * Kega Game Video (KGV1) decoder
3 * Copyright (c) 2010 Daniel Verkamp
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Kega Game Video decoder
27 #include "libavutil/common.h"
28 #include "libavutil/intreadwrite.h"
29 #include "libavutil/imgutils.h"
33 AVCodecContext *avctx;
37 static void decode_flush(AVCodecContext *avctx)
39 KgvContext * const c = avctx->priv_data;
42 avctx->release_buffer(avctx, &c->prev);
45 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
47 const uint8_t *buf = avpkt->data;
48 const uint8_t *buf_end = buf + avpkt->size;
49 KgvContext * const c = avctx->priv_data;
52 int outcnt = 0, maxcnt;
62 if (av_image_check_size(w, h, 0, avctx))
65 if (w != avctx->width || h != avctx->height) {
67 avctx->release_buffer(avctx, &c->prev);
68 avcodec_set_dimensions(avctx, w, h);
74 if ((res = avctx->get_buffer(avctx, &c->cur)) < 0)
76 out = (uint16_t *) c->cur.data[0];
77 if (c->prev.data[0]) {
78 prev = (uint16_t *) c->prev.data[0];
83 for (i = 0; i < 8; i++)
86 while (outcnt < maxcnt && buf_end - 2 > buf) {
87 int code = AV_RL16(buf);
90 if (!(code & 0x8000)) {
91 out[outcnt++] = code; // rgb555 pixel coded directly
97 if ((code & 0x6000) == 0x6000) {
98 // copy from previous frame
99 int oidx = (code >> 10) & 7;
102 count = (code & 0x3FF) + 3;
104 if (offsets[oidx] < 0) {
105 if (buf_end - 3 < buf)
107 offsets[oidx] = AV_RL24(buf);
111 start = (outcnt + offsets[oidx]) % maxcnt;
113 if (maxcnt - start < count)
117 av_log(avctx, AV_LOG_ERROR,
118 "Frame reference does not exist\n");
125 // copy from earlier in this frame
126 int offset = (code & 0x1FFF) + 1;
128 if (!(code & 0x6000)) {
130 } else if ((code & 0x6000) == 0x2000) {
133 if (buf_end - 1 < buf)
142 inp_off = outcnt - offset;
145 if (maxcnt - outcnt < count)
148 for (i = inp_off; i < count + inp_off; i++) {
149 out[outcnt++] = inp[i];
155 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
157 *data_size = sizeof(AVFrame);
158 *(AVFrame*)data = c->cur;
161 avctx->release_buffer(avctx, &c->prev);
162 FFSWAP(AVFrame, c->cur, c->prev);
167 static av_cold int decode_init(AVCodecContext *avctx)
169 KgvContext * const c = avctx->priv_data;
172 avctx->pix_fmt = AV_PIX_FMT_RGB555;
173 avctx->flags |= CODEC_FLAG_EMU_EDGE;
178 static av_cold int decode_end(AVCodecContext *avctx)
184 AVCodec ff_kgv1_decoder = {
186 .type = AVMEDIA_TYPE_VIDEO,
187 .id = AV_CODEC_ID_KGV1,
188 .priv_data_size = sizeof(KgvContext),
191 .decode = decode_frame,
192 .flush = decode_flush,
193 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
194 .capabilities = CODEC_CAP_DR1,