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"
37 static void decode_flush(AVCodecContext *avctx)
39 KgvContext * const c = avctx->priv_data;
41 av_frame_unref(c->prev);
44 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
47 AVFrame *frame = data;
48 const uint8_t *buf = avpkt->data;
49 const uint8_t *buf_end = buf + avpkt->size;
50 KgvContext * const c = avctx->priv_data;
53 int outcnt = 0, maxcnt;
57 return AVERROR_INVALIDDATA;
63 if (w != avctx->width || h != avctx->height) {
64 av_frame_unref(c->prev);
65 if ((res = ff_set_dimensions(avctx, w, h)) < 0)
71 if ((res = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
74 if (c->prev->data[0]) {
75 prev = c->prev->data[0];
80 for (i = 0; i < 8; i++)
83 while (outcnt < maxcnt && buf_end - 2 >= buf) {
84 int code = AV_RL16(buf);
87 if (!(code & 0x8000)) {
88 AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly
93 if ((code & 0x6000) == 0x6000) {
94 // copy from previous frame
95 int oidx = (code >> 10) & 7;
98 count = (code & 0x3FF) + 3;
100 if (offsets[oidx] < 0) {
101 if (buf_end - 3 < buf)
103 offsets[oidx] = AV_RL24(buf);
107 start = (outcnt + offsets[oidx]) % maxcnt;
109 if (maxcnt - start < count || maxcnt - outcnt < count)
113 av_log(avctx, AV_LOG_ERROR,
114 "Frame reference does not exist\n");
118 memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count);
120 // copy from earlier in this frame
121 int offset = (code & 0x1FFF) + 1;
123 if (!(code & 0x6000)) {
125 } else if ((code & 0x6000) == 0x2000) {
128 if (buf_end - 1 < buf)
133 if (outcnt < offset || maxcnt - outcnt < count)
136 av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count);
143 av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
145 av_frame_unref(c->prev);
146 if ((res = av_frame_ref(c->prev, frame)) < 0)
154 static av_cold int decode_init(AVCodecContext *avctx)
156 KgvContext * const c = avctx->priv_data;
158 avctx->pix_fmt = AV_PIX_FMT_RGB555;
159 avctx->flags |= CODEC_FLAG_EMU_EDGE;
161 c->prev = av_frame_alloc();
163 return AVERROR(ENOMEM);
168 static av_cold int decode_end(AVCodecContext *avctx)
170 KgvContext * const c = avctx->priv_data;
171 av_frame_free(&c->prev);
175 AVCodec ff_kgv1_decoder = {
177 .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
178 .type = AVMEDIA_TYPE_VIDEO,
179 .id = AV_CODEC_ID_KGV1,
180 .priv_data_size = sizeof(KgvContext),
183 .decode = decode_frame,
184 .flush = decode_flush,
185 .capabilities = CODEC_CAP_DR1,