1/*
2 * Kega Game Video (KGV1) decoder
3 * Copyright (c) 2010 Daniel Verkamp
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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.
11 *
12 * Libav 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.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * Kega Game Video decoder
25 */
26
27#include "libavutil/intreadwrite.h"
28#include "libavutil/imgutils.h"
29#include "avcodec.h"
30
31typedef struct {
32    AVCodecContext *avctx;
33    AVFrame prev, cur;
34} KgvContext;
35
36static void decode_flush(AVCodecContext *avctx)
37{
38    KgvContext * const c = avctx->priv_data;
39
40    if (c->prev.data[0])
41        avctx->release_buffer(avctx, &c->prev);
42}
43
44static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
45{
46    const uint8_t *buf = avpkt->data;
47    const uint8_t *buf_end = buf + avpkt->size;
48    KgvContext * const c = avctx->priv_data;
49    int offsets[8];
50    uint16_t *out, *prev;
51    int outcnt = 0, maxcnt;
52    int w, h, i, res;
53
54    if (avpkt->size < 2)
55        return -1;
56
57    w = (buf[0] + 1) * 8;
58    h = (buf[1] + 1) * 8;
59    buf += 2;
60
61    if (av_image_check_size(w, h, 0, avctx))
62        return -1;
63
64    if (w != avctx->width || h != avctx->height) {
65        if (c->prev.data[0])
66            avctx->release_buffer(avctx, &c->prev);
67        avcodec_set_dimensions(avctx, w, h);
68    }
69
70    maxcnt = w * h;
71
72    c->cur.reference = 3;
73    if ((res = avctx->get_buffer(avctx, &c->cur)) < 0)
74        return res;
75    out  = (uint16_t *) c->cur.data[0];
76    if (c->prev.data[0]) {
77        prev = (uint16_t *) c->prev.data[0];
78    } else {
79        prev = NULL;
80    }
81
82    for (i = 0; i < 8; i++)
83        offsets[i] = -1;
84
85    while (outcnt < maxcnt && buf_end - 2 > buf) {
86        int code = AV_RL16(buf);
87        buf += 2;
88
89        if (!(code & 0x8000)) {
90            out[outcnt++] = code; // rgb555 pixel coded directly
91        } else {
92            int count;
93            int inp_off;
94            uint16_t *inp;
95
96            if ((code & 0x6000) == 0x6000) {
97                // copy from previous frame
98                int oidx = (code >> 10) & 7;
99                int start;
100
101                count = (code & 0x3FF) + 3;
102
103                if (offsets[oidx] < 0) {
104                    if (buf_end - 3 < buf)
105                        break;
106                    offsets[oidx] = AV_RL24(buf);
107                    buf += 3;
108                }
109
110                start = (outcnt + offsets[oidx]) % maxcnt;
111
112                if (maxcnt - start < count)
113                    break;
114
115                if (!prev) {
116                    av_log(avctx, AV_LOG_ERROR,
117                           "Frame reference does not exist\n");
118                    break;
119                }
120
121                inp = prev;
122                inp_off = start;
123            } else {
124                // copy from earlier in this frame
125                int offset = (code & 0x1FFF) + 1;
126
127                if (!(code & 0x6000)) {
128                    count = 2;
129                } else if ((code & 0x6000) == 0x2000) {
130                    count = 3;
131                } else {
132                    if (buf_end - 1 < buf)
133                        break;
134                    count = 4 + *buf++;
135                }
136
137                if (outcnt < offset)
138                    break;
139
140                inp = out;
141                inp_off = outcnt - offset;
142            }
143
144            if (maxcnt - outcnt < count)
145                break;
146
147            for (i = inp_off; i < count + inp_off; i++) {
148                out[outcnt++] = inp[i];
149            }
150        }
151    }
152
153    if (outcnt - maxcnt)
154        av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
155
156    *data_size = sizeof(AVFrame);
157    *(AVFrame*)data = c->cur;
158
159    if (c->prev.data[0])
160        avctx->release_buffer(avctx, &c->prev);
161    FFSWAP(AVFrame, c->cur, c->prev);
162
163    return avpkt->size;
164}
165
166static av_cold int decode_init(AVCodecContext *avctx)
167{
168    KgvContext * const c = avctx->priv_data;
169
170    c->avctx = avctx;
171    avctx->pix_fmt = PIX_FMT_RGB555;
172    avctx->flags  |= CODEC_FLAG_EMU_EDGE;
173
174    return 0;
175}
176
177static av_cold int decode_end(AVCodecContext *avctx)
178{
179    decode_flush(avctx);
180    return 0;
181}
182
183AVCodec ff_kgv1_decoder = {
184    .name           = "kgv1",
185    .type           = AVMEDIA_TYPE_VIDEO,
186    .id             = CODEC_ID_KGV1,
187    .priv_data_size = sizeof(KgvContext),
188    .init           = decode_init,
189    .close          = decode_end,
190    .decode         = decode_frame,
191    .flush          = decode_flush,
192    .long_name = NULL_IF_CONFIG_SMALL("Kega Game Video"),
193};
194