1/*
2 * Kega Game Video (KGV1) decoder
3 * Copyright (c) 2010 Daniel Verkamp
4 *
5 * This file is part of FFmpeg.
6 *
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.
11 *
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.
16 *
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
20 */
21
22/**
23 * @file
24 * Kega Game Video decoder
25 */
26
27#include "libavutil/common.h"
28#include "libavutil/intreadwrite.h"
29#include "libavutil/imgutils.h"
30#include "avcodec.h"
31#include "internal.h"
32
33typedef struct {
34    uint16_t *frame_buffer;
35    uint16_t *last_frame_buffer;
36} KgvContext;
37
38static void decode_flush(AVCodecContext *avctx)
39{
40    KgvContext * const c = avctx->priv_data;
41
42    av_freep(&c->frame_buffer);
43    av_freep(&c->last_frame_buffer);
44}
45
46static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
47                        AVPacket *avpkt)
48{
49    AVFrame *frame = data;
50    const uint8_t *buf = avpkt->data;
51    const uint8_t *buf_end = buf + avpkt->size;
52    KgvContext * const c = avctx->priv_data;
53    int offsets[8];
54    uint8_t *out, *prev;
55    int outcnt = 0, maxcnt;
56    int w, h, i, res;
57
58    if (avpkt->size < 2)
59        return AVERROR_INVALIDDATA;
60
61    w = (buf[0] + 1) * 8;
62    h = (buf[1] + 1) * 8;
63    buf += 2;
64
65    if (w != avctx->width || h != avctx->height) {
66        av_freep(&c->frame_buffer);
67        av_freep(&c->last_frame_buffer);
68        if ((res = ff_set_dimensions(avctx, w, h)) < 0)
69            return res;
70    }
71
72    if (!c->frame_buffer) {
73        c->frame_buffer      = av_mallocz(avctx->width * avctx->height * 2);
74        c->last_frame_buffer = av_mallocz(avctx->width * avctx->height * 2);
75        if (!c->frame_buffer || !c->last_frame_buffer) {
76            decode_flush(avctx);
77            return AVERROR(ENOMEM);
78        }
79    }
80
81    maxcnt = w * h;
82
83    if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
84        return res;
85    out  = (uint8_t*)c->frame_buffer;
86    prev = (uint8_t*)c->last_frame_buffer;
87
88    for (i = 0; i < 8; i++)
89        offsets[i] = -1;
90
91    while (outcnt < maxcnt && buf_end - 2 >= buf) {
92        int code = AV_RL16(buf);
93        buf += 2;
94
95        if (!(code & 0x8000)) {
96            AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly
97            outcnt++;
98        } else {
99            int count;
100
101            if ((code & 0x6000) == 0x6000) {
102                // copy from previous frame
103                int oidx = (code >> 10) & 7;
104                int start;
105
106                count = (code & 0x3FF) + 3;
107
108                if (offsets[oidx] < 0) {
109                    if (buf_end - 3 < buf)
110                        break;
111                    offsets[oidx] = AV_RL24(buf);
112                    buf += 3;
113                }
114
115                start = (outcnt + offsets[oidx]) % maxcnt;
116
117                if (maxcnt - start < count || maxcnt - outcnt < count)
118                    break;
119
120                if (!prev) {
121                    av_log(avctx, AV_LOG_ERROR,
122                           "Frame reference does not exist\n");
123                    break;
124                }
125
126                memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count);
127            } else {
128                // copy from earlier in this frame
129                int offset = (code & 0x1FFF) + 1;
130
131                if (!(code & 0x6000)) {
132                    count = 2;
133                } else if ((code & 0x6000) == 0x2000) {
134                    count = 3;
135                } else {
136                    if (buf_end - 1 < buf)
137                        break;
138                    count = 4 + *buf++;
139                }
140
141                if (outcnt < offset || maxcnt - outcnt < count)
142                    break;
143
144                av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count);
145            }
146            outcnt += count;
147        }
148    }
149
150    if (outcnt - maxcnt)
151        av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
152
153    av_image_copy_plane(frame->data[0], frame->linesize[0],
154                        (const uint8_t*)c->frame_buffer,  avctx->width * 2,
155                        avctx->width * 2, avctx->height);
156    FFSWAP(uint16_t *, c->frame_buffer, c->last_frame_buffer);
157
158    *got_frame = 1;
159
160    return avpkt->size;
161}
162
163static av_cold int decode_init(AVCodecContext *avctx)
164{
165    avctx->pix_fmt = AV_PIX_FMT_RGB555;
166
167    return 0;
168}
169
170static av_cold int decode_end(AVCodecContext *avctx)
171{
172    decode_flush(avctx);
173    return 0;
174}
175
176AVCodec ff_kgv1_decoder = {
177    .name           = "kgv1",
178    .long_name      = NULL_IF_CONFIG_SMALL("Kega Game Video"),
179    .type           = AVMEDIA_TYPE_VIDEO,
180    .id             = AV_CODEC_ID_KGV1,
181    .priv_data_size = sizeof(KgvContext),
182    .init           = decode_init,
183    .close          = decode_end,
184    .decode         = decode_frame,
185    .flush          = decode_flush,
186    .capabilities   = CODEC_CAP_DR1,
187};
188