xref: /third_party/ffmpeg/libavcodec/kgv1dec.c (revision cabdff1a) 
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 "codec_internal.h"
32#include "internal.h"
33
34typedef struct KgvContext {
35    uint16_t *frame_buffer;
36    uint16_t *last_frame_buffer;
37} KgvContext;
38
39static void decode_flush(AVCodecContext *avctx)
40{
41    KgvContext * const c = avctx->priv_data;
42
43    av_freep(&c->frame_buffer);
44    av_freep(&c->last_frame_buffer);
45}
46
47static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
48                        int *got_frame, AVPacket *avpkt)
49{
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 (avpkt->size < 2 + w*h / 513)
66        return AVERROR_INVALIDDATA;
67
68    if (w != avctx->width || h != avctx->height) {
69        av_freep(&c->frame_buffer);
70        av_freep(&c->last_frame_buffer);
71        if ((res = ff_set_dimensions(avctx, w, h)) < 0)
72            return res;
73    }
74
75    if (!c->frame_buffer) {
76        c->frame_buffer      = av_mallocz(avctx->width * avctx->height * 2);
77        c->last_frame_buffer = av_mallocz(avctx->width * avctx->height * 2);
78        if (!c->frame_buffer || !c->last_frame_buffer) {
79            decode_flush(avctx);
80            return AVERROR(ENOMEM);
81        }
82    }
83
84    maxcnt = w * h;
85
86    if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
87        return res;
88    out  = (uint8_t*)c->frame_buffer;
89    prev = (uint8_t*)c->last_frame_buffer;
90
91    for (i = 0; i < 8; i++)
92        offsets[i] = -1;
93
94    while (outcnt < maxcnt && buf_end - 2 >= buf) {
95        int code = AV_RL16(buf);
96        buf += 2;
97
98        if (!(code & 0x8000)) {
99            AV_WN16A(&out[2 * outcnt], code); // rgb555 pixel coded directly
100            outcnt++;
101        } else {
102            int count;
103
104            if ((code & 0x6000) == 0x6000) {
105                // copy from previous frame
106                int oidx = (code >> 10) & 7;
107                int start;
108
109                count = (code & 0x3FF) + 3;
110
111                if (offsets[oidx] < 0) {
112                    if (buf_end - 3 < buf)
113                        break;
114                    offsets[oidx] = AV_RL24(buf);
115                    buf += 3;
116                }
117
118                start = (outcnt + offsets[oidx]) % maxcnt;
119
120                if (maxcnt - start < count || maxcnt - outcnt < count)
121                    break;
122
123                if (!prev) {
124                    av_log(avctx, AV_LOG_ERROR,
125                           "Frame reference does not exist\n");
126                    break;
127                }
128
129                memcpy(out + 2 * outcnt, prev + 2 * start, 2 * count);
130            } else {
131                // copy from earlier in this frame
132                int offset = (code & 0x1FFF) + 1;
133
134                if (!(code & 0x6000)) {
135                    count = 2;
136                } else if ((code & 0x6000) == 0x2000) {
137                    count = 3;
138                } else {
139                    if (buf_end - 1 < buf)
140                        break;
141                    count = 4 + *buf++;
142                }
143
144                if (outcnt < offset || maxcnt - outcnt < count)
145                    break;
146
147                av_memcpy_backptr(out + 2 * outcnt, 2 * offset, 2 * count);
148            }
149            outcnt += count;
150        }
151    }
152
153    if (outcnt - maxcnt)
154        av_log(avctx, AV_LOG_DEBUG, "frame finished with %d diff\n", outcnt - maxcnt);
155
156    av_image_copy_plane(frame->data[0], frame->linesize[0],
157                        (const uint8_t*)c->frame_buffer,  avctx->width * 2,
158                        avctx->width * 2, avctx->height);
159    FFSWAP(uint16_t *, c->frame_buffer, c->last_frame_buffer);
160
161    *got_frame = 1;
162
163    return avpkt->size;
164}
165
166static av_cold int decode_init(AVCodecContext *avctx)
167{
168    avctx->pix_fmt = AV_PIX_FMT_RGB555;
169
170    return 0;
171}
172
173static av_cold int decode_end(AVCodecContext *avctx)
174{
175    decode_flush(avctx);
176    return 0;
177}
178
179const FFCodec ff_kgv1_decoder = {
180    .p.name         = "kgv1",
181    .p.long_name    = NULL_IF_CONFIG_SMALL("Kega Game Video"),
182    .p.type         = AVMEDIA_TYPE_VIDEO,
183    .p.id           = AV_CODEC_ID_KGV1,
184    .priv_data_size = sizeof(KgvContext),
185    .init           = decode_init,
186    .close          = decode_end,
187    FF_CODEC_DECODE_CB(decode_frame),
188    .flush          = decode_flush,
189    .p.capabilities = AV_CODEC_CAP_DR1,
190    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
191};
192