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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 | ||
33 | typedef struct { | |
34 | uint16_t *frame_buffer; | |
35 | uint16_t *last_frame_buffer; | |
36 | } KgvContext; | |
37 | ||
38 | static 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 | ||
46 | static 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 | ||
163 | static av_cold int decode_init(AVCodecContext *avctx) | |
164 | { | |
165 | avctx->pix_fmt = AV_PIX_FMT_RGB555; | |
166 | ||
167 | return 0; | |
168 | } | |
169 | ||
170 | static av_cold int decode_end(AVCodecContext *avctx) | |
171 | { | |
172 | decode_flush(avctx); | |
173 | return 0; | |
174 | } | |
175 | ||
176 | AVCodec 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 | }; |