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[libav.git] / libavcodec / c93.c
1 /*
2 * Interplay C93 video decoder
3 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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 #include "avcodec.h"
23 #include "bytestream.h"
24
25 typedef struct {
26 AVFrame pictures[2];
27 int currentpic;
28 } C93DecoderContext;
29
30 typedef enum {
31 C93_8X8_FROM_PREV = 0x02,
32 C93_4X4_FROM_PREV = 0x06,
33 C93_4X4_FROM_CURR = 0x07,
34 C93_8X8_2COLOR = 0x08,
35 C93_4X4_2COLOR = 0x0A,
36 C93_4X4_4COLOR_GRP = 0x0B,
37 C93_4X4_4COLOR = 0x0D,
38 C93_NOOP = 0x0E,
39 C93_8X8_INTRA = 0x0F,
40 } C93BlockType;
41
42 #define WIDTH 320
43 #define HEIGHT 192
44
45 #define C93_HAS_PALETTE 0x01
46 #define C93_FIRST_FRAME 0x02
47
48 static int decode_init(AVCodecContext *avctx)
49 {
50 avctx->pix_fmt = PIX_FMT_PAL8;
51 return 0;
52 }
53
54 static int decode_end(AVCodecContext *avctx)
55 {
56 C93DecoderContext * const c93 = avctx->priv_data;
57
58 if (c93->pictures[0].data[0])
59 avctx->release_buffer(avctx, &c93->pictures[0]);
60 if (c93->pictures[1].data[0])
61 avctx->release_buffer(avctx, &c93->pictures[1]);
62 return 0;
63 }
64
65 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
66 uint8_t *from, int offset, int height, int stride)
67 {
68 int i;
69 int width = height;
70 int from_x = offset % WIDTH;
71 int from_y = offset / WIDTH;
72 int overflow = from_x + width - WIDTH;
73
74 if (!from) {
75 /* silently ignoring predictive blocks in first frame */
76 return 0;
77 }
78
79 if (from_y + height > HEIGHT) {
80 av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
81 offset);
82 return -1;
83 }
84
85 if (overflow > 0) {
86 width -= overflow;
87 for (i = 0; i < height; i++) {
88 memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
89 }
90 }
91
92 for (i = 0; i < height; i++) {
93 memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
94 }
95
96 return 0;
97 }
98
99 static inline void draw_n_color(uint8_t *out, int stride, int width,
100 int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
101 {
102 int x, y;
103 for (y = 0; y < height; y++) {
104 if (grps)
105 cols[0] = grps[3 * (y >> 1)];
106 for (x = 0; x < width; x++) {
107 if (grps)
108 cols[1]= grps[(x >> 1) + 1];
109 out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
110 col >>= bpp;
111 }
112 }
113 }
114
115 static int decode_frame(AVCodecContext *avctx, void *data,
116 int *data_size, const uint8_t * buf, int buf_size)
117 {
118 C93DecoderContext * const c93 = avctx->priv_data;
119 AVFrame * const newpic = &c93->pictures[c93->currentpic];
120 AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
121 AVFrame *picture = data;
122 uint8_t *out;
123 int stride, i, x, y, bt = 0;
124
125 c93->currentpic ^= 1;
126
127 newpic->reference = 1;
128 newpic->buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
129 FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
130 if (avctx->reget_buffer(avctx, newpic)) {
131 av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
132 return -1;
133 }
134
135 stride = newpic->linesize[0];
136
137 if (buf[0] & C93_FIRST_FRAME) {
138 newpic->pict_type = FF_I_TYPE;
139 newpic->key_frame = 1;
140 } else {
141 newpic->pict_type = FF_P_TYPE;
142 newpic->key_frame = 0;
143 }
144
145 if (*buf++ & C93_HAS_PALETTE) {
146 uint32_t *palette = (uint32_t *) newpic->data[1];
147 const uint8_t *palbuf = buf + buf_size - 768 - 1;
148 for (i = 0; i < 256; i++) {
149 palette[i] = bytestream_get_be24(&palbuf);
150 }
151 } else {
152 if (oldpic->data[1])
153 memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
154 }
155
156 for (y = 0; y < HEIGHT; y += 8) {
157 out = newpic->data[0] + y * stride;
158 for (x = 0; x < WIDTH; x += 8) {
159 uint8_t *copy_from = oldpic->data[0];
160 unsigned int offset, j;
161 uint8_t cols[4], grps[4];
162 C93BlockType block_type;
163
164 if (!bt)
165 bt = *buf++;
166
167 block_type= bt & 0x0F;
168 switch (block_type) {
169 case C93_8X8_FROM_PREV:
170 offset = bytestream_get_le16(&buf);
171 if (copy_block(avctx, out, copy_from, offset, 8, stride))
172 return -1;
173 break;
174
175 case C93_4X4_FROM_CURR:
176 copy_from = newpic->data[0];
177 case C93_4X4_FROM_PREV:
178 for (j = 0; j < 8; j += 4) {
179 for (i = 0; i < 8; i += 4) {
180 offset = bytestream_get_le16(&buf);
181 if (copy_block(avctx, &out[j*stride+i],
182 copy_from, offset, 4, stride))
183 return -1;
184 }
185 }
186 break;
187
188 case C93_8X8_2COLOR:
189 bytestream_get_buffer(&buf, cols, 2);
190 for (i = 0; i < 8; i++) {
191 draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
192 NULL, *buf++);
193 }
194
195 break;
196
197 case C93_4X4_2COLOR:
198 case C93_4X4_4COLOR:
199 case C93_4X4_4COLOR_GRP:
200 for (j = 0; j < 8; j += 4) {
201 for (i = 0; i < 8; i += 4) {
202 if (block_type == C93_4X4_2COLOR) {
203 bytestream_get_buffer(&buf, cols, 2);
204 draw_n_color(out + i + j*stride, stride, 4, 4,
205 1, cols, NULL, bytestream_get_le16(&buf));
206 } else if (block_type == C93_4X4_4COLOR) {
207 bytestream_get_buffer(&buf, cols, 4);
208 draw_n_color(out + i + j*stride, stride, 4, 4,
209 2, cols, NULL, bytestream_get_le32(&buf));
210 } else {
211 bytestream_get_buffer(&buf, grps, 4);
212 draw_n_color(out + i + j*stride, stride, 4, 4,
213 1, cols, grps, bytestream_get_le16(&buf));
214 }
215 }
216 }
217 break;
218
219 case C93_NOOP:
220 break;
221
222 case C93_8X8_INTRA:
223 for (j = 0; j < 8; j++)
224 bytestream_get_buffer(&buf, out + j*stride, 8);
225 break;
226
227 default:
228 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
229 block_type, x, y);
230 return -1;
231 }
232 bt >>= 4;
233 out += 8;
234 }
235 }
236
237 *picture = *newpic;
238 *data_size = sizeof(AVFrame);
239
240 return buf_size;
241 }
242
243 AVCodec c93_decoder = {
244 "c93",
245 CODEC_TYPE_VIDEO,
246 CODEC_ID_C93,
247 sizeof(C93DecoderContext),
248 decode_init,
249 NULL,
250 decode_end,
251 decode_frame,
252 CODEC_CAP_DR1,
253 };