blob: 78a0945b7aa1a5e1f8cbe5b89e0b23beaa73cf33
1 | /* |
2 | * Discworld II BMV video decoder |
3 | * Copyright (c) 2011 Konstantin Shishkov |
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 "libavutil/avassert.h" |
23 | #include "libavutil/common.h" |
24 | |
25 | #include "avcodec.h" |
26 | #include "bytestream.h" |
27 | #include "internal.h" |
28 | |
29 | enum BMVFlags{ |
30 | BMV_NOP = 0, |
31 | BMV_END, |
32 | BMV_DELTA, |
33 | BMV_INTRA, |
34 | |
35 | BMV_SCROLL = 0x04, |
36 | BMV_PALETTE = 0x08, |
37 | BMV_COMMAND = 0x10, |
38 | BMV_AUDIO = 0x20, |
39 | BMV_EXT = 0x40, |
40 | BMV_PRINT = 0x80 |
41 | }; |
42 | |
43 | #define SCREEN_WIDE 640 |
44 | #define SCREEN_HIGH 429 |
45 | |
46 | typedef struct BMVDecContext { |
47 | AVCodecContext *avctx; |
48 | |
49 | uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)]; |
50 | uint32_t pal[256]; |
51 | const uint8_t *stream; |
52 | } BMVDecContext; |
53 | |
54 | #define NEXT_BYTE(v) (v) = forward ? (v) + 1 : (v) - 1; |
55 | |
56 | static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off) |
57 | { |
58 | unsigned val, saved_val = 0; |
59 | int tmplen = src_len; |
60 | const uint8_t *src, *source_end = source + src_len; |
61 | uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH; |
62 | uint8_t *dst, *dst_end; |
63 | int len, mask; |
64 | int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0); |
65 | int read_two_nibbles, flag; |
66 | int advance_mode; |
67 | int mode = 0; |
68 | int i; |
69 | |
70 | if (src_len <= 0) |
71 | return AVERROR_INVALIDDATA; |
72 | |
73 | if (forward) { |
74 | src = source; |
75 | dst = frame; |
76 | dst_end = frame_end; |
77 | } else { |
78 | src = source + src_len - 1; |
79 | dst = frame_end - 1; |
80 | dst_end = frame - 1; |
81 | } |
82 | for (;;) { |
83 | int shift = 0; |
84 | flag = 0; |
85 | |
86 | /* The mode/len decoding is a bit strange: |
87 | * values are coded as variable-length codes with nibble units, |
88 | * code end is signalled by two top bits in the nibble being nonzero. |
89 | * And since data is bytepacked and we read two nibbles at a time, |
90 | * we may get a nibble belonging to the next code. |
91 | * Hence this convoluted loop. |
92 | */ |
93 | if (!mode || (tmplen == 4)) { |
94 | if (src < source || src >= source_end) |
95 | return AVERROR_INVALIDDATA; |
96 | val = *src; |
97 | read_two_nibbles = 1; |
98 | } else { |
99 | val = saved_val; |
100 | read_two_nibbles = 0; |
101 | } |
102 | if (!(val & 0xC)) { |
103 | for (;;) { |
104 | if(shift>22) |
105 | return -1; |
106 | if (!read_two_nibbles) { |
107 | if (src < source || src >= source_end) |
108 | return AVERROR_INVALIDDATA; |
109 | shift += 2; |
110 | val |= *src << shift; |
111 | if (*src & 0xC) |
112 | break; |
113 | } |
114 | // two upper bits of the nibble is zero, |
115 | // so shift top nibble value down into their place |
116 | read_two_nibbles = 0; |
117 | shift += 2; |
118 | mask = (1 << shift) - 1; |
119 | val = ((val >> 2) & ~mask) | (val & mask); |
120 | NEXT_BYTE(src); |
121 | if ((val & (0xC << shift))) { |
122 | flag = 1; |
123 | break; |
124 | } |
125 | } |
126 | } else if (mode) { |
127 | flag = tmplen != 4; |
128 | } |
129 | if (flag) { |
130 | tmplen = 4; |
131 | } else { |
132 | saved_val = val >> (4 + shift); |
133 | tmplen = 0; |
134 | val &= (1 << (shift + 4)) - 1; |
135 | NEXT_BYTE(src); |
136 | } |
137 | advance_mode = val & 1; |
138 | len = (val >> 1) - 1; |
139 | av_assert0(len>0); |
140 | mode += 1 + advance_mode; |
141 | if (mode >= 4) |
142 | mode -= 3; |
143 | if (len <= 0 || FFABS(dst_end - dst) < len) |
144 | return AVERROR_INVALIDDATA; |
145 | switch (mode) { |
146 | case 1: |
147 | if (forward) { |
148 | if (dst - frame + SCREEN_WIDE < frame_off || |
149 | dst - frame + SCREEN_WIDE + frame_off < 0 || |
150 | frame_end - dst < frame_off + len || |
151 | frame_end - dst < len) |
152 | return AVERROR_INVALIDDATA; |
153 | for (i = 0; i < len; i++) |
154 | dst[i] = dst[frame_off + i]; |
155 | dst += len; |
156 | } else { |
157 | dst -= len; |
158 | if (dst - frame + SCREEN_WIDE < frame_off || |
159 | dst - frame + SCREEN_WIDE + frame_off < 0 || |
160 | frame_end - dst < frame_off + len || |
161 | frame_end - dst < len) |
162 | return AVERROR_INVALIDDATA; |
163 | for (i = len - 1; i >= 0; i--) |
164 | dst[i] = dst[frame_off + i]; |
165 | } |
166 | break; |
167 | case 2: |
168 | if (forward) { |
169 | if (source + src_len - src < len) |
170 | return AVERROR_INVALIDDATA; |
171 | memcpy(dst, src, len); |
172 | dst += len; |
173 | src += len; |
174 | } else { |
175 | if (src - source < len) |
176 | return AVERROR_INVALIDDATA; |
177 | dst -= len; |
178 | src -= len; |
179 | memcpy(dst, src, len); |
180 | } |
181 | break; |
182 | case 3: |
183 | val = forward ? dst[-1] : dst[1]; |
184 | if (forward) { |
185 | memset(dst, val, len); |
186 | dst += len; |
187 | } else { |
188 | dst -= len; |
189 | memset(dst, val, len); |
190 | } |
191 | break; |
192 | } |
193 | if (dst == dst_end) |
194 | return 0; |
195 | } |
196 | } |
197 | |
198 | static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, |
199 | AVPacket *pkt) |
200 | { |
201 | BMVDecContext * const c = avctx->priv_data; |
202 | AVFrame *frame = data; |
203 | int type, scr_off; |
204 | int i, ret; |
205 | uint8_t *srcptr, *outptr; |
206 | |
207 | c->stream = pkt->data; |
208 | type = bytestream_get_byte(&c->stream); |
209 | if (type & BMV_AUDIO) { |
210 | int blobs = bytestream_get_byte(&c->stream); |
211 | if (pkt->size < blobs * 65 + 2) { |
212 | av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n"); |
213 | return AVERROR_INVALIDDATA; |
214 | } |
215 | c->stream += blobs * 65; |
216 | } |
217 | if (type & BMV_COMMAND) { |
218 | int command_size = (type & BMV_PRINT) ? 8 : 10; |
219 | if (c->stream - pkt->data + command_size > pkt->size) { |
220 | av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n"); |
221 | return AVERROR_INVALIDDATA; |
222 | } |
223 | c->stream += command_size; |
224 | } |
225 | if (type & BMV_PALETTE) { |
226 | if (c->stream - pkt->data > pkt->size - 768) { |
227 | av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n"); |
228 | return AVERROR_INVALIDDATA; |
229 | } |
230 | for (i = 0; i < 256; i++) |
231 | c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream); |
232 | } |
233 | if (type & BMV_SCROLL) { |
234 | if (c->stream - pkt->data > pkt->size - 2) { |
235 | av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n"); |
236 | return AVERROR_INVALIDDATA; |
237 | } |
238 | scr_off = (int16_t)bytestream_get_le16(&c->stream); |
239 | } else if ((type & BMV_INTRA) == BMV_INTRA) { |
240 | scr_off = -640; |
241 | } else { |
242 | scr_off = 0; |
243 | } |
244 | |
245 | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
246 | return ret; |
247 | |
248 | if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) { |
249 | av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n"); |
250 | return AVERROR_INVALIDDATA; |
251 | } |
252 | |
253 | memcpy(frame->data[1], c->pal, AVPALETTE_SIZE); |
254 | frame->palette_has_changed = type & BMV_PALETTE; |
255 | |
256 | outptr = frame->data[0]; |
257 | srcptr = c->frame; |
258 | |
259 | for (i = 0; i < avctx->height; i++) { |
260 | memcpy(outptr, srcptr, avctx->width); |
261 | srcptr += avctx->width; |
262 | outptr += frame->linesize[0]; |
263 | } |
264 | |
265 | *got_frame = 1; |
266 | |
267 | /* always report that the buffer was completely consumed */ |
268 | return pkt->size; |
269 | } |
270 | |
271 | static av_cold int decode_init(AVCodecContext *avctx) |
272 | { |
273 | BMVDecContext * const c = avctx->priv_data; |
274 | |
275 | c->avctx = avctx; |
276 | avctx->pix_fmt = AV_PIX_FMT_PAL8; |
277 | |
278 | if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) { |
279 | av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height); |
280 | return AVERROR_INVALIDDATA; |
281 | } |
282 | |
283 | c->frame = c->frame_base + 640; |
284 | |
285 | return 0; |
286 | } |
287 | |
288 | AVCodec ff_bmv_video_decoder = { |
289 | .name = "bmv_video", |
290 | .long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV video"), |
291 | .type = AVMEDIA_TYPE_VIDEO, |
292 | .id = AV_CODEC_ID_BMV_VIDEO, |
293 | .priv_data_size = sizeof(BMVDecContext), |
294 | .init = decode_init, |
295 | .decode = decode_frame, |
296 | .capabilities = AV_CODEC_CAP_DR1, |
297 | .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE, |
298 | }; |
299 |