FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/bmvvideo.c
Date: 2021-09-26 18:22:30
Exec Total Coverage
Lines: 115 158 72.8%
Branches: 67 118 56.8%

Line Branch Exec Source
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 21 static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
57 {
58 21 unsigned val, saved_val = 0;
59 21 int tmplen = src_len;
60 21 const uint8_t *src, *source_end = source + src_len;
61 21 uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
62 uint8_t *dst, *dst_end;
63 int len, mask;
64
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21 int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
65 int read_two_nibbles, flag;
66 int advance_mode;
67 21 int mode = 0;
68 int i;
69
70
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21 if (src_len <= 0)
71 return AVERROR_INVALIDDATA;
72
73
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21 if (forward) {
74 21 src = source;
75 21 dst = frame;
76 21 dst_end = frame_end;
77 } else {
78 src = source + src_len - 1;
79 dst = frame_end - 1;
80 dst_end = frame - 1;
81 }
82 783652 for (;;) {
83 783673 int shift = 0;
84 783673 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
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783673 if (!mode || (tmplen == 4)) {
94
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391887 if (src < source || src >= source_end)
95 return AVERROR_INVALIDDATA;
96 391887 val = *src;
97 391887 read_two_nibbles = 1;
98 } else {
99 391786 val = saved_val;
100 391786 read_two_nibbles = 0;
101 }
102
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783673 if (!(val & 0xC)) {
103 for (;;) {
104
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73874 if(shift>22)
105 return -1;
106
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73874 if (!read_two_nibbles) {
107
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38323 if (src < source || src >= source_end)
108 return AVERROR_INVALIDDATA;
109 38323 shift += 2;
110 38323 val |= (unsigned)*src << shift;
111
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38323 if (*src & 0xC)
112 35465 break;
113 }
114 // two upper bits of the nibble is zero,
115 // so shift top nibble value down into their place
116 38409 read_two_nibbles = 0;
117 38409 shift += 2;
118 38409 mask = (1 << shift) - 1;
119 38409 val = ((val >> 2) & ~mask) | (val & mask);
120
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38409 NEXT_BYTE(src);
121
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38409 if ((val & (0xC << shift))) {
122 35570 flag = 1;
123 35570 break;
124 }
125 }
126
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712638 } else if (mode) {
127 712627 flag = tmplen != 4;
128 }
129
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783673 if (flag) {
130 391872 tmplen = 4;
131 } else {
132 391801 saved_val = val >> (4 + shift);
133 391801 tmplen = 0;
134 391801 val &= (1 << (shift + 4)) - 1;
135
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391801 NEXT_BYTE(src);
136 }
137 783673 advance_mode = val & 1;
138 783673 len = (val >> 1) - 1;
139
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783673 av_assert0(len>0);
140 783673 mode += 1 + advance_mode;
141
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783673 if (mode >= 4)
142 380507 mode -= 3;
143
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783673 if (len <= 0 || FFABS(dst_end - dst) < len)
144 return AVERROR_INVALIDDATA;
145
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783673 switch (mode) {
146 207200 case 1:
147
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207200 if (forward) {
148
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207200 if (dst - frame + SCREEN_WIDE < frame_off ||
149
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207200 dst - frame + SCREEN_WIDE + frame_off < 0 ||
150
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207200 frame_end - dst < frame_off + len ||
151
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207200 frame_end - dst < len)
152 return AVERROR_INVALIDDATA;
153
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4179410 for (i = 0; i < len; i++)
154 3972210 dst[i] = dst[frame_off + i];
155 207200 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 207200 break;
167 312625 case 2:
168
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312625 if (forward) {
169
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312625 if (source + src_len - src < len)
170 return AVERROR_INVALIDDATA;
171 312625 memcpy(dst, src, len);
172 312625 dst += len;
173 312625 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 312625 break;
182 263848 case 3:
183
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263848 val = forward ? dst[-1] : dst[1];
184
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263848 if (forward) {
185 263848 memset(dst, val, len);
186 263848 dst += len;
187 } else {
188 dst -= len;
189 memset(dst, val, len);
190 }
191 263848 break;
192 }
193
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783673 if (dst == dst_end)
194 21 return 0;
195 }
196 }
197
198 21 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
199 AVPacket *pkt)
200 {
201 21 BMVDecContext * const c = avctx->priv_data;
202 21 AVFrame *frame = data;
203 int type, scr_off;
204 int i, ret;
205 uint8_t *srcptr, *outptr;
206
207 21 c->stream = pkt->data;
208 21 type = bytestream_get_byte(&c->stream);
209
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21 if (type & BMV_AUDIO) {
210 21 int blobs = bytestream_get_byte(&c->stream);
211
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21 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 21 c->stream += blobs * 65;
216 }
217
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21 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
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21 if (type & BMV_PALETTE) {
226
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1 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
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257 for (i = 0; i < 256; i++)
231 256 c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream);
232 }
233
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21 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
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21 } else if ((type & BMV_INTRA) == BMV_INTRA) {
240 11 scr_off = -640;
241 } else {
242 10 scr_off = 0;
243 }
244
245
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21 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
246 return ret;
247
248
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21 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 21 memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
254 21 frame->palette_has_changed = type & BMV_PALETTE;
255
256 21 outptr = frame->data[0];
257 21 srcptr = c->frame;
258
259
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9030 for (i = 0; i < avctx->height; i++) {
260 9009 memcpy(outptr, srcptr, avctx->width);
261 9009 srcptr += avctx->width;
262 9009 outptr += frame->linesize[0];
263 }
264
265 21 *got_frame = 1;
266
267 /* always report that the buffer was completely consumed */
268 21 return pkt->size;
269 }
270
271 3 static av_cold int decode_init(AVCodecContext *avctx)
272 {
273 3 BMVDecContext * const c = avctx->priv_data;
274
275 3 c->avctx = avctx;
276 3 avctx->pix_fmt = AV_PIX_FMT_PAL8;
277
278
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3 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 3 c->frame = c->frame_base + 640;
284
285 3 return 0;
286 }
287
288 const 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