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bmvvideo.c
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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,
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 {
48 
50  uint32_t pal[256];
51  const uint8_t *stream;
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;
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 |= (unsigned)*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 
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 
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 };
const char const char void * val
Definition: avisynth_c.h:771
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static int shift(int a, int b)
Definition: sonic.c:82
#define flag(name)
Definition: cbs_h2645.c:345
This structure describes decoded (raw) audio or video data.
Definition: frame.h:201
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int size
Definition: avcodec.h:1401
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1697
const uint8_t * stream
Definition: bmvvideo.c:51
static AVPacket pkt
#define src
Definition: vp8dsp.c:254
AVCodec.
Definition: avcodec.h:3351
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:42
AVCodecContext * avctx
Definition: bmvvideo.c:47
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
Definition: bmvvideo.c:56
BMVFlags
Definition: bmvvideo.c:29
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:40
uint8_t
#define av_cold
Definition: attributes.h:82
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:73
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
#define SCREEN_HIGH
Definition: bmvvideo.c:44
static av_cold int decode_init(AVCodecContext *avctx)
Definition: bmvvideo.c:271
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1400
#define av_log(a,...)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define NEXT_BYTE(v)
Definition: bmvvideo.c:54
static const uint16_t mask[17]
Definition: lzw.c:38
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
simple assert() macros that are a bit more flexible than ISO C assert().
const char * name
Name of the codec implementation.
Definition: avcodec.h:3358
static void frame_end(MpegEncContext *s)
int width
picture width / height.
Definition: avcodec.h:1660
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:232
main external API structure.
Definition: avcodec.h:1488
uint32_t pal[256]
Definition: bmvvideo.c:50
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1886
GLint GLenum type
Definition: opengl_enc.c:105
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:358
#define SCREEN_WIDE
Definition: bmvvideo.c:43
uint8_t * frame
Definition: bmvvideo.c:49
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:215
common internal api header.
common internal and external API header
static double c[64]
void * priv_data
Definition: avcodec.h:1515
int len
uint8_t frame_base[SCREEN_WIDE *(SCREEN_HIGH+1)]
Definition: bmvvideo.c:49
This structure stores compressed data.
Definition: avcodec.h:1377
mode
Use these values in ebur128_init (or'ed).
Definition: ebur128.h:83
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:956
AVCodec ff_bmv_video_decoder
Definition: bmvvideo.c:288
static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *pkt)
Definition: bmvvideo.c:198