Libav
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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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/common.h"
23 
24 #include "avcodec.h"
25 #include "bytestream.h"
26 #include "internal.h"
27 
28 enum BMVFlags{
29  BMV_NOP = 0,
33 
34  BMV_SCROLL = 0x04,
35  BMV_PALETTE = 0x08,
36  BMV_COMMAND = 0x10,
37  BMV_AUDIO = 0x20,
38  BMV_EXT = 0x40,
39  BMV_PRINT = 0x80
40 };
41 
42 #define SCREEN_WIDE 640
43 #define SCREEN_HIGH 429
44 
45 typedef struct BMVDecContext {
47 
49  uint32_t pal[256];
50  const uint8_t *stream;
52 
53 #define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;
54 
55 static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
56 {
57  unsigned val, saved_val = 0;
58  int tmplen = src_len;
59  const uint8_t *src, *source_end = source + src_len;
61  uint8_t *dst, *dst_end;
62  int len, mask;
63  int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
64  int read_two_nibbles, flag;
65  int advance_mode;
66  int mode = 0;
67  int i;
68 
69  if (src_len <= 0)
70  return AVERROR_INVALIDDATA;
71 
72  if (forward) {
73  src = source;
74  dst = frame;
75  dst_end = frame_end;
76  } else {
77  src = source + src_len - 1;
78  dst = frame_end - 1;
79  dst_end = frame - 1;
80  }
81  for (;;) {
82  int shift = 0;
83  flag = 0;
84 
85  /* The mode/len decoding is a bit strange:
86  * values are coded as variable-length codes with nibble units,
87  * code end is signalled by two top bits in the nibble being nonzero.
88  * And since data is bytepacked and we read two nibbles at a time,
89  * we may get a nibble belonging to the next code.
90  * Hence this convoluted loop.
91  */
92  if (!mode || (tmplen == 4)) {
93  if (src < source || src >= source_end)
94  return AVERROR_INVALIDDATA;
95  val = *src;
96  read_two_nibbles = 1;
97  } else {
98  val = saved_val;
99  read_two_nibbles = 0;
100  }
101  if (!(val & 0xC)) {
102  for (;;) {
103  if (!read_two_nibbles) {
104  if (src < source || src >= source_end)
105  return AVERROR_INVALIDDATA;
106  shift += 2;
107  val |= *src << shift;
108  if (*src & 0xC)
109  break;
110  }
111  // two upper bits of the nibble is zero,
112  // so shift top nibble value down into their place
113  read_two_nibbles = 0;
114  shift += 2;
115  mask = (1 << shift) - 1;
116  val = ((val >> 2) & ~mask) | (val & mask);
117  NEXT_BYTE(src);
118  if ((val & (0xC << shift))) {
119  flag = 1;
120  break;
121  }
122  }
123  } else if (mode) {
124  flag = tmplen != 4;
125  }
126  if (flag) {
127  tmplen = 4;
128  } else {
129  saved_val = val >> (4 + shift);
130  tmplen = 0;
131  val &= (1 << (shift + 4)) - 1;
132  NEXT_BYTE(src);
133  }
134  advance_mode = val & 1;
135  len = (val >> 1) - 1;
136  mode += 1 + advance_mode;
137  if (mode >= 4)
138  mode -= 3;
139  if (len <= 0 || FFABS(dst_end - dst) < len)
140  return AVERROR_INVALIDDATA;
141  switch (mode) {
142  case 1:
143  if (forward) {
144  if (dst - frame + SCREEN_WIDE < frame_off ||
145  dst - frame + SCREEN_WIDE + frame_off < 0 ||
146  frame_end - dst < frame_off + len ||
147  frame_end - dst < len)
148  return AVERROR_INVALIDDATA;
149  for (i = 0; i < len; i++)
150  dst[i] = dst[frame_off + i];
151  dst += len;
152  } else {
153  dst -= len;
154  if (dst - frame + SCREEN_WIDE < frame_off ||
155  dst - frame + SCREEN_WIDE + frame_off < 0 ||
156  frame_end - dst < frame_off + len ||
157  frame_end - dst < len)
158  return AVERROR_INVALIDDATA;
159  for (i = len - 1; i >= 0; i--)
160  dst[i] = dst[frame_off + i];
161  }
162  break;
163  case 2:
164  if (forward) {
165  if (source + src_len - src < len)
166  return AVERROR_INVALIDDATA;
167  memcpy(dst, src, len);
168  dst += len;
169  src += len;
170  } else {
171  if (src - source < len)
172  return AVERROR_INVALIDDATA;
173  dst -= len;
174  src -= len;
175  memcpy(dst, src, len);
176  }
177  break;
178  case 3:
179  val = forward ? dst[-1] : dst[1];
180  if (forward) {
181  memset(dst, val, len);
182  dst += len;
183  } else {
184  dst -= len;
185  memset(dst, val, len);
186  }
187  break;
188  default:
189  break;
190  }
191  if (dst == dst_end)
192  return 0;
193  }
194  return 0;
195 }
196 
197 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
198  AVPacket *pkt)
199 {
200  BMVDecContext * const c = avctx->priv_data;
201  AVFrame *frame = data;
202  int type, scr_off;
203  int i, ret;
204  uint8_t *srcptr, *outptr;
205 
206  c->stream = pkt->data;
207  type = bytestream_get_byte(&c->stream);
208  if (type & BMV_AUDIO) {
209  int blobs = bytestream_get_byte(&c->stream);
210  if (pkt->size < blobs * 65 + 2) {
211  av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
212  return AVERROR_INVALIDDATA;
213  }
214  c->stream += blobs * 65;
215  }
216  if (type & BMV_COMMAND) {
217  int command_size = (type & BMV_PRINT) ? 8 : 10;
218  if (c->stream - pkt->data + command_size > pkt->size) {
219  av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
220  return AVERROR_INVALIDDATA;
221  }
222  c->stream += command_size;
223  }
224  if (type & BMV_PALETTE) {
225  if (c->stream - pkt->data > pkt->size - 768) {
226  av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
227  return AVERROR_INVALIDDATA;
228  }
229  for (i = 0; i < 256; i++)
230  c->pal[i] = bytestream_get_be24(&c->stream);
231  }
232  if (type & BMV_SCROLL) {
233  if (c->stream - pkt->data > pkt->size - 2) {
234  av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
235  return AVERROR_INVALIDDATA;
236  }
237  scr_off = (int16_t)bytestream_get_le16(&c->stream);
238  } else if ((type & BMV_INTRA) == BMV_INTRA) {
239  scr_off = -640;
240  } else {
241  scr_off = 0;
242  }
243 
244  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
245  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
246  return ret;
247  }
248 
249  if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
250  av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
251  return AVERROR_INVALIDDATA;
252  }
253 
254  memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
255  frame->palette_has_changed = type & BMV_PALETTE;
256 
257  outptr = frame->data[0];
258  srcptr = c->frame;
259 
260  for (i = 0; i < avctx->height; i++) {
261  memcpy(outptr, srcptr, avctx->width);
262  srcptr += avctx->width;
263  outptr += frame->linesize[0];
264  }
265 
266  *got_frame = 1;
267 
268  /* always report that the buffer was completely consumed */
269  return pkt->size;
270 }
271 
273 {
274  BMVDecContext * const c = avctx->priv_data;
275 
276  c->avctx = avctx;
277  avctx->pix_fmt = AV_PIX_FMT_PAL8;
278 
279  c->frame = c->frame_base + 640;
280 
281  return 0;
282 }
283 
285  .name = "bmv_video",
286  .long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
287  .type = AVMEDIA_TYPE_VIDEO,
288  .id = AV_CODEC_ID_BMV_VIDEO,
289  .priv_data_size = sizeof(BMVDecContext),
290  .init = decode_init,
291  .decode = decode_frame,
292  .capabilities = CODEC_CAP_DR1,
293 };
#define AVPALETTE_SIZE
Definition: avcodec.h:3035
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:54
This structure describes decoded (raw) audio or video data.
Definition: frame.h:135
int size
Definition: avcodec.h:974
void av_log(void *avcl, int level, const char *fmt,...) av_printf_format(3
Send the specified message to the log if the level is less than or equal to the current av_log_level...
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1254
const uint8_t * stream
Definition: bmvvideo.c:50
AVCodec.
Definition: avcodec.h:2796
AVCodecContext * avctx
Definition: bmvvideo.c:46
static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
Definition: bmvvideo.c:55
static int decode(MimicContext *ctx, int quality, int num_coeffs, int is_iframe)
Definition: mimic.c:275
BMVFlags
Definition: bmvvideo.c:28
uint8_t
#define SCREEN_HIGH
Definition: bmvvideo.c:43
static av_cold int decode_init(AVCodecContext *avctx)
Definition: bmvvideo.c:272
const char * name
Name of the codec implementation.
Definition: avcodec.h:2803
#define CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:684
const char data[16]
Definition: mxf.c:70
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:123
#define NEXT_BYTE(v)
Definition: bmvvideo.c:53
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:150
Libavcodec external API header.
static void frame_end(MpegEncContext *s)
int width
picture width / height.
Definition: avcodec.h:1224
8 bit with PIX_FMT_RGB32 palette
Definition: pixfmt.h:76
#define av_cold
Definition: attributes.h:66
main external API structure.
Definition: avcodec.h:1050
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: utils.c:612
uint32_t pal[256]
Definition: bmvvideo.c:49
uint8_t * data
Definition: avcodec.h:973
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:330
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:153
#define SCREEN_WIDE
Definition: bmvvideo.c:42
void * priv_data
Definition: avcodec.h:1092
uint8_t * frame
Definition: bmvvideo.c:48
common internal api header.
static av_cold int init(AVCodecParserContext *s)
Definition: h264_parser.c:499
int len
#define FFABS(a)
Definition: common.h:52
uint8_t frame_base[SCREEN_WIDE *(SCREEN_HIGH+1)]
Definition: bmvvideo.c:48
This structure stores compressed data.
Definition: avcodec.h:950
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:141
AVCodec ff_bmv_video_decoder
Definition: bmvvideo.c:284
static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *pkt)
Definition: bmvvideo.c:197