2 |
#define _VLC_CODES_H_ |
#define _VLC_CODES_H_ |
3 |
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4 |
#include "../portab.h" |
#include "../portab.h" |
5 |
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#include "mbcoding.h" |
6 |
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7 |
#define VLC_ERROR (-1) |
#define VLC_ERROR (-1) |
8 |
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#define ESCAPE 7167 |
9 |
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10 |
typedef struct |
typedef struct |
11 |
{ |
{ |
13 |
int8_t len; |
int8_t len; |
14 |
} VLC; |
} VLC; |
15 |
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16 |
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static VLC *DCT3D[2]; |
17 |
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18 |
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19 |
/****************************************************************** |
/****************************************************************** |
20 |
* common tables between encoder/decoder * |
* common tables between encoder/decoder * |
1227 |
{2, 2}, {2, 2}, {1, 2}, {1, 2}, |
{2, 2}, {2, 2}, {1, 2}, {1, 2}, |
1228 |
}; |
}; |
1229 |
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1230 |
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static __inline int get_coeff(Bitstream * bs, int *run, int *last, |
1231 |
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int intra, int short_video_header) |
1232 |
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{ |
1233 |
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1234 |
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uint32_t mode; |
1235 |
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const VLC *tab; |
1236 |
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int32_t level; |
1237 |
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1238 |
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if(short_video_header) // inter-VLCs will be used for both intra and inter blocks |
1239 |
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intra = 0; |
1240 |
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1241 |
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tab = &DCT3D[intra][BitstreamShowBits(bs, 12)]; |
1242 |
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1243 |
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if(tab->code == -1) |
1244 |
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goto error; |
1245 |
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1246 |
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BitstreamSkip(bs, tab->len); |
1247 |
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1248 |
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if(tab->code != ESCAPE) { |
1249 |
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if(!intra) |
1250 |
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{ |
1251 |
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*run = (tab->code >> 4) & 255; |
1252 |
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level = tab->code & 15; |
1253 |
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*last = (tab->code >> 12) & 1; |
1254 |
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} |
1255 |
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else |
1256 |
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{ |
1257 |
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*run = (tab->code >> 8) & 255; |
1258 |
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level = tab->code & 255; |
1259 |
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*last = (tab->code >> 16) & 1; |
1260 |
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} |
1261 |
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return BitstreamGetBit(bs) ? -level : level; |
1262 |
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} |
1263 |
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1264 |
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if(short_video_header) |
1265 |
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{ |
1266 |
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// escape mode 4 - H.263 type, only used if short_video_header = 1 |
1267 |
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*last = BitstreamGetBit(bs); |
1268 |
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*run = BitstreamGetBits(bs, 6); |
1269 |
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level = BitstreamGetBits(bs, 8); |
1270 |
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1271 |
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if (level == 0 || level == 128) |
1272 |
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DEBUG1("Illegal LEVEL for ESCAPE mode 4:", level); |
1273 |
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1274 |
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return (level >= 128 ? -(256 - level) : level); |
1275 |
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} |
1276 |
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1277 |
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mode = BitstreamShowBits(bs, 2); |
1278 |
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1279 |
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if(mode < 3) { |
1280 |
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BitstreamSkip(bs, (mode == 2) ? 2 : 1); |
1281 |
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1282 |
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tab = &DCT3D[intra][BitstreamShowBits(bs, 12)]; |
1283 |
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if (tab->code == -1) |
1284 |
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goto error; |
1285 |
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1286 |
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BitstreamSkip(bs, tab->len); |
1287 |
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1288 |
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if (!intra) { |
1289 |
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*run = (tab->code >> 4) & 255; |
1290 |
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level = tab->code & 15; |
1291 |
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*last = (tab->code >> 12) & 1; |
1292 |
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} |
1293 |
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else |
1294 |
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{ |
1295 |
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*run = (tab->code >> 8) & 255; |
1296 |
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level = tab->code & 255; |
1297 |
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*last = (tab->code >> 16) & 1; |
1298 |
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} |
1299 |
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1300 |
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if(mode < 2) // first escape mode, level is offset |
1301 |
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level += max_level[*last + (!intra<<1)][*run]; // need to add back the max level |
1302 |
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else if(mode == 2) // second escape mode, run is offset |
1303 |
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*run += max_run[*last + (!intra<<1)][level] + 1; |
1304 |
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1305 |
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return BitstreamGetBit(bs) ? -level : level; |
1306 |
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} |
1307 |
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1308 |
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// third escape mode - fixed length codes |
1309 |
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BitstreamSkip(bs, 2); |
1310 |
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*last = BitstreamGetBits(bs, 1); |
1311 |
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*run = BitstreamGetBits(bs, 6); |
1312 |
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BitstreamSkip(bs, 1); // marker |
1313 |
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level = BitstreamGetBits(bs, 12); |
1314 |
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BitstreamSkip(bs, 1); // marker |
1315 |
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1316 |
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return (level & 0x800) ? (level | (-1 ^ 0xfff)) : level; |
1317 |
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1318 |
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error: |
1319 |
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*run = VLC_ERROR; |
1320 |
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return 0; |
1321 |
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1322 |
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} |
1323 |
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1324 |
#endif /* _VLC_CODES_H */ |
#endif /* _VLC_CODES_H */ |