correct quantizer bias
[libav.git] / libavcodec / common.c
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1/*
2 * Common bit i/o utils
3 * Copyright (c) 2000, 2001 Gerard Lantau.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
27a3e2c5 18 *
17592475 19 * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
de6d9b64 20 */
de6d9b64 21#include "common.h"
1a565432 22#include <math.h>
a9b3f630 23
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24void init_put_bits(PutBitContext *s,
25 UINT8 *buffer, int buffer_size,
26 void *opaque,
27 void (*write_data)(void *, UINT8 *, int))
28{
29 s->buf = buffer;
de6d9b64 30 s->buf_end = s->buf + buffer_size;
de6d9b64 31 s->data_out_size = 0;
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32 if(write_data!=NULL)
33 {
34 fprintf(stderr, "write Data callback is not supported\n");
35 }
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36#ifdef ALT_BITSTREAM_WRITER
37 s->index=0;
38 ((uint32_t*)(s->buf))[0]=0;
39// memset(buffer, 0, buffer_size);
17592475 40#else
17592475 41 s->buf_ptr = s->buf;
d8cf5aea 42 s->bit_left=32;
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43 s->bit_buf=0;
44#endif
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45}
46
de6d9b64 47/* return the number of bits output */
1a565432 48INT64 get_bit_count(PutBitContext *s)
de6d9b64 49{
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50#ifdef ALT_BITSTREAM_WRITER
51 return s->data_out_size * 8 + s->index;
52#else
d8cf5aea 53 return (s->buf_ptr - s->buf + s->data_out_size) * 8 + 32 - (INT64)s->bit_left;
17592475 54#endif
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55}
56
57void align_put_bits(PutBitContext *s)
58{
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59#ifdef ALT_BITSTREAM_WRITER
60 put_bits(s,( - s->index) & 7,0);
61#else
d8cf5aea 62 put_bits(s,s->bit_left & 7,0);
17592475 63#endif
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64}
65
66/* pad the end of the output stream with zeros */
67void flush_put_bits(PutBitContext *s)
68{
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69#ifdef ALT_BITSTREAM_WRITER
70 align_put_bits(s);
71#else
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72 s->bit_buf<<= s->bit_left;
73 while (s->bit_left < 32) {
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74 /* XXX: should test end of buffer */
75 *s->buf_ptr++=s->bit_buf >> 24;
76 s->bit_buf<<=8;
d8cf5aea 77 s->bit_left+=8;
de6d9b64 78 }
d8cf5aea 79 s->bit_left=32;
de6d9b64 80 s->bit_buf=0;
17592475 81#endif
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82}
83
de6d9b64 84/* pad the end of the output stream with zeros */
17592475 85#ifndef ALT_BITSTREAM_WRITER
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86void jflush_put_bits(PutBitContext *s)
87{
88 unsigned int b;
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89 s->bit_buf<<= s->bit_left;
90 s->bit_buf |= ~1U >> (32 - s->bit_left); /* set all the unused bits to one */
de6d9b64 91
d8cf5aea 92 while (s->bit_left < 32) {
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93 b = s->bit_buf >> 24;
94 *s->buf_ptr++ = b;
95 if (b == 0xff)
96 *s->buf_ptr++ = 0;
97 s->bit_buf<<=8;
d8cf5aea 98 s->bit_left+=8;
de6d9b64 99 }
d8cf5aea 100 s->bit_left=32;
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101 s->bit_buf=0;
102}
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103#else
104void jflush_put_bits(PutBitContext *s)
105{
106 int num= ( - s->index) & 7;
107 jput_bits(s, num,0xFF>>(8-num));
108}
109#endif
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110
111/* bit input functions */
112
113void init_get_bits(GetBitContext *s,
114 UINT8 *buffer, int buffer_size)
115{
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116#ifdef ALT_BITSTREAM_READER
117 s->index=0;
118 s->buffer= buffer;
119#else
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120 s->buf = buffer;
121 s->buf_ptr = buffer;
122 s->buf_end = buffer + buffer_size;
123 s->bit_cnt = 0;
124 s->bit_buf = 0;
125 while (s->buf_ptr < s->buf_end &&
126 s->bit_cnt < 32) {
127 s->bit_buf |= (*s->buf_ptr++ << (24 - s->bit_cnt));
128 s->bit_cnt += 8;
129 }
27a3e2c5 130#endif
45870f57 131 s->size= buffer_size;
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132}
133
27a3e2c5 134#ifndef ALT_BITSTREAM_READER
de6d9b64 135/* n must be >= 1 and <= 32 */
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136/* also true: n > s->bit_cnt */
137unsigned int get_bits_long(GetBitContext *s, int n)
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138{
139 unsigned int val;
140 int bit_cnt;
141 unsigned int bit_buf;
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142
143#ifdef STATS
144 st_bit_counts[st_current_index] += n;
145#endif
146
de6d9b64 147 bit_buf = s->bit_buf;
2931ecb9 148 bit_cnt = s->bit_cnt - n;
de6d9b64 149
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150// if (bit_cnt >= 0) {
151// val = bit_buf >> (32 - n);
152// bit_buf <<= n;
153// } else
154 {
155 UINT8 *buf_ptr;
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156 val = bit_buf >> (32 - n);
157 buf_ptr = s->buf_ptr;
158 buf_ptr += 4;
159 /* handle common case: we can read everything */
160 if (buf_ptr <= s->buf_end) {
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161#if ARCH_X86
162 bit_buf = bswap_32(*((unsigned long*)(&buf_ptr[-4])));
163#else
164 bit_buf = (buf_ptr[-4] << 24) |
165 (buf_ptr[-3] << 16) |
de6d9b64 166 (buf_ptr[-2] << 8) |
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167 (buf_ptr[-1]);
168#endif
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169 } else {
170 buf_ptr -= 4;
171 bit_buf = 0;
172 if (buf_ptr < s->buf_end)
173 bit_buf |= *buf_ptr++ << 24;
174 if (buf_ptr < s->buf_end)
175 bit_buf |= *buf_ptr++ << 16;
176 if (buf_ptr < s->buf_end)
177 bit_buf |= *buf_ptr++ << 8;
178 if (buf_ptr < s->buf_end)
179 bit_buf |= *buf_ptr++;
180 }
181 s->buf_ptr = buf_ptr;
182 val |= bit_buf >> (32 + bit_cnt);
183 bit_buf <<= - bit_cnt;
184 bit_cnt += 32;
185 }
186 s->bit_buf = bit_buf;
187 s->bit_cnt = bit_cnt;
188 return val;
189}
27a3e2c5 190#endif
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191
192void align_get_bits(GetBitContext *s)
193{
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194#ifdef ALT_BITSTREAM_READER
195 s->index= (s->index + 7) & (~7);
196#else
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197 int n;
198 n = s->bit_cnt & 7;
199 if (n > 0) {
200 get_bits(s, n);
201 }
27a3e2c5 202#endif
de6d9b64 203}
27a3e2c5 204
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205int check_marker(GetBitContext *s, char *msg)
206{
207 int bit= get_bits1(s);
208 if(!bit) printf("Marker bit missing %s\n", msg);
209
210 return bit;
211}
212
27a3e2c5 213#ifndef ALT_BITSTREAM_READER
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214/* This function is identical to get_bits_long(), the */
215/* only diference is that it doesn't touch the buffer */
216/* it is usefull to see the buffer. */
217
218unsigned int show_bits_long(GetBitContext *s, int n)
219{
220 unsigned int val;
221 int bit_cnt;
222 unsigned int bit_buf;
223 UINT8 *buf_ptr;
224
225 bit_buf = s->bit_buf;
226 bit_cnt = s->bit_cnt - n;
227
228 val = bit_buf >> (32 - n);
229 buf_ptr = s->buf_ptr;
230 buf_ptr += 4;
231
232 /* handle common case: we can read everything */
233 if (buf_ptr <= s->buf_end) {
234#ifdef ARCH_X86
235 bit_buf = bswap_32(*((unsigned long*)(&buf_ptr[-4])));
236#else
237 bit_buf = (buf_ptr[-4] << 24) |
238 (buf_ptr[-3] << 16) |
239 (buf_ptr[-2] << 8) |
240 (buf_ptr[-1]);
241#endif
242 } else {
243 buf_ptr -= 4;
244 bit_buf = 0;
245 if (buf_ptr < s->buf_end)
246 bit_buf |= *buf_ptr++ << 24;
247 if (buf_ptr < s->buf_end)
248 bit_buf |= *buf_ptr++ << 16;
249 if (buf_ptr < s->buf_end)
250 bit_buf |= *buf_ptr++ << 8;
251 if (buf_ptr < s->buf_end)
252 bit_buf |= *buf_ptr++;
253 }
254 val |= bit_buf >> (32 + bit_cnt);
255 bit_buf <<= - bit_cnt;
256 bit_cnt += 32;
257
258 return val;
259}
27a3e2c5 260#endif
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261
262/* VLC decoding */
263
264//#define DEBUG_VLC
265
266#define GET_DATA(v, table, i, wrap, size) \
267{\
268 UINT8 *ptr = (UINT8 *)table + i * wrap;\
269 switch(size) {\
270 case 1:\
271 v = *(UINT8 *)ptr;\
272 break;\
273 case 2:\
274 v = *(UINT16 *)ptr;\
275 break;\
276 default:\
277 v = *(UINT32 *)ptr;\
278 break;\
279 }\
280}
281
282
283static int alloc_table(VLC *vlc, int size)
284{
285 int index;
286 index = vlc->table_size;
287 vlc->table_size += size;
288 if (vlc->table_size > vlc->table_allocated) {
289 vlc->table_allocated += (1 << vlc->bits);
290 vlc->table_bits = realloc(vlc->table_bits,
291 sizeof(INT8) * vlc->table_allocated);
292 vlc->table_codes = realloc(vlc->table_codes,
293 sizeof(INT16) * vlc->table_allocated);
294 if (!vlc->table_bits ||
295 !vlc->table_codes)
296 return -1;
297 }
298 return index;
299}
300
301static int build_table(VLC *vlc, int table_nb_bits,
302 int nb_codes,
303 const void *bits, int bits_wrap, int bits_size,
304 const void *codes, int codes_wrap, int codes_size,
305 UINT32 code_prefix, int n_prefix)
306{
307 int i, j, k, n, table_size, table_index, nb, n1, index;
308 UINT32 code;
309 INT8 *table_bits;
310 INT16 *table_codes;
311
312 table_size = 1 << table_nb_bits;
313 table_index = alloc_table(vlc, table_size);
314#ifdef DEBUG_VLC
315 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
316 table_index, table_size, code_prefix, n_prefix);
317#endif
318 if (table_index < 0)
319 return -1;
320 table_bits = &vlc->table_bits[table_index];
321 table_codes = &vlc->table_codes[table_index];
322
323 for(i=0;i<table_size;i++) {
324 table_bits[i] = 0;
325 table_codes[i] = -1;
326 }
327
328 /* first pass: map codes and compute auxillary table sizes */
329 for(i=0;i<nb_codes;i++) {
330 GET_DATA(n, bits, i, bits_wrap, bits_size);
331 GET_DATA(code, codes, i, codes_wrap, codes_size);
332 /* we accept tables with holes */
333 if (n <= 0)
334 continue;
335#if defined(DEBUG_VLC) && 0
336 printf("i=%d n=%d code=0x%x\n", i, n, code);
337#endif
338 /* if code matches the prefix, it is in the table */
339 n -= n_prefix;
340 if (n > 0 && (code >> n) == code_prefix) {
341 if (n <= table_nb_bits) {
342 /* no need to add another table */
343 j = (code << (table_nb_bits - n)) & (table_size - 1);
344 nb = 1 << (table_nb_bits - n);
345 for(k=0;k<nb;k++) {
346#ifdef DEBUG_VLC
347 printf("%4x: code=%d n=%d\n",
348 j, i, n);
349#endif
350 if (table_bits[j] != 0) {
351 fprintf(stderr, "incorrect codes\n");
352 exit(1);
353 }
354 table_bits[j] = n;
355 table_codes[j] = i;
356 j++;
357 }
358 } else {
359 n -= table_nb_bits;
360 j = (code >> n) & ((1 << table_nb_bits) - 1);
361#ifdef DEBUG_VLC
362 printf("%4x: n=%d (subtable)\n",
363 j, n);
364#endif
365 /* compute table size */
366 n1 = -table_bits[j];
367 if (n > n1)
368 n1 = n;
369 table_bits[j] = -n1;
370 }
371 }
372 }
373
374 /* second pass : fill auxillary tables recursively */
375 for(i=0;i<table_size;i++) {
376 n = table_bits[i];
377 if (n < 0) {
378 n = -n;
379 if (n > table_nb_bits) {
380 n = table_nb_bits;
381 table_bits[i] = -n;
382 }
383 index = build_table(vlc, n, nb_codes,
384 bits, bits_wrap, bits_size,
385 codes, codes_wrap, codes_size,
386 (code_prefix << table_nb_bits) | i,
387 n_prefix + table_nb_bits);
388 if (index < 0)
389 return -1;
390 /* note: realloc has been done, so reload tables */
391 table_bits = &vlc->table_bits[table_index];
392 table_codes = &vlc->table_codes[table_index];
393 table_codes[i] = index;
394 }
395 }
396 return table_index;
397}
398
399
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400/* Build VLC decoding tables suitable for use with get_vlc().
401
402 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
403 bigger it is, the faster is the decoding. But it should not be too
404 big to save memory and L1 cache. '9' is a good compromise.
405
406 'nb_codes' : number of vlcs codes
407
408 'bits' : table which gives the size (in bits) of each vlc code.
409
410 'codes' : table which gives the bit pattern of of each vlc code.
411
412 'xxx_wrap' : give the number of bytes between each entry of the
413 'bits' or 'codes' tables.
414
415 'xxx_size' : gives the number of bytes of each entry of the 'bits'
416 or 'codes' tables.
417
418 'wrap' and 'size' allows to use any memory configuration and types
419 (byte/word/long) to store the 'bits' and 'codes' tables.
420*/
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421int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
422 const void *bits, int bits_wrap, int bits_size,
423 const void *codes, int codes_wrap, int codes_size)
424{
425 vlc->bits = nb_bits;
426 vlc->table_bits = NULL;
427 vlc->table_codes = NULL;
428 vlc->table_allocated = 0;
429 vlc->table_size = 0;
430#ifdef DEBUG_VLC
431 printf("build table nb_codes=%d\n", nb_codes);
432#endif
433
434 if (build_table(vlc, nb_bits, nb_codes,
435 bits, bits_wrap, bits_size,
436 codes, codes_wrap, codes_size,
437 0, 0) < 0) {
438 if (vlc->table_bits)
439 free(vlc->table_bits);
440 if (vlc->table_codes)
441 free(vlc->table_codes);
442 return -1;
443 }
444 return 0;
445}
446
447
448void free_vlc(VLC *vlc)
449{
450 free(vlc->table_bits);
451 free(vlc->table_codes);
452}
453
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454int ff_gcd(int a, int b){
455 if(b) return ff_gcd(b, a%b);
456 else return a;
457}