generate even more complete mpeg4 headers
[libav.git] / libavcodec / common.c
CommitLineData
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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
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131}
132
27a3e2c5 133#ifndef ALT_BITSTREAM_READER
de6d9b64 134/* n must be >= 1 and <= 32 */
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135/* also true: n > s->bit_cnt */
136unsigned int get_bits_long(GetBitContext *s, int n)
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137{
138 unsigned int val;
139 int bit_cnt;
140 unsigned int bit_buf;
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141
142#ifdef STATS
143 st_bit_counts[st_current_index] += n;
144#endif
145
de6d9b64 146 bit_buf = s->bit_buf;
2931ecb9 147 bit_cnt = s->bit_cnt - n;
de6d9b64 148
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149// if (bit_cnt >= 0) {
150// val = bit_buf >> (32 - n);
151// bit_buf <<= n;
152// } else
153 {
154 UINT8 *buf_ptr;
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155 val = bit_buf >> (32 - n);
156 buf_ptr = s->buf_ptr;
157 buf_ptr += 4;
158 /* handle common case: we can read everything */
159 if (buf_ptr <= s->buf_end) {
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160#if ARCH_X86
161 bit_buf = bswap_32(*((unsigned long*)(&buf_ptr[-4])));
162#else
163 bit_buf = (buf_ptr[-4] << 24) |
164 (buf_ptr[-3] << 16) |
de6d9b64 165 (buf_ptr[-2] << 8) |
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166 (buf_ptr[-1]);
167#endif
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168 } else {
169 buf_ptr -= 4;
170 bit_buf = 0;
171 if (buf_ptr < s->buf_end)
172 bit_buf |= *buf_ptr++ << 24;
173 if (buf_ptr < s->buf_end)
174 bit_buf |= *buf_ptr++ << 16;
175 if (buf_ptr < s->buf_end)
176 bit_buf |= *buf_ptr++ << 8;
177 if (buf_ptr < s->buf_end)
178 bit_buf |= *buf_ptr++;
179 }
180 s->buf_ptr = buf_ptr;
181 val |= bit_buf >> (32 + bit_cnt);
182 bit_buf <<= - bit_cnt;
183 bit_cnt += 32;
184 }
185 s->bit_buf = bit_buf;
186 s->bit_cnt = bit_cnt;
187 return val;
188}
27a3e2c5 189#endif
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190
191void align_get_bits(GetBitContext *s)
192{
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193#ifdef ALT_BITSTREAM_READER
194 s->index= (s->index + 7) & (~7);
195#else
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196 int n;
197 n = s->bit_cnt & 7;
198 if (n > 0) {
199 get_bits(s, n);
200 }
27a3e2c5 201#endif
de6d9b64 202}
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203
204#ifndef ALT_BITSTREAM_READER
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205/* This function is identical to get_bits_long(), the */
206/* only diference is that it doesn't touch the buffer */
207/* it is usefull to see the buffer. */
208
209unsigned int show_bits_long(GetBitContext *s, int n)
210{
211 unsigned int val;
212 int bit_cnt;
213 unsigned int bit_buf;
214 UINT8 *buf_ptr;
215
216 bit_buf = s->bit_buf;
217 bit_cnt = s->bit_cnt - n;
218
219 val = bit_buf >> (32 - n);
220 buf_ptr = s->buf_ptr;
221 buf_ptr += 4;
222
223 /* handle common case: we can read everything */
224 if (buf_ptr <= s->buf_end) {
225#ifdef ARCH_X86
226 bit_buf = bswap_32(*((unsigned long*)(&buf_ptr[-4])));
227#else
228 bit_buf = (buf_ptr[-4] << 24) |
229 (buf_ptr[-3] << 16) |
230 (buf_ptr[-2] << 8) |
231 (buf_ptr[-1]);
232#endif
233 } else {
234 buf_ptr -= 4;
235 bit_buf = 0;
236 if (buf_ptr < s->buf_end)
237 bit_buf |= *buf_ptr++ << 24;
238 if (buf_ptr < s->buf_end)
239 bit_buf |= *buf_ptr++ << 16;
240 if (buf_ptr < s->buf_end)
241 bit_buf |= *buf_ptr++ << 8;
242 if (buf_ptr < s->buf_end)
243 bit_buf |= *buf_ptr++;
244 }
245 val |= bit_buf >> (32 + bit_cnt);
246 bit_buf <<= - bit_cnt;
247 bit_cnt += 32;
248
249 return val;
250}
27a3e2c5 251#endif
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252
253/* VLC decoding */
254
255//#define DEBUG_VLC
256
257#define GET_DATA(v, table, i, wrap, size) \
258{\
259 UINT8 *ptr = (UINT8 *)table + i * wrap;\
260 switch(size) {\
261 case 1:\
262 v = *(UINT8 *)ptr;\
263 break;\
264 case 2:\
265 v = *(UINT16 *)ptr;\
266 break;\
267 default:\
268 v = *(UINT32 *)ptr;\
269 break;\
270 }\
271}
272
273
274static int alloc_table(VLC *vlc, int size)
275{
276 int index;
277 index = vlc->table_size;
278 vlc->table_size += size;
279 if (vlc->table_size > vlc->table_allocated) {
280 vlc->table_allocated += (1 << vlc->bits);
281 vlc->table_bits = realloc(vlc->table_bits,
282 sizeof(INT8) * vlc->table_allocated);
283 vlc->table_codes = realloc(vlc->table_codes,
284 sizeof(INT16) * vlc->table_allocated);
285 if (!vlc->table_bits ||
286 !vlc->table_codes)
287 return -1;
288 }
289 return index;
290}
291
292static int build_table(VLC *vlc, int table_nb_bits,
293 int nb_codes,
294 const void *bits, int bits_wrap, int bits_size,
295 const void *codes, int codes_wrap, int codes_size,
296 UINT32 code_prefix, int n_prefix)
297{
298 int i, j, k, n, table_size, table_index, nb, n1, index;
299 UINT32 code;
300 INT8 *table_bits;
301 INT16 *table_codes;
302
303 table_size = 1 << table_nb_bits;
304 table_index = alloc_table(vlc, table_size);
305#ifdef DEBUG_VLC
306 printf("new table index=%d size=%d code_prefix=%x n=%d\n",
307 table_index, table_size, code_prefix, n_prefix);
308#endif
309 if (table_index < 0)
310 return -1;
311 table_bits = &vlc->table_bits[table_index];
312 table_codes = &vlc->table_codes[table_index];
313
314 for(i=0;i<table_size;i++) {
315 table_bits[i] = 0;
316 table_codes[i] = -1;
317 }
318
319 /* first pass: map codes and compute auxillary table sizes */
320 for(i=0;i<nb_codes;i++) {
321 GET_DATA(n, bits, i, bits_wrap, bits_size);
322 GET_DATA(code, codes, i, codes_wrap, codes_size);
323 /* we accept tables with holes */
324 if (n <= 0)
325 continue;
326#if defined(DEBUG_VLC) && 0
327 printf("i=%d n=%d code=0x%x\n", i, n, code);
328#endif
329 /* if code matches the prefix, it is in the table */
330 n -= n_prefix;
331 if (n > 0 && (code >> n) == code_prefix) {
332 if (n <= table_nb_bits) {
333 /* no need to add another table */
334 j = (code << (table_nb_bits - n)) & (table_size - 1);
335 nb = 1 << (table_nb_bits - n);
336 for(k=0;k<nb;k++) {
337#ifdef DEBUG_VLC
338 printf("%4x: code=%d n=%d\n",
339 j, i, n);
340#endif
341 if (table_bits[j] != 0) {
342 fprintf(stderr, "incorrect codes\n");
343 exit(1);
344 }
345 table_bits[j] = n;
346 table_codes[j] = i;
347 j++;
348 }
349 } else {
350 n -= table_nb_bits;
351 j = (code >> n) & ((1 << table_nb_bits) - 1);
352#ifdef DEBUG_VLC
353 printf("%4x: n=%d (subtable)\n",
354 j, n);
355#endif
356 /* compute table size */
357 n1 = -table_bits[j];
358 if (n > n1)
359 n1 = n;
360 table_bits[j] = -n1;
361 }
362 }
363 }
364
365 /* second pass : fill auxillary tables recursively */
366 for(i=0;i<table_size;i++) {
367 n = table_bits[i];
368 if (n < 0) {
369 n = -n;
370 if (n > table_nb_bits) {
371 n = table_nb_bits;
372 table_bits[i] = -n;
373 }
374 index = build_table(vlc, n, nb_codes,
375 bits, bits_wrap, bits_size,
376 codes, codes_wrap, codes_size,
377 (code_prefix << table_nb_bits) | i,
378 n_prefix + table_nb_bits);
379 if (index < 0)
380 return -1;
381 /* note: realloc has been done, so reload tables */
382 table_bits = &vlc->table_bits[table_index];
383 table_codes = &vlc->table_codes[table_index];
384 table_codes[i] = index;
385 }
386 }
387 return table_index;
388}
389
390
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391/* Build VLC decoding tables suitable for use with get_vlc().
392
393 'nb_bits' set thee decoding table size (2^nb_bits) entries. The
394 bigger it is, the faster is the decoding. But it should not be too
395 big to save memory and L1 cache. '9' is a good compromise.
396
397 'nb_codes' : number of vlcs codes
398
399 'bits' : table which gives the size (in bits) of each vlc code.
400
401 'codes' : table which gives the bit pattern of of each vlc code.
402
403 'xxx_wrap' : give the number of bytes between each entry of the
404 'bits' or 'codes' tables.
405
406 'xxx_size' : gives the number of bytes of each entry of the 'bits'
407 or 'codes' tables.
408
409 'wrap' and 'size' allows to use any memory configuration and types
410 (byte/word/long) to store the 'bits' and 'codes' tables.
411*/
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412int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
413 const void *bits, int bits_wrap, int bits_size,
414 const void *codes, int codes_wrap, int codes_size)
415{
416 vlc->bits = nb_bits;
417 vlc->table_bits = NULL;
418 vlc->table_codes = NULL;
419 vlc->table_allocated = 0;
420 vlc->table_size = 0;
421#ifdef DEBUG_VLC
422 printf("build table nb_codes=%d\n", nb_codes);
423#endif
424
425 if (build_table(vlc, nb_bits, nb_codes,
426 bits, bits_wrap, bits_size,
427 codes, codes_wrap, codes_size,
428 0, 0) < 0) {
429 if (vlc->table_bits)
430 free(vlc->table_bits);
431 if (vlc->table_codes)
432 free(vlc->table_codes);
433 return -1;
434 }
435 return 0;
436}
437
438
439void free_vlc(VLC *vlc)
440{
441 free(vlc->table_bits);
442 free(vlc->table_codes);
443}
444