04d7f601 |
/*
* copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
* |
b78e7197 |
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or |
04d7f601 |
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either |
b78e7197 |
* version 2.1 of the License, or (at your option) any later version. |
04d7f601 |
* |
b78e7197 |
* FFmpeg is distributed in the hope that it will be useful, |
04d7f601 |
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public |
b78e7197 |
* License along with FFmpeg; if not, write to the Free Software |
04d7f601 |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
|
caa336b4 |
/** |
ba87f080 |
* @file |
9106a698 |
* bitstream reader API header. |
caa336b4 |
*/
|
9106a698 |
#ifndef AVCODEC_GET_BITS_H
#define AVCODEC_GET_BITS_H |
caa336b4 |
|
99545457 |
#include <stdint.h> |
4af5310d |
|
245976da |
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h" |
6560fa39 |
#include "libavutil/avassert.h" |
e529fe76 |
#include "avcodec.h" |
017c0811 |
#include "mathops.h" |
ffa190d0 |
#include "vlc.h" |
8fbc6aae |
|
8cfbbd92 |
/*
* Safe bitstream reading:
* optionally, the get_bits API can check to ensure that we
* don't read past input buffer boundaries. This is protected
* with CONFIG_SAFE_BITSTREAM_READER at the global level, and
* then below that with UNCHECKED_BITSTREAM_READER at the per-
* decoder level. This means that decoders that check internally
* can "#define UNCHECKED_BITSTREAM_READER 1" to disable
* overread checks.
* Boundary checking causes a minor performance penalty so for
* applications that won't want/need this, it can be disabled
* globally using "#define CONFIG_SAFE_BITSTREAM_READER 0".
*/
#ifndef UNCHECKED_BITSTREAM_READER
#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
#endif
|
caa336b4 |
typedef struct GetBitContext {
const uint8_t *buffer, *buffer_end;
int index;
int size_in_bits; |
8cfbbd92 |
int size_in_bits_plus8; |
caa336b4 |
} GetBitContext;
/* Bitstream reader API docs: |
4af5310d |
* name
* arbitrary name which is used as prefix for the internal variables
*
* gb
* getbitcontext
*
* OPEN_READER(name, gb)
* load gb into local variables
*
* CLOSE_READER(name, gb)
* store local vars in gb
*
* UPDATE_CACHE(name, gb)
* Refill the internal cache from the bitstream.
* After this call at least MIN_CACHE_BITS will be available.
*
* GET_CACHE(name, gb)
* Will output the contents of the internal cache, |
41ed7ab4 |
* next bit is MSB of 32 or 64 bits (FIXME 64 bits). |
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*
* SHOW_UBITS(name, gb, num)
* Will return the next num bits.
*
* SHOW_SBITS(name, gb, num)
* Will return the next num bits and do sign extension.
*
* SKIP_BITS(name, gb, num)
* Will skip over the next num bits.
* Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER.
*
* SKIP_CACHE(name, gb, num)
* Will remove the next num bits from the cache (note SKIP_COUNTER
* MUST be called before UPDATE_CACHE / CLOSE_READER).
*
* SKIP_COUNTER(name, gb, num)
* Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS).
*
* LAST_SKIP_BITS(name, gb, num)
* Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER.
* |
11512d70 |
* BITS_LEFT(name, gb)
* Return the number of bits left
* |
4af5310d |
* For examples see get_bits, show_bits, skip_bits, get_vlc.
*/ |
caa336b4 |
|
1a2484fc |
#ifdef LONG_BITSTREAM_READER
# define MIN_CACHE_BITS 32
#else |
caa336b4 |
# define MIN_CACHE_BITS 25 |
1a2484fc |
#endif |
caa336b4 |
|
b574e1e9 |
#define OPEN_READER_NOSIZE(name, gb) \ |
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unsigned int name ## _index = (gb)->index; \ |
766f0552 |
unsigned int av_unused name ## _cache |
caa336b4 |
|
b574e1e9 |
#if UNCHECKED_BITSTREAM_READER
#define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)
|
91d30579 |
#define BITS_AVAILABLE(name, gb) 1 |
b44b4163 |
#else
#define OPEN_READER(name, gb) \ |
b574e1e9 |
OPEN_READER_NOSIZE(name, gb); \
unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8 |
b44b4163 |
|
91d30579 |
#define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8 |
b44b4163 |
#endif
|
4af5310d |
#define CLOSE_READER(name, gb) (gb)->index = name ## _index |
e42bb0ee |
|
48f2750d |
# ifdef LONG_BITSTREAM_READER
# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))
#else
# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)
#endif
|
aaf47bcd |
#ifdef BITSTREAM_READER_LE |
caa336b4 |
|
48f2750d |
# define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb) |
cea27ac7 |
|
4af5310d |
# define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) |
e42bb0ee |
#else
|
48f2750d |
# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb) |
caa336b4 |
|
4af5310d |
# define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) |
caa336b4 |
|
e42bb0ee |
#endif |
caa336b4 |
|
8cfbbd92 |
#if UNCHECKED_BITSTREAM_READER |
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# define SKIP_COUNTER(name, gb, num) name ## _index += (num) |
8cfbbd92 |
#else
# define SKIP_COUNTER(name, gb, num) \ |
4af5310d |
name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) |
8cfbbd92 |
#endif |
caa336b4 |
|
11512d70 |
#define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index))
|
4af5310d |
#define SKIP_BITS(name, gb, num) \
do { \ |
371cf026 |
SKIP_CACHE(name, gb, num); \
SKIP_COUNTER(name, gb, num); \
} while (0) |
caa336b4 |
|
e42bb0ee |
#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) |
caa336b4 |
|
48f2750d |
#define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num)
#define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num)
#define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num)
#define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num)
|
aaf47bcd |
#ifdef BITSTREAM_READER_LE |
48f2750d |
# define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num)
# define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num) |
e42bb0ee |
#else |
48f2750d |
# define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)
# define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num) |
e42bb0ee |
#endif |
caa336b4 |
|
4af5310d |
#define GET_CACHE(name, gb) ((uint32_t) name ## _cache) |
caa336b4 |
|
e42bb0ee |
static inline int get_bits_count(const GetBitContext *s)
{ |
caa336b4 |
return s->index;
} |
5a7bd283 |
|
6261ef42 |
/**
* Skips the specified number of bits.
* @param n the number of bits to skip,
* For the UNCHECKED_BITSTREAM_READER this must not cause the distance
* from the start to overflow int32_t. Staying within the bitstream + padding
* is sufficient, too.
*/ |
4af5310d |
static inline void skip_bits_long(GetBitContext *s, int n)
{ |
8cfbbd92 |
#if UNCHECKED_BITSTREAM_READER |
6e4703ca |
s->index += n; |
8cfbbd92 |
#else
s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
#endif |
5a7bd283 |
}
|
caa336b4 |
/** |
8ef57a0d |
* Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB). |
115329f1 |
* if MSB not set it is negative |
caa336b4 |
* @param n length in bits
*/ |
e42bb0ee |
static inline int get_xbits(GetBitContext *s, int n)
{ |
6b250e47 |
register int sign; |
caa336b4 |
register int32_t cache; |
d232e09d |
OPEN_READER(re, s); |
ff130d73 |
av_assert2(n>0 && n<=25); |
d232e09d |
UPDATE_CACHE(re, s); |
371cf026 |
cache = GET_CACHE(re, s); |
4af5310d |
sign = ~cache >> 31; |
d232e09d |
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s); |
6b250e47 |
return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; |
2a293ec7 |
}
static inline int get_xbits_le(GetBitContext *s, int n)
{
register int sign;
register int32_t cache;
OPEN_READER(re, s);
av_assert2(n>0 && n<=25);
UPDATE_CACHE_LE(re, s);
cache = GET_CACHE(re, s);
sign = sign_extend(~cache, n) >> 31;
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s);
return (zero_extend(sign ^ cache, n) ^ sign) - sign; |
caa336b4 |
}
|
e42bb0ee |
static inline int get_sbits(GetBitContext *s, int n)
{ |
caa336b4 |
register int tmp; |
d232e09d |
OPEN_READER(re, s); |
6560fa39 |
av_assert2(n>0 && n<=25); |
d232e09d |
UPDATE_CACHE(re, s); |
371cf026 |
tmp = SHOW_SBITS(re, s, n); |
d232e09d |
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s); |
caa336b4 |
return tmp;
}
/** |
990f213e |
* Read 1-25 bits. |
caa336b4 |
*/ |
e42bb0ee |
static inline unsigned int get_bits(GetBitContext *s, int n)
{ |
caa336b4 |
register int tmp; |
d232e09d |
OPEN_READER(re, s); |
6560fa39 |
av_assert2(n>0 && n<=25); |
d232e09d |
UPDATE_CACHE(re, s); |
371cf026 |
tmp = SHOW_UBITS(re, s, n); |
d232e09d |
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s); |
caa336b4 |
return tmp;
}
|
713654d9 |
/**
* Read 0-25 bits.
*/
static av_always_inline int get_bitsz(GetBitContext *s, int n)
{
return n ? get_bits(s, n) : 0;
}
|
48f2750d |
static inline unsigned int get_bits_le(GetBitContext *s, int n)
{
register int tmp;
OPEN_READER(re, s);
av_assert2(n>0 && n<=25);
UPDATE_CACHE_LE(re, s);
tmp = SHOW_UBITS_LE(re, s, n);
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s);
return tmp;
}
|
caa336b4 |
/** |
58c42af7 |
* Show 1-25 bits. |
caa336b4 |
*/ |
e42bb0ee |
static inline unsigned int show_bits(GetBitContext *s, int n)
{ |
caa336b4 |
register int tmp; |
b574e1e9 |
OPEN_READER_NOSIZE(re, s); |
6560fa39 |
av_assert2(n>0 && n<=25); |
d232e09d |
UPDATE_CACHE(re, s); |
371cf026 |
tmp = SHOW_UBITS(re, s, n); |
caa336b4 |
return tmp;
}
|
e42bb0ee |
static inline void skip_bits(GetBitContext *s, int n)
{ |
d232e09d |
OPEN_READER(re, s);
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s); |
caa336b4 |
}
|
e42bb0ee |
static inline unsigned int get_bits1(GetBitContext *s)
{ |
371cf026 |
unsigned int index = s->index; |
4af5310d |
uint8_t result = s->buffer[index >> 3]; |
aaf47bcd |
#ifdef BITSTREAM_READER_LE |
371cf026 |
result >>= index & 7; |
4af5310d |
result &= 1; |
cea27ac7 |
#else |
371cf026 |
result <<= index & 7;
result >>= 8 - 1; |
cea27ac7 |
#endif |
8cfbbd92 |
#if !UNCHECKED_BITSTREAM_READER
if (s->index < s->size_in_bits_plus8)
#endif
index++; |
371cf026 |
s->index = index; |
caa336b4 |
return result;
}
|
e42bb0ee |
static inline unsigned int show_bits1(GetBitContext *s)
{ |
caa336b4 |
return show_bits(s, 1);
}
|
e42bb0ee |
static inline void skip_bits1(GetBitContext *s)
{ |
caa336b4 |
skip_bits(s, 1);
}
/** |
58c42af7 |
* Read 0-32 bits. |
8fbc6aae |
*/ |
e42bb0ee |
static inline unsigned int get_bits_long(GetBitContext *s, int n)
{ |
14090b70 |
av_assert2(n>=0 && n<=32); |
094a82c7 |
if (!n) {
return 0; |
766f0552 |
} else if (n <= MIN_CACHE_BITS) { |
e42bb0ee |
return get_bits(s, n); |
4af5310d |
} else { |
aaf47bcd |
#ifdef BITSTREAM_READER_LE |
5f1c3c78 |
unsigned ret = get_bits(s, 16); |
4af5310d |
return ret | (get_bits(s, n - 16) << 16); |
d1121caa |
#else |
766f0552 |
unsigned ret = get_bits(s, 16) << (n - 16); |
4af5310d |
return ret | get_bits(s, n - 16); |
d1121caa |
#endif |
8fbc6aae |
}
}
/** |
f51c4bfe |
* Read 0-64 bits.
*/ |
7efee140 |
static inline uint64_t get_bits64(GetBitContext *s, int n) |
f51c4bfe |
{ |
41540b36 |
if (n <= 32) { |
f51c4bfe |
return get_bits_long(s, n); |
41540b36 |
} else { |
f51c4bfe |
#ifdef BITSTREAM_READER_LE
uint64_t ret = get_bits_long(s, 32); |
4af5310d |
return ret | (uint64_t) get_bits_long(s, n - 32) << 32; |
f51c4bfe |
#else |
4af5310d |
uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; |
41540b36 |
return ret | get_bits_long(s, 32); |
f51c4bfe |
#endif
}
}
/** |
58c42af7 |
* Read 0-32 bits as a signed integer. |
017c0811 |
*/ |
e42bb0ee |
static inline int get_sbits_long(GetBitContext *s, int n)
{ |
c72fa432 |
// sign_extend(x, 0) is undefined
if (!n)
return 0;
|
017c0811 |
return sign_extend(get_bits_long(s, n), n);
}
/** |
58c42af7 |
* Show 0-32 bits. |
8fbc6aae |
*/ |
e42bb0ee |
static inline unsigned int show_bits_long(GetBitContext *s, int n)
{ |
4af5310d |
if (n <= MIN_CACHE_BITS) { |
e42bb0ee |
return show_bits(s, n); |
4af5310d |
} else { |
371cf026 |
GetBitContext gb = *s; |
edd532db |
return get_bits_long(&gb, n); |
8fbc6aae |
}
}
|
6c98398b |
static inline int check_marker(void *logctx, GetBitContext *s, const char *msg) |
8fbc6aae |
{ |
371cf026 |
int bit = get_bits1(s);
if (!bit) |
6c98398b |
av_log(logctx, AV_LOG_INFO, "Marker bit missing at %d of %d %s\n",
get_bits_count(s) - 1, s->size_in_bits, msg); |
8fbc6aae |
return bit;
}
/** |
d9cf5f51 |
* Initialize GetBitContext. |
059a9348 |
* @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes |
d9cf5f51 |
* larger than the actual read bits because some optimized bitstream
* readers read 32 or 64 bit at once and could read over the end |
caa336b4 |
* @param bit_size the size of the buffer in bits |
d9cf5f51 |
* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow. |
caa336b4 |
*/ |
d9cf5f51 |
static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
int bit_size) |
caa336b4 |
{ |
d9cf5f51 |
int buffer_size;
int ret = 0;
|
e529fe76 |
if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) { |
ea6178ff |
bit_size = 0; |
4af5310d |
buffer = NULL;
ret = AVERROR_INVALIDDATA; |
288f1e68 |
} |
caa336b4 |
|
d9cf5f51 |
buffer_size = (bit_size + 7) >> 3;
|
4af5310d |
s->buffer = buffer;
s->size_in_bits = bit_size; |
8cfbbd92 |
s->size_in_bits_plus8 = bit_size + 8; |
4af5310d |
s->buffer_end = buffer + buffer_size;
s->index = 0;
|
d9cf5f51 |
return ret; |
caa336b4 |
}
|
e28ac6e5 |
/**
* Initialize GetBitContext. |
059a9348 |
* @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes |
e28ac6e5 |
* larger than the actual read bits because some optimized bitstream
* readers read 32 or 64 bit at once and could read over the end
* @param byte_size the size of the buffer in bytes
* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
*/
static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer,
int byte_size)
{ |
ac73d3a1 |
if (byte_size > INT_MAX / 8 || byte_size < 0) |
153fad14 |
byte_size = -1; |
e28ac6e5 |
return init_get_bits(s, buffer, byte_size * 8); |
caa336b4 |
}
|
fd6a021d |
static inline const uint8_t *align_get_bits(GetBitContext *s) |
5a7bd283 |
{ |
371cf026 |
int n = -get_bits_count(s) & 7; |
4af5310d |
if (n)
skip_bits(s, n); |
fd6a021d |
return s->buffer + (s->index >> 3); |
5a7bd283 |
}
|
caa336b4 |
/** |
fd10543e |
* If the vlc code is invalid and max_depth=1, then no bits will be removed.
* If the vlc code is invalid and max_depth>1, then the number of bits removed
* is undefined. |
caa336b4 |
*/ |
e42bb0ee |
#define GET_VLC(code, name, gb, table, bits, max_depth) \
do { \ |
371cf026 |
int n, nb_bits; \
unsigned int index; \
\
index = SHOW_UBITS(name, gb, bits); \
code = table[index][0]; \
n = table[index][1]; \
\
if (max_depth > 1 && n < 0) { \
LAST_SKIP_BITS(name, gb, bits); \
UPDATE_CACHE(name, gb); \
\
nb_bits = -n; \
\
index = SHOW_UBITS(name, gb, nb_bits) + code; \
code = table[index][0]; \
n = table[index][1]; \
if (max_depth > 2 && n < 0) { \
LAST_SKIP_BITS(name, gb, nb_bits); \
UPDATE_CACHE(name, gb); \
\
nb_bits = -n; \
\
index = SHOW_UBITS(name, gb, nb_bits) + code; \
code = table[index][0]; \
n = table[index][1]; \
} \
} \
SKIP_BITS(name, gb, n); \
} while (0)
|
e2836397 |
#define GET_RL_VLC(level, run, name, gb, table, bits, \ |
4af5310d |
max_depth, need_update) \
do { \
int n, nb_bits; \
unsigned int index; \
\
index = SHOW_UBITS(name, gb, bits); \
level = table[index].level; \
n = table[index].len; \
\
if (max_depth > 1 && n < 0) { \
SKIP_BITS(name, gb, bits); \
if (need_update) { \
UPDATE_CACHE(name, gb); \
} \
\
nb_bits = -n; \
\
index = SHOW_UBITS(name, gb, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \ |
906c0b77 |
if (max_depth > 2 && n < 0) { \
LAST_SKIP_BITS(name, gb, nb_bits); \
if (need_update) { \
UPDATE_CACHE(name, gb); \
} \
nb_bits = -n; \
\
index = SHOW_UBITS(name, gb, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
} \ |
4af5310d |
} \
run = table[index].run; \
SKIP_BITS(name, gb, n); \ |
371cf026 |
} while (0) |
caa336b4 |
/** |
5d8122db |
* Parse a vlc code. |
115329f1 |
* @param bits is the number of bits which will be read at once, must be |
caa336b4 |
* identical to nb_bits in init_vlc() |
e42dba48 |
* @param max_depth is the number of times bits bits must be read to completely |
115329f1 |
* read the longest vlc code |
caa336b4 |
* = (max_vlc_length + bits - 1) / bits |
4a94ff4c |
* @returns the code parsed or -1 if no vlc matches |
caa336b4 |
*/ |
849f1035 |
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2], |
e42bb0ee |
int bits, int max_depth) |
caa336b4 |
{
int code; |
115329f1 |
|
d232e09d |
OPEN_READER(re, s);
UPDATE_CACHE(re, s); |
caa336b4 |
|
d232e09d |
GET_VLC(code, re, s, table, bits, max_depth); |
caa336b4 |
|
d232e09d |
CLOSE_READER(re, s); |
4af5310d |
|
caa336b4 |
return code;
}
|
e42bb0ee |
static inline int decode012(GetBitContext *gb)
{ |
a4bff12c |
int n;
n = get_bits1(gb);
if (n == 0)
return 0;
else
return get_bits1(gb) + 1;
}
|
e42bb0ee |
static inline int decode210(GetBitContext *gb)
{ |
a4bff12c |
if (get_bits1(gb))
return 0;
else
return 2 - get_bits1(gb);
}
static inline int get_bits_left(GetBitContext *gb)
{
return gb->size_in_bits - get_bits_count(gb);
}
|
44e8e82d |
static inline int skip_1stop_8data_bits(GetBitContext *gb)
{
if (get_bits_left(gb) <= 0)
return AVERROR_INVALIDDATA;
while (get_bits1(gb)) {
skip_bits(gb, 8);
if (get_bits_left(gb) <= 0)
return AVERROR_INVALIDDATA;
}
return 0;
}
|
9106a698 |
#endif /* AVCODEC_GET_BITS_H */ |