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FFmpeg/libavcodec/get_bits.h
Steinar H. Gunderson 2a293ec7ac avcodec: add Newtek SpeedHQ decoder 
This decoder can decode all existing SpeedHQ formats (SHQ0–5, 7, and 9),
including correct decoding of the alpha channel.

1080p is decoded in 142 fps on one core of my i7-4600U (2.1 GHz Haswell),
about evenly split between bitstream reader and IDCT. There is currently
no attempt at slice or frame threading, even though the format trivially
supports both.

NewTek very helpfully provided a full set of SHQ samples, as well as
source code for an SHQ2 encoder (not included) and assistance with
understanding some details of the format.
2017-01-11 16:02:10 +01:00

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/*
* copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* 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
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* bitstream reader API header.
*/
#ifndef AVCODEC_GET_BITS_H
#define AVCODEC_GET_BITS_H
#include <stdint.h>
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "libavutil/avassert.h"
#include "mathops.h"
#include "vlc.h"
/*
* 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
typedef struct GetBitContext {
const uint8_t *buffer, *buffer_end;
int index;
int size_in_bits;
int size_in_bits_plus8;
} GetBitContext;
/* Bitstream reader API docs:
* 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,
* next bit is MSB of 32 or 64 bits (FIXME 64 bits).
*
* 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.
*
* BITS_LEFT(name, gb)
* Return the number of bits left
*
* For examples see get_bits, show_bits, skip_bits, get_vlc.
*/
#ifdef LONG_BITSTREAM_READER
# define MIN_CACHE_BITS 32
#else
# define MIN_CACHE_BITS 25
#endif
#define OPEN_READER_NOSIZE(name, gb) \
unsigned int name ## _index = (gb)->index; \
unsigned int av_unused name ## _cache
#if UNCHECKED_BITSTREAM_READER
#define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)
#define BITS_AVAILABLE(name, gb) 1
#else
#define OPEN_READER(name, gb) \
OPEN_READER_NOSIZE(name, gb); \
unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8
#define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8
#endif
#define CLOSE_READER(name, gb) (gb)->index = name ## _index
# 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
#ifdef BITSTREAM_READER_LE
# define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb)
# define SKIP_CACHE(name, gb, num) name ## _cache >>= (num)
#else
# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)
# define SKIP_CACHE(name, gb, num) name ## _cache <<= (num)
#endif
#if UNCHECKED_BITSTREAM_READER
# define SKIP_COUNTER(name, gb, num) name ## _index += (num)
#else
# define SKIP_COUNTER(name, gb, num) \
name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num))
#endif
#define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index))
#define SKIP_BITS(name, gb, num) \
do { \
SKIP_CACHE(name, gb, num); \
SKIP_COUNTER(name, gb, num); \
} while (0)
#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
#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)
#ifdef BITSTREAM_READER_LE
# define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num)
# define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num)
#else
# define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)
# define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num)
#endif
#define GET_CACHE(name, gb) ((uint32_t) name ## _cache)
static inline int get_bits_count(const GetBitContext *s)
{
return s->index;
}
static inline void skip_bits_long(GetBitContext *s, int n)
{
#if UNCHECKED_BITSTREAM_READER
s->index += n;
#else
s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
#endif
}
/**
* Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
* if MSB not set it is negative
* @param n length in bits
*/
static inline int get_xbits(GetBitContext *s, int n)
{
register int sign;
register int32_t cache;
OPEN_READER(re, s);
av_assert2(n>0 && n<=25);
UPDATE_CACHE(re, s);
cache = GET_CACHE(re, s);
sign = ~cache >> 31;
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s);
return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
}
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;
}
static inline int get_sbits(GetBitContext *s, int n)
{
register int tmp;
OPEN_READER(re, s);
av_assert2(n>0 && n<=25);
UPDATE_CACHE(re, s);
tmp = SHOW_SBITS(re, s, n);
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s);
return tmp;
}
/**
* Read 1-25 bits.
*/
static inline unsigned int get_bits(GetBitContext *s, int n)
{
register int tmp;
OPEN_READER(re, s);
av_assert2(n>0 && n<=25);
UPDATE_CACHE(re, s);
tmp = SHOW_UBITS(re, s, n);
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s);
return tmp;
}
/**
* Read 0-25 bits.
*/
static av_always_inline int get_bitsz(GetBitContext *s, int n)
{
return n ? get_bits(s, n) : 0;
}
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;
}
/**
* Show 1-25 bits.
*/
static inline unsigned int show_bits(GetBitContext *s, int n)
{
register int tmp;
OPEN_READER_NOSIZE(re, s);
av_assert2(n>0 && n<=25);
UPDATE_CACHE(re, s);
tmp = SHOW_UBITS(re, s, n);
return tmp;
}
static inline void skip_bits(GetBitContext *s, int n)
{
OPEN_READER(re, s);
LAST_SKIP_BITS(re, s, n);
CLOSE_READER(re, s);
}
static inline unsigned int get_bits1(GetBitContext *s)
{
unsigned int index = s->index;
uint8_t result = s->buffer[index >> 3];
#ifdef BITSTREAM_READER_LE
result >>= index & 7;
result &= 1;
#else
result <<= index & 7;
result >>= 8 - 1;
#endif
#if !UNCHECKED_BITSTREAM_READER
if (s->index < s->size_in_bits_plus8)
#endif
index++;
s->index = index;
return result;
}
static inline unsigned int show_bits1(GetBitContext *s)
{
return show_bits(s, 1);
}
static inline void skip_bits1(GetBitContext *s)
{
skip_bits(s, 1);
}
/**
* Read 0-32 bits.
*/
static inline unsigned int get_bits_long(GetBitContext *s, int n)
{
av_assert2(n>=0 && n<=32);
if (!n) {
return 0;
} else if (n <= MIN_CACHE_BITS) {
return get_bits(s, n);
} else {
#ifdef BITSTREAM_READER_LE
unsigned ret = get_bits(s, 16);
return ret | (get_bits(s, n - 16) << 16);
#else
unsigned ret = get_bits(s, 16) << (n - 16);
return ret | get_bits(s, n - 16);
#endif
}
}
/**
* Read 0-64 bits.
*/
static inline uint64_t get_bits64(GetBitContext *s, int n)
{
if (n <= 32) {
return get_bits_long(s, n);
} else {
#ifdef BITSTREAM_READER_LE
uint64_t ret = get_bits_long(s, 32);
return ret | (uint64_t) get_bits_long(s, n - 32) << 32;
#else
uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32;
return ret | get_bits_long(s, 32);
#endif
}
}
/**
* Read 0-32 bits as a signed integer.
*/
static inline int get_sbits_long(GetBitContext *s, int n)
{
// sign_extend(x, 0) is undefined
if (!n)
return 0;
return sign_extend(get_bits_long(s, n), n);
}
/**
* Show 0-32 bits.
*/
static inline unsigned int show_bits_long(GetBitContext *s, int n)
{
if (n <= MIN_CACHE_BITS) {
return show_bits(s, n);
} else {
GetBitContext gb = *s;
return get_bits_long(&gb, n);
}
}
static inline int check_marker(void *logctx, GetBitContext *s, const char *msg)
{
int bit = get_bits1(s);
if (!bit)
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);
return bit;
}
/**
* Initialize GetBitContext.
* @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
* 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 bit_size the size of the buffer in bits
* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.
*/
static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
int bit_size)
{
int buffer_size;
int ret = 0;
if (bit_size >= INT_MAX - 7 || bit_size < 0 || !buffer) {
bit_size = 0;
buffer = NULL;
ret = AVERROR_INVALIDDATA;
}
buffer_size = (bit_size + 7) >> 3;
s->buffer = buffer;
s->size_in_bits = bit_size;
s->size_in_bits_plus8 = bit_size + 8;
s->buffer_end = buffer + buffer_size;
s->index = 0;
return ret;
}
/**
* Initialize GetBitContext.
* @param buffer bitstream buffer, must be AV_INPUT_BUFFER_PADDING_SIZE bytes
* 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)
{
if (byte_size > INT_MAX / 8 || byte_size < 0)
byte_size = -1;
return init_get_bits(s, buffer, byte_size * 8);
}
static inline const uint8_t *align_get_bits(GetBitContext *s)
{
int n = -get_bits_count(s) & 7;
if (n)
skip_bits(s, n);
return s->buffer + (s->index >> 3);
}
/**
* 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.
*/
#define GET_VLC(code, name, gb, table, bits, max_depth) \
do { \
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)
#define GET_RL_VLC(level, run, name, gb, table, bits, \
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; \
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; \
} \
} \
run = table[index].run; \
SKIP_BITS(name, gb, n); \
} while (0)
/**
* Parse a vlc code.
* @param bits is the number of bits which will be read at once, must be
* identical to nb_bits in init_vlc()
* @param max_depth is the number of times bits bits must be read to completely
* read the longest vlc code
* = (max_vlc_length + bits - 1) / bits
*/
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
int bits, int max_depth)
{
int code;
OPEN_READER(re, s);
UPDATE_CACHE(re, s);
GET_VLC(code, re, s, table, bits, max_depth);
CLOSE_READER(re, s);
return code;
}
static inline int decode012(GetBitContext *gb)
{
int n;
n = get_bits1(gb);
if (n == 0)
return 0;
else
return get_bits1(gb) + 1;
}
static inline int decode210(GetBitContext *gb)
{
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);
}
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;
}
#endif /* AVCODEC_GET_BITS_H */
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