Maths

Data Structures

struct  AVRational
 rational number numerator/denominator More...

Enumerations

enum  AVRounding {
  AV_ROUND_ZERO = 0, AV_ROUND_INF = 1, AV_ROUND_DOWN = 2, AV_ROUND_UP = 3,
  AV_ROUND_NEAR_INF = 5
}

Functions

int64_t av_const av_gcd (int64_t a, int64_t b)
 Return the greatest common divisor of a and b.
int64_t av_rescale (int64_t a, int64_t b, int64_t c) av_const
 Rescale a 64-bit integer with rounding to nearest.
int64_t av_rescale_rnd (int64_t a, int64_t b, int64_t c, enum AVRounding) av_const
 Rescale a 64-bit integer with specified rounding.
int64_t av_rescale_q (int64_t a, AVRational bq, AVRational cq) av_const
 Rescale a 64-bit integer by 2 rational numbers.
int64_t av_rescale_q_rnd (int64_t a, AVRational bq, AVRational cq, enum AVRounding) av_const
 Rescale a 64-bit integer by 2 rational numbers with specified rounding.
int av_compare_ts (int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b)
 Compare 2 timestamps each in its own timebases.
int64_t av_compare_mod (uint64_t a, uint64_t b, uint64_t mod)
 Compare 2 integers modulo mod.
static int av_cmp_q (AVRational a, AVRational b)
 Compare two rationals.
static double av_q2d (AVRational a)
 Convert rational to double.
int av_reduce (int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max)
 Reduce a fraction.
AVRational av_mul_q (AVRational b, AVRational c) av_const
 Multiply two rationals.
AVRational av_div_q (AVRational b, AVRational c) av_const
 Divide one rational by another.
AVRational av_add_q (AVRational b, AVRational c) av_const
 Add two rationals.
AVRational av_sub_q (AVRational b, AVRational c) av_const
 Subtract one rational from another.
static av_always_inline AVRational av_inv_q (AVRational q)
 Invert a rational.
AVRational av_d2q (double d, int max) av_const
 Convert a double precision floating point number to a rational.
int av_nearer_q (AVRational q, AVRational q1, AVRational q2)
int av_find_nearest_q_idx (AVRational q, const AVRational *q_list)
 Find the nearest value in q_list to q.

Detailed Description

Enumeration Type Documentation

enum AVRounding
Enumerator:
AV_ROUND_ZERO 

Round toward zero.

AV_ROUND_INF 

Round away from zero.

AV_ROUND_DOWN 

Round toward -infinity.

AV_ROUND_UP 

Round toward +infinity.

AV_ROUND_NEAR_INF 

Round to nearest and halfway cases away from zero.

Definition at line 49 of file mathematics.h.

Function Documentation

int64_t av_const av_gcd ( int64_t  a,
int64_t  b 
)

Return the greatest common divisor of a and b.

If both a and b are 0 or either or both are <0 then behavior is undefined.

int64_t av_rescale ( int64_t  a,
int64_t  b,
int64_t  c 
) const

Rescale a 64-bit integer with rounding to nearest.

A simple a*b/c isn't possible as it can overflow.

int64_t av_rescale_rnd ( int64_t  a,
int64_t  b,
int64_t  c,
enum  AVRounding 
) const

Rescale a 64-bit integer with specified rounding.

A simple a*b/c isn't possible as it can overflow.

int64_t av_rescale_q ( int64_t  a,
AVRational  bq,
AVRational  cq 
) const

Rescale a 64-bit integer by 2 rational numbers.

int64_t av_rescale_q_rnd ( int64_t  a,
AVRational  bq,
AVRational  cq,
enum  AVRounding 
) const

Rescale a 64-bit integer by 2 rational numbers with specified rounding.

int av_compare_ts ( int64_t  ts_a,
AVRational  tb_a,
int64_t  ts_b,
AVRational  tb_b 
)

Compare 2 timestamps each in its own timebases.

The result of the function is undefined if one of the timestamps is outside the int64_t range when represented in the others timebase.

Returns
-1 if ts_a is before ts_b, 1 if ts_a is after ts_b or 0 if they represent the same position
Examples:
output.c.

Referenced by get_audio_frame(), get_video_frame(), and main().

int64_t av_compare_mod ( uint64_t  a,
uint64_t  b,
uint64_t  mod 
)

Compare 2 integers modulo mod.

That is we compare integers a and b for which only the least significant log2(mod) bits are known.

Parameters
modmust be a power of 2
Returns
a negative value if a is smaller than b a positive value if a is greater than b 0 if a equals b
static int av_cmp_q ( AVRational  a,
AVRational  b 
)
inlinestatic

Compare two rationals.

Parameters
afirst rational
bsecond rational
Returns
0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the values is of the form 0/0

Definition at line 55 of file rational.h.

static double av_q2d ( AVRational  a)
inlinestatic

Convert rational to double.

Parameters
arational to convert
Returns
(double) a

Definition at line 69 of file rational.h.

int av_reduce ( int *  dst_num,
int *  dst_den,
int64_t  num,
int64_t  den,
int64_t  max 
)

Reduce a fraction.

This is useful for framerate calculations.

Parameters
dst_numdestination numerator
dst_dendestination denominator
numsource numerator
densource denominator
maxthe maximum allowed for dst_num & dst_den
Returns
1 if exact, 0 otherwise
AVRational av_mul_q ( AVRational  b,
AVRational  c 
) const

Multiply two rationals.

Parameters
bfirst rational
csecond rational
Returns
b*c
AVRational av_div_q ( AVRational  b,
AVRational  c 
) const

Divide one rational by another.

Parameters
bfirst rational
csecond rational
Returns
b/c
AVRational av_add_q ( AVRational  b,
AVRational  c 
) const

Add two rationals.

Parameters
bfirst rational
csecond rational
Returns
b+c
AVRational av_sub_q ( AVRational  b,
AVRational  c 
) const

Subtract one rational from another.

Parameters
bfirst rational
csecond rational
Returns
b-c
static av_always_inline AVRational av_inv_q ( AVRational  q)
static

Invert a rational.

Parameters
qvalue
Returns
1 / q

Definition at line 122 of file rational.h.

AVRational av_d2q ( double  d,
int  max 
) const

Convert a double precision floating point number to a rational.

inf is expressed as {1,0} or {-1,0} depending on the sign.

Parameters
ddouble to convert
maxthe maximum allowed numerator and denominator
Returns
(AVRational) d
int av_nearer_q ( AVRational  q,
AVRational  q1,
AVRational  q2 
)
Returns
1 if q1 is nearer to q than q2, -1 if q2 is nearer than q1, 0 if they have the same distance.
int av_find_nearest_q_idx ( AVRational  q,
const AVRational q_list 
)

Find the nearest value in q_list to q.

Parameters
q_listan array of rationals terminated by {0, 0}
Returns
the index of the nearest value found in the array