Maths
[Common utility functions]


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.
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.

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 66 of file mathematics.h.


Function Documentation

AVRational av_add_q ( AVRational  b,
AVRational  c 
) const

Add two rationals.

Parameters:
b first rational
c second rational
Returns:
b+c

Definition at line 93 of file rational.c.

Referenced by av_sub_q().

static int av_cmp_q ( AVRational  a,
AVRational  b 
) [inline, static]

Compare two rationals.

Parameters:
a first rational
b second 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.

Referenced by av_nearer_q(), avformat_write_header(), decode_slice_header(), dump_stream_format(), ff_h263_aspect_to_info(), mpeg_decode_postinit(), start_frame(), and video_thread().

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:
mod must 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

Definition at line 157 of file mathematics.c.

Referenced by av_read_frame().

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

Definition at line 147 of file mathematics.c.

Referenced by check_output_constraints(), check_recording_time(), ff_gen_syncpoint_search(), ff_interleave_compare_dts(), search_hi_lo_keyframes(), and seg_write_packet().

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:
d double to convert
max the maximum allowed numerator and denominator
Returns:
(AVRational) d

Definition at line 106 of file rational.c.

Referenced by av_get_q(), av_opt_get_q(), av_opt_set_defaults2(), av_parse_ratio(), config_output_props(), microdvd_read_header(), mov_read_tkhd(), mov_read_trak(), mpeg_decode_postinit(), nuv_header(), read_header(), thp_read_header(), transcode_init(), and write_number().

AVRational av_div_q ( AVRational  b,
AVRational  c 
) const

Divide one rational by another.

Parameters:
b first rational
c second rational
Returns:
b/c

Definition at line 88 of file rational.c.

Referenced by avi_read_header(), config_props_output(), and mpeg_decode_postinit().

int av_find_nearest_q_idx ( AVRational  q,
const AVRational q_list 
)

Find the nearest value in q_list to q.

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

Definition at line 138 of file rational.c.

Referenced by transcode_init().

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.

Definition at line 73 of file mathematics.c.

Referenced by av_gcd(), av_parse_ratio(), av_reduce(), avcodec_string(), avformat_find_stream_info(), config_output(), decode_main_header(), dump_stream_format(), eval_expr(), ff_h263_decode_picture_header(), ff_MPV_encode_init(), ff_parse_specific_params(), rtp_send_samples(), and xvid_correct_framerate().

AVRational av_mul_q ( AVRational  b,
AVRational  c 
) const

Multiply two rationals.

Parameters:
b first rational
c second rational
Returns:
b*c

Definition at line 80 of file rational.c.

Referenced by av_div_q(), avi_write_header(), config_input(), config_props(), mpeg_decode_postinit(), and rv20_decode_picture_header().

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.

Definition at line 123 of file rational.c.

Referenced by av_find_nearest_q_idx().

static double av_q2d ( AVRational  a  )  [inline, static]

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

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

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

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.

Definition at line 134 of file mathematics.c.

Referenced by av_rescale_q(), parse_packet(), and rtp_write_header().

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

AVRational av_sub_q ( AVRational  b,
AVRational  c 
) const

Subtract one rational from another.

Parameters:
b first rational
c second rational
Returns:
b-c

Definition at line 101 of file rational.c.


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