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.
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 150 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 140 of file mathematics.c.

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

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_video_rate(), config_output_props(), init(), matroska_read_header(), microdvd_read_header(), mov_read_tkhd(), mov_read_trak(), mpeg_decode_postinit(), nuv_header(), thp_read_header(), 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_reduce(), avcodec_string(), avformat_find_stream_info(), config_output(), decode_main_header(), dump_stream_format(), eval_expr(), ff_parse_specific_params(), h263_decode_picture_header(), init(), MPV_encode_init(), and rtp_send_samples().

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_props(), and mpeg_decode_postinit().

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]

Convert rational to double.

Parameters:

a

rational to convert

Returns:: (double) a

Definition at line 69 of file rational.h.

Referenced by audio_decode_frame(), av_dump_format(), avfilter_start_frame(), avformat_find_stream_info(), avformat_write_header(), avi_write_header(), config_input(), config_output_props(), decode_syncpoint(), do_video_out(), do_video_stats(), draw_text(), dump_stream_format(), dv_write_pack(), end_frame(), fbdev_read_header(), fbdev_read_packet(), ff_rate_control_init(), ff_rate_estimate_qscale(), ff_vbv_update(), filter_samples(), flv_write_header(), get_video_frame(), grab_read_header(), init(), init_input_stream(), init_pass2(), mkv_write_tracks(), modify_qscale(), mov_write_tkhd_tag(), mov_write_trak_tag(), mpeg1_encode_sequence_header(), MPV_encode_init(), MPV_encode_picture(), mxf_write_header(), pkt_dump_internal(), queue_picture(), read_header(), read_seek(), read_thread(), sdl_write_header(), select_frame(), start_frame(), subtitle_thread(), thp_read_header(), transcode(), transcode_init(), v4l2_read_header(), vf_next_put_image(), video_image_display(), video_thread(), write_trailer(), writer_print_time(), x11grab_read_header(), and x11grab_read_packet().

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_num	destination numerator
	dst_den	destination denominator
	num	source numerator
	den	source denominator
	max	the maximum allowed for dst_num & dst_den

Returns:: 1 if exact, 0 otherwise

Definition at line 36 of file rational.c.

Referenced by asf_read_header(), av_add_q(), av_d2q(), av_mul_q(), av_resample_init(), avcodec_string(), avi_write_header(), avpriv_set_pts_info(), config_output(), decode_frame(), decode_sequence_header_adv(), decode_slice_header(), dump_stream_format(), dxa_read_header(), ff_rm_read_mdpr_codecdata(), matroska_read_header(), mov_read_trak(), mov_write_pasp_tag(), mpeg_decode_postinit(), MPV_encode_init(), mxf_parse_mpeg2_frame(), parse_source_parameters(), read_fps(), show_stream(), skeleton_header(), smacker_read_header(), start_frame(), swri_resample_init(), tmv_read_header(), transcode_init(), vmd_read_header(), X264_init(), and yuv4_read_header().

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.

Definition at line 130 of file mathematics.c.

Referenced by asf_build_simple_index(), audio_read_packet(), av_dump_format(), av_seek_frame(), avi_read_header(), compute_pkt_fields(), compute_pkt_fields2(), config_props(), dc1394_read_header(), estimate_timings_from_bit_rate(), ff_gen_search(), ff_update_cur_dts(), filter_samples(), finalize_packet(), flush_encoders(), get_pcr(), mov_build_index(), mov_find_next_sample(), mov_read_trak(), mov_write_tapt_tag(), mp3_parse_vbr_tags(), mpeg_mux_write_packet(), mpegts_write_header(), mpegts_write_packet(), mpegts_write_pes(), mxf_read_seek(), nsv_parse_NSVs_header(), output_packet(), pcm_read_seek(), r3d_read_reda(), rate_emu_sleep(), read_header(), and vqf_read_seek().

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

Rescale a 64-bit integer by 2 rational numbers.

Definition at line 134 of file mathematics.c.

Referenced by av_interleave_packet_per_dts(), avformat_find_stream_info(), avi_read_packet(), avi_read_seek(), compute_chapters_end(), copy_chapters(), decode_frame(), display_picref(), do_audio_out(), do_streamcopy(), do_subtitle_out(), do_video_out(), dv_extract_video_info(), dv_offset_reset(), dv_read_header(), encode_frame(), ff_interleave_add_packet(), ff_interleave_compare_dts(), ff_interleave_new_audio_packet(), ff_mov_write_packet(), ff_write_chained(), fill_all_stream_timings(), flush_encoders(), get_subtitle_pkt(), gsm_read_seek2(), http_prepare_data(), init(), lavfi_read_packet(), main(), mkv_write_chapters(), mov_create_chapter_track(), mov_read_seek(), mov_write_chpl_tag(), mp3_parse_vbr_tags(), ogg_compare_granule(), ogg_get_length(), oggvorbis_encode_frame(), output_packet(), parse_forced_key_frames(), print_report(), read_header(), read_seek2(), rl2_read_seek(), rtcp_send_sr(), rtp_write_header(), rtsp_read_play(), rtsp_read_seek(), seek_subtitle(), source_request_frame(), start_frame(), start_frame_overlay(), transcode(), transcode_init(), transcode_video(), ts_str(), update_stream_timings(), video_thread(), write_audio_frame(), and write_video_frame().

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.

Definition at line 78 of file mathematics.c.

Referenced by applehttp_read_seek(), av_compare_ts(), av_nearer_q(), av_rescale(), av_rescale_q(), av_rescale_rnd(), compute_pkt_fields(), dv_write_pack(), ff_nut_reset_ts(), gxf_compare_field_nb(), gxf_write_media_preamble(), mov_write_edts_tag(), mov_write_mvhd_tag(), mov_write_tkhd_tag(), nut_write_packet(), pcm_read_seek(), read_seek2(), rtmp_read_seek(), rtp_write_header(), vp8_init(), and vqf_read_seek().

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.

Maths [Common utility functions]

Data Structures

Enumerations

Functions

Enumeration Type Documentation

Function Documentation

Maths
[Common utility functions]