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.
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.

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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 67 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(), ff_mxf_get_samples_per_frame(), filter_samples(), mpeg_decode_postinit(), sdl_write_header(), 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_recording_time(), ff_gen_syncpoint_search(), ff_interleave_compare_dts(), hls_read_packet(), ism_write_packet(), nut_write_packet(), 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(), decode_frame(), 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_output(), config_output_props(), 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().

static av_always_inline AVRational av_inv_q

(

AVRational

q

)

[static]

Invert a rational.

Parameters:

q

value

Returns:

1 / q

Definition at line 122 of file rational.h.

Referenced by avformat_find_stream_info(), config_props(), configure_input_video_filter(), ea_read_header(), fbdev_read_header(), ff_raw_video_read_header(), init(), mxf_write_header(), r3d_read_rdvo(), r3d_seek(), transcode_init(), vfw_read_header(), and x11grab_read_header().

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(), rv20_decode_picture_header(), and sdl_write_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]

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(), av_ts_make_time_string(), avformat_find_stream_info(), avformat_write_header(), avi_write_header(), calculate_display_rect(), config_input(), config_output(), config_output_props(), config_props(), decode_frame(), 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_MPV_encode_init(), ff_MPV_encode_picture(), ff_mxf_get_samples_per_frame(), ff_start_frame(), filter_samples(), flv_write_header(), get_fps(), get_video_frame(), grab_read_header(), init(), init_stream(), mkv_write_tracks(), mov_write_tkhd_tag(), mov_write_trak_tag(), mpeg1_encode_sequence_header(), new_video_stream(), output_packet(), pkt_dump_internal(), queue_picture(), read_header(), read_seek(), read_thread(), seg_write_packet(), select_frame(), send_out(), start_frame(), subtitle_thread(), thp_read_header(), transcode_init(), v4l2_read_header(), vf_next_put_image(), 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_guess_sample_aspect_ratio(), av_mul_q(), av_resample_init(), avcodec_string(), avformat_find_stream_info(), avi_write_header(), avpriv_set_pts_info(), config_input(), config_output(), decode_frame(), decode_sequence_header_adv(), decode_slice_header(), dump_stream_format(), dxa_read_header(), ff_audio_resample_init(), ff_MPV_encode_init(), ff_rm_read_mdpr_codecdata(), matroska_read_header(), mov_read_trak(), mov_write_pasp_tag(), mpeg4_encode_vol_header(), mpeg_decode_postinit(), 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(), avi_read_header(), compute_pkt_fields(), compute_pkt_fields2(), config_props(), dc1394_read_common(), estimate_timings_from_bit_rate(), ff_gen_search(), ff_pcm_read_seek(), ff_update_cur_dts(), filter_samples(), finalize_packet(), generate_intervals(), get_pcr(), mov_build_index(), mov_find_next_sample(), mov_read_mvhd(), mov_write_tapt_tag(), mp3_parse_vbr_tags(), mpeg_mux_write_packet(), mpegts_write_header(), mpegts_write_packet_internal(), mpegts_write_pes(), mxf_read_seek(), nsv_parse_NSVs_header(), output_packet(), r3d_read_reda(), rate_emu_sleep(), read_header(), read_xing_toc(), rm_read_header(), sbg_read_header(), sdl_write_header(), seek_frame_internal(), swr_get_delay(), transcode_subtitles(), 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 142 of file mathematics.c.

Referenced by av_mpeg4_decode_header(), avcodec_decode_audio4(), avcodec_decode_subtitle2(), avformat_find_stream_info(), avi_read_packet(), avi_read_seek(), buffer_offset(), caca_write_header(), choose_output(), compute_chapters_end(), copy_chapters(), decode_audio(), decode_frame(), decode_video(), display_picref(), do_audio_out(), do_streamcopy(), do_subtitle_out(), do_video_out(), dv_extract_video_info(), dv_read_header(), end_frame(), end_frame_over(), ff_af_queue_add(), ff_buffersink_read_samples_compat(), ff_dv_offset_reset(), ff_filter_samples(), ff_interleave_add_packet(), ff_interleave_compare_dts(), ff_interleave_new_audio_packet(), ff_interleave_packet_per_dts(), ff_read_packet(), ff_samples_to_time_base(), ff_update_link_current_pts(), ff_write_chained(), fill_all_stream_timings(), filter_samples(), flush_encoders(), get_subtitle_pkt(), guess_ni_flag(), http_prepare_data(), init(), init_convert_timestamp(), lavfi_read_packet(), main(), microdvd_decode_frame(), mkv_write_chapters(), mov_create_chapter_track(), mov_read_seek(), mov_text_decode_frame(), mov_write_chpl_tag(), mov_write_single_packet(), mp3_parse_vbr_tags(), ogg_compare_granule(), output_packet(), parse_forced_key_frames(), plot_spectrum_column(), print_report(), process_frame(), process_input(), push_frame(), push_samples(), r3d_read_rdvo(), r3d_seek(), read_from_fifo(), read_header(), read_seek2(), reap_filters(), request_frame(), rl2_read_seek(), rtcp_send_sr(), rtp_write_header(), rtsp_read_play(), rtsp_read_seek(), sami_decode_frame(), sbg_read_seek2(), seek_subtitle(), send_silence(), source_request_frame(), srt_decode_frame(), start_frame(), start_frame_main(), sub2video_heartbeat(), sub2video_update(), transcode_init(), ts_str(), update_stream_timings(), video_thread(), webvtt_decode_frame(), and write_video_frame().

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(), ff_interleave_packet_per_dts(), parse_packet(), and rtp_write_header().

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 av_compare_ts(), av_nearer_q(), av_rescale(), av_rescale_q_rnd(), av_rescale_rnd(), compute_pkt_fields(), dv_write_pack(), ff_nut_reset_ts(), ff_pcm_read_seek(), filter_samples(), gxf_compare_field_nb(), gxf_write_media_preamble(), handle_file(), hls_read_packet(), hls_read_seek(), mov_write_edts_tag(), mov_write_mvhd_tag(), mov_write_tkhd_tag(), nut_write_packet(), read_seek2(), request_frame(), rtmp_read_seek(), 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.