Maths

Data Structures
struct	AVRational
	rational number numerator/denominator More...

Macros
#define	ff_ctz   ff_ctz_c

Enumerations
enum	AVRounding {   AV_ROUND_ZERO = 0, AV_ROUND_INF = 1, AV_ROUND_DOWN = 2, AV_ROUND_UP = 3,   AV_ROUND_NEAR_INF = 5, AV_ROUND_PASS_MINMAX = 8192 }

Functions
static av_always_inline av_const int	ff_ctz_c (int v)
int	av_ctz (int v)
	Trailing zero bit count.
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.
int64_t	av_rescale_delta (AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb)
	Rescale a timestamp while preserving known durations.
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

Macro Definition Documentation

#define ff_ctz   ff_ctz_c

Definition at line 108 of file intmath.h.

Referenced by av_ctz().

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.
AV_ROUND_PASS_MINMAX	Flag to pass INT64_MIN/MAX through instead of rescaling, this avoids special cases for AV_NOPTS_VALUE.

Definition at line 67 of file mathematics.h.

Function Documentation

static av_always_inline av_const int ff_ctz_c ( int  v )

static

Definition at line 109 of file intmath.h.

int av_ctz

(

int

v

)

Trailing zero bit count.

Parameters

v	input value. If v is 0, the result is undefined.

Returns

the number of trailing 0-bits

Definition at line 36 of file intmath.c.

Referenced by remove_wasted_bits().

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 55 of file mathematics.c.

Referenced by av_gcd(), av_reduce(), avcodec_string(), avformat_find_stream_info(), decode_main_header(), dump_stream_format(), eval_expr(), ff_framesync_configure(), ff_h263_decode_picture_header(), ff_MPV_encode_init(), ff_parse_specific_params(), ff_put_wav_header(), find_frame_rate_index(), rtp_send_samples(), and xvid_correct_framerate().

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 118 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_input(), config_props(), dc1394_read_common(), estimate_timings_from_bit_rate(), ff_gen_search(), ff_interleave_add_packet(), ff_pcm_read_seek(), ff_rtp_check_and_send_back_rr(), ff_update_cur_dts(), filter_frame(), finalize_packet(), generate_intervals(), get_delay(), get_input_packet(), get_pcr(), hls_write_packet(), matroska_read_header(), mkv_write_tracks(), mov_build_index(), mov_find_next_sample(), mov_read_mvhd(), mov_write_tapt_tag(), mov_write_tmcd_tag(), mp3_parse_vbr_tags(), mp3_seek(), 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(), read_header(), read_xing_toc(), request_frame(), rm_read_header(), sbg_read_header(), sdl_write_header(), seek_frame_internal(), transcode_subtitles(), update_wrap_reference(), vivo_read_header(), and vqf_read_seek().

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.

Returns

rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is INT64_MIN or INT64_MAX then a is passed through unchanged.

Definition at line 60 of file mathematics.c.

Referenced by av_compare_ts(), av_nearer_q(), av_rescale(), av_rescale_q_rnd(), av_rescale_rnd(), avformat_seek_file(), compute_pkt_fields(), dv_write_pack(), ff_nut_reset_ts(), ff_pcm_read_seek(), filter_frame(), gxf_compare_field_nb(), gxf_write_media_preamble(), handle_file(), hls_read_packet(), hls_read_seek(), main(), mov_write_edts_tag(), mov_write_mvhd_tag(), mov_write_tkhd_tag(), nut_write_packet(), request_frame(), rtmp_read_seek(), vpx_init(), vqf_read_seek(), and write_audio_frame().

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 130 of file mathematics.c.

Referenced by asf_write_markers(), audio_decode_frame(), av_buffersink_get_samples(), av_mpeg4_decode_header(), av_rescale_delta(), avcodec_decode_audio4(), avcodec_decode_subtitle2(), avformat_find_stream_info(), avformat_seek_file(), avi_read_packet(), avi_read_seek(), avisynth_read_packet_audio(), avisynth_read_seek(), buffer_offset(), caca_write_header(), choose_output(), close_output_stream(), compand_delay(), compand_drain(), compute_chapters_end(), concat_read_packet(), config_input(), copy_chapters(), decode_audio(), decode_frame(), decode_video(), display_frame(), do_audio_out(), do_streamcopy(), do_subtitle_out(), do_video_out(), dv_extract_video_info(), dv_read_header(), ff_af_queue_add(), ff_dv_offset_reset(), ff_filter_frame_needs_framing(), 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_frame(), find_and_decode_index(), flush_encoders(), framesync_inject_frame(), get_subtitle_pkt(), guess_ni_flag(), hls_read_packet(), http_prepare_data(), init(), init_convert_timestamp(), interleave_compare_dts(), interleave_new_audio_packet(), lavfi_read_packet(), main(), matroska_parse_frame(), matroska_read_header(), microdvd_decode_frame(), mkv_write_block(), mkv_write_chapters(), mkv_write_tracks(), mov_create_chapter_track(), mov_read_seek(), mov_text_decode_frame(), mov_write_chpl_tag(), mov_write_single_packet(), mp3_parse_vbr_tags(), mpl2_decode_frame(), mxf_parse_structural_metadata(), mxf_read_seek(), ogg_buffer_data(), ogg_compare_granule(), ogg_write_packet(), output_packet(), parse_forced_key_frames(), plot_spectrum_column(), print_report(), process_frame(), process_input(), pulse_write_packet(), push_frame(), push_samples(), r3d_read_rdvo(), r3d_seek(), rawvideo_read_header(), read_from_fifo(), read_header(), read_interval_packets(), reap_filters(), request_frame(), rescale_interval(), rl2_read_seek(), rtcp_send_sr(), rtp_parse_one_packet(), rtp_write_header(), rtsp_read_play(), rtsp_read_seek(), sami_decode_frame(), sbg_read_seek2(), seek_subtitle(), seg_write_packet(), send_silence(), source_request_frame(), srt_decode_frame(), sub2video_heartbeat(), sub2video_update(), tee_write_packet(), text_decode_frame(), transcode_init(), ts_str(), update_stream_timings(), webvtt_decode_frame(), and write_chapter().

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.

Returns

rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is INT64_MIN or INT64_MAX then a is passed through unchanged.

Definition at line 122 of file mathematics.c.

Referenced by av_rescale_delta(), av_rescale_q(), ff_interleave_add_packet(), filter_frame(), parse_packet(), rescale_interval(), rtp_write_header(), and write_packet().

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 135 of file mathematics.c.

Referenced by check_recording_time(), ff_gen_syncpoint_search(), hls_read_packet(), hls_write_packet(), interleave_compare_dts(), ism_write_packet(), nut_write_packet(), search_hi_lo_keyframes(), and seg_write_packet().

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 145 of file mathematics.c.

Referenced by av_read_frame().

int64_t av_rescale_delta	(	AVRational	in_tb,
		int64_t	in_ts,
		AVRational	fs_tb,
		int	duration,
		int64_t *	last,
		AVRational	out_tb
	)

Rescale a timestamp while preserving known durations.

Parameters

in_ts	Input timestamp
in_tb	Input timesbase
fs_tb	Duration and *last timebase
duration	duration till the next call
out_tb	Output timesbase

Definition at line 152 of file mathematics.c.

Referenced by decode_audio(), and do_streamcopy().

static int av_cmp_q ( AVRational  a, AVRational  b  )

inlinestatic

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(), decode_slice_header(), dump_stream_format(), ff_h263_aspect_to_info(), ff_mxf_get_samples_per_frame(), filter_frame(), find_frame_rate_index(), init_muxer(), mpeg_decode_postinit(), and sdl_write_header().

static double av_q2d ( AVRational  a )

inlinestatic

Convert rational to double.

Parameters

a	rational to convert

Returns

(double) a

Examples:

doc/examples/muxing.c.

Definition at line 69 of file rational.h.

Referenced by audio_decode_frame(), av_dump_format(), av_guess_frame_rate(), av_ts_make_time_string(), avformat_find_stream_info(), avi_write_header(), calculate_display_rect(), config_input(), config_output(), config_output_props(), config_props(), decode_frame(), decode_syncpoint(), do_blend(), do_video_out(), do_video_stats(), draw_text(), dump_stream_format(), dv_write_pack(), fbdev_read_header(), fbdev_read_packet(), ff_filter_frame_framed(), ff_MPV_encode_init(), ff_MPV_encode_picture(), ff_mxf_get_samples_per_frame(), ff_vf_next_put_image(), filter_frame(), filter_slice(), find_compressor(), flv_write_header(), geq_filter_frame(), get_best_frame(), get_fps(), get_video_frame(), grab_read_header(), init(), init_muxer(), init_stream(), init_video(), main(), mkv_write_tracks(), mov_get_mpeg2_xdcam_codec_tag(), mov_write_tkhd_tag(), mov_write_tmcd_tag(), mov_write_trak_tag(), mpeg1_encode_sequence_header(), mxf_compute_sample_count(), output_packet(), pkt_dump_internal(), push_frame(), read_header(), read_seek(), read_thread(), seg_write_packet(), select_frame(), send_out(), subtitle_thread(), thp_read_header(), transcode_init(), update(), v4l2_read_header(), video_thread(), 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 35 of file rational.c.

Referenced by asf_read_header(), av_add_q(), av_d2q(), av_guess_sample_aspect_ratio(), av_mul_q(), av_parse_ratio(), avcodec_string(), avformat_find_stream_info(), avi_write_header(), avpriv_set_pts_info(), compute_dar(), config_input(), decode_frame(), decode_sequence_header_adv(), dump_stream_format(), dxa_read_header(), ff_audio_resample_init(), ff_MPV_encode_init(), ff_rm_read_mdpr_codecdata(), filter_frame(), h264_slice_header_init(), matroska_read_header(), mov_read_trak(), mov_write_pasp_tag(), mpeg4_encode_vol_header(), mpeg_decode_postinit(), mxf_parse_mpeg2_frame(), parse_source_parameters(), parse_video_var(), pcx_encode_frame(), read_fps(), resample_init(), show_stream(), skeleton_header(), smacker_read_header(), tmv_read_header(), transcode_init(), vmd_read_header(), X264_init(), xvid_encode_frame(), and yuv4_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 79 of file rational.c.

Referenced by av_div_q(), avi_write_header(), config_input(), config_output(), config_props(), find_frame_rate_index(), mpeg_decode_postinit(), mxf_compute_sample_count(), put_videoinfoheader2(), rv20_decode_picture_header(), sdl_write_header(), transcode_init(), and update_sar().

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 87 of file rational.c.

Referenced by av_guess_frame_rate(), avi_read_header(), build_frame_code(), config_output(), config_output_props(), config_props(), config_props_output(), and mpeg_decode_postinit().

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 92 of file rational.c.

Referenced by av_sub_q().

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 100 of file rational.c.

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 av_guess_frame_rate(), avformat_find_stream_info(), config_output(), config_props(), configure_input_video_filter(), ea_read_header(), fbdev_read_header(), ff_raw_video_read_header(), find_frame_rate_index(), init(), mov_create_timecode_track(), mxf_compute_sample_count(), mxf_parse_structural_metadata(), mxf_read_seek(), mxf_write_header(), output_packet(), r3d_read_rdvo(), r3d_seek(), read_header(), transcode_init(), vfw_read_header(), vivo_read_header(), and x11grab_read_header().

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 105 of file rational.c.

Referenced by av_get_q(), av_opt_get_q(), av_opt_get_video_rate(), av_opt_set_defaults2(), av_parse_ratio(), config_output_props(), decode_frame(), init(), microdvd_read_header(), mov_read_tkhd(), mov_read_trak(), mpeg_decode_postinit(), nuv_header(), opt_list(), read_header(), thp_read_header(), var_read_float(), and write_number().

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 125 of file rational.c.

Referenced by av_find_nearest_q_idx(), and find_frame_rate_index().

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 140 of file rational.c.

Referenced by transcode_init().