Maths

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

Macros
#define	ff_ctz   ff_ctz_c
#define	ff_ctzll   ff_ctzll_c
#define	ff_clz   ff_clz_c
#define	av_parity   __builtin_parity

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)
	Trailing zero bit count. More...
static av_always_inline av_const int	ff_ctzll_c (long long v)
static av_always_inline av_const unsigned	ff_clz_c (unsigned x)
int64_t av_const	av_gcd (int64_t a, int64_t b)
	Compute the greatest common divisor of a and b. More...
int64_t	av_rescale (int64_t a, int64_t b, int64_t c) av_const
	Rescale a 64-bit integer with rounding to nearest. More...
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. More...
int64_t	av_rescale_q (int64_t a, AVRational bq, AVRational cq) av_const
	Rescale a 64-bit integer by 2 rational numbers. More...
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. More...
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. More...
int64_t	av_compare_mod (uint64_t a, uint64_t b, uint64_t mod)
	Compare 2 integers modulo mod. More...
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. More...
int64_t	av_add_stable (AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc)
	Add a value to a timestamp. More...
static AVRational	av_make_q (int num, int den)
	Create a rational. More...
static int	av_cmp_q (AVRational a, AVRational b)
	Compare two rationals. More...
static double	av_q2d (AVRational a)
	Convert rational to double. More...
int	av_reduce (int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max)
	Reduce a fraction. More...
AVRational	av_mul_q (AVRational b, AVRational c) av_const
	Multiply two rationals. More...
AVRational	av_div_q (AVRational b, AVRational c) av_const
	Divide one rational by another. More...
AVRational	av_add_q (AVRational b, AVRational c) av_const
	Add two rationals. More...
AVRational	av_sub_q (AVRational b, AVRational c) av_const
	Subtract one rational from another. More...
static av_always_inline AVRational	av_inv_q (AVRational q)
	Invert a rational. More...
AVRational	av_d2q (double d, int max) av_const
	Convert a double precision floating point number to a rational. More...
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. More...
uint32_t	av_q2intfloat (AVRational q)
	Converts a AVRational to a IEEE 32bit float. More...

Detailed Description

Macro Definition Documentation

#define ff_ctz   ff_ctz_c

Definition at line 106 of file intmath.h.

Referenced by refill2(), and remove_wasted_bits().

#define ff_ctzll   ff_ctzll_c

Definition at line 126 of file intmath.h.

Referenced by av_gcd().

#define ff_clz   ff_clz_c

Definition at line 142 of file intmath.h.

Referenced by config_input().

#define av_parity   __builtin_parity

Definition at line 158 of file intmath.h.

Referenced by decode_frame(), and validate_cc_data_pair().

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 70 of file mathematics.h.

Function Documentation

static av_always_inline av_const int ff_ctz_c ( int  v )

static

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 115 of file intmath.h.

static av_always_inline av_const int ff_ctzll_c ( long long  v )

static

Definition at line 129 of file intmath.h.

static av_always_inline av_const unsigned ff_clz_c ( unsigned  x )

static

Definition at line 143 of file intmath.h.

int64_t av_const av_gcd	(	int64_t	a,
		int64_t	b
	)

Compute the greatest common divisor of a and b.

Returns

gcd of a and b up to sign; if a >= 0 and b >= 0, return value is >= 0; if a == 0 and b == 0, returns 0.

Definition at line 37 of file mathematics.c.

Referenced by av_reduce(), avcodec_string(), config_output(), decode_main_header(), eval_expr(), ff_framesync_configure(), ff_h263_decode_picture_header(), ff_mpv_encode_init(), ff_parse_specific_params(), ff_put_wav_header(), ff_rfps_add_frame(), 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 129 of file mathematics.c.

Referenced by asf_build_simple_index(), asf_read_simple_index(), audio_read_packet(), av_dict_set_fxp(), av_dump_format(), av_q2intfloat(), avi_read_header(), calculate_bitrate(), check_stream_max_drift(), compute_display_area(), compute_overlay_rect(), compute_pkt_fields(), config_input(), config_output(), config_props(), dc1394_read_common(), dca_parse(), 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(), filter_frame(), finalize_packet(), generate_intervals(), get_delay(), get_input_packet(), get_lin_h(), get_lin_h2(), get_pcr(), get_vcd_padding_size(), matroska_parse_tracks(), mov_build_index(), mov_find_next_sample(), mov_read_mvhd(), mov_write_moov_tag(), mov_write_tapt_tag(), mov_write_tkhd_tag(), mov_write_tmcd_tag(), mp3_seek(), mp3_update_xing(), mpeg_mux_write_packet(), mpegts_init(), mpegts_write_packet_internal(), mpegts_write_pes(), mxf_read_seek(), nsv_parse_NSVs_header(), oma_read_packet(), opengl_compute_display_area(), opus_header(), output_packet(), postProcess_TMPL(), push_frame(), r3d_read_reda(), read_header(), read_xing_toc(), request_frame(), rm_read_header(), sbg_read_header(), seek_frame_internal(), transcode_subtitles(), ts_to_samples(), update_wrap_reference(), vc2_encode_frame(), vivo_read_header(), vqf_read_seek(), and xv_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.

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 58 of file mathematics.c.

Referenced by av_compare_ts(), av_image_check_sar(), av_nearer_q(), av_rescale(), av_rescale_q_rnd(), av_rescale_rnd(), avformat_seek_file(), avresample_get_out_samples(), compute_pkt_fields(), dv_write_pack(), estimate_timings_from_pts(), ff_nut_reset_ts(), ff_pcm_read_seek(), get_out_samples(), 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(), rtmp_read_seek(), vpx_init(), vqf_read_seek(), write_audio_frame(), and write_time().

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 alloc_out_frame(), asf_write_markers(), av_add_stable(), av_buffersink_get_samples(), av_packet_rescale_ts(), av_rescale_delta(), avcodec_decode_audio4(), avcodec_decode_subtitle2(), avf_read_packet(), 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(), check_stream_max_drift(), choose_output(), close_output_stream(), compand_delay(), compand_drain(), compare_ts_with_wrapdetect(), compute_chapters_end(), concat_read_packet(), config_input(), copy_chapters(), create_ass_text(), dash_write_packet(), dash_write_trailer(), decode(), decode_audio(), decode_fctl_chunk(), decode_frame(), decode_syncpoint(), decode_video(), decoder_decode_frame(), display_frame(), do_streamcopy(), do_subtitle_out(), do_video_out(), dv_extract_video_info(), dv_read_header(), ff_af_queue_add(), ff_configure_buffers_for_index(), ff_dv_offset_reset(), ff_filter_frame_needs_framing(), ff_interleave_packet_per_dts(), ff_qsv_encode(), ff_read_packet(), ff_samples_to_time_base(), ff_update_link_current_pts(), ff_write_chained(), fill_all_stream_timings(), fill_timing_for_id3_timestamped_stream(), filter_frame(), find_and_decode_index(), framesync_inject_frame(), get_subtitle_pkt(), hls_read_packet(), http_prepare_data(), init(), init_convert_timestamp(), interleave_compare_dts(), interleave_new_audio_packet(), main(), matroska_parse_frame(), matroska_parse_tracks(), microdvd_decode_frame(), mkv_write_block(), mkv_write_chapters(), mkv_write_track(), mov_create_chapter_track(), mov_read_seek(), mov_read_sidx(), mov_text_decode_frame(), mov_write_chpl_tag(), mov_write_single_packet(), mp3_parse_info_tag(), mp3_parse_vbr_tags(), mpeg4_decode_header(), mpegts_write_packet_internal(), mpl2_decode_frame(), mxf_parse_physical_source_package(), mxf_parse_structural_metadata(), mxf_read_seek(), ni_prepare_read(), nut_write_packet(), ogg_buffer_data(), ogg_compare_granule(), ogg_write_packet_internal(), parse_forced_key_frames(), print_report(), process_frame(), process_input(), process_input_packet(), pulse_write_packet(), push_frame(), push_samples(), qtkit_read_packet(), 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_mpegts_write_packet(), rtp_parse_one_packet(), rtsp_read_play(), rtsp_read_seek(), sami_decode_frame(), save_subtitle_set(), sbg_read_seek2(), seek_chapter(), seek_subtitle(), seek_to_start(), seg_write_packet(), select_frame(), send_silence(), set_srce_frame_dest_pts(), source_request_frame(), srt_decode_frame(), sub2video_heartbeat(), sub2video_update(), submit_frame(), tee_write_packet(), teletext_decode_frame(), text_decode_frame(), transcode_init(), ts_str(), update_stream_timings(), v210_read_header(), wait_frame(), webm_chunk_write_packet(), webvtt_decode_frame(), write_audio_frame(), write_chapter(), write_frame(), write_manifest(), and write_packet().

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 134 of file mathematics.c.

Referenced by av_rescale_delta(), av_rescale_q(), ff_interleave_add_packet(), filter_frame(), lavfi_read_packet(), main(), parse_packet(), process_input(), rescale_interval(), rv10_write_header(), update_stream_timings(), write_packet(), and write_packet_header().

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(), dash_write_packet(), duration_max(), ff_rtp_send_aac(), ff_rtp_send_amr(), ff_rtp_send_xiph(), get_audio_frame(), get_video_frame(), hds_write_packet(), hls_write_packet(), interleave_compare_dts(), ism_write_packet(), main(), mpegts_write_packet_internal(), mux_frames(), nut_write_packet(), packet_after_outpoint(), rtp_send_ilbc(), seek_chapter(), 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 160 of file mathematics.c.

Referenced by av_read_frame(), and compare_ts_with_wrapdetect().

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 timebase
fs_tb	Duration and *last timebase
duration	duration till the next call
out_tb	Output timebase

Definition at line 168 of file mathematics.c.

Referenced by decode_audio(), and do_streamcopy().

int64_t av_add_stable	(	AVRational	ts_tb,
		int64_t	ts,
		AVRational	inc_tb,
		int64_t	inc
	)

Add a value to a timestamp.

This function guarantees that when the same value is repeatly added that no accumulation of rounding errors occurs.

Parameters

ts	Input timestamp
ts_tb	Input timestamp timebase
inc	value to add to ts
inc_tb	inc timebase

Definition at line 191 of file mathematics.c.

Referenced by compute_pkt_fields().

static AVRational av_make_q ( int  num, int  den  )

inlinestatic

Create a rational.

Useful for compilers that do not support compound literals.

Note

The return value is not reduced.

Definition at line 53 of file rational.h.

Referenced by alloc_out_frame(), avf_read_packet(), config_out_props(), config_output(), config_props(), encode_frame(), filter_frame(), mov_read_sidx(), and push_frame().

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 66 of file rational.h.

Referenced by av_nearer_q(), av_opt_is_set_to_default(), compute_display_area(), compute_overlay_rect(), config_output(), dash_write_header(), dump_stream_format(), ff_h263_aspect_to_info(), ff_h264_decode_slice_header(), ff_mxf_get_samples_per_frame(), filter_frame(), find_frame_rate_index(), init_muxer(), mpeg_decode_postinit(), opengl_compute_display_area(), update_pts(), and write_manifest().

static double av_q2d ( AVRational  a )

inlinestatic

Convert rational to double.

Parameters

a	rational to convert

Returns

(double) a

Definition at line 80 of file rational.h.

Referenced by audio_thread(), av_dump_format(), av_guess_frame_rate(), av_ts_make_time_string(), avformat_find_stream_info(), avi_read_seek(), calculate_display_rect(), config_input(), config_output(), config_output_props(), config_props(), configure_video_device(), decode_frame(), decode_syncpoint(), DEFINE_BLEND8(), do_blend(), do_video_out(), do_video_stats(), draw_text(), dump_stream_format(), dv_write_pack(), fbdev_read_header(), fbdev_read_packet(), ff_decklink_read_header(), ff_filter_frame_framed(), ff_mpv_encode_init(), ff_mpv_encode_picture(), ff_rfps_add_frame(), ff_rfps_calculate(), filter_frame(), find_compressor(), flv_write_header(), gdigrab_read_header(), gdigrab_read_packet(), geq_filter_frame(), get_best_frame(), get_fps(), get_video_frame(), grab_read_header(), init(), init_muxer(), init_stream(), init_video(), mkv_write_trailer(), mov_get_h264_codec_tag(), mov_get_mpeg2_xdcam_codec_tag(), mov_write_trak_tag(), mpegvideo_parse(), mxf_compute_sample_count(), output_single_frame(), pkt_dump_internal(), process_input_packet(), push_frame(), read_header(), read_seek(), read_thread(), request_frame(), seg_write_packet(), select_frame(), set_side_data(), set_work_frame_pts(), svc_encode_init(), transcode_init(), update(), v4l2_read_header(), video_thread(), write_manifest(), 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 apng_write_header(), asf_read_header(), av_add_q(), av_d2q(), av_guess_sample_aspect_ratio(), av_mul_q(), av_parse_ratio(), av_resample_init(), avcodec_string(), avformat_find_stream_info(), avi_write_header(), avpriv_set_pts_info(), compute_dar(), config_input(), config_output(), decode_frame(), decode_sequence_header_adv(), dnxhd_decode_header(), dump_stream_format(), dxa_read_header(), export_stream_params(), ff_audio_resample_init(), ff_canopus_parse_info_tag(), ff_mpv_encode_init(), ff_rfps_calculate(), ff_rm_read_mdpr_codecdata(), filter_frame(), flush_packet(), h264_slice_header_init(), libx265_encode_init(), matroska_parse_tracks(), mov_read_header(), mov_read_pasp(), mov_read_trak(), mov_write_pasp_tag(), mpeg4_encode_vol_header(), mxf_parse_mpeg2_frame(), nvenc_encode_init(), parse_video_var(), pcx_encode_frame(), read_fps(), resample_init(), set_sar(), show_stream(), skeleton_header(), smacker_read_header(), tmv_read_header(), transcode_init(), vmd_read_header(), X264_init(), xvid_encode_frame(), yuv4_generate_header(), 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 80 of file rational.c.

Referenced by av_add_stable(), av_div_q(), avcodec_decode_video2(), avcodec_open2(), avformat_find_stream_info(), avi_write_header(), compute_display_area(), compute_overlay_rect(), compute_pkt_fields(), config_input(), config_out_props(), config_output(), config_props(), decode_vol_header(), decode_vop_header(), encode_frame(), ff_compute_frame_duration(), filter_frame(), find_frame_rate_index(), h264_parse(), mpeg_decode_postinit(), mpegvideo_extract_headers(), mxf_compute_sample_count(), opengl_compute_display_area(), put_videoinfoheader2(), rv20_decode_picture_header(), set_work_frame_pts(), transcode_init(), update_sar(), and vc1_extract_header().

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 av_dv_codec_profile2(), 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 93 of file rational.c.

Referenced by av_sub_q(), and init_output_stream().

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.

Referenced by ff_mxf_get_samples_per_frame().

static av_always_inline AVRational av_inv_q ( AVRational  q )

static

Invert a rational.

Parameters

q

value

Returns

1 / q

Definition at line 133 of file rational.h.

Referenced by avcodec_decode_video2(), avcodec_open2(), avformat_find_stream_info(), avi_read_header(), config_output(), config_props(), configure_input_video_filter(), decode_vol_header(), decode_vop_header(), dv_extract_video_info(), dvvideo_decode_frame(), fbdev_read_header(), ff_compute_frame_duration(), ff_raw_video_read_header(), ff_rfps_calculate(), find_frame_rate_index(), gdigrab_read_header(), h264_parse(), init(), init_video_stream(), mov_create_timecode_track(), mpegvideo_extract_headers(), mv_read_header(), mxf_compute_sample_count(), mxf_parse_structural_metadata(), mxf_read_seek(), mxf_write_header(), process_input_packet(), r3d_read_rdvo(), r3d_seek(), read_header(), rm_write_header(), set_work_frame_pts(), smush_read_header(), source_config_props(), transcode_init(), txd_read_header(), vc1_extract_header(), vfw_read_header(), vivo_read_header(), write_frame(), x11grab_read_header(), and yuv4_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 106 of file rational.c.

Referenced by av_opt_get_q(), av_opt_get_video_rate(), av_opt_is_set_to_default(), av_opt_set_defaults2(), av_parse_ratio(), config_output_props(), decode_frame(), decode_header(), fourxm_read_header(), get_aspect_ratio(), 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 126 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 141 of file rational.c.

Referenced by ff_mxf_get_samples_per_frame(), and transcode_init().

uint32_t av_q2intfloat

(

AVRational

q

)

Converts a AVRational to a IEEE 32bit float.

The float is returned in a uint32_t and its value is platform indepenant.

Definition at line 151 of file rational.c.

Referenced by ircam_write_header().