View Source Vtc.Framerate (vtc v0.8.0)
The rate at which a video file frames are played back.
Framerate is measured in frames-per-second (24/1 = 24 frames-per-second).
struct-fields
Struct Fields
playback: The rational representation of the real-world playback speed as a fraction in frames-per-second.ntsc: Atom representing which, if any, NTSC convention this framerate adheres to.
playback-vs-timebase
Playback vs Timebase
For NTSC timecode, the timebase always runs at a whole number of frames-per-second, which the timecode pretends in the playback speed of the Media. This makes timecode string calculations clean and accurate, rather than having partial frames at second and minute boundaries.
So for footage shot at 23.98 NTSC, Timecode is caculated as-if the footage were
running at 24fps, which Vtc calls the 'timebase'.
Link to this section Summary
Parse
Creates a new Framerate with a playback speed or timebase.
As new/2 but raises an error instead.
Inspect
Returns true if the value represents and NTSC framerate.
The rational representation of the timecode's 'logical speed'.
Link to this section Types
@type ntsc() :: :non_drop | :drop | nil
Enum of Ntsc types.
values
Values
:non_dropA non-drop NTSC value.:dropA drop-frame ntsc value.nil: Not an NTSC value
For more information on NTSC standards and framerate conventions, see Frame.io's blogpost on the subject.
@type parse_result() :: {:ok, t()} | {:error, Vtc.Framerate.ParseError.t()}
Type returned by new/2
Type of Framerate
Link to this section Parse
@spec new(Ratio.t() | number() | String.t(), new_opts()) :: parse_result()
Creates a new Framerate with a playback speed or timebase.
arguments
Arguments
rate: Either the playback rate or timebase. For NTSC framerates, the value will be rounded to the nearest correct value.
options
Options
ntsc: Atom representing the which (or whether an) NTSC standard is being used. Default::non-drop.invert?: Iftrue, the resulting rationalratevalue will be flipped so that1/24becomes24/1. This can be helpeful when you are parsing a rate given in seconds-per-frame rather than frames-per-second. Default:false.
Float Precision
Only floats representing a whole number can be passed for non-NTSC rates, as there is no fully precise way to convert fractional floats to rational values.
As new/2 but raises an error instead.
Link to this section Inspect
Returns true if the value represents and NTSC framerate.
Will return true on a Framerate with an :ntsc value of :non_drop and :drop.
The rational representation of the timecode's 'logical speed'.
Returned value is in frames-per-second.