# Struct fidl_fuchsia_media::TimelineFunction

``````#[repr(C)]pub struct TimelineFunction {
pub subject_time: i64,
pub reference_time: i64,
pub subject_delta: u32,
pub reference_delta: u32,
}``````
Expand description

A TimelineFunction represents a relationship between a subject timeline and a reference timeline with a linear relation.

For example, consider a common use case in which reference time is the monotonic clock of a system and subject time is intended presentation time for some media such as a video.

`reference_time` is the value of the monotonic clock at the beginning of playback. `subject_time` is 0 assuming playback starts at the beginning of the media. We then choose a `reference_delta` and `subject_delta` so that `subject_delta` / `reference_delta` represents the desired playback rate, e.g. 0/1 for paused and 1/1 for normal playback.

### §Formulas

With a function we can determine the subject timeline value `s` in terms of reference timeline value `r` with this formula (where `reference_delta` > 0):

s = (r - reference_time) * (subject_delta / reference_delta) + subject_time

And similarly we can find the reference timeline value `r` in terms of subject timeline value `s` with this formula (where `subject_delta` > 0):

r = (s - subject_time) * (reference_delta / subject_delta) + referenc_time

### §Choosing time values

Time values can be arbitrary and our linear relation will of course be the same, but we can use them to represent the bounds of pieces in a piecewise linear relation.

For example, if a user performs skip-chapter, we might want to describe this with a TimelineFunction whose `subject_time` is the time to skip to, `reference_time` is now plus some epsilon, and delta ratio is 1/1 for normal playback rate.

## Fields§

§`subject_time: i64`

A value from the subject timeline that correlates to reference_time.

§`reference_time: i64`

A value from the reference timeline that correlates to subject_time.

§`subject_delta: u32`

The change in the subject timeline corresponding to reference_delta.

§`reference_delta: u32`

The change in the reference timeline corresponding to subject_delta. Cannot be zero.

## Trait Implementations§

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### impl Clone for TimelineFunction

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#### fn clone(&self) -> TimelineFunction

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl Debug for TimelineFunction

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl Decode<TimelineFunction> for TimelineFunction

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#### fn new_empty() -> Self

Creates a valid instance of `Self`. The specific value does not matter, since it will be overwritten by `decode`.
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#### unsafe fn decode( &mut self, decoder: &mut Decoder<'_>, offset: usize, _depth: Depth ) -> Result<()>

Decodes an object of type `T` from the decoder’s buffers into `self`. Read more
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### impl Encode<TimelineFunction> for &TimelineFunction

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#### unsafe fn encode( self, encoder: &mut Encoder<'_>, offset: usize, _depth: Depth ) -> Result<()>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for `Handle::INVALID`. Read more
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### impl<T0: Encode<i64>, T1: Encode<i64>, T2: Encode<u32>, T3: Encode<u32>> Encode<TimelineFunction> for (T0, T1, T2, T3)

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#### unsafe fn encode( self, encoder: &mut Encoder<'_>, offset: usize, depth: Depth ) -> Result<()>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for `Handle::INVALID`. Read more
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### impl Hash for TimelineFunction

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#### fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl Ord for TimelineFunction

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#### fn cmp(&self, other: &TimelineFunction) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
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#### fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more
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#### fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more
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#### fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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### impl PartialEq for TimelineFunction

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#### fn eq(&self, other: &TimelineFunction) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl PartialOrd for TimelineFunction

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#### fn partial_cmp(&self, other: &TimelineFunction) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
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#### fn lt(&self, other: &Rhs) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
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#### fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
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#### fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
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#### fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
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### impl TypeMarker for TimelineFunction

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#### type Owned = TimelineFunction

The owned Rust type which this FIDL type decodes into.
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#### fn inline_align(_context: Context) -> usize

Returns the minimum required alignment of the inline portion of the encoded object. It must be a (nonzero) power of two.
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#### fn inline_size(_context: Context) -> usize

Returns the size of the inline portion of the encoded object, including padding for alignment. Must be a multiple of `inline_align`.
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#### fn encode_is_copy() -> bool

Returns true if the memory layout of `Self::Owned` matches the FIDL wire format and encoding requires no validation. When true, we can optimize encoding arrays and vectors of `Self::Owned` to a single memcpy. Read more
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#### fn decode_is_copy() -> bool

Returns true if the memory layout of `Self::Owned` matches the FIDL wire format and decoding requires no validation. When true, we can optimize decoding arrays and vectors of `Self::Owned` to a single memcpy.
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### impl ValueTypeMarker for TimelineFunction

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#### type Borrowed<'a> = &'a TimelineFunction

The Rust type to use for encoding. This is a particular `Encode<Self>` type cheaply obtainable from `&Self::Owned`. There are three cases: Read more
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#### fn borrow<'a>(value: &'a <Self as TypeMarker>::Owned) -> Self::Borrowed<'a>

Cheaply converts from `&Self::Owned` to `Self::Borrowed`.
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## Blanket Implementations§

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### impl<T> Any for Twhere T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Body for Twhere T: Persistable,

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#### type MarkerAtTopLevel = T

The marker type to use when the body is at the top-level.
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#### type MarkerInResultUnion = T

The marker type to use when the body is nested in a result union.
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### impl<T> Borrow<T> for Twhere T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for Twhere T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> Encode<Ambiguous1> for T

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#### unsafe fn encode( self, _encoder: &mut Encoder<'_>, _offset: usize, _depth: Depth ) -> Result<(), Error>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for `Handle::INVALID`. Read more
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### impl<T> Encode<Ambiguous2> for T

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#### unsafe fn encode( self, _encoder: &mut Encoder<'_>, _offset: usize, _depth: Depth ) -> Result<(), Error>

Encodes the object into the encoder’s buffers. Any handles stored in the object are swapped for `Handle::INVALID`. Read more
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The marker type.
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [`Span`], returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for Twhere U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> ToOwned for Twhere T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a [`WithDispatch`] wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a [`WithDispatch`] wrapper. Read more