#[repr(i32)]
pub enum StateChange { NullToReady = 10, ReadyToPaused = 19, PausedToPlaying = 28, PlayingToPaused = 35, PausedToReady = 26, ReadyToNull = 17, NullToNull = 9, ReadyToReady = 18, PausedToPaused = 27, PlayingToPlaying = 36, }
Expand description

These are the different state changes an element goes through. State::NullState::Playing is called an upwards state change and State::PlayingState::Null a downwards state change.

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NullToReady = 10

state change from NULL to READY.

  • The element must check if the resources it needs are available. Device sinks and -sources typically try to probe the device to constrain their caps.
  • The element opens the device (in case feature need to be probed).
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ReadyToPaused = 19

state change from READY to PAUSED.

  • The element pads are activated in order to receive data in PAUSED. Streaming threads are started.
  • Some elements might need to return StateChangeReturn::Async and complete the state change when they have enough information. It is a requirement for sinks to return StateChangeReturn::Async and complete the state change when they receive the first buffer or EventType::Eos (preroll). Sinks also block the dataflow when in PAUSED.
  • A pipeline resets the running_time to 0.
  • Live sources return StateChangeReturn::NoPreroll and don’t generate data.
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PausedToPlaying = 28

state change from PAUSED to PLAYING.

  • Most elements ignore this state change.
  • The pipeline selects a Clock and distributes this to all the children before setting them to PLAYING. This means that it is only allowed to synchronize on the Clock in the PLAYING state.
  • The pipeline uses the Clock and the running_time to calculate the base_time. The base_time is distributed to all children when performing the state change.
  • Sink elements stop blocking on the preroll buffer or event and start rendering the data.
  • Sinks can post GST_MESSAGE_EOS in the PLAYING state. It is not allowed to post GST_MESSAGE_EOS when not in the PLAYING state.
  • While streaming in PAUSED or PLAYING elements can create and remove sometimes pads.
  • Live sources start generating data and return StateChangeReturn::Success.
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PlayingToPaused = 35

state change from PLAYING to PAUSED.

  • Most elements ignore this state change.
  • The pipeline calculates the running_time based on the last selected Clock and the base_time. It stores this information to continue playback when going back to the PLAYING state.
  • Sinks unblock any Clock wait calls.
  • When a sink does not have a pending buffer to play, it returns StateChangeReturn::Async from this state change and completes the state change when it receives a new buffer or an EventType::Eos.
  • Any queued GST_MESSAGE_EOS items are removed since they will be reposted when going back to the PLAYING state. The EOS messages are queued in Bin containers.
  • Live sources stop generating data and return StateChangeReturn::NoPreroll.
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PausedToReady = 26

state change from PAUSED to READY.

  • Sinks unblock any waits in the preroll.
  • Elements unblock any waits on devices
  • Chain or get_range functions return FlowReturn::Flushing.
  • The element pads are deactivated so that streaming becomes impossible and all streaming threads are stopped.
  • The sink forgets all negotiated formats
  • Elements remove all sometimes pads
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ReadyToNull = 17

state change from READY to NULL.

  • Elements close devices
  • Elements reset any internal state.
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NullToNull = 9

state change from NULL to NULL. (Since: 1.14)

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ReadyToReady = 18

state change from READY to READY, This might happen when going to PAUSED asynchronously failed, in that case elements should make sure they are in a proper, coherent READY state. (Since: 1.14)

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PausedToPaused = 27

state change from PAUSED to PAUSED. This might happen when elements were in PLAYING state and ‘lost state’, they should make sure to go back to real ‘PAUSED’ state (prerolling for example). (Since: 1.14)

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PlayingToPlaying = 36

state change from PLAYING to PLAYING. (Since: 1.14)

Implementations§

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impl StateChange

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pub fn name<'a>(self) -> &'a GStr

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impl StateChange

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pub fn new(current: State, next: State) -> Self

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pub fn current(self) -> State

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pub fn next(self) -> State

Trait Implementations§

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impl Clone for StateChange

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fn clone(&self) -> StateChange

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 StateChange

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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 Display for StateChange

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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 From<StateChange> for Value

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fn from(v: StateChange) -> Self

Converts to this type from the input type.
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impl<'a> FromValue<'a> for StateChange

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type Checker = GenericValueTypeChecker<StateChange>

Value type checker.
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unsafe fn from_value(value: &'a Value) -> Self

Get the contained value from a Value. Read more
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impl HasParamSpec for StateChange

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type ParamSpec = ParamSpecEnum

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type SetValue = StateChange

Preferred value to be used as setter for the associated ParamSpec.
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type BuilderFn = fn(_: &str, _: StateChange) -> ParamSpecEnumBuilder<'_, StateChange>

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fn param_spec_builder() -> Self::BuilderFn

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impl Hash for StateChange

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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 StateChange

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

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

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

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

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

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fn eq(&self, other: &StateChange) -> 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 StateChange

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fn partial_cmp(&self, other: &StateChange) -> 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 StaticType for StateChange

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fn static_type() -> Type

Returns the type identifier of Self.
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impl ToValue for StateChange

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fn to_value(&self) -> Value

Convert a value to a Value.
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fn value_type(&self) -> Type

Returns the type identifier of self. Read more
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impl ValueType for StateChange

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type Type = StateChange

Type to get the Type from. Read more
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impl Copy for StateChange

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impl Eq for StateChange

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impl StructuralPartialEq for StateChange

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where 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> Borrow<T> for T
where 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 T
where 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> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where 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> IntoClosureReturnValue for T
where T: Into<Value>,

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impl<T> Property for T
where T: HasParamSpec,

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type Value = T

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impl<T> PropertyGet for T
where T: HasParamSpec,

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type Value = T

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fn get<R, F>(&self, f: F) -> R
where F: Fn(&<T as PropertyGet>::Value) -> R,

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impl<T> StaticTypeExt for T
where T: StaticType,

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fn ensure_type()

Ensures that the type has been registered with the type system.
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impl<T> ToOwned for T
where 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> ToSendValue for T
where T: Send + ToValue + ?Sized,

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fn to_send_value(&self) -> SendValue

Returns a SendValue clone of self.
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impl<T> ToString for T
where T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where 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> TryFromClosureReturnValue for T
where T: for<'a> FromValue<'a> + StaticType + 'static,

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impl<T, U> TryInto<U> for T
where 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.