Struct gstreamer_base::BaseTransform [−][src]
pub struct BaseTransform(_);
Expand description
This base class is for filter elements that process data. Elements
that are suitable for implementation using BaseTransform are ones
where the size and caps of the output is known entirely from the input
caps and buffer sizes. These include elements that directly transform
one buffer into another, modify the contents of a buffer in-place, as
well as elements that collate multiple input buffers into one output buffer,
or that expand one input buffer into multiple output buffers. See below
for more concrete use cases.
It provides for:
-
one sinkpad and one srcpad
-
Possible formats on sink and source pad implemented with custom transform_caps function. By default uses same format on sink and source.
-
Handles state changes
-
Does flushing
-
Push mode
-
Pull mode if the sub-class transform can operate on arbitrary data
Use Cases
Passthrough mode
-
Element has no interest in modifying the buffer. It may want to inspect it, in which case the element should have a transform_ip function. If there is no transform_ip function in passthrough mode, the buffer is pushed intact.
-
The
GstBaseTransformClass.passthrough_on_same_capsvariable will automatically set/unset passthrough based on whether the element negotiates the same caps on both pads. -
GstBaseTransformClass.passthrough_on_same_capson an element that doesn’t implement a transform_caps function is useful for elements that only inspect data (such as level) -
Example elements
-
Level
-
Videoscale, audioconvert, videoconvert, audioresample in certain modes.
Modifications in-place - input buffer and output buffer are the same thing.
-
The element must implement a transform_ip function.
-
Output buffer size must <= input buffer size
-
If the always_in_place flag is set, non-writable buffers will be copied and passed to the transform_ip function, otherwise a new buffer will be created and the transform function called.
-
Incoming writable buffers will be passed to the transform_ip function immediately.
-
only implementing transform_ip and not transform implies always_in_place =
true -
Example elements:
-
Volume
-
Audioconvert in certain modes (signed/unsigned conversion)
-
videoconvert in certain modes (endianness swapping)
Modifications only to the caps/metadata of a buffer
-
The element does not require writable data, but non-writable buffers should be subbuffered so that the meta-information can be replaced.
-
Elements wishing to operate in this mode should replace the prepare_output_buffer method to create subbuffers of the input buffer and set always_in_place to
true -
Example elements
-
Capsfilter when setting caps on outgoing buffers that have none.
-
identity when it is going to re-timestamp buffers by datarate.
Normal mode
- always_in_place flag is not set, or there is no transform_ip function
- Element will receive an input buffer and output buffer to operate on.
- Output buffer is allocated by calling the prepare_output_buffer function.
- Example elements:
- Videoscale, videoconvert, audioconvert when doing scaling/conversions
Special output buffer allocations
-
Elements which need to do special allocation of their output buffers beyond allocating output buffers via the negotiated allocator or buffer pool should implement the prepare_output_buffer method.
-
Example elements:
-
efence
Sub-class settable flags on GstBaseTransform
-
passthrough
-
Implies that in the current configuration, the sub-class is not interested in modifying the buffers.
-
Elements which are always in passthrough mode whenever the same caps has been negotiated on both pads can set the class variable passthrough_on_same_caps to have this behaviour automatically.
-
always_in_place
-
Determines whether a non-writable buffer will be copied before passing to the transform_ip function.
-
Implied
trueif no transform function is implemented. -
Implied
falseif ONLY transform function is implemented.
This is an Abstract Base Class, you cannot instantiate it.
Implements
BaseTransformExt, gst::prelude::ElementExt, gst::prelude::ObjectExt, trait@glib::ObjectExt, BaseTransformExtManual
Trait Implementations
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
Returns the type identifier of Self.
Auto Trait Implementations
Blanket Implementations
Mutably borrows from an owned value. Read more
Upcasts an object to a superclass or interface T. Read more
Upcasts an object to a reference of its superclass or interface T. Read more
Tries to downcast to a subclass or interface implementor T. Read more
Tries to downcast to a reference of its subclass or interface implementor T. Read more
Tries to cast to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Tries to cast to reference to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Casts to T unconditionally. Read more
Casts to &T unconditionally. Read more
Abort the state change of the element. This function is used by elements that do asynchronous state changes and find out something is wrong. Read more
Adds a pad (link point) to self. pad’s parent will be set to self;
see GstObjectExt::set_parent() for refcounting information. Read more
pub fn change_state(
&self,
transition: StateChange
) -> Result<StateChangeSuccess, StateChangeError>[src]
pub fn change_state(
&self,
transition: StateChange
) -> Result<StateChangeSuccess, StateChangeError>[src]Perform transition on self. Read more
pub fn continue_state(
&self,
ret: impl Into<StateChangeReturn>
) -> Result<StateChangeSuccess, StateChangeError>[src]
pub fn continue_state(
&self,
ret: impl Into<StateChangeReturn>
) -> Result<StateChangeSuccess, StateChangeError>[src]Commit the state change of the element and proceed to the next
pending state if any. This function is used
by elements that do asynchronous state changes.
The core will normally call this method automatically when an
element returned StateChangeReturn::Success from the state change function. Read more
v1_14 only.v1_14 only.v1_14 only.pub fn compatible_pad<P>(&self, pad: &P, caps: Option<&Caps>) -> Option<Pad> where
P: IsA<Pad>, [src]pub fn state(
&self,
timeout: impl Into<Option<ClockTime>>
) -> (Result<StateChangeSuccess, StateChangeError>, State, State)[src]pub fn link_filtered<P>(&self, dest: &P, filter: &Caps) -> Result<(), BoolError> where
P: IsA<Element>, [src]pub fn link_pads<P>(
&self,
srcpadname: Option<&str>,
dest: &P,
destpadname: Option<&str>
) -> Result<(), BoolError> where
P: IsA<Element>, [src]pub fn link_pads_filtered<P>(
&self,
srcpadname: Option<&str>,
dest: &P,
destpadname: Option<&str>,
filter: &Caps
) -> Result<(), BoolError> where
P: IsA<Element>, [src]pub fn link_pads_full<P>(
&self,
srcpadname: Option<&str>,
dest: &P,
destpadname: Option<&str>,
flags: PadLinkCheck
) -> Result<(), BoolError> where
P: IsA<Element>, [src]pub fn request_pad(
&self,
templ: &PadTemplate,
name: Option<&str>,
caps: Option<&Caps>
) -> Option<Pad>[src]v1_20 only.pub fn unlink_pads<P>(&self, srcpadname: &str, dest: &P, destpadname: &str) where
P: IsA<Element>, [src]pub fn connect_no_more_pads<F>(&self, f: F) -> SignalHandlerId where
F: 'static + Fn(&O) + Send + Sync, [src]pub fn connect_pad_added<F>(&self, f: F) -> SignalHandlerId where
F: 'static + Fn(&O, &Pad) + Send + Sync, [src]pub fn connect_pad_removed<F>(&self, f: F) -> SignalHandlerId where
F: 'static + Fn(&O, &Pad) + Send + Sync, [src]pub fn message_full<T>(
&self,
type_: ElementMessageType,
code: T,
message: Option<&str>,
debug: Option<&str>,
file: &str,
function: &str,
line: u32
) where
T: MessageErrorDomain, [src]pub fn message_full_with_details<T>(
&self,
type_: ElementMessageType,
code: T,
message: Option<&str>,
debug: Option<&str>,
file: &str,
function: &str,
line: u32,
structure: Structure
) where
T: MessageErrorDomain, [src]
pub fn message_full_with_details<T>(
&self,
type_: ElementMessageType,
code: T,
message: Option<&str>,
debug: Option<&str>,
file: &str,
function: &str,
line: u32,
structure: Structure
) where
T: MessageErrorDomain, [src]v1_10 only.pub fn add_property_deep_notify_watch(
&self,
property_name: Option<&str>,
include_value: bool
) -> NotifyWatchId[src]
pub fn add_property_deep_notify_watch(
&self,
property_name: Option<&str>,
include_value: bool
) -> NotifyWatchId[src]v1_10 only.pub fn add_property_notify_watch(
&self,
property_name: Option<&str>,
include_value: bool
) -> NotifyWatchId[src]
pub fn add_property_notify_watch(
&self,
property_name: Option<&str>,
include_value: bool
) -> NotifyWatchId[src]v1_10 only.v1_10 only.pub fn query_convert<V, U>(&self, src_val: V) -> Option<U> where
V: Into<GenericFormattedValue>,
U: SpecificFormattedValue, [src]pub fn query_convert_generic<V>(
&self,
src_val: V,
dest_format: Format
) -> Option<GenericFormattedValue> where
V: Into<GenericFormattedValue>, [src]pub fn seek<V>(
&self,
rate: f64,
flags: SeekFlags,
start_type: SeekType,
start: V,
stop_type: SeekType,
stop: V
) -> Result<(), BoolError> where
V: Into<GenericFormattedValue>, [src]pub fn seek_simple<V>(
&self,
seek_flags: SeekFlags,
seek_pos: V
) -> Result<(), BoolError> where
V: Into<GenericFormattedValue>, [src]v1_10 only.v1_10 only.pub fn add_control_binding<P>(&self, binding: &P) -> Result<(), BoolError> where
P: IsA<ControlBinding>, [src]
pub fn add_control_binding<P>(&self, binding: &P) -> Result<(), BoolError> where
P: IsA<ControlBinding>, [src]Attach the ControlBinding to the object. If there already was a
ControlBinding for this property it will be replaced. Read more
A default error function that uses g_printerr() to display the error message
and the optional debug string.. Read more
Gets the corresponding ControlBinding for the property. This should be
unreferenced again after use. Read more
Obtain the control-rate for this self. Audio processing Element
objects will use this rate to sub-divide their processing loop and call
sync_values() in between. The length of the processing segment
should be up to control-rate nanoseconds. Read more
Returns the parent of self. This function increases the refcount
of the parent object so you should gst_object_unref() it after usage. Read more
Generates a string describing the path of self in
the object hierarchy. Only useful (or used) for debugging. Read more
Gets the value for the given controlled property at the requested time. Read more
pub fn connect_parent_notify<F>(&self, f: F) -> SignalHandlerId where
F: 'static + Fn(&O) + Send + Sync, [src]Returns true if the object is an instance of (can be cast to) T.
pub fn set_properties(
&self,
property_values: &[(&str, &dyn ToValue)]
) -> Result<(), BoolError>[src]pub fn set_properties_from_value(
&self,
property_values: &[(&str, Value)]
) -> Result<(), BoolError>[src]pub fn set_property<'a, N, V>(
&self,
property_name: N,
value: V
) -> Result<(), BoolError> where
V: ToValue,
N: Into<&'a str>, [src]pub fn set_property_from_value<'a, N>(
&self,
property_name: N,
value: &Value
) -> Result<(), BoolError> where
N: Into<&'a str>, [src]pub fn property<'a, N>(&self, property_name: N) -> Result<Value, BoolError> where
N: Into<&'a str>, [src]Safety Read more
Safety Read more
Safety Read more
Safety Read more
pub fn connect_notify<F>(&self, name: Option<&str>, f: F) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec) + Send + Sync, [src]pub fn connect_notify_local<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec), [src]pub unsafe fn connect_notify_unsafe<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: Fn(&T, &ParamSpec), [src]pub fn has_property<'a, N>(&self, property_name: N, type_: Option<Type>) -> bool where
N: Into<&'a str>, [src]pub fn find_property<'a, N>(&self, property_name: N) -> Option<ParamSpec> where
N: Into<&'a str>, [src]pub fn connect<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value> + Send + Sync + 'static,
N: Into<&'a str>, [src]Same as connect but takes a SignalId instead of a signal name.
pub fn connect_local<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value> + 'static,
N: Into<&'a str>, [src]Same as connect_local but takes a SignalId instead of a signal name.
pub unsafe fn connect_unsafe<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value>,
N: Into<&'a str>, [src]Same as connect_unsafe but takes a SignalId instead of a signal name.
Emit signal by signal id.
Emit signal with details by signal id.
Emit signal by it’s name.
pub fn bind_property<'a, O, N, M>(
&'a self,
source_property: N,
target: &'a O,
target_property: M
) -> BindingBuilder<'a> where
O: ObjectType,
N: Into<&'a str>,
M: Into<&'a str>, [src]Same as emit but takes Value for the arguments.
Same as emit_by_name but takes Value for the arguments.
Returns a SendValue clone of self.
impl<'a, T, C> FromValueOptional<'a> for T where
C: ValueTypeChecker<Error = ValueTypeMismatchOrNoneError>,
T: FromValue<'a, Checker = C>, [src]