Struct gstreamer_base::BaseSrc [−][src]
pub struct BaseSrc(_);
Expand description
This is a generic base class for source elements. The following types of sources are supported:
- random access sources like files
- seekable sources
- live sources
The source can be configured to operate in any gst::Format with the
BaseSrcExt::set_format() method. The currently set format determines
the format of the internal gst::Segment and any gst::EventType::Segment
events. The default format for BaseSrc is gst::Format::Bytes.
BaseSrc always supports push mode scheduling. If the following
conditions are met, it also supports pull mode scheduling:
- The format is set to
gst::Format::Bytes(default). GstBaseSrcClass::is_seekablereturnstrue.
If all the conditions are met for operating in pull mode, BaseSrc is
automatically seekable in push mode as well. The following conditions must
be met to make the element seekable in push mode when the format is not
gst::Format::Bytes:
GstBaseSrcClass::is_seekablereturnstrue.GstBaseSrcClass::querycan convert all supported seek formats to the internal format as set withBaseSrcExt::set_format().GstBaseSrcClass::do_seekis implemented, performs the seek and returnstrue.
When the element does not meet the requirements to operate in pull mode, the
offset and length in the GstBaseSrcClass::create method should be ignored.
It is recommended to subclass PushSrc instead, in this situation. If the
element can operate in pull mode but only with specific offsets and
lengths, it is allowed to generate an error when the wrong values are passed
to the GstBaseSrcClass::create function.
BaseSrc has support for live sources. Live sources are sources that when
paused discard data, such as audio or video capture devices. A typical live
source also produces data at a fixed rate and thus provides a clock to publish
this rate.
Use BaseSrcExt::set_live() to activate the live source mode.
A live source does not produce data in the PAUSED state. This means that the
GstBaseSrcClass::create method will not be called in PAUSED but only in
PLAYING. To signal the pipeline that the element will not produce data, the
return value from the READY to PAUSED state will be
gst::StateChangeReturn::NoPreroll.
A typical live source will timestamp the buffers it creates with the current running time of the pipeline. This is one reason why a live source can only produce data in the PLAYING state, when the clock is actually distributed and running.
Live sources that synchronize and block on the clock (an audio source, for
example) can use BaseSrcExt::wait_playing() when the
GstBaseSrcClass::create function was interrupted by a state change to
PAUSED.
The GstBaseSrcClass::get_times method can be used to implement pseudo-live
sources. It only makes sense to implement the GstBaseSrcClass::get_times
function if the source is a live source. The GstBaseSrcClass::get_times
function should return timestamps starting from 0, as if it were a non-live
source. The base class will make sure that the timestamps are transformed
into the current running_time. The base source will then wait for the
calculated running_time before pushing out the buffer.
For live sources, the base class will by default report a latency of 0. For pseudo live sources, the base class will by default measure the difference between the first buffer timestamp and the start time of get_times and will report this value as the latency. Subclasses should override the query function when this behaviour is not acceptable.
There is only support in BaseSrc for exactly one source pad, which
should be named “src”. A source implementation (subclass of BaseSrc)
should install a pad template in its class_init function, like so:
static void
my_element_class_init (GstMyElementClass *klass)
{
GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
// srctemplate should be a #GstStaticPadTemplate with direction
// %GST_PAD_SRC and name "src"
gst_element_class_add_static_pad_template (gstelement_class, &srctemplate);
gst_element_class_set_static_metadata (gstelement_class,
"Source name",
"Source",
"My Source element",
"The author <my.sink@my.email>");
}
Controlled shutdown of live sources in applications
Applications that record from a live source may want to stop recording in a controlled way, so that the recording is stopped, but the data already in the pipeline is processed to the end (remember that many live sources would go on recording forever otherwise). For that to happen the application needs to make the source stop recording and send an EOS event down the pipeline. The application would then wait for an EOS message posted on the pipeline’s bus to know when all data has been processed and the pipeline can safely be stopped.
An application may send an EOS event to a source element to make it
perform the EOS logic (send EOS event downstream or post a
GST_MESSAGE_SEGMENT_DONE on the bus). This can typically be done
with the ElementExtManual::send_event() function on the element or its parent bin.
After the EOS has been sent to the element, the application should wait for an EOS message to be posted on the pipeline’s bus. Once this EOS message is received, it may safely shut down the entire pipeline.
This is an Abstract Base Class, you cannot instantiate it.
Implements
BaseSrcExt, gst::prelude::ElementExt, gst::prelude::ObjectExt, trait@glib::ObjectExt, BaseSrcExtManual
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]