Struct gstreamer_base::BaseParse [−][src]
pub struct BaseParse(_);
Expand description
This base class is for parser elements that process data and splits it into separate audio/video/whatever frames.
It provides for:
- provides one sink pad and one source pad
- handles state changes
- can operate in pull mode or push mode
- handles seeking in both modes
- handles events (SEGMENT/EOS/FLUSH)
- handles queries (POSITION/DURATION/SEEKING/FORMAT/CONVERT)
- handles flushing
The purpose of this base class is to provide the basic functionality of a parser and share a lot of rather complex code.
Description of the parsing mechanism:
Set-up phase
-
BaseParsecallsGstBaseParseClass::startto inform subclass that data processing is about to start now. -
BaseParseclass callsGstBaseParseClass::set_sink_capsto inform the subclass about incoming sinkpad caps. Subclass could already set the srcpad caps accordingly, but this might be delayed until callingBaseParseExtManual::finish_frame()with a non-queued frame. -
At least at this point subclass needs to tell the
BaseParseclass how big data chunks it wants to receive (minimum frame size ). It can do this withBaseParseExt::set_min_frame_size(). -
BaseParseclass sets up appropriate data passing mode (pull/push) and starts to process the data.
Parsing phase
-
BaseParsegathers at least min_frame_size bytes of data either by pulling it from upstream or collecting buffers in an internalAdapter. -
A buffer of (at least) min_frame_size bytes is passed to subclass with
GstBaseParseClass::handle_frame. Subclass checks the contents and can optionally returngst::FlowReturn::Okalong with an amount of data to be skipped to find a valid frame (which will result in a subsequent DISCONT). If, otherwise, the buffer does not hold a complete frame,GstBaseParseClass::handle_framecan merely return and will be called again when additional data is available. In push mode this amounts to an additional input buffer (thus minimal additional latency), in pull mode this amounts to some arbitrary reasonable buffer size increase.
Of course, BaseParseExt::set_min_frame_size() could also be used if
a very specific known amount of additional data is required. If,
however, the buffer holds a complete valid frame, it can pass the
size of this frame to BaseParseExtManual::finish_frame().
If acting as a converter, it can also merely indicate consumed input
data while simultaneously providing custom output data. Note that
baseclass performs some processing (such as tracking overall consumed
data rate versus duration) for each finished frame, but other state
is only updated upon each call to GstBaseParseClass::handle_frame
(such as tracking upstream input timestamp).
Subclass is also responsible for setting the buffer metadata
(e.g. buffer timestamp and duration, or keyframe if applicable).
(although the latter can also be done by BaseParse if it is
appropriately configured, see below). Frame is provided with
timestamp derived from upstream (as much as generally possible),
duration obtained from configuration (see below), and offset
if meaningful (in pull mode).
Note that GstBaseParseClass::handle_frame might receive any small
amount of input data when leftover data is being drained (e.g. at
EOS).
-
As part of finish frame processing, just prior to actually pushing the buffer in question, it is passed to
GstBaseParseClass::pre_push_framewhich gives subclass yet one last chance to examine buffer metadata, or to send some custom (tag) events, or to perform custom (segment) filtering. -
During the parsing process
GstBaseParseClasswill handle both srcpad and sinkpad events. They will be passed to subclass ifGstBaseParseClass::sink_eventorGstBaseParseClass::src_eventimplementations have been provided.
Shutdown phase
BaseParseclass callsGstBaseParseClass::stopto inform the subclass that data parsing will be stopped.
Subclass is responsible for providing pad template caps for source and
sink pads. The pads need to be named “sink” and “src”. It also needs to
set the fixed caps on srcpad, when the format is ensured (e.g. when
base class calls subclass’ GstBaseParseClass::set_sink_caps function).
This base class uses gst::Format::Default as a meaning of frames. So,
subclass conversion routine needs to know that conversion from
gst::Format::Time to gst::Format::Default must return the
frame number that can be found from the given byte position.
BaseParse uses subclasses conversion methods also for seeking (or
otherwise uses its own default one, see also below).
Subclass start and stop functions will be called to inform the beginning
and end of data processing.
Things that subclass need to take care of:
-
Provide pad templates
-
Fixate the source pad caps when appropriate
-
Inform base class how big data chunks should be retrieved. This is done with
BaseParseExt::set_min_frame_size()function. -
Examine data chunks passed to subclass with
GstBaseParseClass::handle_frameand pass proper frame(s) toBaseParseExtManual::finish_frame(), and setting src pad caps and timestamps on frame. -
Provide conversion functions
-
Update the duration information with
BaseParseExtManual::set_duration() -
Optionally passthrough using
BaseParseExt::set_passthrough() -
Configure various baseparse parameters using
BaseParseExt::set_average_bitrate(),BaseParseExt::set_syncable()andBaseParseExtManual::set_frame_rate(). -
In particular, if subclass is unable to determine a duration, but parsing (or specs) yields a frames per seconds rate, then this can be provided to
BaseParseto enable it to cater for buffer time metadata (which will be taken from upstream as much as possible). Internally keeping track of frame durations and respective sizes that have been pushed providesBaseParsewith an estimated bitrate. A defaultGstBaseParseClass::convert(used if not overridden) will then use these rates to perform obvious conversions. These rates are also used to update (estimated) duration at regular frame intervals.
This is an Abstract Base Class, you cannot instantiate it.
Implements
BaseParseExt, gst::prelude::ElementExt, gst::prelude::ObjectExt, trait@glib::ObjectExt, BaseParseExtManual
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]