#[repr(transparent)]
pub struct Clip { /* private fields */ }
Expand description

Clip-s are the core objects of a Layer. Each clip may exist in a single layer but may control several TrackElement-s that span several Track-s. A clip will ensure that all its children share the same property::TimelineElement::start and property::TimelineElement::duration in their tracks, which will match the property::TimelineElement::start and property::TimelineElement::duration of the clip itself. Therefore, changing the timing of the clip will change the timing of the children, and a change in the timing of a child will change the timing of the clip and subsequently all its siblings. As such, a clip can be treated as a singular object in its layer.

For most uses of a Timeline, it is often sufficient to only interact with Clip-s directly, which will take care of creating and organising the elements of the timeline’s tracks.

Core Children

In more detail, clips will usually have some core TrackElement children, which are created by the clip when it is added to a layer in a timeline. The type and form of these core children will depend on the clip’s subclass. You can use TrackElementExt::is_core() to determine whether a track element is considered such a core track element. Note, if a core track element is part of a clip, it will always be treated as a core child of the clip. You can connect to the signal::Container::child-added signal to be notified of their creation.

When a child is added to a clip, the timeline will select its tracks using signal::Timeline::select-tracks-for-object. Note that it may be the case that the child will still have no set property::TrackElement::track after this process. For example, if the timeline does not have a track of the corresponding property::Track::track-type. A clip can safely contain such children, which may have their track set later, although they will play no functioning role in the timeline in the meantime.

If a clip may create track elements with various property::TrackElement::track-type(s), such as a UriClip, but you only want it to create a subset of these types, you should set the property::Clip::supported-formats of the clip to the subset of types. This should be done before adding the clip to a layer.

If a clip will produce several core elements of the same property::TrackElement::track-type, you should connect to the timeline’s signal::Timeline::select-tracks-for-object signal to coordinate which tracks each element should land in. Note, no two core children within a clip can share the same Track, so you should not select the same track for two separate core children. Provided you stick to this rule, it is still safe to select several tracks for the same core child, the core child will be copied into the additional tracks. You can manually add the child to more tracks later using ClipExt::add_child_to_track(). If you do not wish to use a core child, you can always select no track.

The property::TimelineElement::in-point of the clip will control the property::TimelineElement::in-point of its core children to be the same value if their property::TrackElement::has-internal-source is set to true.

The property::TimelineElement::max-duration of the clip is the minimum property::TimelineElement::max-duration of its core children. If you set its value to anything other than its current value, this will also set the property::TimelineElement::max-duration of all its core children to the same value if their property::TrackElement::has-internal-source is set to true. As a special case, whilst a clip does not yet have any core children, its property::TimelineElement::max-duration may be set to indicate what its value will be once they are created.

Effects

Some subclasses (SourceClip and BaseEffectClip) may also allow their objects to have additional non-core BaseEffect-s elements as children. These are additional effects that are applied to the output data of the core elements. They can be added to the clip using ClipExt::add_top_effect(), which will take care of adding the effect to the timeline’s tracks. The new effect will be placed between the clip’s core track elements and its other effects. As such, the newly added effect will be applied to any source data before the other existing effects. You can change the ordering of effects using ClipExt::set_top_effect_index().

Tracks are selected for top effects in the same way as core children. If you add a top effect to a clip before it is part of a timeline, and later add the clip to a timeline, the track selection for the top effects will occur just after the track selection for the core children. If you add a top effect to a clip that is already part of a timeline, the track selection will occur immediately. Since a top effect must be applied on top of a core child, if you use signal::Timeline::select-tracks-for-object, you should ensure that the added effects are destined for a Track that already contains a core child.

In addition, if the core child in the track is not property::TrackElement::active, then neither can any of its effects be property::TrackElement::active. Therefore, if a core child is made in-active, all of the additional effects in the same track will also become in-active. Similarly, if an effect is set to be active, then the core child will also become active, but other effects will be left alone. Finally, if an active effect is added to the track of an in-active core child, it will become in-active as well. Note, in contrast, setting a core child to be active, or an effect to be in-active will not change the other children in the same track.

Time Effects

Some effects also change the timing of their data (see BaseEffect for what counts as a time effect). Note that a BaseEffectClip will refuse time effects, but a Source will allow them.

When added to a clip, time effects may adjust the timing of other children in the same track. Similarly, when changing the order of effects, making them (in)-active, setting their time property values or removing time effects. These can cause the property::Clip::duration-limit to change in value. However, if such an operation would ever cause the property::TimelineElement::duration to shrink such that a clip’s Source is totally overlapped in the timeline, the operation would be prevented. Note that the same can happen when adding non-time effects with a finite property::TimelineElement::max-duration.

Therefore, when working with time effects, you should – more so than usual – not assume that setting the properties of the clip’s children will succeed. In particular, you should use TimelineElementExt::set_child_property_full() when setting the time properties.

If you wish to preserve the internal duration of a source in a clip during these time effect operations, you can do something like the following.

⚠️ The following code is in c ⚠️

void
do_time_effect_change (GESClip * clip)
{
  GList *tmp, *children;
  GESTrackElement *source;
  GstClockTime source_outpoint;
  GstClockTime new_end;
  GError *error = NULL;

  // choose some active source in a track to preserve the internal
  // duration of
  source = ges_clip_get_track_element (clip, NULL, GES_TYPE_SOURCE);

  // note its current internal end time
  source_outpoint = ges_clip_get_internal_time_from_timeline_time (
        clip, source, GES_TIMELINE_ELEMENT_END (clip), NULL);

  // handle invalid out-point

  // stop the children's control sources from clamping when their
  // out-point changes with a change in the time effects
  children = ges_container_get_children (GES_CONTAINER (clip), FALSE);

  for (tmp = children; tmp; tmp = tmp->next)
    ges_track_element_set_auto_clamp_control_source (tmp->data, FALSE);

  // add time effect, or set their children properties, or move them around
  ...
  // user can make sure that if a time effect changes one source, we should
  // also change the time effect for another source. E.g. if
  // "GstVideorate::rate" is set to 2.0, we also set "GstPitch::rate" to
  // 2.0

  // Note the duration of the clip may have already changed if the
  // duration-limit of the clip dropped below its current value

  new_end = ges_clip_get_timeline_time_from_internal_time (
        clip, source, source_outpoint, &error);
  // handle error

  if (!ges_timeline_elemnet_edit_full (GES_TIMELINE_ELEMENT (clip),
        -1, GES_EDIT_MODE_TRIM, GES_EDGE_END, new_end, &error))
    // handle error

  for (tmp = children; tmp; tmp = tmp->next)
    ges_track_element_set_auto_clamp_control_source (tmp->data, TRUE);

  g_list_free_full (children, gst_object_unref);
  gst_object_unref (source);
}

This is an Abstract Base Class, you cannot instantiate it.

Implements

ClipExt, GESContainerExt, TimelineElementExt, glib::ObjectExt, ExtractableExt, MetaContainerExt, [TimelineElementExtManual][trait@crate::prelude::TimelineElementExtManual]

Implementations

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Feeds this value into the given Hasher. Read more

Feeds a slice of this type into the given Hasher. Read more

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

Restrict a value to a certain interval. Read more

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

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

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

Returns the type identifier of Self.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

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

Performs the conversion.

Performs the conversion.

Returns true if the object is an instance of (can be cast to) T.

Returns the type of the object.

Returns the ObjectClass of the object. Read more

Returns the class of the object.

Returns the class of the object in the given type T. Read more

Returns the interface T of the object. Read more

Similar to Self::set_property but fails instead of panicking.

Sets the property property_name of the object to value value. Read more

Similar to Self::set_property but fails instead of panicking.

Sets the property property_name of the object to value value. Read more

Similar to Self::set_properties but fails instead of panicking.

Sets multiple properties of the object at once. Read more

Similar to Self::set_properties_from_value but fails instead of panicking.

Sets multiple properties of the object at once. Read more

Similar to Self::property but fails instead of panicking.

Gets the property property_name of the object and cast it to the type V. Read more

Similar to Self::property_value but fails instead of panicking.

Gets the property property_name of the object. Read more

Check if the object has a property property_name of the given type_. Read more

Get the type of the property property_name of this object. Read more

Get the ParamSpec of the property property_name of this object.

Return all ParamSpec of the properties of this object.

Freeze all property notifications until the return guard object is dropped. Read more

Set arbitrary data on this object with the given key. Read more

Return previously set arbitrary data of this object with the given key. Read more

Retrieve previously set arbitrary data of this object with the given key. Read more

Set arbitrary data on this object with the given key. Read more

Return previously set arbitrary data of this object with the given key. Read more

Retrieve previously set arbitrary data of this object with the given key. Read more

Block a given signal handler. Read more

Unblock a given signal handler.

Stop emission of the currently emitted signal.

Stop emission of the currently emitted signal by the (possibly detailed) signal name.

Similar to Self::connect but fails instead of panicking.

Connect to the signal signal_name on this object. Read more

Similar to Self::connect_id but fails instead of panicking.

Connect to the signal signal_id on this object. Read more

Similar to Self::connect_local but fails instead of panicking.

Connect to the signal signal_name on this object. Read more

Similar to Self::connect_local_id but fails instead of panicking.

Connect to the signal signal_id on this object. Read more

Similar to Self::connect_unsafe but fails instead of panicking.

Connect to the signal signal_name on this object. Read more

Similar to Self::connect_unsafe_id but fails instead of panicking.

Similar to Self::connect_closure but fails instead of panicking.

Connect a closure to the signal signal_name on this object. Read more

Similar to Self::connect_closure_id but fails instead of panicking.

Connect a closure to the signal signal_id on this object. Read more

Limits the lifetime of closure to the lifetime of the object. When the object’s reference count drops to zero, the closure will be invalidated. An invalidated closure will ignore any calls to Closure::invoke. Read more

Connect to the signal signal_id on this object. Read more

Similar to Self::emit but fails instead of panicking.

Emit signal by signal id. Read more

Similar to Self::emit_with_values but fails instead of panicking.

Same as Self::emit but takes Value for the arguments.

Similar to Self::emit_by_name but fails instead of panicking.

Emit signal by its name. Read more

Similar to Self::emit_by_name_with_values but fails instead of panicking.

Emit signal by its name. Read more

Similar to Self::emit_by_name_with_details but fails instead of panicking.

Emit signal by its name with details. Read more

Similar to Self::emit_by_name_with_details_and_values but fails instead of panicking.

Emit signal by its name with details. Read more

Similar to Self::emit_with_details but fails instead of panicking.

Emit signal by signal id with details. Read more

Similar to Self::emit_with_details_and_values but fails instead of panicking.

Emit signal by signal id with details. Read more

Disconnect a previously connected signal handler.

Connect to the notify signal of the object. Read more

Connect to the notify signal of the object. Read more

Connect to the notify signal of the object. Read more

Notify that the given property has changed its value. Read more

Notify that the given property has changed its value. Read more

Downgrade this object to a weak reference.

Bind property source_property on this object to the target_property on the target object. Read more

Returns the strong reference count of this object.

Ensures that the type has been registered with the type system.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

Returns a SendValue clone of self.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.