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Specs: Add effect API Draft

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Thibault Saunier 2010-12-07 13:47:47 +01:00 committed by Edward Hervey
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225
docs/design/effects.txt
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@ -10,6 +10,7 @@ Summary
B. Effects configurability
C. Keyframes
4. Use-cases
5. API draft
The goal of this proposal is to find a simple way to handle effects through an
API which would allow developers to handle any use-case
@ -87,22 +88,234 @@ C. Keyframes
4. Use-cases
-----------
The user wants to add an effect to an entire clip => GESTimelineObject new API
UC-1. The user wants to add an effect to an entire clip => GESTimelineObject new API
The user wants to add an effect to an entire layer => GESTimelineLayer API.
UC-2. The user wants to add an effect to an entire layer => GESTimelineLayer API.
The developer wants to allow his users to configure effects => mapping between
UC-3. The developer wants to allow his users to configure effects => mapping between
GESTrackEffect and the configurable properties of elements (GESEffect).
The user wants to add an effect on a special portion of a clip, we should
UC-4. The user wants to add an effect on a special portion of a clip, we should
allow him to configure that thanks to a system of keyframes. FIXME
We want to implement an effect which isn't only composed by a bin, but is more
UC-5. We want to implement an effect which isn't only composed by a bin, but is more
complexe than that (ex: "effect '24'") => we have the GESTrackOperation
which is the base class (abstract) for this kind of implementation. We should
also have a GESPropertiesMapping abstract class which would be the base
class of GESEffect and could be used in this use-case.
A developer wants to implement effect which handle music and video at the same
UC-6. A developer wants to implement effect which handle music and video at the same
time, Would the solution be to implement a GESTimelineEffect to handle this
special usecase? FIXME
UC-7. The developers wants to configure each elements of an effect the way he wants
with a full control over it.
UC-8. Developers want to expose all effects present on the system to the end-user
5. API draft V1
------------
A. The GESEffectDescriptor
It is a structure that describes effects so they can easily be instanciate.
They can be composed of a simple description of a the bin, they can also
define more complexe effects, the GESEffectContainer will be able to handle
those cases.
/**
* ges_effect_descriptor_get_effect_name:
*
* Returns the name of the effect
*/
const gchar *
ges_effect_descriptor_get_effect_name (GESEffectDescriptor *self);
/**
* ges_effect_descriptor_get_effect_description:
*
* Returns the description of the effect
*/
const gchar *
ges_effect_descriptor_get_effect_description (GESEffectDescriptor *self);
/**
* ges_effect_descriptor_get_effect_categories:
*
* Returns an array of
*/
gchar **
ges_effect_descriptor_get_effect_categories (GESEffectDescriptor *self);
B. GESEffectRegistry API:
This should be a singleton since we don't want an app to instanciate more
than one registry. It should be able to get effects from various sources.
(UC-8)
/**
* ges_effect_registry_new:
*
* Returns a newly created #GESEffectRegistry
*/
GESEffectRegistry *
ges_effect_registry_new (void);
-> Usecases:
+ Have a registry of all effects that are on the système (UC-8)
/**
* ges_effect_registry_get_all:
*
* @self: The origin #GESEffectRegistry
*
* Returns a #GList of #GESEffectDescriptors. The
*/
GList *
ges_effect_registry_get_all (GESEffectRegistry *self);
-> Usecases:
+ Get all effects descriptors that are on the système (UC-8)
/**
* ges_effect_set_thumbnail:
*
* @self: The origin #GESEffect
*
* Returns %TRUE if it has been set, %FALSE otherwize
*/
gboolean *
ges_effect_set_thumbnail (GESEffect *self, ?? *thumbnail);
/**
* ges_effect_get_thumbnail:
*
* @self: The origin #GESEffect
*
* Returns the #GstBuffer or %NULL if the thumbnail hasen't been set yet.
*/
?? *
ges_effect_get_thumbnail (GESEffect *self);
=> Can we think about a way to add effects thumbnails directly in Gst or use
system thumbnails when running on Gnome?
C. The GESffectContainer API
This is an interface which would be first implemented in GESTimelineObject
and GESTimelineLayer.
/**
* ges_effect_container_add_effect:
*
* @object: The origin #GESEffectContainer
*
* Adds a new effect corresponding to the @effect_desc to the #GESEffectContainer
* If an effect with the exact same bin_desc as already been added to this @object,
* it will not be added, and the corresponding #GESEffect will be returned.
*
* Returns: The newly created #GESEffect, or %NULL if there was an error.
*/
GESEffect *ges_effect_container_add_effect (GESEffectContainer *object,
GESEffectDescriptor *effect_desc, gchar *name);
=> Usecases:
+ We can add any kind of effects to any object which comes from a class that
implements this interface (UC-1 and UC-2)
/**
* ges_effect_container_get_effects:
*
* @object: The origin #GESEffectContainer
*
*
* Returns the #GList of #GESEffect that are applied on the
* @object.
* The refcount of the objects will be increased. The user will have to
* unref each #GESEffect and free the #GList.
*/
GList *ges_effect_container_get_effects (GESEffectContainer *object);
-> Usecases:
+ First step to allow to allow the configuration of effects (UC-3)
/**
* ges_effect_container_get_effect_from_name:
*
* @object: The origin #GESEffectContainer
*
* Returns the #GESEffect that as @name as a name or NULL if we can't find that
* effect. The refcount of the objects will be increased. The user will have to
* unref each #GESEffect and free the #GList.
*/
GESEffect *ges_effect_container_get_effect_from_name (GESEffectContainer *object,
const gchar *name);
-> Usecases:
+ First step to allow the configuration of effects (UC-3)
/**
* ges_effect_container_remove:
*
* @object: The origin #GESEffectContainer
*
* The refcount of the objects will be increased. The user will have to unref each
* #GESEffect and free the #GList.
*/
gboolean *ges_effect_container_get_effect_from_name (GESEffectContainer *object,
const gchar *name);
-> Usecases:
+ First step to allow to allow the configuration of effects (UC-3)
D - The GESEffect API:
This class is an abstract class which aims at mapping all properties of an effect
so we can configure it through this API. They shouldn't be instanciate by clients,
but they are created calling ges_effect_container_add_effect().
/**
* ges_effect_get_all_properties:
*
* @self: The origin #GESEffectContainer
*
* Returns an array of the GParamSpec** that can be configured. They should be
* freed after use.
*/
GList *ges_effect_get_all_properties(GESEffect *self);
-> Usecases:
+ Let user configure effects easily (UC-3)
/**
* ges_effect_set_property:
*
* @self: The origin #GESEffectContainer
* @property_name : the name of the property to set
* @value : the value
*
* Returns an array of the GParamSpec** that can be configured. They should be
* freed after use.
*/
gboolean *ges_effect_set_property (GESEffect *self, gchar *property_name,
GValue *value);
-> Usecases:
+ Let user configure effects easily (UC-3)
/**
* ges_effect_get_gst_elements:
*
* @self: The origin #GESEffectContainer
*
* Returns a #GList of all the GstElement-s that are usefull in the effect.
* The user is responsible for unreffing all elements and freeing the
* #GList
*/
GList *ges_effect_get_gst_elements (GESEffect *self);
-> Usecases:
+ Let user have the full control of effects configuration (UC-3)
/**
* ges_effect_get_descriptor:
*
* @self: The origin #GESEffect
*
* Returns the #GESEffectDescriptor that describes the effect.
*/
GList *ges_effect_get_descriptor (GESEffect *self);
-> Usecases:
+ The user want's to have all the characteristic of an effect
=> We are still missing spec to handle Keyframes