GES.Asset

g GES.Asset GES.Asset GES.MetaContainer GES.MetaContainer GES.MetaContainer->GES.Asset GObject.GInterface GObject.GInterface GObject.GInterface->GES.MetaContainer Gio.AsyncInitable Gio.AsyncInitable GObject.GInterface->Gio.AsyncInitable Gio.Initable Gio.Initable GObject.GInterface->Gio.Initable GObject.Object GObject.Object GObject.Object->GES.Asset Gio.AsyncInitable->GES.Asset Gio.Initable->GES.Asset

Subclasses

GES.ClipAsset, GES.Project, GES.TrackElementAsset

Methods

Inherited

GObject.Object (37), GES.MetaContainer (40), Gio.AsyncInitable (4), Gio.Initable (2)

Structs

GObject.ObjectClass (5)

class

needs_reload (extractable_type, id)

class

request (extractable_type, id)

class

request_async (extractable_type, id, cancellable, callback, *user_data)

class

request_finish (res)

extract ()

get_error ()

get_extractable_type ()

get_id ()

get_proxy ()

get_proxy_target ()

list_proxies ()

set_proxy (proxy)

unproxy (proxy)

Virtual Methods

Inherited

GObject.Object (7), Gio.AsyncInitable (2), Gio.Initable (1)

do_extract ()

do_inform_proxy (proxy_id)

do_proxied (proxy)

do_request_id_update (proposed_new_id, error)

do_start_loading ()

Properties

Name

Type

Flags

Short Description

extractable-type

GObject.GType

r/w/co

The type of the Object that can be extracted out of the asset

id

str

r/w/co

The unique identifier of the asset

proxy

GES.Asset

r/w

The asset default proxy.

proxy-target

GES.Asset

r

The target of a proxy asset.

Signals

Inherited

GObject.Object (1), GES.MetaContainer (1)

Fields

Inherited

GObject.Object (1), GES.MetaContainer (1)

Name

Type

Access

Description

parent

GObject.Object

r

Class Details

class GES.Asset(**kwargs)
Bases

GObject.Object, GES.MetaContainer, Gio.AsyncInitable, Gio.Initable

Abstract

No

Structure

GES.AssetClass

A GES.Asset in the GStreamer Editing Services represents a resources that can be used. In particular, any class that implements the GES.Extractable interface may have some associated assets with a corresponding GES.Asset :extractable-type, from which its objects can be extracted using GES.Asset.extract(). Some examples would be GES.Clip, GES.Formatter and GES.TrackElement.

All assets that are created within GES are stored in a cache; one per each GES.Asset :id and GES.Asset :extractable-type pair. These assets can be fetched, and initialized if they do not yet exist in the cache, using GES.Asset.request().

``` c GES.Asset *effect_asset; GES.Effect *effect;

// You create an asset for an effect effect_asset = GES.Asset.request (GES_TYPE_EFFECT, “agingtv”, None);

// And now you can extract an instance of GES.Effect from that asset effect = GES_EFFECT (GES.Asset.extract (effect_asset));

```

The advantage of using assets, rather than simply creating the object directly, is that the currently loaded resources can be listed with GES.list_assets() and displayed to an end user. For example, to show which media files have been loaded, and a standard list of effects. In fact, the GES library already creates assets for GES.TransitionClip and GES.Formatter, which you can use to list all the available transition types and supported formats.

The other advantage is that GES.Asset implements GES.MetaContainer, so metadata can be set on the asset, with some subclasses automatically creating this metadata on initiation.

For example, to display information about the supported formats, you could do the following:

GList *formatter_assets, *tmp;

//  List all  the transitions
formatter_assets = ges_list_assets (GES_TYPE_FORMATTER);

// Print some infos about the formatter GESAsset
for (tmp = formatter_assets; tmp; tmp = tmp->next) {
  gst_print ("Name of the formatter: %s, file extension it produces: %s",
    ges_meta_container_get_string (
      GES_META_CONTAINER (tmp->data), GES_META_FORMATTER_NAME),
    ges_meta_container_get_string (
      GES_META_CONTAINER (tmp->data), GES_META_FORMATTER_EXTENSION));
}

g_list_free (transition_assets);
ID

Each asset is uniquely defined in the cache by its GES.Asset :extractable-type and GES.Asset :id. Depending on the GES.Asset :extractable-type, the GES.Asset :id can be used to parametrise the creation of the object upon extraction. By default, a class that implements GES.Extractable will only have a single associated asset, with an GES.Asset :id set to the type name of its objects. However, this is overwritten by some implementations, which allow a class to have multiple associated assets. For example, for GES.TransitionClip the GES.Asset :id will be a nickname of the GES.TransitionClip :vtype. You should check the documentation for each extractable type to see if they differ from the default.

Moreover, each GES.Asset :extractable-type may also associate itself with a specific asset subclass. In such cases, when their asset is requested, an asset of this subclass will be returned instead.

Managing

You can use a GES.Project to easily manage the assets of a GES.Timeline.

Proxies

Some assets can (temporarily) act as the GES.Asset :proxy of another asset. When the original asset is requested from the cache, the proxy will be returned in its place. This can be useful if, say, you want to substitute a GES.UriClipAsset corresponding to a high resolution media file with the asset of a lower resolution stand in.

An asset may even have several proxies, the first of which will act as its default and be returned on requests, but the others will be ordered to take its place once it is removed. You can add a proxy to an asset, or set its default, using GES.Asset.set_proxy(), and you can remove them with GES.Asset.unproxy().

classmethod needs_reload(extractable_type, id)[source]
Parameters
Returns

True if the specified asset exists in the cache and could be marked for reloading.

Return type

bool

Indicate that an existing GES.Asset in the cache should be reloaded upon the next request. This can be used when some condition has changed, which may require that an existing asset should be updated. For example, if an external resource has changed or now become available.

Note, the asset is not immediately changed, but will only actually reload on the next call to GES.Asset.request() or GES.Asset.request_async().

classmethod request(extractable_type, id)[source]
Parameters
Raises

GLib.Error

Returns

A reference to the requested asset, or None if an error occurred.

Return type

GES.Asset or None

Returns an asset with the given properties. If such an asset already exists in the cache (it has been previously created in GES), then a reference to the existing asset is returned. Otherwise, a newly created asset is returned, and also added to the cache.

If the requested asset has been loaded with an error, then error is set, if given, and None will be returned instead.

Note that the given id may not be exactly the GES.Asset :id that is set on the returned asset. For instance, it may be adjusted into a standard format. Or, if a GES.Extractable type does not have its extraction parametrised, as is the case by default, then the given id may be ignored entirely and the GES.Asset :id set to some standard, in which case a None id can be given.

Similarly, the given extractable_type may not be exactly the GES.Asset :extractable-type that is set on the returned asset. Instead, the actual extractable type may correspond to a subclass of the given extractable_type, depending on the given id.

Moreover, depending on the given extractable_type, the returned asset may belong to a subclass of GES.Asset.

Finally, if the requested asset has a GES.Asset :proxy, then the proxy that is found at the end of the chain of proxies is returned (a proxy’s proxy will take its place, and so on, unless it has no proxy).

Some asset subclasses only support asynchronous construction of its assets, such as GES.UriClip. For such assets this method will fail, and you should use GES.Asset.request_async() instead. In the case of GES.UriClip, you can use GES.UriClipAsset.request_sync() if you only want to wait for the request to finish.

classmethod request_async(extractable_type, id, cancellable, callback, *user_data)[source]
Parameters

Requests an asset with the given properties asynchronously (see GES.Asset.request()). When the asset has been initialized or fetched from the cache, the given callback function will be called. The asset can then be retrieved in the callback using the GES.Asset.request_finish() method on the given Gio.AsyncResult.

Note that the source object passed to the callback will be the GES.Asset corresponding to the request, but it may not have loaded correctly and therefore can not be used as is. Instead, GES.Asset.request_finish() should be used to fetch a usable asset, or indicate that an error occurred in the asset’s creation.

Note that the callback will be called in the GLib.MainLoop running under the same GLib.MainContext that GES.init() was called in. So, if you wish the callback to be invoked outside the default GLib.MainContext, you can call GLib.MainContext.push_thread_default() in a new thread before calling GES.init().

Example of an asynchronous asset request: ``` c // The request callback static void asset_loaded_cb (GES.Asset * source, Gio.AsyncResult * res, object user_data) { GES.Asset *asset; GLib.Error *error = None;

asset = GES.Asset.request_finish (res, &error); if (asset) { gst_print (“The file: %s is usable as a GES.UriClip", GES.Asset.get_id (asset)); } else { gst_print (“The file: %s is *not* usable as a GES.UriClip because: %s”, GES.Asset.get_id (source), error->message); }

Gst.Object.unref (asset); }

// The request: GES.Asset.request_async (GES_TYPE_URI_CLIP, some_uri, None, (Gio.AsyncReadyCallback) asset_loaded_cb, user_data); ```

classmethod request_finish(res)[source]
Parameters

res (Gio.AsyncResult) – The task result to fetch the asset from

Raises

GLib.Error

Returns

The requested asset, or None if an error occurred.

Return type

GES.Asset

Fetches an asset requested by GES.Asset.request_async(), which finalises the request.

extract()[source]
Raises

GLib.Error

Returns

A newly created object, or None if an error occurred.

Return type

GES.Extractable

Extracts a new GES.Asset :extractable-type object from the asset. The GES.Asset :id of the asset may determine the properties and state of the newly created object.

get_error()[source]
Returns

The error set on asset, or None if no error occurred when asset was loaded.

Return type

GLib.Error or None

Retrieve the error that was set on the asset when it was loaded.

New in version 1.8.

get_extractable_type()[source]
Returns

The extractable type of self.

Return type

GObject.GType

Gets the GES.Asset :extractable-type of the asset.

get_id()[source]
Returns

The ID of self.

Return type

str

Gets the GES.Asset :id of the asset.

get_proxy()[source]
Returns

The default proxy of self.

Return type

GES.Asset or None

Gets the default GES.Asset :proxy of the asset.

get_proxy_target()[source]
Returns

The asset that self is a proxy of.

Return type

GES.Asset or None

Gets the GES.Asset :proxy-target of the asset.

Note that the proxy target may have loaded with an error, so you should call GES.Asset.get_error() on the returned target.

list_proxies()[source]
Returns

The list of proxies that self has.

Return type

[GES.Asset]

Get all the proxies that the asset has. The first item of the list will be the default GES.Asset :proxy. The second will be the proxy that is ‘next in line’ to be default, and so on.

set_proxy(proxy)[source]
Parameters

proxy (GES.Asset or None) – A new default proxy for self

Returns

True if proxy was successfully set as the default for self.

Return type

bool

Sets the GES.Asset :proxy for the asset.

If proxy is among the existing proxies of the asset (see GES.Asset.list_proxies()) it will be moved to become the default proxy. Otherwise, if proxy is not None, it will be added to the list of proxies, as the new default. The previous default proxy will become ‘next in line’ for if the new one is removed, and so on. As such, this will **not** actually remove the previous default proxy (use GES.Asset.unproxy() for that).

Note that an asset can only act as a proxy for one other asset.

As a special case, if proxy is None, then this method will actually remove **all** proxies from the asset.

unproxy(proxy)[source]
Parameters

proxy (GES.Asset) – An existing proxy of self

Returns

True if proxy was successfully removed from self's proxy list.

Return type

bool

Removes the proxy from the available list of proxies for the asset. If the given proxy is the default proxy of the list, then the next proxy in the available list (see GES.Asset.list_proxies()) will become the default. If there are no other proxies, then the asset will no longer have a default GES.Asset :proxy.

do_extract() virtual
Returns

A newly created object, or None if an error occurred.

Return type

GES.Extractable

Extracts a new GES.Asset :extractable-type object from the asset. The GES.Asset :id of the asset may determine the properties and state of the newly created object.

do_inform_proxy(proxy_id) virtual
Parameters

proxy_id (str) –

do_proxied(proxy) virtual
Parameters

proxy (GES.Asset) –

do_request_id_update(proposed_new_id, error) virtual
Parameters
Return type

bool

do_start_loading() virtual
Return type

GES.AssetLoadingReturn

Property Details

GES.Asset.props.extractable_type
Name

extractable-type

Type

GObject.GType

Default Value

<GType GObject>

Flags

READABLE, WRITABLE, CONSTRUCT_ONLY

The GES.Extractable object type that can be extracted from the asset.

GES.Asset.props.id
Name

id

Type

str

Default Value

None

Flags

READABLE, WRITABLE, CONSTRUCT_ONLY

The ID of the asset. This should be unique amongst all assets with the same GES.Asset :extractable-type. Depending on the associated GES.Extractable implementation, this id may convey some information about the GObject.Object that should be extracted. Note that, as such, the ID will have an expected format, and you can not choose this value arbitrarily. By default, this will be set to the type name of the GES.Asset :extractable-type, but you should check the documentation of the extractable type to see whether they differ from the default behaviour.

GES.Asset.props.proxy
Name

proxy

Type

GES.Asset

Default Value

None

Flags

READABLE, WRITABLE

The default proxy for this asset, or None if it has no proxy. A proxy will act as a substitute for the original asset when the original is requested (see GES.Asset.request()).

Setting this property will not usually remove the existing proxy, but will replace it as the default (see GES.Asset.set_proxy()).

GES.Asset.props.proxy_target
Name

proxy-target

Type

GES.Asset

Default Value

None

Flags

READABLE

The asset that this asset is a proxy for, or None if it is not a proxy for another asset.

Note that even if this asset is acting as a proxy for another asset, but this asset is not the default GES.Asset :proxy, then proxy-target will *still* point to this other asset. So you should check the GES.Asset :proxy property of target-proxy before assuming it is the current default proxy for the target.

Note that the GObject.Object ::notify for this property is emitted after the GES.Asset :proxy GObject.Object ::notify for the corresponding (if any) asset it is now the proxy of/no longer the proxy of.