Registry

One registry holds the metadata of a set of plugins.

<emphasis role="bold">Design:</emphasis>

The gstreamer.Registry object is a list of plugins and some functions for dealing with them. Each gstreamer.Plugin is matched 1-1 with a file on disk, and may or may not be loaded at a given time.

The primary source, at all times, of plugin information is each plugin file itself. Thus, if an application wants information about a particular plugin, or wants to search for a feature that satisfies given criteria, the primary means of doing so is to load every plugin and look at the resulting information that is gathered in the default registry. Clearly, this is a time consuming process, so we cache information in the registry file. The format and location of the cache file is internal to gstreamer.

On startup, plugins are searched for in the plugin search path. The following locations are checked in this order:

* location from --gst-plugin-path commandline option. * the GST_PLUGIN_PATH environment variable. * the GST_PLUGIN_SYSTEM_PATH environment variable. * default locations (if GST_PLUGIN_SYSTEM_PATH is not set). Those default locations are: $XDG_DATA_HOME/gstreamer-$GST_API_VERSION/plugins/ and $prefix/libs/gstreamer-$GST_API_VERSION/. $XDG_DATA_HOME defaults to $HOME/.local/share.

The registry cache file is loaded from $XDG_CACHE_HOME/gstreamer-$GST_API_VERSION/registry-$ARCH.bin (where $XDG_CACHE_HOME defaults to $HOME/.cache) or the file listed in the GST_REGISTRY env var. One reason to change the registry location is for testing.

For each plugin that is found in the plugin search path, there could be 3 possibilities for cached information:

* the cache may not contain information about a given file. * the cache may have stale information. * the cache may have current information.

In the first two cases, the plugin is loaded and the cache updated. In addition to these cases, the cache may have entries for plugins that are not relevant to the current process. These are marked as not available to the current process. If the cache is updated for whatever reason, it is marked dirty.

A dirty cache is written out at the end of initialization. Each entry is checked to make sure the information is minimally valid. If not, the entry is simply dropped.

Implementation notes:

The "cache" and "registry" are different concepts and can represent different sets of plugins. For various reasons, at init time, the cache is stored in the default registry, and plugins not relevant to the current process are marked with the GST_PLUGIN_FLAG_CACHED bit. These plugins are removed at the end of initialization.

Constructors

this
this(GstRegistry* gstRegistry, bool ownedRef = false)

Sets our main struct and passes it to the parent class.

Members

Functions

addFeature
bool addFeature(PluginFeature feature)

Add the feature to the registry. The feature-added signal will be emitted.

addOnFeatureAdded
gulong addOnFeatureAdded(void delegate(PluginFeature, Registry) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

Signals that a feature has been added to the registry (possibly replacing a previously-added one by the same name)

addOnPluginAdded
gulong addOnPluginAdded(void delegate(Plugin, Registry) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

Signals that a plugin has been added to the registry (possibly replacing a previously-added one by the same name)

addPlugin
bool addPlugin(Plugin plugin)

Add the plugin to the registry. The plugin-added signal will be emitted.

checkFeatureVersion
bool checkFeatureVersion(string featureName, uint minMajor, uint minMinor, uint minMicro)

Checks whether a plugin feature by the given name exists in registry and whether its version is at least the version required.

featureFilter
ListG featureFilter(GstPluginFeatureFilter filter, bool first, void* userData)

Runs a filter against all features of the plugins in the registry and returns a GList with the results. If the first flag is set, only the first match is returned (as a list with a single object).

findFeature
PluginFeature findFeature(string name, GType type)

Find the pluginfeature with the given name and type in the registry.

findPlugin
Plugin findPlugin(string name)

Find the plugin with the given name in the registry. The plugin will be reffed; caller is responsible for unreffing.

getFeatureList
ListG getFeatureList(GType type)

Retrieves a GList of gstreamer.PluginFeature of type.

getFeatureListByPlugin
ListG getFeatureListByPlugin(string name)

Retrieves a GList of features of the plugin with name name.

getFeatureListCookie
uint getFeatureListCookie()

Returns the registry's feature list cookie. This changes every time a feature is added or removed from the registry.

getPluginList
ListG getPluginList()

Get a copy of all plugins registered in the given registry. The refcount of each element in the list in incremented.

getRegistryStruct
GstRegistry* getRegistryStruct(bool transferOwnership = false)

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

lookup
Plugin lookup(string filename)

Look up a plugin in the given registry with the given filename. If found, plugin is reffed.

lookupFeature
PluginFeature lookupFeature(string name)

Find a gstreamer.PluginFeature with name in registry.

pluginFilter
ListG pluginFilter(GstPluginFilter filter, bool first, void* userData)

Runs a filter against all plugins in the registry and returns a GList with the results. If the first flag is set, only the first match is returned (as a list with a single object). Every plugin is reffed; use Plugin.listFree after use, which will unref again.

removeFeature
void removeFeature(PluginFeature feature)

Remove the feature from the registry.

removePlugin
void removePlugin(Plugin plugin)

Remove the plugin from the registry.

scanPath
bool scanPath(string path)

Scan the given path for plugins to add to the registry. The syntax of the path is specific to the registry.

Static functions

forkIsEnabled
bool forkIsEnabled()

By default GStreamer will perform scanning and rebuilding of the registry file using a helper child process.

forkSetEnabled
void forkSetEnabled(bool enabled)

Applications might want to disable/enable spawning of a child helper process when rebuilding the registry. See Registry.forkIsEnabled for more information.

get
Registry get()

Retrieves the singleton plugin registry. The caller does not own a reference on the registry, as it is alive as long as GStreamer is initialized.

getType
GType getType()

Variables

gstRegistry
GstRegistry* gstRegistry;

the main Gtk struct

Inherited Members

From ObjectGst

gstObject
GstObject* gstObject;

the main Gtk struct

getObjectGstStruct
GstObject* getObjectGstStruct(bool transferOwnership = false)

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

getType
GType getType()
checkUniqueness
bool checkUniqueness(ListG list, string name)

Checks to see if there is any object named name in list. This function does not do any locking of any kind. You might want to protect the provided list with the lock of the owner of the list. This function will lock each GstObject in the list to compare the name, so be careful when passing a list with a locked object.

defaultDeepNotify
void defaultDeepNotify(ObjectG object, ObjectGst orig, ParamSpec pspec, string[] excludedProps)

A default deep_notify signal callback for an object. The user data should contain a pointer to an array of strings that should be excluded from the notify. The default handler will print the new value of the property using g_print.

refSink
void* refSink(void* object)

Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference.

replace
bool replace(ref ObjectGst oldobj, ObjectGst newobj)

Atomically modifies a pointer to point to a new object. The reference count of oldobj is decreased and the reference count of newobj is increased.

addControlBinding
bool addControlBinding(ControlBinding binding)

Attach the gstreamer.ControlBinding to the object. If there already was a gstreamer.ControlBinding for this property it will be replaced.

defaultError
void defaultError(ErrorG error, string dbg)

A default error function that uses g_printerr() to display the error message and the optional debug sting..

getControlBinding
ControlBinding getControlBinding(string propertyName)

Gets the corresponding gstreamer.ControlBinding for the property. This should be unreferenced again after use.

getControlRate
GstClockTime getControlRate()

Obtain the control-rate for this object. Audio processing gstreamer.Element objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() inbetween. The length of the processing segment should be up to control-rate nanoseconds.

getGValueArray
bool getGValueArray(string propertyName, GstClockTime timestamp, GstClockTime interval, Value[] values)

Gets a number of gobject.Values for the given controlled property starting at the requested time. The array values need to hold enough space for n_values of gobject.Value

getName
string getName()

Returns a copy of the name of object. Caller should g_free() the return value after usage. For a nameless object, this returns NULL, which you can safely g_free() as well.

getParent
ObjectGst getParent()

Returns the parent of object. This function increases the refcount of the parent object so you should gst_object_unref() it after usage.

getPathString
string getPathString()

Generates a string describing the path of object in the object hierarchy. Only useful (or used) for debugging.

getValue
Value getValue(string propertyName, GstClockTime timestamp)

Gets the value for the given controlled property at the requested time.

getValueArray
bool getValueArray(string propertyName, GstClockTime timestamp, GstClockTime interval, uint nValues, void* values)

Gets a number of values for the given controlled property starting at the requested time. The array values need to hold enough space for n_values of the same type as the objects property's type.

hasActiveControlBindings
bool hasActiveControlBindings()

Check if the object has active controlled properties.

hasAncestor
bool hasAncestor(ObjectGst ancestor)

Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a gstreamer.Element is inside a gstreamer.Pipeline

hasAsAncestor
bool hasAsAncestor(ObjectGst ancestor)

Check if object has an ancestor ancestor somewhere up in the hierarchy. One can e.g. check if a gstreamer.Element is inside a gstreamer.Pipeline

hasAsParent
bool hasAsParent(ObjectGst parent)

Check if parent is the parent of object. E.g. a gstreamer.Element can check if it owns a given gstreamer.Pad

doref
ObjectGst doref()

Increments the reference count on object. This function does not take the lock on object because it relies on atomic refcounting.

removeControlBinding
bool removeControlBinding(ControlBinding binding)

Removes the corresponding gstreamer.ControlBinding If it was the last ref of the binding, it will be disposed.

setControlBindingDisabled
void setControlBindingDisabled(string propertyName, bool disabled)

This function is used to disable the control bindings on a property for some time, i.e. gst_object_sync_values() will do nothing for the property.

setControlBindingsDisabled
void setControlBindingsDisabled(bool disabled)

This function is used to disable all controlled properties of the object for some time, i.e. gst_object_sync_values() will do nothing.

setControlRate
void setControlRate(GstClockTime controlRate)

Change the control-rate for this object. Audio processing gstreamer.Element objects will use this rate to sub-divide their processing loop and call gst_object_sync_values() inbetween. The length of the processing segment should be up to control-rate nanoseconds.

setName
bool setName(string name)

Sets the name of object, or gives object a guaranteed unique name (if name is NULL). This function makes a copy of the provided name, so the caller retains ownership of the name it sent.

setParent
bool setParent(ObjectGst parent)

Sets the parent of object to parent. The object's reference count will be incremented, and any floating reference will be removed (see gst_object_ref_sink()).

suggestNextSync
GstClockTime suggestNextSync()

Returns a suggestion for timestamps where buffers should be split to get best controller results.

syncValues
bool syncValues(GstClockTime timestamp)

Sets the properties of the object, according to the gstreamer.ControlSources that (maybe) handle them and for the given timestamp.

unparent
void unparent()

Clear the parent of object, removing the associated reference. This function decreases the refcount of object.

unref
void unref()

Decrements the reference count on object. If reference count hits zero, destroy object. This function does not take the lock on object as it relies on atomic refcounting.

addOnDeepNotify
gulong addOnDeepNotify(void delegate(ObjectGst, ParamSpec, ObjectGst) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

The deep notify signal is used to be notified of property changes. It is typically attached to the toplevel bin to receive notifications from all the elements contained in that bin.

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