GstDeviceProvider

GstDeviceProvider — A device provider

Functions

Types and Values

Includes

#include <gst/gst.h>

Description

A GstDeviceProvider subclass is provided by a plugin that handles devices if there is a way to programatically list connected devices. It can also optionally provide updates to the list of connected devices.

Each GstDeviceProvider subclass is a singleton, a plugin should normally provide a single subclass for all devices.

Applications would normally use a GstDeviceMonitor to monitor devices from all relevant providers.

Functions

gst_device_provider_can_monitor ()

gboolean
gst_device_provider_can_monitor (GstDeviceProvider *provider);

gst_device_provider_class_add_metadata ()

void
gst_device_provider_class_add_metadata
                               (GstDeviceProviderClass *klass,
                                const gchar *key,
                                const gchar *value);

Set key with value as metadata in klass .

Parameters

klass

class to set metadata for

 

key

the key to set

 

value

the value to set

 

Since 1.4


gst_device_provider_class_add_static_metadata ()

void
gst_device_provider_class_add_static_metadata
                               (GstDeviceProviderClass *klass,
                                const gchar *key,
                                const gchar *value);

Set key with value as metadata in klass .

Same as gst_device_provider_class_add_metadata(), but value must be a static string or an inlined string, as it will not be copied. (GStreamer plugins will be made resident once loaded, so this function can be used even from dynamically loaded plugins.)

Parameters

klass

class to set metadata for

 

key

the key to set

 

value

the value to set.

[transfer full]

Since 1.4


gst_device_provider_class_get_metadata ()

const gchar *
gst_device_provider_class_get_metadata
                               (GstDeviceProviderClass *klass,
                                const gchar *key);

Get metadata with key in klass .

Parameters

klass

class to get metadata for

 

key

the key to get

 

Returns

the metadata for key .

Since 1.4


gst_device_provider_class_set_metadata ()

void
gst_device_provider_class_set_metadata
                               (GstDeviceProviderClass *klass,
                                const gchar *longname,
                                const gchar *classification,
                                const gchar *description,
                                const gchar *author);

Sets the detailed information for a GstDeviceProviderClass.

This function is for use in _class_init functions only.

Parameters

klass

class to set metadata for

 

longname

The long English name of the device provider. E.g. "File Sink"

 

classification

String describing the type of device provider, as an unordered list separated with slashes ('/'). See draft-klass.txt of the design docs for more details and common types. E.g: "Sink/File"

 

description

Sentence describing the purpose of the device provider. E.g: "Write stream to a file"

 

author

Name and contact details of the author(s). Use \n to separate multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"

 

Since 1.4


gst_device_provider_class_set_static_metadata ()

void
gst_device_provider_class_set_static_metadata
                               (GstDeviceProviderClass *klass,
                                const gchar *longname,
                                const gchar *classification,
                                const gchar *description,
                                const gchar *author);

Sets the detailed information for a GstDeviceProviderClass.

This function is for use in _class_init functions only.

Same as gst_device_provider_class_set_metadata(), but longname , classification , description , and author must be static strings or inlined strings, as they will not be copied. (GStreamer plugins will be made resident once loaded, so this function can be used even from dynamically loaded plugins.)

Parameters

klass

class to set metadata for

 

longname

The long English name of the element. E.g. "File Sink".

[transfer full]

classification

String describing the type of element, as an unordered list separated with slashes ('/'). See draft-klass.txt of the design docs for more details and common types. E.g: "Sink/File".

[transfer full]

description

Sentence describing the purpose of the element. E.g: "Write stream to a file".

[transfer full]

author

Name and contact details of the author(s). Use \n to separate multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>".

[transfer full]

Since 1.4


gst_device_provider_device_add ()

void
gst_device_provider_device_add (GstDeviceProvider *provider,
                                GstDevice *device);

Posts a message on the provider's GstBus to inform applications that a new device has been added.

This is for use by subclasses.

Parameters

provider

a GstDeviceProvider

 

device

a GstDevice that has been added.

[transfer full]

Since 1.4


gst_device_provider_device_remove ()

void
gst_device_provider_device_remove (GstDeviceProvider *provider,
                                   GstDevice *device);

Posts a message on the provider's GstBus to inform applications that a device has been removed.

This is for use by subclasses.

Parameters

provider

a GstDeviceProvider

 

device

a GstDevice that has been removed

 

Since 1.4


gst_device_provider_get_bus ()

GstBus *
gst_device_provider_get_bus (GstDeviceProvider *provider);

Gets the GstBus of this GstDeviceProvider

Parameters

provider

a GstDeviceProvider

 

Returns

a GstBus.

[transfer full]

Since 1.4


gst_device_provider_get_devices ()

GList *
gst_device_provider_get_devices (GstDeviceProvider *provider);

Gets a list of devices that this provider understands. This may actually probe the hardware if the provider is not currently started.

Parameters

provider

A GstDeviceProvider

 

Returns

a GList of GstDevice.

[transfer full][element-type GstDevice]

Since 1.4


gst_device_provider_get_factory ()

GstDeviceProviderFactory *
gst_device_provider_get_factory (GstDeviceProvider *provider);

Retrieves the factory that was used to create this device provider.

Parameters

provider

a GstDeviceProvider to request the device provider factory of.

 

Returns

the GstDeviceProviderFactory used for creating this device provider. no refcounting is needed.

[transfer none]

Since 1.4


gst_device_provider_register ()

gboolean
gst_device_provider_register (GstPlugin *plugin,
                              const gchar *name,
                              guint rank,
                              GType type);

Create a new device providerfactory capable of instantiating objects of the type and add the factory to plugin .

Parameters

plugin

GstPlugin to register the device provider with, or NULL for a static device provider.

[allow-none]

name

name of device providers of this type

 

rank

rank of device provider (higher rank means more importance when autoplugging)

 

type

GType of device provider to register

 

Returns

TRUE, if the registering succeeded, FALSE on error

Since 1.4


gst_device_provider_start ()

gboolean
gst_device_provider_start (GstDeviceProvider *provider);

Starts providering the devices. This will cause GST_MESSAGE_DEVICE_ADDED and GST_MESSAGE_DEVICE_REMOVED messages to be posted on the provider's bus when devices are added or removed from the system.

Since the GstDeviceProvider is a singleton, gst_device_provider_start() may already have been called by another user of the object, gst_device_provider_stop() needs to be called the same number of times.

Parameters

provider

A GstDeviceProvider

 

Returns

TRUE if the device providering could be started

Since 1.4


gst_device_provider_stop ()

void
gst_device_provider_stop (GstDeviceProvider *provider);

Decreases the use-count by one. If the use count reaches zero, this GstDeviceProvider will stop providering the devices. This needs to be called the same number of times that gst_device_provider_start() was called.

Parameters

provider

A GstDeviceProvider

 

Since 1.4

Types and Values

struct GstDeviceProvider

struct GstDeviceProvider {
  GstObject         parent;

  /* Protected by the Object lock */
  GList *devices;
};

The structure of the base GstDeviceProvider

Members

GstObject parent;

The parent GstObject

 

GList *devices;

a GList of the GstDevice objects

 

Since 1.4


struct GstDeviceProviderClass

struct GstDeviceProviderClass {
  GstObjectClass    parent_class;

  GstDeviceProviderFactory     *factory;

  GList*      (*probe) (GstDeviceProvider * provider);

  gboolean    (*start) (GstDeviceProvider * provider);
  void        (*stop)  (GstDeviceProvider * provider);
};

The structure of the base GstDeviceProviderClass

Members

GstObjectClass parent_class;

the parent GstObjectClass structure

 

GstDeviceProviderFactory *factory;

a pointer to the GstDeviceProviderFactory that creates this provider

 

probe ()

Returns a list of devices that are currently available. This should never block.

 

start ()

Starts monitoring for new devices. Only subclasses that can know that devices have been added or remove need to implement this method.

 

stop ()

Stops monitoring for new devices. Only subclasses that implement the start() method need to implement this method.

 

Since 1.4

See Also

GstDevice, GstDeviceMonitor