GstDeviceMonitor

GstDeviceMonitor — A device monitor and prober

Functions

Types and Values

Includes

#include <gst/gst.h>

Description

Applications should create a GstDeviceMonitor when they want to probe, list and monitor devices of a specific type. The GstDeviceMonitor will create the appropriate GstDeviceProvider objects and manage them. It will then post messages on its GstBus for devices that have been added and removed.

The device monitor will monitor all devices matching the filters that the application has set.

The basic use pattern of a device monitor is as follows:

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static gboolean
my_bus_func (GstBus * bus, GstMessage * message, gpointer user_data)
{
   GstDevice *device;
   gchar *name;

   switch (GST_MESSAGE_TYPE (message)) {
     case GST_MESSAGE_DEVICE_ADDED:
       gst_message_parse_device_added (message, &device);
       name = gst_device_get_display_name (device);
       g_print("Device added: %s\n", name);
       g_free (name);
       break;
     case GST_MESSAGE_DEVICE_REMOVED:
       gst_message_parse_device_removed (message, &device);
       name = gst_device_get_display_name (device);
       g_print("Device removed: %s\n", name);
       g_free (name);
       break;
     default:
       break;
   }

   return G_SOURCE_CONTINUE;
}

GstDeviceMonitor *
setup_raw_video_source_device_monitor (void) {
   GstDeviceMonitor *monitor;
   GstBus *bus;
   GstCaps *caps;

   monitor = gst_device_monitor_new ();

   bus = gst_device_monitor_get_bus (monitor);
   gst_bus_add_watch (bus, my_bus_func, NULL);
   gst_object_unref (bus);

   caps = gst_caps_new_empty_simple ("video/x-raw");
   gst_device_monitor_add_filter (monitor, "Video/Source", caps);
   gst_caps_unref (caps);

   gst_device_monitor_start (monitor);

   return monitor;
}

Functions

gst_device_monitor_new ()

GstDeviceMonitor *
gst_device_monitor_new (void);

Create a new GstDeviceMonitor

Returns

a new device monitor.

[transfer full]

Since 1.4


gst_device_monitor_get_bus ()

GstBus *
gst_device_monitor_get_bus (GstDeviceMonitor *monitor);

Gets the GstBus of this GstDeviceMonitor

Parameters

monitor

a GstDeviceProvider

 

Returns

a GstBus.

[transfer full]

Since 1.4


gst_device_monitor_add_filter ()

guint
gst_device_monitor_add_filter (GstDeviceMonitor *monitor,
                               const gchar *classes,
                               GstCaps *caps);

Adds a filter for which GstDevice will be monitored, any device that matches all classes and the GstCaps will be returned.

Filters must be added before the GstDeviceMonitor is started.

Parameters

monitor

a device monitor

 

classes

device classes to use as filter or NULL for any class.

[allow-none]

caps

the GstCaps to filter or NULL for ANY.

[allow-none]

Returns

The id of the new filter or 0 if no provider matched the filter's classes.

Since 1.4


gst_device_monitor_remove_filter ()

gboolean
gst_device_monitor_remove_filter (GstDeviceMonitor *monitor,
                                  guint filter_id);

Removes a filter from the GstDeviceMonitor using the id that was returned by gst_device_monitor_add_filter().

Parameters

monitor

a device monitor

 

filter_id

the id of the filter

 

Returns

TRUE of the filter id was valid, FALSE otherwise

Since 1.4


gst_device_monitor_start ()

gboolean
gst_device_monitor_start (GstDeviceMonitor *monitor);

Starts monitoring the devices, one this has succeeded, the GST_MESSAGE_DEVICE_ADDED and GST_MESSAGE_DEVICE_REMOVED messages will be emitted on the bus when the list of devices changes.

Parameters

monitor

A GstDeviceMonitor

 

Returns

TRUE if the device monitoring could be started

Since 1.4


gst_device_monitor_stop ()

void
gst_device_monitor_stop (GstDeviceMonitor *monitor);

Stops monitoring the devices.

Parameters

monitor

A GstDeviceProvider

 

Since 1.4


gst_device_monitor_get_devices ()

GList *
gst_device_monitor_get_devices (GstDeviceMonitor *monitor);

Gets a list of devices from all of the relevant monitors. This may actually probe the hardware if the monitor is not currently started.

Parameters

monitor

A GstDeviceProvider

 

Returns

a GList of GstDevice.

[transfer full][element-type GstDevice]

Since 1.4

Types and Values

struct GstDeviceMonitor

struct GstDeviceMonitor {
  GstObject                parent;
};

Opaque device monitor object structure.

Members

GstObject parent;

the parent GstObject structure

 

Since 1.4


struct GstDeviceMonitorClass

struct GstDeviceMonitorClass {
  GstObjectClass           parent_class;
};

Opaque device monitor class structure.

Members

GstObjectClass parent_class;

the parent GstObjectClass structure

 

Since 1.4

See Also

GstDevice, GstDeviceProvider