GstDeviceMonitor: GStreamer 1.0 Core Reference Manual

## GstDeviceMonitor GstDeviceMonitor — A device monitor and prober |

## Functions

GstDeviceMonitor * | gst_device_monitor_new ()
GstBus * | gst_device_monitor_get_bus ()
guint | gst_device_monitor_add_filter ()
gboolean | gst_device_monitor_remove_filter ()
gboolean | gst_device_monitor_start ()
void | gst_device_monitor_stop ()
GList * | gst_device_monitor_get_devices ()

## Types and Values

struct | GstDeviceMonitor
struct | GstDeviceMonitorClass

## 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

Since: 1.4

## See Also

GstDevice, GstDeviceProvider