GstCaps * caps Read / Write
gchar * multicast-group Read / Write
gint port Read / Write
gchar * uri Read / Write
gint buffer-size Read / Write
guint64 timeout Read / Write
gint skip-first-bytes Read / Write
gboolean auto-multicast Read / Write
gchar * multicast-iface Read / Write
gboolean reuse Read / Write
gboolean close-socket Read / Write
GSocket * socket Read / Write
GSocket * used-socket Read
gchar * address Read / Write

Types and Values

struct GstUDPSrc

Object Hierarchy

    ╰── GInitiallyUnowned
        ╰── GstObject
            ╰── GstElement
                ╰── GstBaseSrc
                    ╰── GstPushSrc
                        ╰── GstUDPSrc

Implemented Interfaces

GstUDPSrc implements GstURIHandler.


udpsrc is a network source that reads UDP packets from the network. It can be combined with RTP depayloaders to implement RTP streaming.

The udpsrc element supports automatic port allocation by setting the “port” property to 0. After setting the udpsrc to PAUSED, the allocated port can be obtained by reading the port property.

udpsrc can read from multicast groups by setting the “multicast-group” property to the IP address of the multicast group.

Alternatively one can provide a custom socket to udpsrc with the “socket” property, udpsrc will then not allocate a socket itself but use the provided one.

The “caps” property is mainly used to give a type to the UDP packet so that they can be autoplugged in GStreamer pipelines. This is very usefull for RTP implementations where the contents of the UDP packets is transfered out-of-bounds using SDP or other means.

The “buffer-size” property is used to change the default kernel buffersizes used for receiving packets. The buffer size may be increased for high-volume connections, or may be decreased to limit the possible backlog of incoming data. The system places an absolute limit on these values, on Linux, for example, the default buffer size is typically 50K and can be increased to maximally 100K.

The “skip-first-bytes” property is used to strip off an arbitrary number of bytes from the start of the raw udp packet and can be used to strip off proprietary header, for example.

The udpsrc is always a live source. It does however not provide a GstClock, this is left for upstream elements such as an RTP session manager or demuxer (such as an MPEG demuxer). As with all live sources, the captured buffers will have their timestamp set to the current running time of the pipeline.

udpsrc implements a GstURIHandler interface that handles udp://host:port type URIs.

If the “timeout” property is set to a value bigger than 0, udpsrc will generate an element message named


if no data was recieved in the given timeout. The message's structure contains one field:

  • guint64 "timeout": the timeout in microseconds that expired when waiting for data.

The message is typically used to detect that no UDP arrives in the receiver because it is blocked by a firewall.

A custom file descriptor can be configured with the “socket” property. The socket will be closed when setting the element to READY by default. This behaviour can be overriden with the “close-socket” property, in which case the application is responsible for closing the file descriptor.


gst-launch-1.0 -v udpsrc ! fakesink dump=1
A pipeline to read from the default port and dump the udp packets. To actually generate udp packets on the default port one can use the udpsink element. When running the following pipeline in another terminal, the above mentioned pipeline should dump data packets to the console.
gst-launch-1.0 -v audiotestsrc ! udpsink
gst-launch-1.0 -v udpsrc port=0 ! fakesink
read udp packets from a free port.


Element Information




Wim Taymans <wim@fluendo.com>, Thijs Vermeir <thijs.vermeir@barco.com>



Element Pads










Types and Values

struct GstUDPSrc

struct GstUDPSrc;

Property Details

The “caps” property

  “caps”                     GstCaps *

The caps of the source pad.

Flags: Read / Write

The “multicast-group” property

  “multicast-group”          gchar *

The Address of multicast group to join. (DEPRECATED: Use address property instead).

Flags: Read / Write

Default value: ""

The “port” property

  “port”                     gint

The port to receive the packets from, 0=allocate.

Flags: Read / Write

Allowed values: [0,65535]

Default value: 5004

The “uri” property

  “uri”                      gchar *

URI in the form of udp://multicast_group:port.

Flags: Read / Write

Default value: "udp://"

The “buffer-size” property

  “buffer-size”              gint

Size of the kernel receive buffer in bytes, 0=default.

Flags: Read / Write

Allowed values: >= 0

Default value: 0

The “timeout” property

  “timeout”                  guint64

Post a message after timeout nanoseconds (0 = disabled).

Flags: Read / Write

Default value: 0

The “skip-first-bytes” property

  “skip-first-bytes”         gint

number of bytes to skip for each udp packet.

Flags: Read / Write

Allowed values: >= 0

Default value: 0

The “auto-multicast” property

  “auto-multicast”           gboolean

Automatically join/leave multicast groups.

Flags: Read / Write

Default value: TRUE

The “multicast-iface” property

  “multicast-iface”          gchar *

The network interface on which to join the multicast group.

Flags: Read / Write

Default value: NULL

The “reuse” property

  “reuse”                    gboolean

Enable reuse of the port.

Flags: Read / Write

Default value: TRUE

The “close-socket” property

  “close-socket”             gboolean

Close socket if passed as property on state change.

Flags: Read / Write

Default value: TRUE

The “socket” property

  “socket”                   GSocket *

Socket to use for UDP reception. (NULL == allocate).

Flags: Read / Write

The “used-socket” property

  “used-socket”              GSocket *

Socket currently in use for UDP reception. (NULL = no socket).

Flags: Read

The “address” property

  “address”                  gchar *

Address to receive packets for. This is equivalent to the multicast-group property for now.

Flags: Read / Write

Default value: ""

See Also

udpsink, multifdsink