multifdsink

multifdsink — Send data to multiple file descriptors

Synopsis




            GstMultiFdSink;
enum        GstRecoverPolicy;
enum        GstSyncMethod;
enum        GstClientStatus;

Object Hierarchy


  GObject
   +----GstObject
         +----GstElement
               +----GstBaseSink
                     +----GstMultiFdSink
                           +----GstTCPServerSink

Properties


  "buffers-max"          gint                  : Read / Write
  "buffers-queued"       guint                 : Read
  "buffers-soft-max"     gint                  : Read / Write
  "bytes-served"         guint64               : Read
  "bytes-to-serve"       guint64               : Read
  "mode"                 GstFDSetMode          : Read / Write
  "protocol"             GstTCPProtocol        : Read / Write
  "recover-policy"       GstRecoverPolicy      : Read / Write
  "sync-clients"         gboolean              : Read / Write
  "sync-method"          GstSyncMethod         : Read / Write
  "timeout"              guint64               : Read / Write

Signal Prototypes


"add"       void        user_function      (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);
"clear"     void        user_function      (GstMultiFdSink *gstmultifdsink,
                                            gpointer user_data);
"client-added"
            void        user_function      (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);
"client-removed"
            void        user_function      (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            GstClientStatus status,
                                            gpointer user_data);
"get-stats" GValueArray*user_function      (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);
"remove"    void        user_function      (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);

Description

This plugin writes incoming data to a set of filedescriptors. The filedescriptors can be added to multifdsink by emiting the "add" signal. For each descriptor added the "client-added" signal will be called.

Clients can be removed from multifdsink by emiting the "remove" signal. For each descriptor removed the "client-removed" signal will be called. The "client-removed" signal can also be fired when multifdsink decides that a client is not active anymore or, depending on the value of the "recover-policy" if the client is reading to slow. In all cases, multifdsink will never close a filedescriptor itself, the application has to do that itself, for example, in the "client-removed" signal callback.

Multifdsink internally keeps a queue of the incomming buffers and uses a separate thread to send the buffers to the clients. This ensures that no client write can block the pipeline and that clients can read with different speeds.

When adding a client to multifdsink, the "sync-method" property will define which buffer will be sent first to the client. Clients can be sent respectively the most recent buffer (which might not be decodable by the client when it is not a keyframe), the next keyframe received in multifdsink (which can take some time depending on the keyframe rate, or the last received keyframe (which will cause a burst-on-connect).

When streaming data, clients are allowed to read at a different rate than the rate at which multifdsink receives data. If the client is reading too fast, no data will be send to the client until multifdsink receives more data. If the client however reads too slow, data for that client will bunch up in multifdsink. Two properties control the amount of data (buffers) that is queued in multifdsink: "buffers-max" and "buffers-soft-max". A client with a lag of "buffers-max" is removed from multifdsink forcibly.

A client with a lag of at least "buffers-soft-max" enters the recovery procedure which is controled with the "recover-policy" property. A recover policy of NONE will do nothing, RESYNC_LATEST will send the most recently received buffer as the next buffer for the client, RESYNC_SOFT_LIMIT positions the client to the soft limit in the buffer queue and RESYNC_KEYFRAME positions the client to the most recent keyframe in the buffer queue.

multifdsink will synchronize on the clock before serving the buffers to the clients.

Example pipeline:

gst-launch -v videotestsrc ! multifdsink

This pipeline will not do a lot since it is not possible from a gst-launch line to add filedescriptors to multifdsink.

Last reviewed on 2006-03-01 (0.10.4)

Element Information

plugin tcp
author Thomas Vander Stichele <thomas at apestaart dot org>, Wim Taymans <wim@fluendo.com>
class Sink/Network

Details

GstMultiFdSink

typedef struct _GstMultiFdSink GstMultiFdSink;

The multifdsink object structure.


enum GstRecoverPolicy

typedef enum
{
  GST_RECOVER_POLICY_NONE,
  GST_RECOVER_POLICY_RESYNC_LATEST,
  GST_RECOVER_POLICY_RESYNC_SOFT_LIMIT,
  GST_RECOVER_POLICY_RESYNC_KEYFRAME,
} GstRecoverPolicy;

Possible values for the recovery procedure to use when a client consumes data too slow and has a backlag of more that soft-limit buffers.

GST_RECOVER_POLICY_NONE no recovering is done
GST_RECOVER_POLICY_RESYNC_LATEST client is moved to last buffer
GST_RECOVER_POLICY_RESYNC_SOFT_LIMIT client is moved to the soft limit
GST_RECOVER_POLICY_RESYNC_KEYFRAME client is moved to latest keyframe

enum GstSyncMethod

typedef enum
{
  GST_SYNC_METHOD_LATEST,
  GST_SYNC_METHOD_NEXT_KEYFRAME,
  GST_SYNC_METHOD_LATEST_KEYFRAME,
} GstSyncMethod;

This enum defines the selection of the first buffer that is sent to a new client.

GST_SYNC_METHOD_LATEST client receives most recent buffer
GST_SYNC_METHOD_NEXT_KEYFRAME client receives next keyframe
GST_SYNC_METHOD_LATEST_KEYFRAME client receives latest keyframe (burst)

enum GstClientStatus

typedef enum
{
  GST_CLIENT_STATUS_OK          = 0,
  GST_CLIENT_STATUS_CLOSED      = 1,
  GST_CLIENT_STATUS_REMOVED     = 2,
  GST_CLIENT_STATUS_SLOW        = 3,
  GST_CLIENT_STATUS_ERROR       = 4,
  GST_CLIENT_STATUS_DUPLICATE   = 5,
} GstClientStatus;

This specifies the reason why a client was removed from multifdsink and is received in the "client-removed" signal.

GST_CLIENT_STATUS_OK client is ok
GST_CLIENT_STATUS_CLOSED client closed the socket
GST_CLIENT_STATUS_REMOVED client is removed
GST_CLIENT_STATUS_SLOW client is too slow
GST_CLIENT_STATUS_ERROR client is in error
GST_CLIENT_STATUS_DUPLICATE same client added twice

Properties

The "buffers-max" property

  "buffers-max"          gint                  : Read / Write

max number of buffers to queue (-1 = no limit).

Allowed values: >= -1

Default value: -1


The "buffers-queued" property

  "buffers-queued"       guint                 : Read

Number of buffers currently queued.

Default value: 0


The "buffers-soft-max" property

  "buffers-soft-max"     gint                  : Read / Write

Recover client when going over this limit (-1 = no limit).

Allowed values: >= -1

Default value: -1


The "bytes-served" property

  "bytes-served"         guint64               : Read

Total number of bytes send to all clients.

Default value: 0


The "bytes-to-serve" property

  "bytes-to-serve"       guint64               : Read

Number of bytes received to serve to clients.

Default value: 0


The "mode" property

  "mode"                 GstFDSetMode          : Read / Write

The mode for selecting activity on the fds.

Default value: Poll


The "protocol" property

  "protocol"             GstTCPProtocol        : Read / Write

The protocol to wrap data in.

Default value: GST_TCP_PROTOCOL_NONE


The "recover-policy" property

  "recover-policy"       GstRecoverPolicy      : Read / Write

How to recover when client reaches the soft max.

Default value: Do not try to recover


The "sync-clients" property

  "sync-clients"         gboolean              : Read / Write

(DEPRECATED) Sync clients to a keyframe.

Default value: FALSE


The "sync-method" property

  "sync-method"          GstSyncMethod         : Read / Write

How to sync new clients to the stream.

Default value: Serve starting from the latest buffer


The "timeout" property

  "timeout"              guint64               : Read / Write

Maximum inactivity timeout in nanoseconds for a client (0 = no limit).

Default value: 0

Signals

The "add" signal

void        user_function                  (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);

Hand the given open file descriptor to multifdsink to write to.

gstmultifdsink : the multifdsink element to emit this signal on
fd : the file descriptor to add to multifdsink
user_data : user data set when the signal handler was connected.

The "clear" signal

void        user_function                  (GstMultiFdSink *gstmultifdsink,
                                            gpointer user_data);

Remove all file descriptors from multifdsink. Since multifdsink did not open fd's itself, it does not explicitly close the fd. The application should do so by connecting to the client-removed callback.

gstmultifdsink : the multifdsink element to emit this signal on
user_data : user data set when the signal handler was connected.

The "client-added" signal

void        user_function                  (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);

The given file descriptor was added to multifdsink. This signal will be emited from the streaming thread so application should be prepared for that.

gstmultifdsink : the multifdsink element that emitted this signal
fd : the file descriptor that was added to multifdsink
user_data : user data set when the signal handler was connected.

The "client-removed" signal

void        user_function                  (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            GstClientStatus status,
                                            gpointer user_data);

The given file descriptor was removed from multifdsink. This signal will be emited from the streaming thread so applications should be prepared for that.

gstmultifdsink : the multifdsink element that emitted this signal
fd : the file descriptor that was removed from multifdsink
status : the reason why the client was removed
user_data : user data set when the signal handler was connected.

The "get-stats" signal

GValueArray*user_function                  (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);

Get statistics about fd. This function returns a GValueArray to ease automatic wrapping for bindings.

gstmultifdsink : the multifdsink element to emit this signal on
fd : the file descriptor to get stats of from multifdsink
user_data : user data set when the signal handler was connected.
Returns : a GValueArray with the statistics. The array contains 5 guint64 values that represent respectively total number of bytes sent, time when the client was added, time when the client was disconnected/removed, time the client is/was active, last activity time. All times are expressed in nanoseconds (GstClockTime).

The "remove" signal

void        user_function                  (GstMultiFdSink *gstmultifdsink,
                                            gint fd,
                                            gpointer user_data);

Remove the given open file descriptor from multifdsink.

gstmultifdsink : the multifdsink element to emit this signal on
fd : the file descriptor to remove from multifdsink
user_data : user data set when the signal handler was connected.

See Also

tcpserversink