multifdsink

multifdsink — Send data to multiple filedescriptors

Synopsis

struct              GstMultiFdSink;
enum                GstRecoverPolicy;
enum                GstSyncMethod;
enum                GstClientStatus;
enum                GstTCPProtocol;
enum                GstTCPUnitType;

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
  "buffers-min"              gint                  : Read / Write
  "burst-unit"               GstTCPUnitType        : Read / Write
  "burst-value"              guint64               : Read / Write
  "bytes-min"                gint                  : Read / Write
  "time-min"                 gint64                : Read / Write
  "unit-type"                GstTCPUnitType        : Read / Write
  "units-max"                gint64                : Read / Write
  "units-soft-max"           gint64                : Read / Write
  "qos-dscp"                 gint                  : Read / Write
  "handle-read"              gboolean              : Read / Write
  "resend-streamheader"      gboolean              : Read / Write
  "num-fds"                  guint                 : Read

Signals

  "add"                                            : Action
  "clear"                                          : Action
  "client-added"                                   : Run Last
  "client-removed"                                 : Run Last
  "get-stats"                                      : Action
  "remove"                                         : Action
  "client-fd-removed"                              : Run Last
  "add-full"                                       : Action
  "remove-flush"                                   : Action

Description

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

As of version 0.10.8, a client can also be added with the "add-full" signal that allows for more control over what and how much data a client initially receives.

Clients can be removed from multifdsink by emitting 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" property, if the client is reading too slowly. In all cases, multifdsink will never close a file descriptor itself. The user of multifdsink is responsible for closing all file descriptors. This can for example be done in response to the "client-fd-removed" signal. Note that multifdsink still has a reference to the file descriptor when the "client-removed" signal is emitted, so that "get-stats" can be performed on the descriptor; it is therefore not safe to close the file descriptor in the "client-removed" signal handler, and you should use the "client-fd-removed" signal to safely close the fd.

Multifdsink internally keeps a queue of the incoming 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 in the queued buffers will be sent first to the client. Clients can be sent the most recent buffer (which might not be decodable by the client if 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 simple burst-on-connect). Multifdsink will always keep at least one keyframe in its internal buffers when the sync-mode is set to latest-keyframe.

As of version 0.10.8, there are additional values for the "sync-method" property to allow finer control over burst-on-connect behaviour. By selecting the 'burst' method a minimum burst size can be chosen, 'burst-keyframe' additionally requires that the burst begin with a keyframe, and 'burst-with-keyframe' attempts to burst beginning with a keyframe, but will prefer a minimum burst size even if it requires not starting with a keyframe.

Multifdsink can be instructed to keep at least a minimum amount of data expressed in time or byte units in its internal queues with the "time-min" and "bytes-min" properties respectively. These properties are useful if the application adds clients with the "add-full" signal to make sure that a burst connect can actually be honored.

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 slowly, data for that client will be queued up in multifdsink. Two properties control the amount of data (buffers) that is queued in multifdsink: "buffers-max" and "buffers-soft-max". A client that falls behind by "buffers-max" is removed from multifdsink forcibly.

A client with a lag of at least "buffers-soft-max" enters the recovery procedure which is controlled 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 at the most recent keyframe in the buffer queue.

multifdsink will by default synchronize on the clock before serving the buffers to the clients. This behaviour can be disabled by setting the sync property to FALSE. Multifdsink will by default not do QoS and will never drop late buffers.

Last reviewed on 2006-09-12 (0.10.10)

Synopsis

Element Information

plugin

tcp

author

Thomas Vander Stichele <thomas at apestaart dot org>, Wim Taymans <wim@fluendo.com>

class

Sink/Network

Element Pads

name

sink

direction

sink

presence

always

details

ANY

Details

struct GstMultiFdSink

struct 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,
  GST_SYNC_METHOD_BURST,
  GST_SYNC_METHOD_BURST_KEYFRAME,
  GST_SYNC_METHOD_BURST_WITH_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)

GST_SYNC_METHOD_BURST

client receives specific amount of data

GST_SYNC_METHOD_BURST_KEYFRAME

client receives specific amount of data starting from latest keyframe

GST_SYNC_METHOD_BURST_WITH_KEYFRAME

client receives specific amount of data from a keyframe, or if there is not enough data after the keyframe, starting before the keyframe

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,
  GST_CLIENT_STATUS_FLUSHING    = 6
} 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

GST_CLIENT_STATUS_FLUSHING

client is flushing out the remaining buffers.

enum GstTCPProtocol

typedef enum {
  GST_TCP_PROTOCOL_NONE,
  GST_TCP_PROTOCOL_GDP
} GstTCPProtocol;

This enum is provided by the tcp/multifd elements to configure the format of data transmission/reception.

The GDP protocol wraps data buffers in a header that also carries format information and timestamps. The None value indicates the data is sent/received as-is. In that case, format information and timestamping must be transmitted separately, or implicit in the bytestream itself.

GST_TCP_PROTOCOL_NONE

Raw data transmission

GST_TCP_PROTOCOL_GDP

GstBuffers are wrapped and sent/received using the GDP protocol.

enum GstTCPUnitType

typedef enum {
  GST_TCP_UNIT_TYPE_UNDEFINED,
  GST_TCP_UNIT_TYPE_BUFFERS,
  GST_TCP_UNIT_TYPE_TIME,
  GST_TCP_UNIT_TYPE_BYTES
} GstTCPUnitType;

The units used to specify limits.

GST_TCP_UNIT_TYPE_UNDEFINED

undefined

GST_TCP_UNIT_TYPE_BUFFERS

buffers

GST_TCP_UNIT_TYPE_TIME

timeunits (in nanoseconds)

GST_TCP_UNIT_TYPE_BYTES

bytes

Property Details

The "buffers-max" property

  "buffers-max"              gint                  : Read / Write

max number of buffers to queue for a client (-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 (deprecated).

Default value: Poll


The "protocol" property

  "protocol"                 GstTCPProtocol        : Read / Write

The protocol to wrap data in. GDP protocol here is deprecated. Please use gdppay element.

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


The "buffers-min" property

  "buffers-min"              gint                  : Read / Write

min number of buffers to queue (-1 = as few as possible).

Allowed values: >= -1

Default value: -1


The "burst-unit" property

  "burst-unit"               GstTCPUnitType        : Read / Write

The format of the burst units (when sync-method is burst[[-with]-keyframe]).

Default value: Undefined


The "burst-value" property

  "burst-value"              guint64               : Read / Write

The amount of burst expressed in burst-unit.

Default value: 0


The "bytes-min" property

  "bytes-min"                gint                  : Read / Write

min number of bytes to queue (-1 = as little as possible).

Allowed values: >= -1

Default value: -1


The "time-min" property

  "time-min"                 gint64                : Read / Write

min number of time to queue (-1 = as little as possible).

Allowed values: >= -1

Default value: -1


The "unit-type" property

  "unit-type"                GstTCPUnitType        : Read / Write

The unit to measure the max/soft-max/queued properties.

Default value: Buffers


The "units-max" property

  "units-max"                gint64                : Read / Write

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

Allowed values: >= -1

Default value: -1


The "units-soft-max" property

  "units-soft-max"           gint64                : Read / Write

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

Allowed values: >= -1

Default value: -1


The "qos-dscp" property

  "qos-dscp"                 gint                  : Read / Write

Quality of Service, differentiated services code point (-1 default).

Allowed values: [-1,63]

Default value: -1


The "handle-read" property

  "handle-read"              gboolean              : Read / Write

Handle client reads and discard the data.

Default value: TRUE


The "resend-streamheader" property

  "resend-streamheader"      gboolean              : Read / Write

Resend the streamheader if it changes in the caps.

Default value: TRUE


The "num-fds" property

  "num-fds"                  guint                 : Read

The current number of client file descriptors.

Default value: 0

Signal Details

The "add" signal

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

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)           : Action

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-fd-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)           : Run Last

The given file descriptor was added to multifdsink. This signal will be emitted 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)           : Run Last

The given file descriptor is about to be removed from multifdsink. This signal will be emitted from the streaming thread so applications should be prepared for that.

gstmultifdsink still holds a handle to fd so it is possible to call the get-stats signal from this callback. For the same reason it is not safe to close() and reuse fd in this callback.

gstmultifdsink :

the multifdsink element that emitted this signal

fd :

the file descriptor that is to be 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)           : Action

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 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 (in epoch seconds), number of buffers dropped. All times are expressed in nanoseconds (GstClockTime). The array can be 0-length if the client was not found.

The "remove" signal

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

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.

The "client-fd-removed" signal

void                user_function                      (GstMultiFdSink *gstmultifdsink,
                                                        gint            fd,
                                                        gpointer        user_data)           : Run Last

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

In this callback, gstmultifdsink has removed all the information associated with fd and it is therefore not possible to call get-stats with fd. It is however safe to close() and reuse fd in the callback.

gstmultifdsink :

the multifdsink element that emitted this signal

fd :

the file descriptor that was removed from multifdsink

user_data :

user data set when the signal handler was connected.

Since 0.10.7


The "add-full" signal

void                user_function                      (GstMultiFdSink *gstmultifdsink,
                                                        gint            fd,
                                                        GstSyncMethod   sync,
                                                        GstTCPUnitType  unit_type_min,
                                                        guint64         value_min,
                                                        GstTCPUnitType  unit_type_max,
                                                        guint64         value_max,
                                                        gpointer        user_data)           : Action

Hand the given open file descriptor to multifdsink to write to and specify the burst parameters for the new connection.

gstmultifdsink :

the multifdsink element to emit this signal on

fd :

the file descriptor to add to multifdsink

sync :

the sync method to use

unit_type_min :

the unit-type of value_min

value_min :

the minimum amount of data to burst expressed in unit_type_min units.

unit_type_max :

the unit-type of value_max

value_max :

the maximum amount of data to burst expressed in unit_type_max units.

user_data :

user data set when the signal handler was connected.

The "remove-flush" signal

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

Remove the given open file descriptor from multifdsink after flushing all the pending data to the fd.

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