multifdsink

## multifdsink multifdsink |

## Properties

gboolean | handle-read | Read / Write

## Signals

void | add | Action
void | add-full | Action
void | client-added | Run Last
void | client-fd-removed | Run Last
void | client-removed | Run Last
GstStructure* | get-stats | Action
void | remove | Action
void | remove-flush | Action

## Types and Values

struct | GstMultiFdSink

## Object Hierarchy

        GObject
        ╰── GInitiallyUnowned
            ╰── GstObject
                ╰── GstElement
                    ╰── GstBaseSink
                        ╰── GstMultiHandleSink
                            ╰── GstMultiFdSink

## 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.

The multifdsink element needs to be set into READY, PAUSED or PLAYING state before operations such as adding clients are possible.

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.

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.

## 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

## Functions

## Types and Values

### struct GstMultiFdSink

    struct GstMultiFdSink;

The multifdsink object structure.

## Property Details

### The `“handle-read”` property

      “handle-read”              gboolean

Handle client reads and discard the data.

Flags: Read / Write

Default value: TRUE

## Signal Details

### The `“add”` signal

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

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

#### Parameters

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. |

Flags: Action

### The `“add-full”` signal

    void
    user_function (GstMultiFdSink              *gstmultifdsink,
                   gint                         fd,
                   GstMultiHandleSinkSyncMethod sync,
                   GstFormat                    format_min,
                   guint64                      value_min,
                   GstFormat                    format_max,
                   guint64                      value_max,
                   gpointer                     user_data)

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

#### Parameters

gstmultifdsink | the multifdsink element to emit this signal on |
fd | the file descriptor to add to multifdsink |
sync | the sync method to use |
format_min | the format of `value_min` |
value_min | the minimum amount of data to burst expressed in `format_min` units. |
format_max | the format of `value_max` |
value_max | the maximum amount of data to burst expressed in `format_max` units. |
user_data | user data set when the signal handler was connected. |

Flags: Action

### 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 emitted from the streaming thread so application should be prepared for that.

#### Parameters

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. |

Flags: Run Last

### The `“client-fd-removed”` signal

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

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.

#### Parameters

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. |

Flags: Run Last

### The `“client-removed”` signal

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

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.

#### Parameters

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. |

Flags: Run Last

### The `“get-stats”` signal

    GstStructure*
    user_function (GstMultiFdSink *gstmultifdsink,
                   gint            fd,
                   gpointer        user_data)

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

#### Parameters

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 GstStructure with the statistics. The structures contains guint64 values that represent respectively: total number of bytes sent (bytes-sent), time when the client was added (connect-time), time when the client was disconnected/removed (disconnect-time), time the client is/was active (connect-duration), last activity time (in epoch seconds) (last-activity-time), number of buffers dropped (buffers-dropped), the timestamp of the first buffer (first-buffer-ts) and of the last buffer (last-buffer-ts). All times are expressed in nanoseconds (GstClockTime). The structure can be empty if the client was not found.

Flags: Action

### The `“remove”` signal

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

Remove the given open file descriptor from multifdsink.

#### Parameters

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. |

Flags: Action

### The `“remove-flush”` signal

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

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

#### Parameters

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. |

Flags: Action

## See Also

tcpserversink