## FsStream

FsStream — A stream in a session in a conference

## Synopsis

    #include <gst/farsight/fs-conference-iface.h>

                        FsStream;
                        FsStreamClass;
    enum                FsStreamDirection;
    enum                FsStreamState;
    gboolean            fs_stream_set_remote_candidates     (FsStream *stream,
                                                             GList *candidates,
                                                             GError **error);
    gboolean            fs_stream_set_remote_codecs         (FsStream *stream,
                                                             GList *remote_codecs,
                                                             GError **error);
    gboolean            fs_stream_force_remote_candidates   (FsStream *stream,
                                                             GList *remote_candidates,
                                                             GError **error);
    void                fs_stream_add_id                    (FsStream *stream,
                                                             guint id);
    void                fs_stream_emit_error                (FsStream *stream,
                                                             gint error_no,
                                                             const gchar *error_msg,
                                                             const gchar *debug_msg);
    void                fs_stream_emit_src_pad_added        (FsStream *stream,
                                                             GstPad *pad,
                                                             FsCodec *codec);

## Object Hierarchy

      GObject
       +----FsStream

## Properties

      "current-recv-codecs"      FsCodecGList*         : Read
      "direction"                FsStreamDirection     : Read / Write / Construct
      "negotiated-codecs"        FsCodecGList*         : Read
      "participant"              FsParticipant*        : Read / Write / Construct Only
      "remote-codecs"            FsCodecGList*         : Read
      "session"                  FsSession*            : Read / Write / Construct Only

## Signals

      "error"                                          : Run Last
      "src-pad-added"                                  : Run Last

## Description

This object is the base implementation of a Farsight Stream. It needs to be derived and implemented by a Farsight conference GStreamer element. A Farsight Stream is a media stream originating from a FsParticipant inside a FsSession. In fact, a FsStream instance is obtained by adding a participant into a session using `fs_session_new_stream()`.

This will communicate asynchronous events to the user through GstMessage of type GST_MESSAGE_ELEMENT sent over the GstBus.

### The "`farsight-new-local-candidate`" message

    "stream"           FsStream          The stream that emits the message
    "candidate"        FsCandidate       The new candidate

This message is emitted when a new local candidate is discovered.

### The "`farsight-local-candidates-prepared`" message

    "stream"           FsStream          The stream that emits the message

This signal is emitted when all local candidates have been prepared, an ICE implementation would send its SDP offer or answer.

### The "`farsight-new-active-candidate-pair`" message

    "stream"           FsStream          The stream that emits the message
    "local-candidate"  FsCandidate       Local candidate being used
    "remote-candidate" FsCandidate       Remote candidate being used

This message is emitted when there is a new active candidate pair that has been established. This is specially useful for ICE where the active candidate pair can change automatically due to network conditions. The user must not modify the candidates and must copy them if he wants to use them outside the callback scope. This message is emitted once per component.

### The "`farsight-recv-codecs-changed`" message

    "stream"           FsStream          The stream that emits the message
    "codecs"           FsCodecGList      A GList of FsCodec

This message is emitted when the content of the "current-recv-codecs" property changes. It is normally emitted right after the "src-pad-added" signal only if that codec was not previously received in this stream, but it can also be emitted if the pad already exists, but the source material that will come to it is different. The list of new recv-codecs is included in the message

### The "`farsight-component-state-changed`" message

    "stream"           FsStream          The stream that emits the message
    "component"        guint             The component whose state changed
    "state"            FsStreamState     The new state of the component

This message is emitted the state of a component of a stream changes.

## Details

### FsStream

    typedef struct _FsStream FsStream;

All members are private, access them using methods and properties

### FsStreamClass

    typedef struct {
      GObjectClass parent_class;

      /*virtual functions */
      gboolean (*set_remote_candidates) (FsStream *stream,
                                         GList *candidates,
                                         GError **error);

      gboolean (*force_remote_candidates) (FsStream *stream,
          GList *remote_candidates,
          GError **error);

      gboolean (*set_remote_codecs) (FsStream *stream,
                                     GList *remote_codecs, GError **error);

      void (*add_id) (FsStream *stream,
                      guint id);
    } FsStreamClass;

You must override add_remote_candidate in a subclass. If you have to negotiate codecs, then you must override set_remote_codecs too

GObjectClass `parent_class`; | Our parent
`set_remote_candidates` () | Set sthe remote candidates
`force_remote_candidates` () | Forces certain remote candidates
`set_remote_codecs` () | Sets the list of remote codecs
`add_id` () | Add a known id to be associated with this stream

### enum FsStreamDirection

    typedef enum
    {
      FS_DIRECTION_NONE = 0,
      FS_DIRECTION_SEND = 1<<0,
      FS_DIRECTION_RECV = 1<<1,
      FS_DIRECTION_BOTH = FS_DIRECTION_SEND | FS_DIRECTION_RECV
    } FsStreamDirection;

An enum for specifying the direction of a stream

`FS_DIRECTION_NONE` | No direction specified
`FS_DIRECTION_SEND` | Send only
`FS_DIRECTION_RECV` | Receive only
`FS_DIRECTION_BOTH` | Send and receive

### enum FsStreamState

    typedef enum
    {
      FS_STREAM_STATE_FAILED,
      FS_STREAM_STATE_DISCONNECTED,
      FS_STREAM_STATE_GATHERING,
      FS_STREAM_STATE_CONNECTING,
      FS_STREAM_STATE_CONNECTED,
      FS_STREAM_STATE_READY
    } FsStreamState;

These are the possible states of a stream, a simple multicast stream could only be in "disconnected" or "ready" state. An stream using an ICE transmitter would use all of these.

`FS_STREAM_STATE_FAILED` | connectivity checks have been completed, but connectivity was not established
`FS_STREAM_STATE_DISCONNECTED` | no activity scheduled
`FS_STREAM_STATE_GATHERING` | gathering local candidates
`FS_STREAM_STATE_CONNECTING` | establishing connectivity
`FS_STREAM_STATE_CONNECTED` | at least one working candidate pair
`FS_STREAM_STATE_READY` | ICE concluded, candidate pair selection is now final

### fs_stream_set_remote_candidates ()

    gboolean            fs_stream_set_remote_candidates     (FsStream *stream,
                                                             GList *candidates,
                                                             GError **error);

This function sets the list of remote candidates. Any new candidates are added to the list. The candidates will be used to establish a connection with the peer. A copy will be made so the user must free the passed candidate using `fs_candidate_destroy()` when done.

`stream` : | an FsStream
`candidates` : | an GList of FsCandidate representing the remote candidates
`error` : | location of a GError, or `NULL` if no error occured
Returns : | TRUE if the candidate was valid, FALSE otherwise

### fs_stream_set_remote_codecs ()

    gboolean            fs_stream_set_remote_codecs         (FsStream *stream,
                                                             GList *remote_codecs,
                                                             GError **error);

This function will set the list of remote codecs for this stream. If the given remote codecs couldn't be negotiated with the list of local codecs or already negotiated codecs for the corresponding FsSession, `error` will be set and `FALSE` will be returned. The `remote_codecs` list will be copied so it must be free'd using `fs_codec_list_destroy()` when done.

`stream` : | a FsStream
`remote_codecs` : | a GList of FsCodec representing the remote codecs
`error` : | location of a GError, or `NULL` if no error occured
Returns : | `FALSE` if the remote codecs couldn't be set.

### fs_stream_force_remote_candidates ()

    gboolean            fs_stream_force_remote_candidates   (FsStream *stream,
                                                             GList *remote_candidates,
                                                             GError **error);

This function forces data to be sent immediately to the selected remote candidate, by-passing any connectivity checks. There should be at most one candidate per component.

`stream` : | a FsStream
`remote_candidates` : | a GList of FsCandidate to force
`error` : | location of a GError, or `NULL` if no error occured
Returns : | `TRUE` if the candidates could be forced, `FALSE` otherwise

### fs_stream_add_id ()

    void                fs_stream_add_id                    (FsStream *stream,
                                                             guint id);

This function is used to add data identifiers that allow the plugin to recognize packets that are meant for id. For example, in RTP, one would set the SSRCs that are expected.

Depending on the protocol, one may be able to add more than one ID to a stream (in RTP you can have multiple SSRCs in a stream). If a protocol supports only one id, adding a new one will overwrite it. If an ID was already set on a stream, adding it to another stream will override the previdous decision.

For most protocols, calling this function is optional as the incoming data can be matched with a stream by its source IP address. This is mostly useful if one is using multicast or is behind a muxer server.

`stream` : | a FsStream
`id` : | The id to add to the stream

### fs_stream_emit_error ()

    void                fs_stream_emit_error                (FsStream *stream,
                                                             gint error_no,
                                                             const gchar *error_msg,
                                                             const gchar *debug_msg);

This function emits the "error"" signal, it should only be called by subclasses.

`stream` : | FsStream on which to emit the error signal
`error_no` : | The number of the error
`error_msg` : | Error message to be displayed to user
`debug_msg` : | Debugging error message

### fs_stream_emit_src_pad_added ()

    void                fs_stream_emit_src_pad_added        (FsStream *stream,
                                                             GstPad *pad,
                                                             FsCodec *codec);

Emits the "src-pad-added"" signal, it should only be called by subclasses.

`stream` : | FsStream on which to emit the src-pad-added signal
`pad` : | the GstPad that this FsStream has created
`codec` : | The FsCodec for this pad

## Property Details

### The `"current-recv-codecs"` property

      "current-recv-codecs"      FsCodecGList*         : Read

This is the list of codecs that have been received by this stream. The user must free the list if `fs_codec_list_destroy()`. The "farsight-recv-codecs-changed" message is send on the GstBus when the value of this property changes. It is normally emitted right after "src-pad-added" only if that codec was not previously received in this stream, but it can also be emitted if the pad already exists, but the source material that will come to it is different.

### The `"direction"` property

      "direction"                FsStreamDirection     : Read / Write / Construct

The direction of the stream. This property is set initially as a parameter to the `fs_session_new_stream()` function. It can be changed later if required by setting this property.

### The `"negotiated-codecs"` property

      "negotiated-codecs"        FsCodecGList*         : Read

This is the list of negotiatied codecs, it is the same list as the list of FsCodec from the parent FsSession, except that the codec config data has been replaced with the data from the remote codecs for this stream. This is the list of FsCodec used to receive data from this stream. It is a GList of FsCodec.

### The `"participant"` property

      "participant"              FsParticipant*        : Read / Write / Construct Only

The FsParticipant for this stream. This property is a construct param and is read-only construction.

### The `"remote-codecs"` property

      "remote-codecs"            FsCodecGList*         : Read

This is the list of remote codecs for this stream. They must be set by the user as soon as they are known using `fs_stream_set_remote_codecs()` (generally through external signaling). It is a GList of FsCodec.

### The `"session"` property

      "session"                  FsSession*            : Read / Write / Construct Only

The FsSession for this stream. This property is a construct param and is read-only construction.

## Signal Details

### The `"error"` signal

    void                user_function                      (FsStream *self,
                                                            FsError   errorno,
                                                            gchar    *error_msg,
                                                            gchar    *debug_msg,
                                                            gpointer  user_data)      : Run Last

This signal is emitted in any error condition

`self` : | FsStream that emitted the signal
`errorno` : | The number of the error
`error_msg` : | Error message to be displayed to user
`debug_msg` : | Debugging error message
`user_data` : | user data set when the signal handler was connected.

### The `"src-pad-added"` signal

    void                user_function                      (FsStream *self,
                                                            GstPad   *pad,
                                                            FsCodec  *codec,
                                                            gpointer  user_data)      : Run Last

This signal is emitted when a new gst source pad has been created for a specific codec being received. There will be a different source pad for each codec that is received. The user must ref the GstPad if he wants to keep it. The user should not modify the FsCodec and must copy it if he wants to use it outside the callback scope.

This signal is not emitted on the main thread, but on GStreamer's streaming thread!

`self` : | FsStream that emitted the signal
`pad` : | GstPad of the new source pad
`codec` : | FsCodec of the codec being received on the new source pad
`user_data` : | user data set when the signal handler was connected.