struct GstPad

struct GstPad {
  gpointer                       element_private;

  GstPadTemplate                *padtemplate;

  GstPadDirection                direction;
};

The GstPad structure. Use the functions to update the variables.

enum GstPadDirection

typedef enum {
  GST_PAD_UNKNOWN,
  GST_PAD_SRC,
  GST_PAD_SINK
} GstPadDirection;

The direction of a pad.

enum GstPadFlags

typedef enum {
  GST_PAD_FLAG_BLOCKED          = (GST_OBJECT_FLAG_LAST << 0),
  GST_PAD_FLAG_FLUSHING         = (GST_OBJECT_FLAG_LAST << 1),
  GST_PAD_FLAG_EOS              = (GST_OBJECT_FLAG_LAST << 2),
  GST_PAD_FLAG_BLOCKING         = (GST_OBJECT_FLAG_LAST << 3),
  GST_PAD_FLAG_NEED_PARENT      = (GST_OBJECT_FLAG_LAST << 4),
  GST_PAD_FLAG_NEED_RECONFIGURE = (GST_OBJECT_FLAG_LAST << 5),
  GST_PAD_FLAG_PENDING_EVENTS   = (GST_OBJECT_FLAG_LAST << 6),
  GST_PAD_FLAG_FIXED_CAPS       = (GST_OBJECT_FLAG_LAST << 7),
  GST_PAD_FLAG_PROXY_CAPS       = (GST_OBJECT_FLAG_LAST << 8),
  GST_PAD_FLAG_PROXY_ALLOCATION = (GST_OBJECT_FLAG_LAST << 9),
  GST_PAD_FLAG_PROXY_SCHEDULING = (GST_OBJECT_FLAG_LAST << 10),
  /* padding */
  GST_PAD_FLAG_LAST        = (GST_OBJECT_FLAG_LAST << 16)
} GstPadFlags;

Pad state flags

enum GstPadLinkReturn

typedef enum {
  GST_PAD_LINK_OK               =  0,
  GST_PAD_LINK_WRONG_HIERARCHY  = -1,
  GST_PAD_LINK_WAS_LINKED       = -2,
  GST_PAD_LINK_WRONG_DIRECTION  = -3,
  GST_PAD_LINK_NOFORMAT         = -4,
  GST_PAD_LINK_NOSCHED          = -5,
  GST_PAD_LINK_REFUSED          = -6
} GstPadLinkReturn;

Result values from gst_pad_link and friends.

GST_PAD_LINK_FAILED()

#define GST_PAD_LINK_FAILED(ret) ((ret) < GST_PAD_LINK_OK)

Macro to test if the given GstPadLinkReturn value indicates a failed link step.

GST_PAD_LINK_SUCCESSFUL()

#define GST_PAD_LINK_SUCCESSFUL(ret) ((ret) >= GST_PAD_LINK_OK)

Macro to test if the given GstPadLinkReturn value indicates a successful link step.

enum GstPadLinkCheck

typedef enum {
  GST_PAD_LINK_CHECK_NOTHING       = 0,
  GST_PAD_LINK_CHECK_HIERARCHY     = 1 << 0,
  GST_PAD_LINK_CHECK_TEMPLATE_CAPS = 1 << 1,
  GST_PAD_LINK_CHECK_CAPS          = 1 << 2,

  GST_PAD_LINK_CHECK_DEFAULT       = GST_PAD_LINK_CHECK_HIERARCHY | GST_PAD_LINK_CHECK_CAPS
} GstPadLinkCheck;

The amount of checking to be done when linking pads. GST_PAD_LINK_CHECK_CAPS and GST_PAD_LINK_CHECK_TEMPLATE_CAPS are mutually exclusive. If both are specified, expensive but safe GST_PAD_LINK_CHECK_CAPS are performed.

enum GstFlowReturn

typedef enum {
  /* custom success starts here */
  GST_FLOW_CUSTOM_SUCCESS_2 = 102,
  GST_FLOW_CUSTOM_SUCCESS_1 = 101,
  GST_FLOW_CUSTOM_SUCCESS = 100,

  /* core predefined */
  GST_FLOW_OK		  =  0,
  /* expected failures */
  GST_FLOW_NOT_LINKED     = -1,
  GST_FLOW_FLUSHING       = -2,
  /* error cases */
  GST_FLOW_EOS            = -3,
  GST_FLOW_NOT_NEGOTIATED = -4,
  GST_FLOW_ERROR	  = -5,
  GST_FLOW_NOT_SUPPORTED  = -6,

  /* custom error starts here */
  GST_FLOW_CUSTOM_ERROR   = -100,
  GST_FLOW_CUSTOM_ERROR_1 = -101,
  GST_FLOW_CUSTOM_ERROR_2 = -102
} GstFlowReturn;

The result of passing data to a pad.

Note that the custom return values should not be exposed outside of the element scope.

gst_flow_get_name ()

const gchar *       gst_flow_get_name                   (GstFlowReturn ret);

Gets a string representing the given flow return.

gst_flow_to_quark ()

GQuark              gst_flow_to_quark                   (GstFlowReturn ret);

Get the unique quark for the given GstFlowReturn.

enum GstPadMode

typedef enum {
  GST_PAD_MODE_NONE,
  GST_PAD_MODE_PUSH,
  GST_PAD_MODE_PULL
} GstPadMode;

The status of a GstPad. After activating a pad, which usually happens when the parent element goes from READY to PAUSED, the GstPadMode defines if the pad operates in push or pull mode.

gst_pad_mode_get_name ()

const gchar *       gst_pad_mode_get_name               (GstPadMode mode);

Return the name of a pad mode, for use in debug messages mostly.

gst_pad_get_name()

#define gst_pad_get_name(pad) gst_object_get_name (GST_OBJECT_CAST (pad))

Get a copy of the name of the pad. g_free() after usage.

MT safe.

gst_pad_get_direction ()

GstPadDirection     gst_pad_get_direction               (GstPad *pad);

Gets the direction of the pad. The direction of the pad is decided at construction time so this function does not take the LOCK.

gst_pad_get_parent()

#define gst_pad_get_parent(pad) gst_object_get_parent (GST_OBJECT_CAST (pad))

Get the parent of pad. This function increases the refcount of the parent object so you should gst_object_unref() it after usage. Can return NULL if the pad did not have a parent.

MT safe.

gst_pad_get_parent_element ()

GstElement *        gst_pad_get_parent_element          (GstPad *pad);

Gets the parent of pad, cast to a GstElement. If a pad has no parent or its parent is not an element, return NULL.

gst_pad_get_pad_template ()

GstPadTemplate *    gst_pad_get_pad_template            (GstPad *pad);

Gets the template for pad.

gst_pad_link ()

GstPadLinkReturn    gst_pad_link                        (GstPad *srcpad,
                                                         GstPad *sinkpad);

Links the source pad and the sink pad.

gst_pad_link_full ()

GstPadLinkReturn    gst_pad_link_full                   (GstPad *srcpad,
                                                         GstPad *sinkpad,
                                                         GstPadLinkCheck flags);

Links the source pad and the sink pad.

This variant of gst_pad_link provides a more granular control on the checks being done when linking. While providing some considerable speedups the caller of this method must be aware that wrong usage of those flags can cause severe issues. Refer to the documentation of GstPadLinkCheck for more information.

MT Safe.

gst_pad_unlink ()

gboolean            gst_pad_unlink                      (GstPad *srcpad,
                                                         GstPad *sinkpad);

Unlinks the source pad from the sink pad. Will emit the "unlinked" signal on both pads.

gst_pad_is_linked ()

gboolean            gst_pad_is_linked                   (GstPad *pad);

Checks if a pad is linked to another pad or not.

gst_pad_can_link ()

gboolean            gst_pad_can_link                    (GstPad *srcpad,
                                                         GstPad *sinkpad);

Checks if the source pad and the sink pad are compatible so they can be linked.

gst_pad_get_allowed_caps ()

GstCaps *           gst_pad_get_allowed_caps            (GstPad *pad);

Gets the capabilities of the allowed media types that can flow through pad and its peer.

The allowed capabilities is calculated as the intersection of the results of calling gst_pad_query_caps() on pad and its peer. The caller owns a reference on the resulting caps.

gst_pad_get_current_caps ()

GstCaps *           gst_pad_get_current_caps            (GstPad *pad);

Gets the capabilities currently configured on pad with the last GST_EVENT_CAPS event.

gst_pad_get_pad_template_caps ()

GstCaps *           gst_pad_get_pad_template_caps       (GstPad *pad);

Gets the capabilities for pad's template.

gst_pad_get_peer ()

GstPad *            gst_pad_get_peer                    (GstPad *pad);

Gets the peer of pad. This function refs the peer pad so you need to unref it after use.

gst_pad_use_fixed_caps ()

void                gst_pad_use_fixed_caps              (GstPad *pad);

A helper function you can use that sets the FIXED_CAPS flag This way the default CAPS query will always return the negotiated caps or in case the pad is not negotiated, the padtemplate caps.

The negotiated caps are the caps of the last CAPS event that passed on the pad. Use this function on a pad that, once it negotiated to a CAPS, cannot be renegotiated to something else.

gst_pad_has_current_caps ()

gboolean            gst_pad_has_current_caps            (GstPad *pad);

Check if pad has caps set on it with a GST_EVENT_CAPS event.

gst_pad_get_sticky_event ()

GstEvent *          gst_pad_get_sticky_event            (GstPad *pad,
                                                         GstEventType event_type,
                                                         guint idx);

Returns a new reference of the sticky event of type event_type from the event.

GstPadStickyEventsForeachFunction ()

gboolean            (*GstPadStickyEventsForeachFunction)
                                                        (GstPad *pad,
                                                         GstEvent **event,
                                                         gpointer user_data);

Callback used by gst_pad_sticky_events_foreach().

When this function returns TRUE, the next event will be returned. When FALSE is returned, gst_pad_sticky_events_foreach() will return.

When event is set to NULL, the item will be removed from the list of sticky events. When event has been made writable, the new buffer reference can be assigned to event. This function is responsible for unreffing the old event when removing or modifying.

gst_pad_sticky_events_foreach ()

void                gst_pad_sticky_events_foreach       (GstPad *pad,
                                                         GstPadStickyEventsForeachFunction foreach_func,
                                                         gpointer user_data);

Iterates all sticky events on pad and calls foreach_func for every event. If foreach_func returns FALSE the iteration is immediately stopped.

gst_pad_is_active ()

gboolean            gst_pad_is_active                   (GstPad *pad);

Query if a pad is active

enum GstPadProbeReturn

typedef enum {
  GST_PAD_PROBE_DROP,
  GST_PAD_PROBE_OK,
  GST_PAD_PROBE_REMOVE,
  GST_PAD_PROBE_PASS,
} GstPadProbeReturn;

Different return values for the GstPadProbeCallback.

enum GstPadProbeType

typedef enum {
  GST_PAD_PROBE_TYPE_INVALID          = 0,
  /* flags to control blocking */
  GST_PAD_PROBE_TYPE_IDLE             = (1 << 0),
  GST_PAD_PROBE_TYPE_BLOCK            = (1 << 1),
  /* flags to select datatypes */
  GST_PAD_PROBE_TYPE_BUFFER           = (1 << 4),
  GST_PAD_PROBE_TYPE_BUFFER_LIST      = (1 << 5),
  GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM = (1 << 6),
  GST_PAD_PROBE_TYPE_EVENT_UPSTREAM   = (1 << 7),
  GST_PAD_PROBE_TYPE_EVENT_FLUSH      = (1 << 8),
  GST_PAD_PROBE_TYPE_QUERY_DOWNSTREAM = (1 << 9),
  GST_PAD_PROBE_TYPE_QUERY_UPSTREAM   = (1 << 10),
  /* flags to select scheduling mode */
  GST_PAD_PROBE_TYPE_PUSH             = (1 << 12),
  GST_PAD_PROBE_TYPE_PULL             = (1 << 13),

  /* flag combinations */
  GST_PAD_PROBE_TYPE_BLOCKING         = GST_PAD_PROBE_TYPE_IDLE | GST_PAD_PROBE_TYPE_BLOCK,
  GST_PAD_PROBE_TYPE_DATA_DOWNSTREAM  = GST_PAD_PROBE_TYPE_BUFFER | GST_PAD_PROBE_TYPE_BUFFER_LIST | GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM,
  GST_PAD_PROBE_TYPE_DATA_UPSTREAM    = GST_PAD_PROBE_TYPE_EVENT_UPSTREAM,
  GST_PAD_PROBE_TYPE_DATA_BOTH        = GST_PAD_PROBE_TYPE_DATA_DOWNSTREAM | GST_PAD_PROBE_TYPE_DATA_UPSTREAM,
  GST_PAD_PROBE_TYPE_BLOCK_DOWNSTREAM = GST_PAD_PROBE_TYPE_BLOCK | GST_PAD_PROBE_TYPE_DATA_DOWNSTREAM,
  GST_PAD_PROBE_TYPE_BLOCK_UPSTREAM   = GST_PAD_PROBE_TYPE_BLOCK | GST_PAD_PROBE_TYPE_DATA_UPSTREAM,
  GST_PAD_PROBE_TYPE_EVENT_BOTH       = GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM | GST_PAD_PROBE_TYPE_EVENT_UPSTREAM,
  GST_PAD_PROBE_TYPE_QUERY_BOTH       = GST_PAD_PROBE_TYPE_QUERY_DOWNSTREAM | GST_PAD_PROBE_TYPE_QUERY_UPSTREAM,
  GST_PAD_PROBE_TYPE_ALL_BOTH         = GST_PAD_PROBE_TYPE_DATA_BOTH | GST_PAD_PROBE_TYPE_QUERY_BOTH,
  GST_PAD_PROBE_TYPE_SCHEDULING       = GST_PAD_PROBE_TYPE_PUSH | GST_PAD_PROBE_TYPE_PULL
} GstPadProbeType;

The different probing types that can occur. When either one of GST_PAD_PROBE_TYPE_IDLE or GST_PAD_PROBE_TYPE_BLOCK is used, the probe will be a blocking probe.

struct GstPadProbeInfo

struct GstPadProbeInfo {
  GstPadProbeType type;
  gulong id;
  gpointer data;
  guint64 offset;
  guint size;
};

Info passed in the GstPadProbeCallback.

GST_PAD_PROBE_INFO_TYPE()

#define GST_PAD_PROBE_INFO_TYPE(d)         ((d)->type)

GST_PAD_PROBE_INFO_ID()

#define GST_PAD_PROBE_INFO_ID(d)           ((d)->id)

GST_PAD_PROBE_INFO_DATA()

#define GST_PAD_PROBE_INFO_DATA(d)         ((d)->data)

GST_PAD_PROBE_INFO_BUFFER()

#define GST_PAD_PROBE_INFO_BUFFER(d)       GST_BUFFER_CAST(GST_PAD_PROBE_INFO_DATA(d))

GST_PAD_PROBE_INFO_BUFFER_LIST()

#define GST_PAD_PROBE_INFO_BUFFER_LIST(d)  GST_BUFFER_LIST_CAST(GST_PAD_PROBE_INFO_DATA(d))

GST_PAD_PROBE_INFO_EVENT()

#define GST_PAD_PROBE_INFO_EVENT(d)        GST_EVENT_CAST(GST_PAD_PROBE_INFO_DATA(d))

GST_PAD_PROBE_INFO_QUERY()

#define GST_PAD_PROBE_INFO_QUERY(d)        GST_QUERY_CAST(GST_PAD_PROBE_INFO_DATA(d))

gst_pad_probe_info_get_buffer ()

GstBuffer *         gst_pad_probe_info_get_buffer       (GstPadProbeInfo *info);

gst_pad_probe_info_get_buffer_list ()

GstBufferList *     gst_pad_probe_info_get_buffer_list  (GstPadProbeInfo *info);

gst_pad_probe_info_get_event ()

GstEvent *          gst_pad_probe_info_get_event        (GstPadProbeInfo *info);

gst_pad_probe_info_get_query ()

GstQuery *          gst_pad_probe_info_get_query        (GstPadProbeInfo *info);

GST_PAD_PROBE_INFO_OFFSET()

#define GST_PAD_PROBE_INFO_OFFSET(d)       ((d)->offset)

GST_PAD_PROBE_INFO_SIZE()

#define GST_PAD_PROBE_INFO_SIZE(d)         ((d)->size)

GstPadProbeCallback ()

GstPadProbeReturn   (*GstPadProbeCallback)              (GstPad *pad,
                                                         GstPadProbeInfo *info,
                                                         gpointer user_data);

Callback used by gst_pad_add_probe(). Gets called to notify about the current blocking type.

The callback is allowed to modify the data pointer in info.

gst_pad_add_probe ()

gulong              gst_pad_add_probe                   (GstPad *pad,
                                                         GstPadProbeType mask,
                                                         GstPadProbeCallback callback,
                                                         gpointer user_data,
                                                         GDestroyNotify destroy_data);

Be notified of different states of pads. The provided callback is called for every state that matches mask.

gst_pad_remove_probe ()

void                gst_pad_remove_probe                (GstPad *pad,
                                                         gulong id);

Remove the probe with id from pad.

MT safe.

gst_pad_is_blocked ()

gboolean            gst_pad_is_blocked                  (GstPad *pad);

Checks if the pad is blocked or not. This function returns the last requested state of the pad. It is not certain that the pad is actually blocking at this point (see gst_pad_is_blocking()).

gst_pad_is_blocking ()

gboolean            gst_pad_is_blocking                 (GstPad *pad);

Checks if the pad is blocking or not. This is a guaranteed state of whether the pad is actually blocking on a GstBuffer or a GstEvent.

gst_pad_get_offset ()

gint64              gst_pad_get_offset                  (GstPad *pad);

Get the offset applied to the running time of pad. pad has to be a source pad.

gst_pad_set_offset ()

void                gst_pad_set_offset                  (GstPad *pad,
                                                         gint64 offset);

Set the offset that will be applied to the running time of pad.

gst_pad_new ()

GstPad *            gst_pad_new                         (const gchar *name,
                                                         GstPadDirection direction);

Creates a new pad with the given name in the given direction. If name is NULL, a guaranteed unique name (across all pads) will be assigned. This function makes a copy of the name so you can safely free the name.

gst_pad_new_from_template ()

GstPad *            gst_pad_new_from_template           (GstPadTemplate *templ,
                                                         const gchar *name);

Creates a new pad with the given name from the given template. If name is NULL, a guaranteed unique name (across all pads) will be assigned. This function makes a copy of the name so you can safely free the name.

gst_pad_new_from_static_template ()

GstPad *            gst_pad_new_from_static_template    (GstStaticPadTemplate *templ,
                                                         const gchar *name);

Creates a new pad with the given name from the given static template. If name is NULL, a guaranteed unique name (across all pads) will be assigned. This function makes a copy of the name so you can safely free the name.

gst_pad_set_chain_function()

#define gst_pad_set_chain_function(p,f)         gst_pad_set_chain_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_chain_function_full() with NULL for the user_data and notify.

gst_pad_set_chain_function_full ()

void                gst_pad_set_chain_function_full     (GstPad *pad,
                                                         GstPadChainFunction chain,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given chain function for the pad. The chain function is called to process a GstBuffer input buffer. see GstPadChainFunction for more details.

GstPadChainFunction ()

GstFlowReturn       (*GstPadChainFunction)              (GstPad *pad,
                                                         GstObject *parent,
                                                         GstBuffer *buffer);

A function that will be called on sinkpads when chaining buffers. The function typically processes the data contained in the buffer and either consumes the data or passes it on to the internally linked pad(s).

The implementer of this function receives a refcount to buffer and should gst_buffer_unref() when the buffer is no longer needed.

When a chain function detects an error in the data stream, it must post an error on the bus and return an appropriate GstFlowReturn value.

gst_pad_set_chain_list_function()

#define gst_pad_set_chain_list_function(p,f)    gst_pad_set_chain_list_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_chain_list_function_full() with NULL for the user_data and notify.

gst_pad_set_chain_list_function_full ()

void                gst_pad_set_chain_list_function_full
                                                        (GstPad *pad,
                                                         GstPadChainListFunction chainlist,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given chain list function for the pad. The chainlist function is called to process a GstBufferList input buffer list. See GstPadChainListFunction for more details.

GstPadChainListFunction ()

GstFlowReturn       (*GstPadChainListFunction)          (GstPad *pad,
                                                         GstObject *parent,
                                                         GstBufferList *list);

A function that will be called on sinkpads when chaining buffer lists. The function typically processes the data contained in the buffer list and either consumes the data or passes it on to the internally linked pad(s).

The implementer of this function receives a refcount to list and should gst_buffer_list_unref() when the list is no longer needed.

When a chainlist function detects an error in the data stream, it must post an error on the bus and return an appropriate GstFlowReturn value.

gst_pad_get_range ()

GstFlowReturn       gst_pad_get_range                   (GstPad *pad,
                                                         guint64 offset,
                                                         guint size,
                                                         GstBuffer **buffer);

When pad is flushing this function returns GST_FLOW_FLUSHING immediately and buffer is NULL.

Calls the getrange function of pad, see GstPadGetRangeFunction for a description of a getrange function. If pad has no getrange function installed (see gst_pad_set_getrange_function()) this function returns GST_FLOW_NOT_SUPPORTED.

If buffer points to a variable holding NULL, a valid new GstBuffer will be placed in buffer when this function returns GST_FLOW_OK. The new buffer must be freed with gst_buffer_unref() after usage.

When buffer points to a variable that points to a valid GstBuffer, the buffer will be filled with the result data when this function returns GST_FLOW_OK. If the provided buffer is larger than size, only size bytes will be filled in the result buffer and its size will be updated accordingly.

Note that less than size bytes can be returned in buffer when, for example, an EOS condition is near or when buffer is not large enough to hold size bytes. The caller should check the result buffer size to get the result size.

When this function returns any other result value than GST_FLOW_OK, buffer will be unchanged.

This is a lowlevel function. Usualy gst_pad_pull_range() is used.

gst_pad_set_getrange_function()

#define gst_pad_set_getrange_function(p,f)      gst_pad_set_getrange_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_getrange_function_full() with NULL for the user_data and notify.

gst_pad_set_getrange_function_full ()

void                gst_pad_set_getrange_function_full  (GstPad *pad,
                                                         GstPadGetRangeFunction get,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given getrange function for the pad. The getrange function is called to produce a new GstBuffer to start the processing pipeline. see GstPadGetRangeFunction for a description of the getrange function.

GstPadGetRangeFunction ()

GstFlowReturn       (*GstPadGetRangeFunction)           (GstPad *pad,
                                                         GstObject *parent,
                                                         guint64 offset,
                                                         guint length,
                                                         GstBuffer **buffer);

This function will be called on source pads when a peer element request a buffer at the specified offset and length. If this function returns GST_FLOW_OK, the result buffer will be stored in buffer. The contents of buffer is invalid for any other return value.

This function is installed on a source pad with gst_pad_set_getrange_function() and can only be called on source pads after they are successfully activated with gst_pad_activate_mode() with the GST_PAD_MODE_PULL.

offset and length are always given in byte units. offset must normally be a value between 0 and the length in bytes of the data available on pad. The length (duration in bytes) can be retrieved with a GST_QUERY_DURATION or with a GST_QUERY_SEEKING.

Any offset larger or equal than the length will make the function return GST_FLOW_EOS, which corresponds to EOS. In this case buffer does not contain a valid buffer.

The buffer size of buffer will only be smaller than length when offset is near the end of the stream. In all other cases, the size of buffer must be exactly the requested size.

It is allowed to call this function with a 0 length and valid offset, in which case buffer will contain a 0-sized buffer and the function returns GST_FLOW_OK.

When this function is called with a -1 offset, the sequentially next buffer of length length in the stream is returned.

When this function is called with a -1 length, a buffer with a default optimal length is returned in buffer. The length might depend on the value of offset.

gst_pad_set_event_function()

#define gst_pad_set_event_function(p,f)         gst_pad_set_event_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_event_function_full() with NULL for the user_data and notify.

gst_pad_set_event_function_full ()

void                gst_pad_set_event_function_full     (GstPad *pad,
                                                         GstPadEventFunction event,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given event handler for the pad.

GstPadEventFunction ()

gboolean            (*GstPadEventFunction)              (GstPad *pad,
                                                         GstObject *parent,
                                                         GstEvent *event);

Function signature to handle an event for the pad.

gst_pad_set_link_function()

#define gst_pad_set_link_function(p,f)          gst_pad_set_link_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_link_function_full() with NULL for the user_data and notify.

gst_pad_set_link_function_full ()

void                gst_pad_set_link_function_full      (GstPad *pad,
                                                         GstPadLinkFunction link,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given link function for the pad. It will be called when the pad is linked with another pad.

The return value GST_PAD_LINK_OK should be used when the connection can be made.

The return value GST_PAD_LINK_REFUSED should be used when the connection cannot be made for some reason.

If link is installed on a source pad, it should call the GstPadLinkFunction of the peer sink pad, if present.

GstPadLinkFunction ()

GstPadLinkReturn    (*GstPadLinkFunction)               (GstPad *pad,
                                                         GstObject *parent,
                                                         GstPad *peer);

Function signature to handle a new link on the pad.

gst_pad_set_unlink_function()

#define gst_pad_set_unlink_function(p,f)        gst_pad_set_unlink_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_unlink_function_full() with NULL for the user_data and notify.

gst_pad_set_unlink_function_full ()

void                gst_pad_set_unlink_function_full    (GstPad *pad,
                                                         GstPadUnlinkFunction unlink,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given unlink function for the pad. It will be called when the pad is unlinked.

GstPadUnlinkFunction ()

void                (*GstPadUnlinkFunction)             (GstPad *pad,
                                                         GstObject *parent);

Function signature to handle a unlinking the pad prom its peer.

gst_pad_proxy_query_caps ()

gboolean            gst_pad_proxy_query_caps            (GstPad *pad,
                                                         GstQuery *query);

Calls gst_pad_query_caps() for all internally linked pads fof pad and returns the intersection of the results.

This function is useful as a default caps query function for an element that can handle any stream format, but requires all its pads to have the same caps. Two such elements are tee and adder.

gst_pad_proxy_query_accept_caps ()

gboolean            gst_pad_proxy_query_accept_caps     (GstPad *pad,
                                                         GstQuery *query);

Calls gst_pad_accept_caps() for all internally linked pads of pad and returns the intersection of the results.

This function is useful as a default accept caps query function for an element that can handle any stream format, but requires caps that are acceptable for all oposite pads.

gst_pad_set_activate_function()

#define gst_pad_set_activate_function(p,f)      gst_pad_set_activate_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_activate_function_full() with NULL for the user_data and notify.

gst_pad_set_activate_function_full ()

void                gst_pad_set_activate_function_full  (GstPad *pad,
                                                         GstPadActivateFunction activate,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given activate function for pad. The activate function will dispatch to gst_pad_activate_mode() to perform the actual activation. Only makes sense to set on sink pads.

Call this function if your sink pad can start a pull-based task.

GstPadActivateFunction ()

gboolean            (*GstPadActivateFunction)           (GstPad *pad,
                                                         GstObject *parent);

This function is called when the pad is activated during the element READY to PAUSED state change. By default this function will call the activate function that puts the pad in push mode but elements can override this function to activate the pad in pull mode if they wish.

gst_pad_set_activatemode_function()

#define gst_pad_set_activatemode_function(p,f)  gst_pad_set_activatemode_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_activatemode_function_full() with NULL for the user_data and notify.

gst_pad_set_activatemode_function_full ()

void                gst_pad_set_activatemode_function_full
                                                        (GstPad *pad,
                                                         GstPadActivateModeFunction activatemode,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given activate_mode function for the pad. An activate_mode function prepares the element for data passing.

GstPadActivateModeFunction ()

gboolean            (*GstPadActivateModeFunction)       (GstPad *pad,
                                                         GstObject *parent,
                                                         GstPadMode mode,
                                                         gboolean active);

The prototype of the push and pull activate functions.

gst_pad_needs_reconfigure ()

gboolean            gst_pad_needs_reconfigure           (GstPad *pad);

Check the GST_PAD_FLAG_NEED_RECONFIGURE flag on pad and return TRUE if the flag was set.

gst_pad_check_reconfigure ()

gboolean            gst_pad_check_reconfigure           (GstPad *pad);

Check and clear the GST_PAD_FLAG_NEED_RECONFIGURE flag on pad and return TRUE if the flag was set.

gst_pad_mark_reconfigure ()

void                gst_pad_mark_reconfigure            (GstPad *pad);

Mark a pad for needing reconfiguration. The next call to gst_pad_check_reconfigure() will return TRUE after this call.

gst_pad_push ()

GstFlowReturn       gst_pad_push                        (GstPad *pad,
                                                         GstBuffer *buffer);

Pushes a buffer to the peer of pad.

This function will call installed block probes before triggering any installed data probes.

The function proceeds calling gst_pad_chain() on the peer pad and returns the value from that function. If pad has no peer, GST_FLOW_NOT_LINKED will be returned.

In all cases, success or failure, the caller loses its reference to buffer after calling this function.

gst_pad_push_event ()

gboolean            gst_pad_push_event                  (GstPad *pad,
                                                         GstEvent *event);

Sends the event to the peer of the given pad. This function is mainly used by elements to send events to their peer elements.

This function takes owership of the provided event so you should gst_event_ref() it if you want to reuse the event after this call.

gst_pad_push_list ()

GstFlowReturn       gst_pad_push_list                   (GstPad *pad,
                                                         GstBufferList *list);

Pushes a buffer list to the peer of pad.

This function will call installed block probes before triggering any installed data probes.

The function proceeds calling the chain function on the peer pad and returns the value from that function. If pad has no peer, GST_FLOW_NOT_LINKED will be returned. If the peer pad does not have any installed chainlist function every group buffer of the list will be merged into a normal GstBuffer and chained via gst_pad_chain().

In all cases, success or failure, the caller loses its reference to list after calling this function.

gst_pad_pull_range ()

GstFlowReturn       gst_pad_pull_range                  (GstPad *pad,
                                                         guint64 offset,
                                                         guint size,
                                                         GstBuffer **buffer);

Pulls a buffer from the peer pad or fills up a provided buffer.

This function will first trigger the pad block signal if it was installed.

When pad is not linked GST_FLOW_NOT_LINKED is returned else this function returns the result of gst_pad_get_range() on the peer pad. See gst_pad_get_range() for a list of return values and for the semantics of the arguments of this function.

If buffer points to a variable holding NULL, a valid new GstBuffer will be placed in buffer when this function returns GST_FLOW_OK. The new buffer must be freed with gst_buffer_unref() after usage. When this function returns any other result value, buffer will still point to NULL.

When buffer points to a variable that points to a valid GstBuffer, the buffer will be filled with the result data when this function returns GST_FLOW_OK. When this function returns any other result value, buffer will be unchanged. If the provided buffer is larger than size, only size bytes will be filled in the result buffer and its size will be updated accordingly.

Note that less than size bytes can be returned in buffer when, for example, an EOS condition is near or when buffer is not large enough to hold size bytes. The caller should check the result buffer size to get the result size.

gst_pad_activate_mode ()

gboolean            gst_pad_activate_mode               (GstPad *pad,
                                                         GstPadMode mode,
                                                         gboolean active);

Activates or deactivates the given pad in mode via dispatching to the pad's activatemodefunc. For use from within pad activation functions only.

If you don't know what this is, you probably don't want to call it.

gst_pad_send_event ()

gboolean            gst_pad_send_event                  (GstPad *pad,
                                                         GstEvent *event);

Sends the event to the pad. This function can be used by applications to send events in the pipeline.

If pad is a source pad, event should be an upstream event. If pad is a sink pad, event should be a downstream event. For example, you would not send a GST_EVENT_EOS on a src pad; EOS events only propagate downstream. Furthermore, some downstream events have to be serialized with data flow, like EOS, while some can travel out-of-band, like GST_EVENT_FLUSH_START. If the event needs to be serialized with data flow, this function will take the pad's stream lock while calling its event function.

To find out whether an event type is upstream, downstream, or downstream and serialized, see GstEventTypeFlags, gst_event_type_get_flags(), GST_EVENT_IS_UPSTREAM, GST_EVENT_IS_DOWNSTREAM, and GST_EVENT_IS_SERIALIZED. Note that in practice that an application or plugin doesn't need to bother itself with this information; the core handles all necessary locks and checks.

This function takes owership of the provided event so you should gst_event_ref() it if you want to reuse the event after this call.

gst_pad_event_default ()

gboolean            gst_pad_event_default               (GstPad *pad,
                                                         GstObject *parent,
                                                         GstEvent *event);

Invokes the default event handler for the given pad.

The EOS event will pause the task associated with pad before it is forwarded to all internally linked pads,

The the event is sent to all pads internally linked to pad. This function takes ownership of event.

gst_pad_query ()

gboolean            gst_pad_query                       (GstPad *pad,
                                                         GstQuery *query);

Dispatches a query to a pad. The query should have been allocated by the caller via one of the type-specific allocation functions. The element that the pad belongs to is responsible for filling the query with an appropriate response, which should then be parsed with a type-specific query parsing function.

Again, the caller is responsible for both the allocation and deallocation of the query structure.

Please also note that some queries might need a running pipeline to work.

gst_pad_peer_query ()

gboolean            gst_pad_peer_query                  (GstPad *pad,
                                                         GstQuery *query);

Performs gst_pad_query() on the peer of pad.

The caller is responsible for both the allocation and deallocation of the query structure.

gst_pad_query_default ()

gboolean            gst_pad_query_default               (GstPad *pad,
                                                         GstObject *parent,
                                                         GstQuery *query);

Invokes the default query handler for the given pad. The query is sent to all pads internally linked to pad. Note that if there are many possible sink pads that are internally linked to pad, only one will be sent the query. Multi-sinkpad elements should implement custom query handlers.

gst_pad_query_position ()

gboolean            gst_pad_query_position              (GstPad *pad,
                                                         GstFormat format,
                                                         gint64 *cur);

Queries a pad for the stream position.

gst_pad_query_duration ()

gboolean            gst_pad_query_duration              (GstPad *pad,
                                                         GstFormat format,
                                                         gint64 *duration);

Queries a pad for the total stream duration.

gst_pad_query_convert ()

gboolean            gst_pad_query_convert               (GstPad *pad,
                                                         GstFormat src_format,
                                                         gint64 src_val,
                                                         GstFormat dest_format,
                                                         gint64 *dest_val);

Queries a pad to convert src_val in src_format to dest_format.

gst_pad_query_accept_caps ()

gboolean            gst_pad_query_accept_caps           (GstPad *pad,
                                                         GstCaps *caps);

Check if the given pad accepts the caps.

gst_pad_query_caps ()

GstCaps *           gst_pad_query_caps                  (GstPad *pad,
                                                         GstCaps *filter);

Gets the capabilities this pad can produce or consume. Note that this method doesn't necessarily return the caps set by gst_pad_set_caps() - use gst_pad_get_current_caps() for that instead. gst_pad_query_caps returns all possible caps a pad can operate with, using the pad's CAPS query function, If the query fails, this function will return filter, if not NULL, otherwise ANY.

When called on sinkpads filter contains the caps that upstream could produce in the order preferred by upstream. When called on srcpads filter contains the caps accepted by downstream in the preffered order. filter might be NULL but if it is not NULL the returned caps will be a subset of filter.

Note that this function does not return writable GstCaps, use gst_caps_make_writable() before modifying the caps.

gst_pad_peer_query_position ()

gboolean            gst_pad_peer_query_position         (GstPad *pad,
                                                         GstFormat format,
                                                         gint64 *cur);

Queries the peer of a given sink pad for the stream position.

gst_pad_peer_query_duration ()

gboolean            gst_pad_peer_query_duration         (GstPad *pad,
                                                         GstFormat format,
                                                         gint64 *duration);

Queries the peer pad of a given sink pad for the total stream duration.

gst_pad_peer_query_convert ()

gboolean            gst_pad_peer_query_convert          (GstPad *pad,
                                                         GstFormat src_format,
                                                         gint64 src_val,
                                                         GstFormat dest_format,
                                                         gint64 *dest_val);

Queries the peer pad of a given sink pad to convert src_val in src_format to dest_format.

gst_pad_peer_query_accept_caps ()

gboolean            gst_pad_peer_query_accept_caps      (GstPad *pad,
                                                         GstCaps *caps);

Check if the peer of pad accepts caps. If pad has no peer, this function returns TRUE.

gst_pad_peer_query_caps ()

GstCaps *           gst_pad_peer_query_caps             (GstPad *pad,
                                                         GstCaps *filter);

Gets the capabilities of the peer connected to this pad. Similar to gst_pad_query_caps().

When called on srcpads filter contains the caps that upstream could produce in the order preferred by upstream. When called on sinkpads filter contains the caps accepted by downstream in the preffered order. filter might be NULL but if it is not NULL the returned caps will be a subset of filter.

gst_pad_set_query_function()

#define gst_pad_set_query_function(p,f)   gst_pad_set_query_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_query_function_full() with NULL for the user_data and notify.

gst_pad_set_query_function_full ()

void                gst_pad_set_query_function_full     (GstPad *pad,
                                                         GstPadQueryFunction query,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Set the given query function for the pad.

GstPadQueryFunction ()

gboolean            (*GstPadQueryFunction)              (GstPad *pad,
                                                         GstObject *parent,
                                                         GstQuery *query);

The signature of the query function.

gst_pad_set_iterate_internal_links_function()

#define gst_pad_set_iterate_internal_links_function(p,f) gst_pad_set_iterate_internal_links_function_full((p),(f),NULL,NULL)

Calls gst_pad_set_iterate_internal_links_function_full() with NULL for the user_data and notify.

gst_pad_set_iterate_internal_links_function_full ()

void                gst_pad_set_iterate_internal_links_function_full
                                                        (GstPad *pad,
                                                         GstPadIterIntLinkFunction iterintlink,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Sets the given internal link iterator function for the pad.

GstPadIterIntLinkFunction ()

GstIterator *       (*GstPadIterIntLinkFunction)        (GstPad *pad,
                                                         GstObject *parent);

The signature of the internal pad link iterator function.

gst_pad_iterate_internal_links ()

GstIterator *       gst_pad_iterate_internal_links      (GstPad *pad);

Gets an iterator for the pads to which the given pad is linked to inside of the parent element.

Each GstPad element yielded by the iterator will have its refcount increased, so unref after use.

Free-function: gst_iterator_free

gst_pad_iterate_internal_links_default ()

GstIterator *       gst_pad_iterate_internal_links_default
                                                        (GstPad *pad,
                                                         GstObject *parent);

Iterate the list of pads to which the given pad is linked to inside of the parent element. This is the default handler, and thus returns an iterator of all of the pads inside the parent element with opposite direction.

The caller must free this iterator after use with gst_iterator_free().

gst_pad_set_element_private ()

void                gst_pad_set_element_private         (GstPad *pad,
                                                         gpointer priv);

Set the given private data gpointer on the pad. This function can only be used by the element that owns the pad. No locking is performed in this function.

gst_pad_get_element_private ()

gpointer            gst_pad_get_element_private         (GstPad *pad);

Gets the private data of a pad. No locking is performed in this function.

gst_pad_create_stream_id ()

gchar *             gst_pad_create_stream_id            (GstPad *pad,
                                                         GstElement *parent,
                                                         const gchar *stream_id);

Creates a stream-id for the source GstPad pad by combining the upstream information with the optional stream_id of the stream of pad. pad must have a parent GstElement and which must have zero or one sinkpad. stream_id can only be NULL if the parent element of pad has only a single source pad.

This function generates an unique stream-id by getting the upstream stream-start event stream ID and appending stream_id to it. If the element has no sinkpad it will generate an upstream stream-id by doing an URI query on the element and in the worst case just uses a random number. Source elements that don't implement the URI handler interface should ideally generate a unique, deterministic stream-id manually instead.

gst_pad_create_stream_id_printf ()

gchar *             gst_pad_create_stream_id_printf     (GstPad *pad,
                                                         GstElement *parent,
                                                         const gchar *stream_id,
                                                         ...);

Creates a stream-id for the source GstPad pad by combining the upstream information with the optional stream_id of the stream of pad. pad must have a parent GstElement and which must have zero or one sinkpad. stream_id can only be NULL if the parent element of pad has only a single source pad.

This function generates an unique stream-id by getting the upstream stream-start event stream ID and appending stream_id to it. If the element has no sinkpad it will generate an upstream stream-id by doing an URI query on the element and in the worst case just uses a random number. Source elements that don't implement the URI handler interface should ideally generate a unique, deterministic stream-id manually instead.

gst_pad_create_stream_id_printf_valist ()

gchar *             gst_pad_create_stream_id_printf_valist
                                                        (GstPad *pad,
                                                         GstElement *parent,
                                                         const gchar *stream_id,
                                                         va_list var_args);

Creates a stream-id for the source GstPad pad by combining the upstream information with the optional stream_id of the stream of pad. pad must have a parent GstElement and which must have zero or one sinkpad. stream_id can only be NULL if the parent element of pad has only a single source pad.

This function generates an unique stream-id by getting the upstream stream-start event stream ID and appending stream_id to it. If the element has no sinkpad it will generate an upstream stream-id by doing an URI query on the element and in the worst case just uses a random number. Source elements that don't implement the URI handler interface should ideally generate a unique, deterministic stream-id manually instead.

GstPadForwardFunction ()

gboolean            (*GstPadForwardFunction)            (GstPad *pad,
                                                         gpointer user_data);

A forward function is called for all internally linked pads, see gst_pad_forward().

gst_pad_forward ()

gboolean            gst_pad_forward                     (GstPad *pad,
                                                         GstPadForwardFunction forward,
                                                         gpointer user_data);

Calls forward for all internally linked pads of pad. This function deals with dynamically changing internal pads and will make sure that the forward function is only called once for each pad.

When forward returns TRUE, no further pads will be processed.

gst_pad_chain ()

GstFlowReturn       gst_pad_chain                       (GstPad *pad,
                                                         GstBuffer *buffer);

Chain a buffer to pad.

The function returns GST_FLOW_FLUSHING if the pad was flushing.

If the buffer type is not acceptable for pad (as negotiated with a preceeding GST_EVENT_CAPS event), this function returns GST_FLOW_NOT_NEGOTIATED.

The function proceeds calling the chain function installed on pad (see gst_pad_set_chain_function()) and the return value of that function is returned to the caller. GST_FLOW_NOT_SUPPORTED is returned if pad has no chain function.

In all cases, success or failure, the caller loses its reference to buffer after calling this function.

gst_pad_chain_list ()

GstFlowReturn       gst_pad_chain_list                  (GstPad *pad,
                                                         GstBufferList *list);

Chain a bufferlist to pad.

The function returns GST_FLOW_FLUSHING if the pad was flushing.

If pad was not negotiated properly with a CAPS event, this function returns GST_FLOW_NOT_NEGOTIATED.

The function proceeds calling the chainlist function installed on pad (see gst_pad_set_chain_list_function()) and the return value of that function is returned to the caller. GST_FLOW_NOT_SUPPORTED is returned if pad has no chainlist function.

In all cases, success or failure, the caller loses its reference to list after calling this function.

MT safe.

gst_pad_start_task ()

gboolean            gst_pad_start_task                  (GstPad *pad,
                                                         GstTaskFunction func,
                                                         gpointer user_data,
                                                         GDestroyNotify notify);

Starts a task that repeatedly calls func with user_data. This function is mostly used in pad activation functions to start the dataflow. The GST_PAD_STREAM_LOCK of pad will automatically be acquired before func is called.

gst_pad_pause_task ()

gboolean            gst_pad_pause_task                  (GstPad *pad);

Pause the task of pad. This function will also wait until the function executed by the task is finished if this function is not called from the task function.

gst_pad_stop_task ()

gboolean            gst_pad_stop_task                   (GstPad *pad);

Stop the task of pad. This function will also make sure that the function executed by the task will effectively stop if not called from the GstTaskFunction.

This function will deadlock if called from the GstTaskFunction of the task. Use gst_task_pause() instead.

Regardless of whether the pad has a task, the stream lock is acquired and released so as to ensure that streaming through this pad has finished.