GstPad The connection between Elements #GstElement are connected to each other via "pads", which are extremely light-weight generic connections. After two pad are retrieved from an element with gst_element_get_pad(), the pads can be connected with gst_pad_connect(). PedTemplates are use to describe the runtime behaviour of an element and what pads it will have during its lifetime. Pads are typically created from a padtemplate with GST_PADTEMPLATE_NEW() or with the factory macro GST_PADTEMPLATE_FACTORY(). Pad and PadTemplates have #GstCaps attached to it to describe the media type they are capable of dealing with. gst_pad_get_caps() and gst_pad_set_caps() are used to manipulate the caps of the pads. gst_padtemplate_get_caps() is used to get the caps of a padtemplate. It's not possible to modify the caps of a padtemplate after creation. The following code example shows the code to create a pad from a padtemplate. GST_PADTEMPLATE_FACTORY (my_factory, "sink", /* the name of the pad */ GST_PAD_SINK, /* the direction of the pad */ GST_PAD_ALWAYS, /* when this pad will be present */ GST_CAPS_NEW ( /* the capabilities of the padtemplate */ "my_caps", "audio/raw", "format", GST_PROPS_STRING ("int"), "channels", GST_PROPS_INT_RANGE (1, 6) ) ) void my_method (void) { GstPad *pad; pad = gst_pad_new_from_template (GST_PADTEMPLATE_GET (my_factory), "sink"); ... } Pads created from a padtemplate cannot set capabilities that are incompatible with the padtemplates capabilities. Pads without padtemplates can be created with gst_pad_new() which takes a direction and a name as an argument. gst_pad_get_parent() will retrieve the GstElement that owns the pad. GstElements creating a pad will typicilally use the various gst_pad_set_*_function() calls to register callbacks for various events on the pads. GstElements will use gst_pad_push() and gst_pad_pull() to push out or pull a buffer in. The gst_pad_pullregion() function can be used to request for a buffer with a specific offset (in time or in bytes). #GstCaps, #GstElement Get the name of the pad. @pad: the pad to query Get the private data set by the element that owns the pad. @pad: the pad to query Get the parent element of this pad. @pad: the pad to query Get the padtemplate that was used to create this pad. NULL if no padtemplate was used. @pad: the pad to query Return the real pad of this pad. @pad: the pad to query Get the pad direction. @pad: the pad to query Get the capabilities of a pad. @pad: the pad to query Get the peerpad of this pad. @pad: the pad to query Is this pad connected. @pad: the pad to check Can this pad be used to pull a buffer. @pad: the pad to check The function that will be called when chaining buffers. @pad: the pad that performed the chain @buf: the buffer that is chained The function that will be called when pulling a buffer. @pad: the pad to get a buffer from @Returns: a #GstBuffer The function that will be called when pulling a region buffer. You can specify which buffer to get using an offset/length pair or a start/stop timecode pair. @pad: the pad to get a buffer from @type: the type of region to get (time or offset based) @offset: the offset of the region to get @len: the length of the region to get @Returns: a #GstBuffer @size: the size of the region to get The function that will be called when a QoS message is sent. @pad: the pad that sent the QoS message @qos_message: the message The function that will be called in an EOS case. @pad: the pad that needs to be set to EOS state @Returns: TRUE if EOS was successful, FALSE otherwise The function that will be called when the caps of the pad has changed. @pad: The pad that has its caps changed @caps: the new caps of the pad The function that will be called when a bufferpool is requested from this pad. @pad: the pad with the bufferpool @Returns: the GstBufferPool associated with this pad. The possible results from padnegotiation. @GST_PAD_NEGOTIATE_FAIL: The pads could not agree about the media type. @GST_PAD_NEGOTIATE_AGREE: The pads agreed about the media type. @GST_PAD_NEGOTIATE_TRY: The pad did not agree and suggests another media type. The function that will be called when negotiating. @pad: The pad that is being negotiated @caps: The current caps that are being negotiated @data: A generic gpointer that can be used to store user_data @Returns: The result of the negotiation process The function that will be called when pushing a buffers. @pad: the pad to push @buf: a GstBuffer to push The function that will be called when pulling buffers. @pad: the pad to pull @Returns: a GstBuffer the region types for #gst_pad_pullregion. @GST_REGION_NONE: no type specified @GST_REGION_OFFSET_LEN: an offet/length pair @GST_REGION_TIME_LEN: a time start/length pair The function that will be called when pulling a region buffer. You can specify which buffer to get using an offset/length pair or a start/stop timecode pair. @pad: the pad to get a buffer from @type: the type of region to get (time or offset based) @offset: the offset of the region to get @len: the length of the region to get @Returns: a #GstBuffer The direction this pad is. @GST_PAD_UNKNOWN: direction is unknown @GST_PAD_SRC: this is a source pad @GST_PAD_SINK: this is a sink pad Flags for the pad. @GST_PAD_DISABLED: the pad is disabled @GST_PAD_EOS: the pad is in end of stream state @GST_PAD_FLAG_LAST: subclasses can use this number to enumerate their flags @name: @direction: @Returns: Destroy the pad. @pad: the pad to destroy @templ: @name: @Returns: @temp: @pad: @Returns: @pad: @chain: @pad: @get: @pad: @getregion: @pad: @nego: @pad: @qos: @pad: @eos: @pad: @newcaps: @pad: @bufpool: @pad: @caps: @Returns: @pad: @Returns: @srcpad: @sinkpad: @Returns: @pad: @name: @pad: @Returns: @pad: @priv: @pad: @Returns: @pad: @parent: @pad: @Returns: @pad: @Returns: @pad: @sched: @pad: @Returns: @pad: @ghostpad: @pad: @ghostpad: @pad: @Returns: @pad: @Returns: @srcpad: @sinkpad: @Returns: @srcpad: @sinkpad: @pad: @buf: @buffer: @pad: @Returns: @pad: @type: @offset: @len: @Returns: @size: @pad: @Returns: @pad: @Returns: @pad: @qos_message: Call the EOS function of the pad @pad: the pad to call the eos function of. @self: @parent: @element: @elements: @srcpad: @destpad: @caps: @Returns: @counter: @count: @pad: @Returns: @pad: @Returns: @pad: @Returns: @pad: @Returns: @pad: @caps: @direction: @threadstate: @peer: @bufpen: @regiontype: @offset: @len: @sched: @chainfunc: @getfunc: @getregionfunc: @qosfunc: @eosfunc: @pushfunc: @pullfunc: @pullregionfunc: @negotiatefunc: @newcapsfunc: @bufferpoolfunc: @ghostpads: Get the length of the region that is being pulled. @pad: the real pad to query. Get the offset of the region that is being pulled. @pad: the real pad to query. @pad: Get the type of the region that is being pulled. @pad: the real pad to query. Get the direction of the real pad. @pad: the realpad to query. Get the caps of the real pad. @pad: the real pad to query. Get the peer element of the real pad. @pad: the real pad to query. Get the bufpen of the real pad. @pad: the real pad to query. Get the chain function of the real pad. @pad: the real pad to query. Get get getfunction of the real pad. @pad: the real pad to query. Get the getregion function of the real pad. @pad: the real pad to query. Get the pushfunction of the real pad. @pad: the real pad to query. Get the pullfunction of the real pad. @pad: the real pad to query. Get the pullregion function of the real pad. @pad: the real pad to query. Get the QoS function of the real pad. @pad: the real pad to query. Get the EOS function of the real pad. @pad: the real pad to query. Get the negotiate function from the real pad. @pad: the real pad to query. Get the newcaps function from the real pad. @pad: the real pad to query. Get the bufferpoolfunction from the real pad. @pad: the real pad to query. Get the real pad of this ghost pad. @pad: the real pad to query. @pad: @realpad: @name: @pad: @Returns: Indicates when this pad will become available. @GST_PAD_ALWAYS: the pad is always available @GST_PAD_SOMETIMES: the pad will become available depending on the media stream @GST_PAD_REQUEST: th pad is only available on request with gst_element_request_pad_by_name() or gst_element_request_compatible_pad(). @object: @name_template: @direction: @presence: @caps: Get a handle to the padtemplate #GstCaps @templ: the template to query Get the direction of the padtemplate. @templ: the template to query Get the nametemplate of the padtemplate. @templ: the template to query Get the presence of the padtemplate. @templ: the template to query Create a new padtemplate. @padname: the nametemplate for the pads that will be created with this template @dir: the direction of the pads. @pres: the presence of the pads. @a...: the capabilities of this padtemplate usually created with GST_CAPS_NEW() Create a factory for a padtemplate. This can be used if you only want one instance of the padtemplate. Use GST_PADTEMPLATE_GET() to get the unique padtemplate. @name: th name of the factory @padname: the nametemplate of the pads @dir: the direction of the pads. @pres: the presence of the pads. @a...: the capabilities of this padtemplate, usually created with GST_CAPS_NEW() Get the padtemplate of the factory created with GST_PADTEMPLATE_FACTORY() @fact: the factory name to get the padtemplate from. @name_template: @direction: @presence: @caps: @Varargs: @Returns: @parent: @Returns: @templ: @parent: @Returns: @templ: @Returns: @templ: @name: @Returns: