mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-04 23:46:43 +00:00
0b3089e537
Original commit message from CVS: first try at hunting old elements that where renamed like : - parsewav (never existed, should be wavparse) - vorbisfile (now oggdemux ! vorbisdec) - disksink (now filesink)
143 lines
3 KiB
Text
143 lines
3 KiB
Text
INITIAL RAMBLINGS
|
|
-----------------
|
|
|
|
some random ramblings about the event system:
|
|
|
|
Possible candidates for events
|
|
------------------------------
|
|
|
|
- QoS
|
|
- EOS
|
|
- Seek
|
|
- caps nego??
|
|
- bufferpool get??
|
|
- ...
|
|
|
|
Assumptions for events
|
|
----------------------
|
|
|
|
- They are tied to a pad.
|
|
- get rid of gst_pad_set_*_function (except for the chain/get ones)
|
|
- occur async to dataflow. (need locking?)
|
|
- fixed set of events only for core features. (elements cannot abuse
|
|
events for doing dataflow)
|
|
|
|
Questions
|
|
---------
|
|
|
|
limit the valid directions an event can travel in? ie. Can EOS only
|
|
travel downstream (left to right)?
|
|
|
|
eg. Seek travels upstream, but it makes sense to also make it travel
|
|
downstream (the case of a filesink, where we overwrite the header)
|
|
|
|
|
|
Setting an event function
|
|
-------------------------
|
|
|
|
void gst_pad_set_event_function (GstPad *pad, gint event_mask,
|
|
GstEventFunction *function);
|
|
|
|
|
|
event masks:
|
|
|
|
typedef enum {
|
|
GST_EVENT_EOS = (1 << 0),
|
|
GST_EVENT_QOS = (1 << 1),
|
|
GST_EVENT_SEEK = (1 << 2),
|
|
GST_EVENT_CAPS = (1 << 3),
|
|
} GstEventType;
|
|
|
|
Event structure
|
|
---------------
|
|
|
|
typedef struct {
|
|
GstEventType type;
|
|
GstEventMinorType minor;
|
|
guint64 timestamp; /* also sequence number ?? */
|
|
|
|
union {
|
|
/* EOS stuff */
|
|
/* QoS stuff */
|
|
/* Seek stuff */
|
|
GstSeekType type; /* time, bytes, ... */
|
|
gint64 offset;
|
|
gint64 lenth;
|
|
/* Caps stuff */
|
|
GstCaps *caps;
|
|
} data;
|
|
} GstEvent;
|
|
|
|
|
|
typedef enum {
|
|
GST_EVENT_MINOR_NONE,
|
|
/* EOS stuff */
|
|
|
|
/* QoS stuff */
|
|
/* Seek stuff */
|
|
GST_EVENT_MINOR_OFFSET,
|
|
GST_EVENT_MINOR_TIME,
|
|
|
|
/* caps nego stuff */
|
|
GST_EVENT_MINOR_CAPS_TRY,
|
|
GST_EVENT_MINOR_CAPS_START,
|
|
GST_EVENT_MINOR_CAPS_FINAL,
|
|
} GstEventMinorType;
|
|
|
|
|
|
Receiving events
|
|
----------------
|
|
|
|
a sample GstEventFunction, the event functions returns TRUE if the event is handled,
|
|
FALSE otherwise.
|
|
|
|
gboolean
|
|
gst_anelement_handle_event (GstPad *pad, GstEvent *event)
|
|
{
|
|
if (event->type == GST_EVENT_EOS) {
|
|
/* do something */
|
|
return TRUE;
|
|
}
|
|
else if (event->type == GST_EVENT_CAPS) {
|
|
if (event->minor == GST_EVENT_CAPS_TRY) {
|
|
/* try using this caps structure */
|
|
return TRUE; /* return FALSE to proxy ???*/
|
|
}
|
|
}
|
|
return FALSE;
|
|
}
|
|
|
|
|
|
Default event handler for pads
|
|
------------------------------
|
|
|
|
gboolean
|
|
gst_pad_handle_event (GstPad *pad, GstEvent *event)
|
|
{
|
|
GstElement *element;
|
|
GList *pads;
|
|
GstPad *srcpad;
|
|
gboolean result = TRUE;
|
|
GstPadDirection dir = GST_PAD_DIRECTION (pad);
|
|
|
|
g_return_val_if_fail (pad != NULL, FALSE);
|
|
g_return_val_if_fail (GST_IS_REAL_PAD(pad), FALSE); // NOTE the restriction
|
|
|
|
element = GST_ELEMENT (gst_object_get_parent (GST_OBJECT (pad)));
|
|
|
|
/* send out the events to all pad with opposite direction */
|
|
pads = gst_element_get_pad_list(element);
|
|
while (pads) {
|
|
otherpad = GST_PAD(pads->data);
|
|
pads = g_list_next(pads);
|
|
|
|
if (gst_pad_get_direction(otherpad) != dir) {
|
|
result &= gst_pad_send_event (GST_REAL_PAD(otherpad), event);
|
|
}
|
|
}
|
|
|
|
/* result is combined result of all handlers? */
|
|
return result;
|
|
}
|
|
|
|
|