mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-07-26 16:28:25 +00:00
49de56dd1f
Original commit message from CVS: * docs/design/part-gstghostpad.txt: Small update. * gst/gstbin.c: (unlink_pads), (gst_bin_add_func), (gst_bin_remove_func): Unlinking pads while holding the bin LOCK is not a good idea. * gst/gstpad.c: (gst_pad_class_init), (gst_pad_link_check_hierarchy), (gst_pad_get_caps_unlocked), (gst_pad_accept_caps), (gst_pad_set_caps), (gst_pad_send_event): No prob setting template after creating the pad.
302 lines
9.2 KiB
Plaintext
302 lines
9.2 KiB
Plaintext
Ghostpads
|
|
---------
|
|
|
|
GhostPads are used to build complex compound elements out of
|
|
existing elements. They are used to expose internal element pads
|
|
on the complex element.
|
|
|
|
Some design requirements
|
|
|
|
- Must look like a real GstPad on both sides.
|
|
- target of Ghostpad must be changeable
|
|
|
|
|
|
* a GhostPad is implemented using a smaller GstProxyPad class:
|
|
|
|
|
|
GstProxyPad
|
|
(------------------)
|
|
| GstPad |
|
|
|------------------|
|
|
| GstPad *target |
|
|
(------------------)
|
|
|
|
|
|
GstGhostPad
|
|
(------------------) -\
|
|
| GstPad | |
|
|
|------------------| > GstProxyPad
|
|
| GstPad *target | |
|
|
|------------------| -/
|
|
| GstPad *internal |
|
|
(------------------)
|
|
|
|
|
|
Some use case follow with a description of how the datastructure
|
|
is modified.
|
|
|
|
|
|
* Creating a ghostpad with a target:
|
|
|
|
gst_ghost_pad_new (char *name, GstPad *target)
|
|
|
|
1) create new GstGhostPad X
|
|
2) X name set to @name
|
|
3) X direction is the same as the target
|
|
4) the target is set to @target
|
|
5) internal is NULL
|
|
6) link/unlink and activate functions are set up
|
|
on GstGhostPad.
|
|
|
|
|
|
(--------------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------------> | sink |
|
|
|------------| |------)
|
|
| internal *---->// (--------------
|
|
(------------)
|
|
|
|
- Automatically takes same direction as target.
|
|
- target is filled in automatically.
|
|
|
|
|
|
* Creating a ghostpad without a target
|
|
|
|
gst_ghost_pad_new_notarget (char *name, GstPadDirection dir)
|
|
|
|
1) create new GstGhostPad X
|
|
2) X name set to @name
|
|
3) X direction is @dir
|
|
4) internal is NULL
|
|
5) link/unlink and activate functions are set up
|
|
on GstGhostPad.
|
|
|
|
|
|
(- X --------)
|
|
| |
|
|
| target *------>//
|
|
|------------|
|
|
| internal *---->//
|
|
(------------)
|
|
|
|
- allows for setting the target later
|
|
|
|
|
|
* Setting target on an untargetted unlinked ghostpad
|
|
|
|
gst_ghost_pad_set_target (char *name, GstPad *newtarget)
|
|
|
|
(- X --------)
|
|
| |
|
|
| target *------>//
|
|
|------------|
|
|
| internal *---->//
|
|
(------------)
|
|
|
|
1) assert direction of newtarget == X direction
|
|
2) target is set to newtarget
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
|------------| |------)
|
|
| internal *--->// (--------
|
|
(------------)
|
|
|
|
|
|
* Setting target on an targetted unlinked ghostpad
|
|
|
|
gst_ghost_pad_set_target (char *name, GstPad *newtarget)
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
|------------| |------)
|
|
| internal *--->// (--------
|
|
(------------)
|
|
|
|
1) assert direction of newtarget == X direction
|
|
2) target is set to newtarget
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
|------------| |------)
|
|
| internal *--->// (--------
|
|
(------------)
|
|
|
|
|
|
* Linking a pad to an untargetted ghostpad:
|
|
|
|
gst_pad_link (src, X)
|
|
|
|
|
|
(- X --------)
|
|
| |
|
|
| target *------>//
|
|
|------------|
|
|
| internal *---->//
|
|
(------------)
|
|
-------)
|
|
|
|
|
(-----|
|
|
| src |
|
|
(-----|
|
|
-------)
|
|
|
|
|
|
1) link function is called
|
|
a) new GstProxyPad Y is created
|
|
b) Y direction is same as peer
|
|
c) Y target is set to peer
|
|
d) X internal pad is set to Y (X is parent of Y)
|
|
e) Y is activated in the same mode as X
|
|
f) core makes link from src to X
|
|
|
|
|
|
(- X --------)
|
|
| |
|
|
| target *----->//
|
|
>|------------|
|
|
(real pad link) / | internal * |
|
|
/ (----------|-)
|
|
/ |
|
|
-------) / V
|
|
| / (- Y ------)
|
|
(-----|/ | |
|
|
| src |<-------------* target |
|
|
(-----| (----------)
|
|
-------)
|
|
|
|
|
|
* Linking a pad to a targetted ghostpad:
|
|
|
|
gst_pad_link (src, X)
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
|------------| |------)
|
|
| internal *--->// (--------
|
|
(------------)
|
|
-------)
|
|
|
|
|
(-----|
|
|
| src |
|
|
(-----|
|
|
-------)
|
|
|
|
|
|
1) link function is called
|
|
a) new GstProxyPad Y is created
|
|
b) Y direction is same as peer
|
|
c) Y target is set to peer
|
|
d) X internal pad is set to Y (X is parent of Y)
|
|
e) link is made from Y to X target (sink)
|
|
f) Y is activated in the same mode as X
|
|
g) core makes link from src to X
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
>|------------| >|------)
|
|
(real pad link) / | internal * | / (--------
|
|
/ (----------|-) /
|
|
/ | /
|
|
-------) / V / (real pad link)
|
|
| / (- Y ------) /
|
|
(-----|/ | |/
|
|
| src |<-------------* target |
|
|
(-----| (----------)
|
|
-------)
|
|
|
|
|
|
* Setting target on untargetted linked ghostpad:
|
|
|
|
gst_ghost_pad_set_target (char *name, GstPad *newtarget)
|
|
|
|
|
|
(- X --------)
|
|
| |
|
|
| target *----->//
|
|
>|------------|
|
|
(real pad link) / | internal * |
|
|
/ (----------|-)
|
|
/ |
|
|
-------) / V
|
|
| / (- Y ------)
|
|
(-----|/ | |
|
|
| src |<-------------* target |
|
|
(-----| (----------)
|
|
-------)
|
|
|
|
1) assert direction of newtarget == X direction
|
|
2) X target is set to newtarget
|
|
3) Y (X internal) is linked to newtarget
|
|
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
>|------------| >|------)
|
|
(real pad link) / | internal * | / (--------
|
|
/ (----------|-) /
|
|
/ | /
|
|
-------) / V / (real pad link)
|
|
| / (- Y ------) /
|
|
(-----|/ | |/
|
|
| src |<-------------* target |
|
|
(-----| (----------)
|
|
-------)
|
|
|
|
|
|
* Setting target on targetted linked ghostpad:
|
|
|
|
gst_ghost_pad_set_target (char *name, GstPad *newtarget)
|
|
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
>|------------| >|------)
|
|
(real pad link) / | internal * | / (--------
|
|
/ (----------|-) /
|
|
/ | /
|
|
-------) / V / (real pad link)
|
|
| / (- Y ------) /
|
|
(-----|/ | |/
|
|
| src |<-------------* target |
|
|
(-----| (----------)
|
|
-------)
|
|
|
|
1) assert direction of newtarget == X direction
|
|
2) Y and X target are unlinked
|
|
2) X target is set to newtarget
|
|
3) Y (X internal) is linked to newtarget
|
|
|
|
|
|
(--------
|
|
(- X --------) |
|
|
| | |------)
|
|
| target *------------->| sink |
|
|
>|------------| >|------)
|
|
(real pad link) / | internal * | / (--------
|
|
/ (----------|-) /
|
|
/ | /
|
|
-------) / V / (real pad link)
|
|
| / (- Y ------) /
|
|
(-----|/ | |/
|
|
| src |<-------------* target |
|
|
(-----| (----------)
|
|
-------)
|
|
|
|
|