mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-29 19:50:40 +00:00
72 lines
2.4 KiB
Text
72 lines
2.4 KiB
Text
Lazy Caps
|
|
=========
|
|
|
|
The idea is to have caps where we evaluate the structures as needed. We can have
|
|
these variants of lazy caps:
|
|
|
|
- construction (e.g. from_string)
|
|
- need user_data (the string/string-array)
|
|
- need a free_func for the user_data
|
|
- need a get_structure_func to fill structure slots as needed
|
|
- we can more easily make this iterator based too
|
|
- operations (e.g. intersect) (see [1]).
|
|
- need user_data (the iterator)
|
|
- need a free_func for the user_data
|
|
- need a get_structure_func to fill structure slots as needed
|
|
|
|
We should add PERFORMANCE category logging to methods that cause lazy caps to be
|
|
fully evaluated. To get maximum speed benefit we need to inspect places that
|
|
loop over structures of a caps and turn them into while() loops where possible.
|
|
|
|
We can use GST_CAPS_FLAGS_LAZY to indicate that caps are not fully constructed.
|
|
Once caps are fully evaluated, we can remove the flag (and call the free_func).
|
|
|
|
Lazy caps might need a lock to protect multiple threads requesting a structure
|
|
(get_structure_func).
|
|
|
|
Accessors
|
|
---------
|
|
guint gst_caps_get_size (const GstCaps *caps);
|
|
- needs to fully evaluate the caps if iterator based :/
|
|
|
|
GstStructure *gst_caps_get_structure (const GstCaps *caps, guint index);- needs to fully evaluate the caps if iterator based :/
|
|
- needs to evaluate all entries up to index if iterator based
|
|
- needs to only evaluate requested index if e.g. parse based
|
|
|
|
gchar *gst_caps_to_string (const GstCaps * caps)
|
|
- needs to fully evaluate the caps
|
|
- it is used in debugging and serialisation
|
|
|
|
Construction
|
|
------------
|
|
|
|
Manipulation
|
|
------------
|
|
void gst_caps_append (GstCaps *caps1, GstCaps *caps2);
|
|
- use an iterator
|
|
|
|
void gst_caps_merge (GstCaps *caps1, GstCaps *caps2);
|
|
- use an iterator
|
|
|
|
void gst_caps_append_structure (GstCaps *caps, GstStructure *structure);
|
|
void gst_caps_remove_structure (GstCaps *caps, guint idx);
|
|
void gst_caps_merge_structure (GstCaps *caps,
|
|
- fully evaluate caps?
|
|
|
|
GstCaps * gst_caps_copy_nth (const GstCaps *caps, guint nth);
|
|
- eval stucture and copy
|
|
|
|
void gst_caps_truncate (GstCaps *caps);
|
|
- eval first structure as needed and remove GST_CAPS_FLAGS_LAZY + call free_func
|
|
|
|
void gst_caps_set_value (GstCaps *caps, const char *field, const GValue *value);
|
|
void gst_caps_set_simple (GstCaps *caps, const char *field, ...);
|
|
void gst_caps_set_simple_valist (GstCaps *caps, const char *field, va_list varargs);
|
|
- fully evaluate caps
|
|
|
|
|
|
Operations
|
|
----------
|
|
|
|
|
|
[1] https://bugzilla.gnome.org/show_bug.cgi?id=618853
|