diff --git a/docs/random/ensonic/lazycaps.txt b/docs/random/ensonic/lazycaps.txt new file mode 100644 index 0000000000..b631472719 --- /dev/null +++ b/docs/random/ensonic/lazycaps.txt @@ -0,0 +1,70 @@ +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 +- 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. + +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