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70 lines
2.3 KiB
Text
70 lines
2.3 KiB
Text
Lazy Caps
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=========
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The idea is to have caps where we evaluate the structures as needed. We can have
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these variants of lazy caps:
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- construction (e.g. from_string)
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- need user_data (the string/string-array)
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- need a free_func for the user_data
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- need a get_structure_func to fill structure slots as needed
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- operations (e.g. intersect) (see [1]).
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- need user_data (the iterator)
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- need a free_func for the user_data
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- need a get_structure_func to fill structure slots as needed
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We should add PERFORMANCE category logging to methods that cause lazy caps to be
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fully evaluated.
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We can use GST_CAPS_FLAGS_LAZY to indicate that caps are not fully constructed.
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Once caps are fully evaluated, we can remove the flag (and call the free_func).
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Lazy caps might need a lock to protect multiple threads requesting a structure
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(get_structure_func).
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Accessors
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---------
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guint gst_caps_get_size (const GstCaps *caps);
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- needs to fully evaluate the caps if iterator based :/
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GstStructure *gst_caps_get_structure (const GstCaps *caps, guint index);- needs to fully evaluate the caps if iterator based :/
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- needs to evaluate all entries up to index if iterator based
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- needs to only evaluate requested index if e.g. parse based
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gchar *gst_caps_to_string (const GstCaps * caps)
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- needs to fully evaluate the caps
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- it is used in debugging and serialisation
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Construction
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------------
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Manipulation
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------------
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void gst_caps_append (GstCaps *caps1, GstCaps *caps2);
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- use an iterator
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void gst_caps_merge (GstCaps *caps1, GstCaps *caps2);
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- use an iterator
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void gst_caps_append_structure (GstCaps *caps, GstStructure *structure);
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void gst_caps_remove_structure (GstCaps *caps, guint idx);
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void gst_caps_merge_structure (GstCaps *caps,
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- fully evaluate caps?
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GstCaps * gst_caps_copy_nth (const GstCaps *caps, guint nth);
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- eval stucture and copy
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void gst_caps_truncate (GstCaps *caps);
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- eval first structure as needed and remove GST_CAPS_FLAGS_LAZY + call free_func
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void gst_caps_set_value (GstCaps *caps, const char *field, const GValue *value);
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void gst_caps_set_simple (GstCaps *caps, const char *field, ...);
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void gst_caps_set_simple_valist (GstCaps *caps, const char *field, va_list varargs);
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- fully evaluate caps
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Operations
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----------
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[1] https://bugzilla.gnome.org/show_bug.cgi?id=618853
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