2 * Copyright (C) <2003> David A. Schleef <ds@schleef.org>
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
22 * @short_description: Structure describing sets of media formats
23 * @see_also: #GstStructure
25 * Caps (capabilities) are lighweight refcounted objects describing media types.
26 * They are composed of an array of #GstStructure.
28 * Caps are exposed on #GstPadTemplate to describe all possible types a
29 * given pad can handle. They are also stored in the #GstRegistry along with
30 * a description of the #GstElement.
32 * Caps are exposed on the element pads using the gst_pad_get_caps() pad
33 * function. This function describes the possible types that the pad can
34 * handle or produce at runtime.
36 * Caps are also attached to buffers to describe to content of the data
37 * pointed to by the buffer with gst_buffer_set_caps(). Caps attached to
38 * a #GstBuffer allow for format negotiation upstream and downstream.
40 * A #GstCaps can be constructed with the following code fragment:
43 * <title>Creating caps</title>
46 * caps = gst_caps_new_simple ("video/x-raw-yuv",
47 * "format", GST_TYPE_FOURCC, GST_MAKE_FOURCC ('I', '4', '2', '0'),
48 * "framerate", GST_TYPE_FRACTION, 25, 1,
49 * "pixel-aspect-ratio", GST_TYPE_FRACTION, 1, 1,
50 * "width", G_TYPE_INT, 320,
51 * "height", G_TYPE_INT, 240,
56 * A #GstCaps is fixed when it has no properties with ranges or lists. Use
57 * gst_caps_is_fixed() to test for fixed caps. Only fixed caps can be
58 * set on a #GstPad or #GstBuffer.
60 * Various methods exist to work with the media types such as subtracting
63 * Last reviewed on 2007-02-13 (0.10.10)
72 #include "gst_private.h"
75 #define DEBUG_REFCOUNT
77 #define CAPS_POISON(caps) G_STMT_START{ \
79 GstCaps *_newcaps = gst_caps_copy (caps); \
80 gst_caps_unref(caps); \
84 #define STRUCTURE_POISON(structure) G_STMT_START{ \
86 GstStructure *_newstruct = gst_structure_copy (structure); \
87 gst_structure_free(structure); \
88 structure = _newstruct; \
91 #define IS_WRITABLE(caps) \
92 (g_atomic_int_get (&(caps)->refcount) == 1)
94 /* lock to protect multiple invocations of static caps to caps conversion */
95 G_LOCK_DEFINE_STATIC (static_caps_lock);
97 static void gst_caps_transform_to_string (const GValue * src_value,
99 static gboolean gst_caps_from_string_inplace (GstCaps * caps,
100 const gchar * string);
101 static GstCaps *gst_caps_copy_conditional (GstCaps * src);
104 gst_caps_get_type (void)
106 static GType gst_caps_type = 0;
108 if (G_UNLIKELY (gst_caps_type == 0)) {
109 gst_caps_type = g_boxed_type_register_static ("GstCaps",
110 (GBoxedCopyFunc) gst_caps_copy_conditional,
111 (GBoxedFreeFunc) gst_caps_unref);
113 g_value_register_transform_func (gst_caps_type,
114 G_TYPE_STRING, gst_caps_transform_to_string);
117 return gst_caps_type;
120 /* creation/deletion */
123 * gst_caps_new_empty:
125 * Creates a new #GstCaps that is empty. That is, the returned
126 * #GstCaps contains no media formats.
127 * Caller is responsible for unreffing the returned caps.
129 * Returns: the new #GstCaps
132 gst_caps_new_empty (void)
134 GstCaps *caps = g_slice_new (GstCaps);
136 caps->type = GST_TYPE_CAPS;
139 caps->structs = g_ptr_array_new ();
141 #ifdef DEBUG_REFCOUNT
142 GST_CAT_LOG (GST_CAT_CAPS, "created caps %p", caps);
151 * Creates a new #GstCaps that indicates that it is compatible with
154 * Returns: the new #GstCaps
157 gst_caps_new_any (void)
159 GstCaps *caps = gst_caps_new_empty ();
161 caps->flags = GST_CAPS_FLAGS_ANY;
167 * gst_caps_new_simple:
168 * @media_type: the media type of the structure
169 * @fieldname: first field to set
170 * @...: additional arguments
172 * Creates a new #GstCaps that contains one #GstStructure. The
173 * structure is defined by the arguments, which have the same format
174 * as gst_structure_new().
175 * Caller is responsible for unreffing the returned caps.
177 * Returns: the new #GstCaps
180 gst_caps_new_simple (const char *media_type, const char *fieldname, ...)
183 GstStructure *structure;
186 caps = gst_caps_new_empty ();
188 va_start (var_args, fieldname);
189 structure = gst_structure_new_valist (media_type, fieldname, var_args);
192 gst_caps_append_structure (caps, structure);
199 * @struct1: the first structure to add
200 * @...: additional structures to add
202 * Creates a new #GstCaps and adds all the structures listed as
203 * arguments. The list must be NULL-terminated. The structures
204 * are not copied; the returned #GstCaps owns the structures.
206 * Returns: the new #GstCaps
209 gst_caps_new_full (GstStructure * struct1, ...)
214 va_start (var_args, struct1);
215 caps = gst_caps_new_full_valist (struct1, var_args);
222 * gst_caps_new_full_valist:
223 * @structure: the first structure to add
224 * @var_args: additional structures to add
226 * Creates a new #GstCaps and adds all the structures listed as
227 * arguments. The list must be NULL-terminated. The structures
228 * are not copied; the returned #GstCaps owns the structures.
230 * Returns: the new #GstCaps
233 gst_caps_new_full_valist (GstStructure * structure, va_list var_args)
237 caps = gst_caps_new_empty ();
240 gst_caps_append_structure (caps, structure);
241 structure = va_arg (var_args, GstStructure *);
249 * @caps: the #GstCaps to copy
251 * Creates a new #GstCaps as a copy of the old @caps. The new caps will have a
252 * refcount of 1, owned by the caller. The structures are copied as well.
254 * Note that this function is the semantic equivalent of a gst_caps_ref()
255 * followed by a gst_caps_make_writable(). If you only want to hold on to a
256 * reference to the data, you should use gst_caps_ref().
258 * When you are finished with the caps, call gst_caps_unref() on it.
260 * Returns: the new #GstCaps
263 gst_caps_copy (const GstCaps * caps)
266 GstStructure *structure;
269 g_return_val_if_fail (GST_IS_CAPS (caps), NULL);
271 newcaps = gst_caps_new_empty ();
272 newcaps->flags = caps->flags;
274 for (i = 0; i < caps->structs->len; i++) {
275 structure = gst_caps_get_structure (caps, i);
276 gst_caps_append_structure (newcaps, gst_structure_copy (structure));
283 _gst_caps_free (GstCaps * caps)
285 GstStructure *structure;
288 /* The refcount must be 0, but since we're only called by gst_caps_unref,
289 * don't bother testing. */
291 for (i = 0; i < caps->structs->len; i++) {
292 structure = (GstStructure *) gst_caps_get_structure (caps, i);
293 gst_structure_set_parent_refcount (structure, NULL);
294 gst_structure_free (structure);
296 g_ptr_array_free (caps->structs, TRUE);
298 memset (caps, 0xff, sizeof (GstCaps));
301 #ifdef DEBUG_REFCOUNT
302 GST_CAT_LOG (GST_CAT_CAPS, "freeing caps %p", caps);
304 g_slice_free (GstCaps, caps);
308 * gst_caps_make_writable:
309 * @caps: the #GstCaps to make writable
311 * Returns a writable copy of @caps.
313 * If there is only one reference count on @caps, the caller must be the owner,
314 * and so this function will return the caps object unchanged. If on the other
315 * hand there is more than one reference on the object, a new caps object will
316 * be returned. The caller's reference on @caps will be removed, and instead the
317 * caller will own a reference to the returned object.
319 * In short, this function unrefs the caps in the argument and refs the caps
320 * that it returns. Don't access the argument after calling this function. See
321 * also: gst_caps_ref().
323 * Returns: the same #GstCaps object.
326 gst_caps_make_writable (GstCaps * caps)
330 g_return_val_if_fail (caps != NULL, NULL);
332 /* we are the only instance reffing this caps */
333 if (g_atomic_int_get (&caps->refcount) == 1)
337 copy = gst_caps_copy (caps);
338 gst_caps_unref (caps);
345 * @caps: the #GstCaps to reference
347 * Add a reference to a #GstCaps object.
349 * From this point on, until the caller calls gst_caps_unref() or
350 * gst_caps_make_writable(), it is guaranteed that the caps object will not
351 * change. This means its structures won't change, etc. To use a #GstCaps
352 * object, you must always have a refcount on it -- either the one made
353 * implicitly by gst_caps_new(), or via taking one explicitly with this
356 * Returns: the same #GstCaps object.
359 gst_caps_ref (GstCaps * caps)
361 g_return_val_if_fail (caps != NULL, NULL);
363 #ifdef DEBUG_REFCOUNT
364 GST_CAT_LOG (GST_CAT_REFCOUNTING, "%p %d->%d", caps,
365 GST_CAPS_REFCOUNT_VALUE (caps), GST_CAPS_REFCOUNT_VALUE (caps) + 1);
367 g_return_val_if_fail (GST_CAPS_REFCOUNT_VALUE (caps) > 0, NULL);
369 g_atomic_int_inc (&caps->refcount);
376 * @caps: the #GstCaps to unref
378 * Unref a #GstCaps and and free all its structures and the
379 * structures' values when the refcount reaches 0.
382 gst_caps_unref (GstCaps * caps)
384 g_return_if_fail (caps != NULL);
386 #ifdef DEBUG_REFCOUNT
387 GST_CAT_LOG (GST_CAT_REFCOUNTING, "%p %d->%d", caps,
388 GST_CAPS_REFCOUNT_VALUE (caps), GST_CAPS_REFCOUNT_VALUE (caps) - 1);
391 g_return_if_fail (GST_CAPS_REFCOUNT_VALUE (caps) > 0);
393 /* if we ended up with the refcount at zero, free the caps */
394 if (G_UNLIKELY (g_atomic_int_dec_and_test (&caps->refcount)))
395 _gst_caps_free (caps);
399 gst_static_caps_get_type (void)
401 static GType staticcaps_type = 0;
403 if (G_UNLIKELY (staticcaps_type == 0)) {
404 staticcaps_type = g_pointer_type_register_static ("GstStaticCaps");
406 return staticcaps_type;
411 * gst_static_caps_get:
412 * @static_caps: the #GstStaticCaps to convert
414 * Converts a #GstStaticCaps to a #GstCaps.
416 * Returns: A pointer to the #GstCaps. Unref after usage. Since the
417 * core holds an additional ref to the returned caps,
418 * use gst_caps_make_writable() on the returned caps to modify it.
421 gst_static_caps_get (GstStaticCaps * static_caps)
425 g_return_val_if_fail (static_caps != NULL, NULL);
427 caps = (GstCaps *) static_caps;
429 /* refcount is 0 when we need to convert */
430 if (G_UNLIKELY (g_atomic_int_get (&caps->refcount) == 0)) {
434 G_LOCK (static_caps_lock);
435 /* check if other thread already updated */
436 if (G_UNLIKELY (g_atomic_int_get (&caps->refcount) > 0))
439 string = static_caps->string;
441 if (G_UNLIKELY (string == NULL))
444 GST_CAT_LOG (GST_CAT_CAPS, "creating %p", static_caps);
446 /* we construct the caps on the stack, then copy over the struct into our
447 * real caps, refcount last. We do this because we must leave the refcount
448 * of the result caps to 0 so that other threads don't run away with the
449 * caps while we are constructing it. */
450 temp.type = GST_TYPE_CAPS;
452 temp.structs = g_ptr_array_new ();
454 /* initialize the caps to a refcount of 1 so the caps can be writable for
455 * the next statement */
458 /* convert to string */
459 if (G_UNLIKELY (!gst_caps_from_string_inplace (&temp, string)))
460 g_critical ("Could not convert static caps \"%s\"", string);
462 /* now copy stuff over to the real caps. */
463 caps->type = temp.type;
464 caps->flags = temp.flags;
465 caps->structs = temp.structs;
466 /* and bump the refcount so other threads can now read */
467 g_atomic_int_set (&caps->refcount, 1);
469 GST_CAT_LOG (GST_CAT_CAPS, "created %p", static_caps);
471 G_UNLOCK (static_caps_lock);
473 /* ref the caps, makes it not writable */
481 G_UNLOCK (static_caps_lock);
482 g_warning ("static caps %p string is NULL", static_caps);
488 static GstStructure *
489 gst_caps_remove_and_get_structure (GstCaps * caps, guint idx)
491 /* don't use index_fast, gst_caps_do_simplify relies on the order */
492 GstStructure *s = g_ptr_array_remove_index (caps->structs, idx);
494 gst_structure_set_parent_refcount (s, NULL);
499 gst_structure_is_equal_foreach (GQuark field_id, const GValue * val2,
502 GstStructure *struct1 = (GstStructure *) data;
503 const GValue *val1 = gst_structure_id_get_value (struct1, field_id);
507 if (gst_value_compare (val1, val2) == GST_VALUE_EQUAL) {
515 gst_caps_structure_is_subset_field (GQuark field_id, const GValue * value,
518 GstStructure *subtract_from = user_data;
519 GValue subtraction = { 0, };
523 other = gst_structure_id_get_value (subtract_from, field_id);
525 /* field is missing in one set */
532 if (!gst_value_subtract (&subtraction, other, value)) {
533 /* empty result -> values are the same, or first was a value and
535 * verify that result is empty by swapping args */
536 if (!gst_value_subtract (&subtraction, value, other)) {
539 g_value_unset (&subtraction);
543 res = gst_value_compare (&subtraction, other);
544 g_value_unset (&subtraction);
546 if (res == GST_VALUE_EQUAL) {
547 /* value was empty ? */
555 gst_caps_structure_is_subset (const GstStructure * minuend,
556 const GstStructure * subtrahend)
558 if ((minuend->name != subtrahend->name) ||
559 (gst_structure_n_fields (minuend) !=
560 gst_structure_n_fields (subtrahend))) {
564 return gst_structure_foreach ((GstStructure *) subtrahend,
565 gst_caps_structure_is_subset_field, (gpointer) minuend);
570 * @caps1: the #GstCaps that will be appended to
571 * @caps2: the #GstCaps to append
573 * Appends the structures contained in @caps2 to @caps1. The structures in
574 * @caps2 are not copied -- they are transferred to @caps1, and then @caps2 is
575 * freed. If either caps is ANY, the resulting caps will be ANY.
578 gst_caps_append (GstCaps * caps1, GstCaps * caps2)
580 GstStructure *structure;
583 g_return_if_fail (GST_IS_CAPS (caps1));
584 g_return_if_fail (GST_IS_CAPS (caps2));
585 g_return_if_fail (IS_WRITABLE (caps1));
586 g_return_if_fail (IS_WRITABLE (caps2));
591 if (gst_caps_is_any (caps1) || gst_caps_is_any (caps2)) {
592 /* FIXME: this leaks */
593 caps1->flags |= GST_CAPS_FLAGS_ANY;
594 for (i = caps2->structs->len - 1; i >= 0; i--) {
595 structure = gst_caps_remove_and_get_structure (caps2, i);
596 gst_structure_free (structure);
599 int len = caps2->structs->len;
601 for (i = 0; i < len; i++) {
602 structure = gst_caps_remove_and_get_structure (caps2, 0);
603 gst_caps_append_structure (caps1, structure);
606 gst_caps_unref (caps2); /* guaranteed to free it */
611 * @caps1: the #GstCaps that will take the new entries
612 * @caps2: the #GstCaps to merge in
614 * Appends the structures contained in @caps2 to @caps1 if they are not yet
615 * expressed by @caps1. The structures in @caps2 are not copied -- they are
616 * transferred to @caps1, and then @caps2 is freed.
617 * If either caps is ANY, the resulting caps will be ANY.
622 gst_caps_merge (GstCaps * caps1, GstCaps * caps2)
624 GstStructure *structure;
627 g_return_if_fail (GST_IS_CAPS (caps1));
628 g_return_if_fail (GST_IS_CAPS (caps2));
629 g_return_if_fail (IS_WRITABLE (caps1));
630 g_return_if_fail (IS_WRITABLE (caps2));
635 if (gst_caps_is_any (caps1)) {
636 for (i = caps2->structs->len - 1; i >= 0; i--) {
637 structure = gst_caps_remove_and_get_structure (caps2, i);
638 gst_structure_free (structure);
640 } else if (gst_caps_is_any (caps2)) {
641 caps1->flags |= GST_CAPS_FLAGS_ANY;
642 for (i = caps1->structs->len - 1; i >= 0; i--) {
643 structure = gst_caps_remove_and_get_structure (caps1, i);
644 gst_structure_free (structure);
647 int len = caps2->structs->len;
649 for (i = 0; i < len; i++) {
650 structure = gst_caps_remove_and_get_structure (caps2, 0);
651 gst_caps_merge_structure (caps1, structure);
654 GstCaps *com = gst_caps_intersect (caps1, caps2);
655 GstCaps *add = gst_caps_subtract (caps2, com);
657 GST_DEBUG ("common : %d", gst_caps_get_size (com));
658 GST_DEBUG ("adding : %d", gst_caps_get_size (add));
659 gst_caps_append (caps1, add);
660 gst_caps_unref (com);
663 gst_caps_unref (caps2); /* guaranteed to free it */
667 * gst_caps_append_structure:
668 * @caps: the #GstCaps that will be appended to
669 * @structure: the #GstStructure to append
671 * Appends @structure to @caps. The structure is not copied; @caps
672 * becomes the owner of @structure.
675 gst_caps_append_structure (GstCaps * caps, GstStructure * structure)
677 g_return_if_fail (GST_IS_CAPS (caps));
678 g_return_if_fail (IS_WRITABLE (caps));
680 if (G_LIKELY (structure)) {
681 g_return_if_fail (structure->parent_refcount == NULL);
684 STRUCTURE_POISON (structure);
687 gst_structure_set_parent_refcount (structure, &caps->refcount);
688 g_ptr_array_add (caps->structs, structure);
693 * gst_caps_remove_structure:
694 * @caps: the #GstCaps to remove from
695 * @idx: Index of the structure to remove
697 * removes the stucture with the given index from the list of structures
698 * contained in @caps.
701 gst_caps_remove_structure (GstCaps * caps, guint idx)
703 GstStructure *structure;
705 g_return_if_fail (caps != NULL);
706 g_return_if_fail (idx <= gst_caps_get_size (caps));
707 g_return_if_fail (IS_WRITABLE (caps));
709 structure = gst_caps_remove_and_get_structure (caps, idx);
710 gst_structure_free (structure);
714 * gst_caps_merge_structure:
715 * @caps: the #GstCaps that will the the new structure
716 * @structure: the #GstStructure to merge
718 * Appends @structure to @caps if its not already expressed by @caps. The
719 * structure is not copied; @caps becomes the owner of @structure.
722 gst_caps_merge_structure (GstCaps * caps, GstStructure * structure)
724 g_return_if_fail (GST_IS_CAPS (caps));
725 g_return_if_fail (IS_WRITABLE (caps));
727 if (G_LIKELY (structure)) {
728 GstStructure *structure1;
730 gboolean unique = TRUE;
732 g_return_if_fail (structure->parent_refcount == NULL);
735 STRUCTURE_POISON (structure);
738 /* check each structure */
739 for (i = caps->structs->len - 1; i >= 0; i--) {
740 structure1 = gst_caps_get_structure (caps, i);
741 /* if structure is a subset of structure1, then skip it */
742 if (gst_caps_structure_is_subset (structure1, structure)) {
748 gst_structure_set_parent_refcount (structure, &caps->refcount);
749 g_ptr_array_add (caps->structs, structure);
751 gst_structure_free (structure);
761 * Gets the number of structures contained in @caps.
763 * Returns: the number of structures that @caps contains
766 gst_caps_get_size (const GstCaps * caps)
768 g_return_val_if_fail (GST_IS_CAPS (caps), 0);
770 return caps->structs->len;
774 * gst_caps_get_structure:
776 * @index: the index of the structure
778 * Finds the structure in @caps that has the index @index, and
781 * WARNING: This function takes a const GstCaps *, but returns a
782 * non-const GstStructure *. This is for programming convenience --
783 * the caller should be aware that structures inside a constant
784 * #GstCaps should not be modified.
786 * Returns: a pointer to the #GstStructure corresponding to @index
789 gst_caps_get_structure (const GstCaps * caps, guint index)
791 g_return_val_if_fail (GST_IS_CAPS (caps), NULL);
792 g_return_val_if_fail (index < caps->structs->len, NULL);
794 return g_ptr_array_index (caps->structs, index);
799 * @caps: the #GstCaps to copy
800 * @nth: the nth structure to copy
802 * Creates a new #GstCaps and appends a copy of the nth structure
803 * contained in @caps.
805 * Returns: the new #GstCaps
808 gst_caps_copy_nth (const GstCaps * caps, guint nth)
811 GstStructure *structure;
813 g_return_val_if_fail (GST_IS_CAPS (caps), NULL);
815 newcaps = gst_caps_new_empty ();
816 newcaps->flags = caps->flags;
818 if (caps->structs->len > nth) {
819 structure = gst_caps_get_structure (caps, nth);
820 gst_caps_append_structure (newcaps, gst_structure_copy (structure));
828 * @caps: the #GstCaps to truncate
830 * Destructively discard all but the first structure from @caps. Useful when
831 * fixating. @caps must be writable.
834 gst_caps_truncate (GstCaps * caps)
838 g_return_if_fail (GST_IS_CAPS (caps));
839 g_return_if_fail (IS_WRITABLE (caps));
841 i = caps->structs->len - 1;
844 gst_caps_remove_structure (caps, i--);
848 * gst_caps_set_simple:
849 * @caps: the #GstCaps to set
850 * @field: first field to set
851 * @...: additional parameters
853 * Sets fields in a simple #GstCaps. A simple #GstCaps is one that
854 * only has one structure. The arguments must be passed in the same
855 * manner as gst_structure_set(), and be NULL-terminated.
858 gst_caps_set_simple (GstCaps * caps, const char *field, ...)
860 GstStructure *structure;
863 g_return_if_fail (GST_IS_CAPS (caps));
864 g_return_if_fail (caps->structs->len == 1);
865 g_return_if_fail (IS_WRITABLE (caps));
867 structure = gst_caps_get_structure (caps, 0);
869 va_start (var_args, field);
870 gst_structure_set_valist (structure, field, var_args);
875 * gst_caps_set_simple_valist:
876 * @caps: the #GstCaps to copy
877 * @field: first field to set
878 * @varargs: additional parameters
880 * Sets fields in a simple #GstCaps. A simple #GstCaps is one that
881 * only has one structure. The arguments must be passed in the same
882 * manner as gst_structure_set(), and be NULL-terminated.
885 gst_caps_set_simple_valist (GstCaps * caps, const char *field, va_list varargs)
887 GstStructure *structure;
889 g_return_if_fail (GST_IS_CAPS (caps));
890 g_return_if_fail (caps->structs->len == 1);
891 g_return_if_fail (IS_WRITABLE (caps));
893 structure = gst_caps_get_structure (caps, 0);
895 gst_structure_set_valist (structure, field, varargs);
902 * @caps: the #GstCaps to test
904 * Determines if @caps represents any media format.
906 * Returns: TRUE if @caps represents any format.
909 gst_caps_is_any (const GstCaps * caps)
911 g_return_val_if_fail (GST_IS_CAPS (caps), FALSE);
913 return (caps->flags & GST_CAPS_FLAGS_ANY);
918 * @caps: the #GstCaps to test
920 * Determines if @caps represents no media formats.
922 * Returns: TRUE if @caps represents no formats.
925 gst_caps_is_empty (const GstCaps * caps)
927 g_return_val_if_fail (GST_IS_CAPS (caps), FALSE);
929 if (caps->flags & GST_CAPS_FLAGS_ANY)
932 return (caps->structs == NULL) || (caps->structs->len == 0);
936 gst_caps_is_fixed_foreach (GQuark field_id, const GValue * value,
939 return gst_value_is_fixed (value);
944 * @caps: the #GstCaps to test
946 * Fixed #GstCaps describe exactly one format, that is, they have exactly
947 * one structure, and each field in the structure describes a fixed type.
948 * Examples of non-fixed types are GST_TYPE_INT_RANGE and GST_TYPE_LIST.
950 * Returns: TRUE if @caps is fixed
953 gst_caps_is_fixed (const GstCaps * caps)
955 GstStructure *structure;
957 g_return_val_if_fail (GST_IS_CAPS (caps), FALSE);
959 if (caps->structs->len != 1)
962 structure = gst_caps_get_structure (caps, 0);
964 return gst_structure_foreach (structure, gst_caps_is_fixed_foreach, NULL);
968 * gst_caps_is_equal_fixed:
969 * @caps1: the #GstCaps to test
970 * @caps2: the #GstCaps to test
972 * Tests if two #GstCaps are equal. This function only works on fixed
975 * Returns: TRUE if the arguments represent the same format
978 gst_caps_is_equal_fixed (const GstCaps * caps1, const GstCaps * caps2)
980 GstStructure *struct1, *struct2;
982 g_return_val_if_fail (gst_caps_is_fixed (caps1), FALSE);
983 g_return_val_if_fail (gst_caps_is_fixed (caps2), FALSE);
985 struct1 = gst_caps_get_structure (caps1, 0);
986 struct2 = gst_caps_get_structure (caps2, 0);
988 if (struct1->name != struct2->name) {
991 if (struct1->fields->len != struct2->fields->len) {
995 return gst_structure_foreach (struct1, gst_structure_is_equal_foreach,
1000 * gst_caps_is_always_compatible:
1001 * @caps1: the #GstCaps to test
1002 * @caps2: the #GstCaps to test
1004 * A given #GstCaps structure is always compatible with another if
1005 * every media format that is in the first is also contained in the
1006 * second. That is, @caps1 is a subset of @caps2.
1008 * Returns: TRUE if @caps1 is a subset of @caps2.
1011 gst_caps_is_always_compatible (const GstCaps * caps1, const GstCaps * caps2)
1013 g_return_val_if_fail (GST_IS_CAPS (caps1), FALSE);
1014 g_return_val_if_fail (GST_IS_CAPS (caps2), FALSE);
1016 return gst_caps_is_subset (caps1, caps2);
1020 * gst_caps_is_subset:
1021 * @subset: a #GstCaps
1022 * @superset: a potentially greater #GstCaps
1024 * Checks if all caps represented by @subset are also represented by @superset.
1025 * <note>This function does not work reliably if optional properties for caps
1026 * are included on one caps and omitted on the other.</note>
1028 * Returns: %TRUE if @subset is a subset of @superset
1031 gst_caps_is_subset (const GstCaps * subset, const GstCaps * superset)
1036 g_return_val_if_fail (subset != NULL, FALSE);
1037 g_return_val_if_fail (superset != NULL, FALSE);
1039 if (gst_caps_is_empty (subset) || gst_caps_is_any (superset))
1041 if (gst_caps_is_any (subset) || gst_caps_is_empty (superset))
1044 caps = gst_caps_subtract (subset, superset);
1045 ret = gst_caps_is_empty (caps);
1046 gst_caps_unref (caps);
1051 * gst_caps_is_equal:
1052 * @caps1: a #GstCaps
1053 * @caps2: another #GstCaps
1055 * Checks if the given caps represent the same set of caps.
1056 * <note>This function does not work reliably if optional properties for caps
1057 * are included on one caps and omitted on the other.</note>
1059 * This function deals correctly with passing NULL for any of the caps.
1061 * Returns: TRUE if both caps are equal.
1064 gst_caps_is_equal (const GstCaps * caps1, const GstCaps * caps2)
1066 /* NULL <-> NULL is allowed here */
1070 /* one of them NULL => they are different (can't be both NULL because
1071 * we checked that above) */
1072 if (caps1 == NULL || caps2 == NULL)
1075 if (gst_caps_is_fixed (caps1) && gst_caps_is_fixed (caps2))
1076 return gst_caps_is_equal_fixed (caps1, caps2);
1078 return gst_caps_is_subset (caps1, caps2) && gst_caps_is_subset (caps2, caps1);
1084 const GstStructure *intersect;
1090 gst_caps_structure_intersect_field (GQuark id, const GValue * val1,
1093 IntersectData *idata = (IntersectData *) data;
1094 GValue dest_value = { 0 };
1095 const GValue *val2 = gst_structure_id_get_value (idata->intersect, id);
1098 gst_structure_id_set_value (idata->dest, id, val1);
1099 } else if (idata->first_run) {
1100 if (gst_value_intersect (&dest_value, val1, val2)) {
1101 gst_structure_id_set_value (idata->dest, id, &dest_value);
1102 g_value_unset (&dest_value);
1111 static GstStructure *
1112 gst_caps_structure_intersect (const GstStructure * struct1,
1113 const GstStructure * struct2)
1117 g_return_val_if_fail (struct1 != NULL, NULL);
1118 g_return_val_if_fail (struct2 != NULL, NULL);
1120 if (struct1->name != struct2->name)
1123 data.dest = gst_structure_id_empty_new (struct1->name);
1124 data.intersect = struct2;
1125 data.first_run = TRUE;
1126 if (!gst_structure_foreach ((GstStructure *) struct1,
1127 gst_caps_structure_intersect_field, &data))
1130 data.intersect = struct1;
1131 data.first_run = FALSE;
1132 if (!gst_structure_foreach ((GstStructure *) struct2,
1133 gst_caps_structure_intersect_field, &data))
1139 gst_structure_free (data.dest);
1144 static GstStructure *
1145 gst_caps_structure_union (const GstStructure * struct1,
1146 const GstStructure * struct2)
1150 const GstStructureField *field1;
1151 const GstStructureField *field2;
1154 /* FIXME this doesn't actually work */
1156 if (struct1->name != struct2->name)
1159 dest = gst_structure_id_empty_new (struct1->name);
1161 for (i = 0; i < struct1->fields->len; i++) {
1162 GValue dest_value = { 0 };
1164 field1 = GST_STRUCTURE_FIELD (struct1, i);
1165 field2 = gst_structure_id_get_field (struct2, field1->name);
1167 if (field2 == NULL) {
1170 if (gst_value_union (&dest_value, &field1->value, &field2->value)) {
1171 gst_structure_set_value (dest, g_quark_to_string (field1->name),
1174 ret = gst_value_compare (&field1->value, &field2->value);
1186 * gst_caps_intersect:
1187 * @caps1: a #GstCaps to intersect
1188 * @caps2: a #GstCaps to intersect
1190 * Creates a new #GstCaps that contains all the formats that are common
1191 * to both @caps1 and @caps2.
1193 * Returns: the new #GstCaps
1196 gst_caps_intersect (const GstCaps * caps1, const GstCaps * caps2)
1198 guint64 i; /* index can be up to 2 * G_MAX_UINT */
1201 GstStructure *struct1;
1202 GstStructure *struct2;
1204 GstStructure *istruct;
1206 g_return_val_if_fail (GST_IS_CAPS (caps1), NULL);
1207 g_return_val_if_fail (GST_IS_CAPS (caps2), NULL);
1209 /* caps are exactly the same pointers, just copy one caps */
1211 return gst_caps_copy (caps1);
1213 /* empty caps on either side, return empty */
1214 if (gst_caps_is_empty (caps1) || gst_caps_is_empty (caps2))
1215 return gst_caps_new_empty ();
1217 /* one of the caps is any, just copy the other caps */
1218 if (gst_caps_is_any (caps1))
1219 return gst_caps_copy (caps2);
1220 if (gst_caps_is_any (caps2))
1221 return gst_caps_copy (caps1);
1223 dest = gst_caps_new_empty ();
1225 /* run zigzag on top line then right line, this preserves the caps order
1226 * much better than a simple loop.
1228 * This algorithm zigzags over the caps structures as demonstrated in
1229 * the folowing matrix:
1237 * First we iterate over the caps1 structures (top line) intersecting
1238 * the structures diagonally down, then we iterate over the caps2
1241 for (i = 0; i < caps1->structs->len + caps2->structs->len - 1; i++) {
1242 /* caps1 index goes from 0 to caps1->structs->len-1 */
1243 j = MIN (i, caps1->structs->len - 1);
1244 /* caps2 index stays 0 until i reaches caps1->structs->len, then it counts
1245 * up from 1 to caps2->structs->len - 1 */
1248 /* now run the diagonal line, end condition is the left or bottom
1250 while (k < caps2->structs->len) {
1251 struct1 = gst_caps_get_structure (caps1, j);
1252 struct2 = gst_caps_get_structure (caps2, k);
1254 istruct = gst_caps_structure_intersect (struct1, struct2);
1256 gst_caps_append_structure (dest, istruct);
1257 /* move down left */
1260 break; /* so we don't roll back to G_MAXUINT */
1269 const GstStructure *subtract_from;
1276 gst_caps_structure_subtract_field (GQuark field_id, const GValue * value,
1279 SubtractionEntry *e = user_data;
1280 GValue subtraction = { 0, };
1281 const GValue *other;
1282 GstStructure *structure;
1284 other = gst_structure_id_get_value (e->subtract_from, field_id);
1288 if (!gst_value_subtract (&subtraction, other, value))
1290 if (gst_value_compare (&subtraction, other) == GST_VALUE_EQUAL) {
1291 g_value_unset (&subtraction);
1294 structure = gst_structure_copy (e->subtract_from);
1295 gst_structure_id_set_value (structure, field_id, &subtraction);
1296 g_value_unset (&subtraction);
1297 e->put_into = g_slist_prepend (e->put_into, structure);
1303 gst_caps_structure_subtract (GSList ** into, const GstStructure * minuend,
1304 const GstStructure * subtrahend)
1309 e.subtract_from = minuend;
1312 ret = gst_structure_foreach ((GstStructure *) subtrahend,
1313 gst_caps_structure_subtract_field, &e);
1319 for (walk = e.put_into; walk; walk = g_slist_next (walk)) {
1320 gst_structure_free (walk->data);
1322 g_slist_free (e.put_into);
1328 * gst_caps_subtract:
1329 * @minuend: #GstCaps to substract from
1330 * @subtrahend: #GstCaps to substract
1332 * Subtracts the @subtrahend from the @minuend.
1333 * <note>This function does not work reliably if optional properties for caps
1334 * are included on one caps and omitted on the other.</note>
1336 * Returns: the resulting caps
1339 gst_caps_subtract (const GstCaps * minuend, const GstCaps * subtrahend)
1344 GstCaps *dest = NULL, *src;
1346 g_return_val_if_fail (minuend != NULL, NULL);
1347 g_return_val_if_fail (subtrahend != NULL, NULL);
1349 if (gst_caps_is_empty (minuend) || gst_caps_is_any (subtrahend)) {
1350 return gst_caps_new_empty ();
1352 if (gst_caps_is_empty (subtrahend))
1353 return gst_caps_copy (minuend);
1355 /* FIXME: Do we want this here or above?
1356 The reason we need this is that there is no definition about what
1357 ANY means for specific types, so it's not possible to reduce ANY partially
1358 You can only remove everything or nothing and that is done above.
1359 Note: there's a test that checks this behaviour. */
1360 g_return_val_if_fail (!gst_caps_is_any (minuend), NULL);
1361 g_assert (subtrahend->structs->len > 0);
1363 src = gst_caps_copy (minuend);
1364 for (i = 0; i < subtrahend->structs->len; i++) {
1365 sub = gst_caps_get_structure (subtrahend, i);
1367 gst_caps_unref (src);
1370 dest = gst_caps_new_empty ();
1371 for (j = 0; j < src->structs->len; j++) {
1372 min = gst_caps_get_structure (src, j);
1373 if (gst_structure_get_name_id (min) == gst_structure_get_name_id (sub)) {
1376 if (gst_caps_structure_subtract (&list, min, sub)) {
1379 for (walk = list; walk; walk = g_slist_next (walk)) {
1380 gst_caps_append_structure (dest, (GstStructure *) walk->data);
1382 g_slist_free (list);
1384 gst_caps_append_structure (dest, gst_structure_copy (min));
1387 gst_caps_append_structure (dest, gst_structure_copy (min));
1390 if (gst_caps_is_empty (dest)) {
1391 gst_caps_unref (src);
1396 gst_caps_unref (src);
1397 gst_caps_do_simplify (dest);
1403 * @caps1: a #GstCaps to union
1404 * @caps2: a #GstCaps to union
1406 * Creates a new #GstCaps that contains all the formats that are in
1407 * either @caps1 and @caps2.
1409 * This function deals correctly with passing NULL for any of the caps.
1411 * Returns: the new #GstCaps
1414 gst_caps_union (const GstCaps * caps1, const GstCaps * caps2)
1419 if (!caps1 && !caps2)
1420 return gst_caps_new_empty ();
1422 if (!caps1 || gst_caps_is_empty (caps1))
1423 return gst_caps_copy (caps2);
1425 if (!caps2 || gst_caps_is_empty (caps2))
1426 return gst_caps_copy (caps1);
1428 if (gst_caps_is_any (caps1) || gst_caps_is_any (caps2))
1429 return gst_caps_new_any ();
1431 dest1 = gst_caps_copy (caps1);
1432 dest2 = gst_caps_copy (caps2);
1433 gst_caps_append (dest1, dest2);
1435 gst_caps_do_simplify (dest1);
1439 typedef struct _NormalizeForeach
1442 GstStructure *structure;
1447 gst_caps_normalize_foreach (GQuark field_id, const GValue * value, gpointer ptr)
1449 NormalizeForeach *nf = (NormalizeForeach *) ptr;
1453 if (G_VALUE_TYPE (value) == GST_TYPE_LIST) {
1454 for (i = 1; i < gst_value_list_get_size (value); i++) {
1455 const GValue *v = gst_value_list_get_value (value, i);
1456 GstStructure *structure = gst_structure_copy (nf->structure);
1458 gst_structure_id_set_value (structure, field_id, v);
1459 gst_caps_append_structure (nf->caps, structure);
1462 gst_value_init_and_copy (&val, gst_value_list_get_value (value, 0));
1463 gst_structure_id_set_value (nf->structure, field_id, &val);
1464 g_value_unset (&val);
1472 * gst_caps_normalize:
1473 * @caps: a #GstCaps to normalize
1475 * Creates a new #GstCaps that represents the same set of formats as
1476 * @caps, but contains no lists. Each list is expanded into separate
1479 * Returns: the new #GstCaps
1482 gst_caps_normalize (const GstCaps * caps)
1484 NormalizeForeach nf;
1488 g_return_val_if_fail (GST_IS_CAPS (caps), NULL);
1490 newcaps = gst_caps_copy (caps);
1493 for (i = 0; i < newcaps->structs->len; i++) {
1494 nf.structure = gst_caps_get_structure (newcaps, i);
1496 while (!gst_structure_foreach (nf.structure,
1497 gst_caps_normalize_foreach, &nf));
1504 gst_caps_compare_structures (gconstpointer one, gconstpointer two)
1507 const GstStructure *struct1 = *((const GstStructure **) one);
1508 const GstStructure *struct2 = *((const GstStructure **) two);
1510 /* FIXME: this orders alphabetically, but ordering the quarks might be faster
1511 So what's the best way? */
1512 ret = strcmp (gst_structure_get_name (struct1),
1513 gst_structure_get_name (struct2));
1517 return gst_structure_n_fields (struct2) - gst_structure_n_fields (struct1);
1524 GstStructure *compare;
1529 gst_caps_structure_figure_out_union (GQuark field_id, const GValue * value,
1532 UnionField *u = user_data;
1533 const GValue *val = gst_structure_id_get_value (u->compare, field_id);
1537 g_value_unset (&u->value);
1540 if (gst_value_compare (val, value) == GST_VALUE_EQUAL)
1543 g_value_unset (&u->value);
1547 gst_value_union (&u->value, val, value);
1552 gst_caps_structure_simplify (GstStructure ** result,
1553 const GstStructure * simplify, GstStructure * compare)
1556 UnionField field = { 0, {0,}, NULL };
1558 /* try to subtract to get a real subset */
1559 if (gst_caps_structure_subtract (&list, simplify, compare)) {
1560 switch (g_slist_length (list)) {
1565 *result = list->data;
1566 g_slist_free (list);
1572 for (walk = list; walk; walk = g_slist_next (walk)) {
1573 gst_structure_free (walk->data);
1575 g_slist_free (list);
1581 /* try to union both structs */
1582 field.compare = compare;
1583 if (gst_structure_foreach ((GstStructure *) simplify,
1584 gst_caps_structure_figure_out_union, &field)) {
1585 gboolean ret = FALSE;
1587 /* now we know all of simplify's fields are the same in compare
1588 * but at most one field: field.name */
1589 if (G_IS_VALUE (&field.value)) {
1590 if (gst_structure_n_fields (simplify) == gst_structure_n_fields (compare)) {
1591 gst_structure_id_set_value (compare, field.name, &field.value);
1595 g_value_unset (&field.value);
1596 } else if (gst_structure_n_fields (simplify) <=
1597 gst_structure_n_fields (compare)) {
1598 /* compare is just more specific, will be optimized away later */
1599 /* FIXME: do this here? */
1600 GST_LOG ("found a case that will be optimized later.");
1602 gchar *one = gst_structure_to_string (simplify);
1603 gchar *two = gst_structure_to_string (compare);
1606 ("caps mismatch: structures %s and %s claim to be possible to unify, but aren't",
1618 gst_caps_switch_structures (GstCaps * caps, GstStructure * old,
1619 GstStructure * new, gint i)
1621 gst_structure_set_parent_refcount (old, NULL);
1622 gst_structure_free (old);
1623 gst_structure_set_parent_refcount (new, &caps->refcount);
1624 g_ptr_array_index (caps->structs, i) = new;
1628 * gst_caps_do_simplify:
1629 * @caps: a #GstCaps to simplify
1631 * Modifies the given @caps inplace into a representation that represents the
1632 * same set of formats, but in a simpler form. Component structures that are
1633 * identical are merged. Component structures that have values that can be
1634 * merged are also merged.
1636 * Returns: TRUE, if the caps could be simplified
1639 gst_caps_do_simplify (GstCaps * caps)
1641 GstStructure *simplify, *compare, *result = NULL;
1643 gboolean changed = FALSE;
1645 g_return_val_if_fail (caps != NULL, FALSE);
1646 g_return_val_if_fail (IS_WRITABLE (caps), FALSE);
1648 if (gst_caps_get_size (caps) < 2)
1651 g_ptr_array_sort (caps->structs, gst_caps_compare_structures);
1653 start = caps->structs->len - 1;
1654 for (i = caps->structs->len - 1; i >= 0; i--) {
1655 simplify = gst_caps_get_structure (caps, i);
1656 if (gst_structure_get_name_id (simplify) !=
1657 gst_structure_get_name_id (gst_caps_get_structure (caps, start)))
1659 for (j = start; j >= 0; j--) {
1662 compare = gst_caps_get_structure (caps, j);
1663 if (gst_structure_get_name_id (simplify) !=
1664 gst_structure_get_name_id (compare)) {
1667 if (gst_caps_structure_simplify (&result, simplify, compare)) {
1669 gst_caps_switch_structures (caps, simplify, result, i);
1672 gst_caps_remove_structure (caps, i);
1684 /* gst_caps_do_simplify (caps); */
1688 #ifndef GST_DISABLE_LOADSAVE
1690 * gst_caps_save_thyself:
1691 * @caps: a #GstCaps structure
1692 * @parent: a XML parent node
1694 * Serializes a #GstCaps to XML and adds it as a child node of @parent.
1696 * Returns: a XML node pointer
1699 gst_caps_save_thyself (const GstCaps * caps, xmlNodePtr parent)
1701 char *s = gst_caps_to_string (caps);
1703 xmlNewChild (parent, NULL, (xmlChar *) "caps", (xmlChar *) s);
1709 * gst_caps_load_thyself:
1710 * @parent: a XML node
1712 * Creates a #GstCaps from its XML serialization.
1714 * Returns: a new #GstCaps structure
1717 gst_caps_load_thyself (xmlNodePtr parent)
1719 if (strcmp ("caps", (char *) parent->name) == 0) {
1720 return gst_caps_from_string ((gchar *) xmlNodeGetContent (parent));
1731 * @caps: a pointer to #GstCaps
1732 * @newcaps: a #GstCaps to replace *caps
1734 * Replaces *caps with @newcaps. Unrefs the #GstCaps in the location
1735 * pointed to by @caps, if applicable, then modifies @caps to point to
1736 * @newcaps. An additional ref on @newcaps is taken.
1738 * This function does not take any locks so you might want to lock
1739 * the object owning @caps pointer.
1742 gst_caps_replace (GstCaps ** caps, GstCaps * newcaps)
1746 g_return_if_fail (caps != NULL);
1750 if (newcaps != oldcaps) {
1752 gst_caps_ref (newcaps);
1757 gst_caps_unref (oldcaps);
1762 * gst_caps_to_string:
1765 * Converts @caps to a string representation. This string representation
1766 * can be converted back to a #GstCaps by gst_caps_from_string().
1768 * For debugging purposes its easier to do something like this:
1770 * GST_LOG ("caps are %" GST_PTR_FORMAT, caps);
1772 * This prints the caps in human readble form.
1774 * Returns: a newly allocated string representing @caps.
1777 gst_caps_to_string (const GstCaps * caps)
1782 /* NOTE: This function is potentially called by the debug system,
1783 * so any calls to gst_log() (and GST_DEBUG(), GST_LOG(), etc.)
1784 * should be careful to avoid recursion. This includes any functions
1785 * called by gst_caps_to_string. In particular, calls should
1786 * not use the GST_PTR_FORMAT extension. */
1789 return g_strdup ("NULL");
1791 if (gst_caps_is_any (caps)) {
1792 return g_strdup ("ANY");
1794 if (gst_caps_is_empty (caps)) {
1795 return g_strdup ("EMPTY");
1798 /* estimate a rough string length to avoid unnecessary reallocs in GString */
1800 for (i = 0; i < caps->structs->len; i++) {
1801 slen += STRUCTURE_ESTIMATED_STRING_LEN (gst_caps_get_structure (caps, i));
1804 s = g_string_sized_new (slen);
1805 for (i = 0; i < caps->structs->len; i++) {
1806 GstStructure *structure;
1809 /* ';' is now added by gst_structure_to_string */
1810 g_string_append_c (s, ' ');
1813 structure = gst_caps_get_structure (caps, i);
1814 priv_gst_structure_append_to_gstring (structure, s);
1816 if (s->len && s->str[s->len - 1] == ';') {
1817 /* remove latest ';' */
1818 s->str[--s->len] = '\0';
1820 return g_string_free (s, FALSE);
1824 gst_caps_from_string_inplace (GstCaps * caps, const gchar * string)
1826 GstStructure *structure;
1829 g_return_val_if_fail (string, FALSE);
1830 if (strcmp ("ANY", string) == 0) {
1831 caps->flags = GST_CAPS_FLAGS_ANY;
1834 if (strcmp ("EMPTY", string) == 0) {
1838 structure = gst_structure_from_string (string, &s);
1839 if (structure == NULL) {
1842 gst_caps_append_structure (caps, structure);
1846 while (g_ascii_isspace (*s))
1851 structure = gst_structure_from_string (s, &s);
1852 if (structure == NULL) {
1855 gst_caps_append_structure (caps, structure);
1863 * gst_caps_from_string:
1864 * @string: a string to convert to #GstCaps
1866 * Converts @caps from a string representation.
1868 * Returns: a newly allocated #GstCaps
1871 gst_caps_from_string (const gchar * string)
1875 caps = gst_caps_new_empty ();
1876 if (gst_caps_from_string_inplace (caps, string)) {
1879 gst_caps_unref (caps);
1885 gst_caps_transform_to_string (const GValue * src_value, GValue * dest_value)
1887 g_return_if_fail (G_IS_VALUE (src_value));
1888 g_return_if_fail (G_IS_VALUE (dest_value));
1889 g_return_if_fail (G_VALUE_HOLDS (src_value, GST_TYPE_CAPS));
1890 g_return_if_fail (G_VALUE_HOLDS (dest_value, G_TYPE_STRING)
1891 || G_VALUE_HOLDS (dest_value, G_TYPE_POINTER));
1893 dest_value->data[0].v_pointer =
1894 gst_caps_to_string (src_value->data[0].v_pointer);
1898 gst_caps_copy_conditional (GstCaps * src)
1901 return gst_caps_ref (src);