2 Canonical caps/structure strings (those created by gst_caps_to_string()
3 and gst_structure_to_string()) do not have AUTO_VALUE.
7 - SIMPLE_STRINGs should cover most simple cases that don't interfere
8 with other parts of the gst_caps or gst_parse grammar
9 - forward-parsed grammar
10 - quoted strings handle backslash escaping as well as XML-style (&ack;)
13 CAPS = STRUCTURE [ ';' STRUCTURE ]*
15 STRUCTURE = STRUCTURE_NAME [ ',' FIELD ]*
17 STRUCTURE_NAME = STRING
19 FIELD = FIELD_NAME '=' TYPED_VALUE
21 FIELD_NAME = SIMPLE_STRING
23 TYPED_VALUE = CANONICAL_VALUE | AUTO_VALUE
25 CANONICAL_VALUE = '{' TYPED_VALUE [ ',' TYPED_VALUE ]* '}'
26 | '[' TYPED_VALUE ',' TYPED_VALUE ']'
29 AUTO_VALUE = [-+]?[0-9][0-9]*
30 | [-+]?[0-9][0-9]*[.][0-9]*[eE][-+][0-9]*
39 SIMPLE_STRING = [A-Za-z0-9_+-:./]+
41 TYPE = "int" | "i" | "float" | "f" | "double" | "d" | "fourcc" | "4"
42 | "boolean" | "bool" | "b"
49 "audio/raw", rate=(int)44100
50 "audio/raw", rate=(int)44100, signed=(boolean)true
51 "audio/raw", rate={ (int)44100, (int)48000 }
52 "audio/raw", rate=[ (int)8000, (int)48000 ]