<INCLUDE>gst/gst.h</INCLUDE>
<SECTION>
+<FILE>gobject2gtk</FILE>
+GObject
+G_MAXUINT
+G_MAXULONG
+g_object_ref
+g_object_unref
+G_TYPE_CHECK_INSTANCE_CAST
+G_TYPE_CHECK_INSTANCE_TYPE
+G_TYPE_CHECK_CLASS_CAST
+G_TYPE_CHECK_CLASS_TYPE
+G_TYPE_FROM_CLASS
+G_OBJECT_TYPE
+G_OBJECT_CLASS_TYPE
+G_TYPE_NONE
+G_TYPE_CHAR
+G_TYPE_UCHAR
+G_TYPE_BOOLEAN
+G_TYPE_INT
+G_TYPE_UINT
+G_TYPE_LONG
+G_TYPE_ULONG
+G_TYPE_ENUM
+G_TYPE_FLAGS
+G_TYPE_FLOAT
+G_TYPE_DOUBLE
+G_TYPE_STRING
+G_TYPE_POINTER
+G_TYPE_BOXED
+G_TYPE_PARAM
+g_cclosure_marshal_VOID__VOID
+g_cclosure_marshal_VOID__BOOLEAN
+g_cclosure_marshal_VOID__CHAR
+g_cclosure_marshal_VOID__UCHAR
+g_cclosure_marshal_VOID__INT
+g_cclosure_marshal_VOID__UINT
+g_cclosure_marshal_VOID__LONG
+g_cclosure_marshal_VOID__ULONG
+g_cclosure_marshal_VOID__ENUM
+g_cclosure_marshal_VOID__FLAGS
+g_cclosure_marshal_VOID__FLOAT
+g_cclosure_marshal_VOID__DOUBLE
+g_cclosure_marshal_VOID__STRING
+g_cclosure_marshal_VOID__PARAM
+g_cclosure_marshal_VOID__BOXED
+g_cclosure_marshal_VOID__POINTER
+g_cclosure_marshal_STRING__OBJECT_POINTER
+g_cclosure_marshal_VOID__UINT_POINTER
+gst_marshal_VOID__OBJECT_POINTER
+gst_marshal_VOID__INT_INT
+g_object_get_property
+g_object_set
+GType
+GTypeFlags
+GClassInitFunc
+GBaseInitFunc
+GInstanceInitFunc
+g_type_class_ref
+g_type_class_unref
+g_type_name
+g_type_from_name
+GEnumValue
+g_enum_register_static
+GTypeInfo
+G_TYPE_FLAG_ABSTRACT
+g_type_register_static
+g2g_type_register_static
+g_object_new
+g2g_object_new
+G_SIGNAL_RUN_LAST
+G_SIGNAL_RUN_FIRST
+GCallback
+G_CALLBACK
+g_signal_newc
+g2g_signal_newc
+g_signal_lookup
+g_signal_handler_block
+g_signal_handler_unblock
+GValue
+GParamFlags
+G_VALUE_TYPE
+G_PARAM_READWRITE
+G_PARAM_READABLE
+G_PARAM_WRITABLE
+G_OBJECT_WARN_INVALID_PROPERTY_ID
+GParamSpec
+g_value_init
+g_object_class_install_property
+g2g_object_class_install_property
+g_object_class_find_property
+g2g_object_class_find_property
+g_object_class_list_properties
+g2g_object_class_list_properties
+G_IS_PARAM_SPEC_ENUM
+g_param_spec_boolean
+g2g_param_spec_boolean
+g_param_spec_int
+g2g_param_spec_int
+g_param_spec_uint
+g2g_param_spec_uint
+g_param_spec_long
+g2g_param_spec_long
+g_param_spec_ulong
+g2g_param_spec_ulong
+g_param_spec_float
+g2g_param_spec_float
+g_param_spec_double
+g2g_param_spec_double
+g_param_spec_enum
+g2g_param_spec_enum
+g_param_spec_pointer
+g2g_param_spec_pointer
+g_param_spec_string
+g2g_param_spec_string
+g_value_get_boolean
+g_value_set_boolean
+g_value_get_enum
+g_value_set_enum
+g_value_get_int
+g_value_set_int
+g_value_get_uint
+g_value_set_uint
+g_value_get_long
+g_value_set_long
+g_value_get_ulong
+g_value_set_ulong
+g_value_get_float
+g_value_set_float
+g_value_get_double
+g_value_set_double
+g_value_get_string
+g_value_set_string
+g_value_get_pointer
+g_value_set_pointer
+G_OBJECT
+<TITLE>GObject</TITLE>
+g_object_get_type
+<SUBSECTION Standard>
+g_cclosure_marshal_VOID__OBJECT
+G_IS_OBJECT
+G_TYPE_OBJECT
+g2g_object_get_type
+G_OBJECT_CLASS
+G_IS_OBJECT_CLASS
+G_OBJECT_GET_CLASS
+</SECTION>
+
+<SECTION>
<FILE>cothreads</FILE>
CURRENT_STACK_FRAME
cothread_state
GST_BUFFER_TIMESTAMP
GST_BUFFER_BUFFERPOOL
GST_BUFFER_POOL_PRIVATE
+GST_BUFFER_POOL_LOCK
GST_BUFFER_LOCK
GST_BUFFER_TRYLOCK
GST_BUFFER_UNLOCK
</SECTION>
<SECTION>
-<FILE>gstmeta</FILE>
-GST_META_FLAGS
-GST_META_FLAG_IS_SET
-GST_META_FLAG_SET
-GST_META_FLAG_UNSET
-GstMetaFlags
-GstMeta
-gst_meta_new_size
-gst_meta_new
-gst_meta_ref
-gst_meta_unref
-<SUBSECTION Standard>
-GST_META
-</SECTION>
-
-<SECTION>
<FILE>gstobject</FILE>
<TITLE>GstObject</TITLE>
GstObjectFlags
gst_util_get_double_arg
gst_util_get_string_arg
gst_util_get_pointer_arg
-gst_util_get_widget_arg
gst_util_dump_mem
<SUBSECTION Standard>
</SECTION>
GST_IS_MULTIDISKSRC_CLASS
</SECTION>
-<SECTION>
-<INCLUDE>gst/meta/spectrum.h</INCLUDE>
-<FILE>spectrum</FILE>
-MetaAudioSpectrum
-</SECTION>
-
@obj:
+<!-- ##### SECTION ./tmpl/gstmeta.sgml:Short_Description ##### -->
+Provide context for buffers
+
+
<!-- ##### MACRO DEBUG_ENTER_STRING ##### -->
<para>
@overlay_info:
@dga_info:
+<!-- ##### FUNCTION gst_meta_ref ##### -->
+<para>
+
+</para>
+
+@meta:
+
<!-- ##### SECTION ./tmpl/gstaudiosink.sgml:See_Also ##### -->
<para>
</para>
+<!-- ##### FUNCTION gst_meta_unref ##### -->
+<para>
+
+</para>
+
+@meta:
+
<!-- ##### STRUCT GstSineSrc ##### -->
<para>
@sheight:
@bytes_per_line:
+<!-- ##### SECTION ./tmpl/spectrum.sgml:Title ##### -->
+spectrum
+
+
<!-- ##### SECTION ./tmpl/GstElement.sgml:Long_Description ##### -->
<para>
</para>
+<!-- ##### SECTION ./tmpl/spectrum.sgml:Short_Description ##### -->
+Frequencies of a spectrum analysis.
+
+
<!-- ##### FUNCTION gst_asyncdisksrc_get_type ##### -->
<para>
@name:
@Returns:
+<!-- ##### MACRO GST_META_FLAGS ##### -->
+<para>
+Retrieve the flags of the given meta information.
+</para>
+
+@meta: the meta information
+
<!-- ##### FUNCTION gst_element_request_pad ##### -->
<para>
@obj: Element to check for state.
@flag: State to check for, must be a single bit in guint32.
+<!-- ##### STRUCT GstMeta ##### -->
+<para>
+
+</para>
+
+@lock: for locking purposes
+@flags: the flags of the meta data
+@data: the meta data
+@size: the size of the meta data
+
<!-- ##### FUNCTION gst_xml_new_from_memory ##### -->
<para>
</para>
+<!-- ##### SECTION ./tmpl/gstmeta.sgml:See_Also ##### -->
+<para>
+
+</para>
+
+
<!-- ##### MACRO GST_IS_TEE_CLASS ##### -->
<para>
@arg:
+<!-- ##### SECTION ./tmpl/gstmeta.sgml:Long_Description ##### -->
+<para>
+The point of the metadata is to provide some context for each buffer. In
+the case of audio data, for instance, it would provide the samplerate, bit
+depth, and channel count.
+</para>
+
+<para>
+The trick is that there may be multiple types of metadata ganged onto a
+single buffer. This is why they're going to be a GList. This does mean
+extra overhead in all cases, but I think it's minimal. The GList type
+uses a chunk allocater so we're not wasting too much memory or time when
+adding to the list.
+</para>
+
+<para>
+The trick is dealing with these structs as they pass through a pipeline,
+since they have potentially different mutability properties. For
+instance, if you've got a mp3 decoder connected to a tee, which sends the
+buffers off to both the decoder and a spectrum analyzer (and then a
+visualization element). The preferred setup would be where every time a
+audio/raw metadata comes down the pipe (indicating a potential change in
+audio format), the audiosink and spectrum would just save off pointers.
+</para>
+
+<para>
+So when exactly does this metadata go away (deallocated)? Well, that
+means metadata has to be refcounted. But that gets rather hairy. OK, in
+the simple case you create a metadata struct, it comes with refcount set
+to 1. You pass it through, it stays one, eventually someone drops the
+last reference on the buffer it's tied to, you free the metadata too.
+Easy. What if you tee? You could go through and for every metadata in
+the buffer, increment the refcount by the same as the buffer. So in the
+above case (tee'd), the audiosink and spectrum would get the buffer with a
+refcount of 2, and it'd have a metadata with refcount 2. Do they ref it
+each themselves, then unref the buffer? Or do they remove the metadata?
+Removing the metadata would require a buffer CoW, which would suck, so
+yes, they'd just ref the metadata.
+</para>
+
+<para>
+But.... what if they're all in different threads? Then we're off into
+the magical world of mutexes. Everything with a refcount in a threaded
+world must be mutexed, else you can do atomic increment and atomic
+dec and test. Can this be done from C easily? Perhaps it needs to be found
+from kernel includes via autoconf?
+</para>
+
+<para>
+The goal in designing the way metadata will be defined and used is to keep
+it as simple as possible. The basis for accomplishing this is the fact
+that in order to actually use (rather than just pass) the metadata, you
+have to know what the fields are, which means you have to have compiled in
+support for that metadata at build time. Therefore, if you're using
+metadata, you must have build-time access to the necessary include file
+that defines it.
+</para>
+
+<para>
+So, given that you've got an include file, it would be nice if the whole
+thing could be contained there. This would limit the need to be linked
+against something, or have load-time requirements as to that has to be
+loaded before you are.
+</para>
+
+<para>
+Given that really all metadata is is a region of memory of a given size
+with a certain signature, this isn't all that hard. First you lay out the
+struct that defines the metadata. Then you set up #defines that expand to
+the size of the struct in question, as well as the four-cc code that
+defines the type.
+</para>
+
+<para>
+The work is done by a few #defines, a la the #defines used in all Gtk
+objects. The first is a NEW() method that allocates the memory for the
+metadata and fills in all the normal fields (type, size, utility
+functions). Because of the way it's defined (as a #define, no less),
+you'll have to invoke it as META_NEW(meta), since it can't return()
+anything.
+</para>
+
+<para>
+Another #define will check to make sure a meta is indeed that type by
+verifying the type code and size. Theoretically, meta types can overlap
+with the same fourcc code, as long as they have different sizes. But I
+probably ought to have a global public registry so people writing things
+don't conflict. MSFT got that right, at least.
+</para>
+
+<para>
+So, a hairy problem is what to do when there are utility functions
+associated with one of these things. One option is to not bother with
+them. This is very likely a possible solution, since metadata is supposed
+to be flat memory of a given size. Not much to do to either free or copy
+it, is there?
+</para>
+
+
<!-- ##### SECTION ./tmpl/gstconnection.sgml:Title ##### -->
GstConnection
</para>
+<!-- ##### MACRO GST_META_FLAG_UNSET ##### -->
+<para>
+Clear a flag in the meta data.
+</para>
+
+@meta: the meta data
+@flag: the flag to clear
+
<!-- ##### MACRO GST_IS_FAKESRC ##### -->
<para>
@obj:
+<!-- ##### FUNCTION gst_meta_new_size ##### -->
+<para>
+
+</para>
+
+@size:
+@Returns:
+
<!-- ##### MACRO ERROR_OBJECT ##### -->
<para>
</para>
+<!-- ##### ENUM GstMetaFlags ##### -->
+<para>
+Flags indicating properties about the meta data.
+</para>
+
+@GST_META_FREEABLE: the meta data can be freed
+
+<!-- ##### SECTION ./tmpl/spectrum.sgml:See_Also ##### -->
+<para>
+
+</para>
+
+
<!-- ##### MACRO GST_CONNECTION ##### -->
<para>
</para>
+<!-- ##### SECTION ./tmpl/gstmeta.sgml:Title ##### -->
+GstMeta
+
+
<!-- ##### TYPEDEF GstCapsFactory ##### -->
<para>
@obj:
+<!-- ##### FUNCTION gst_util_get_widget_arg ##### -->
+<para>
+
+</para>
+
+@object:
+@argname:
+@Returns:
+
<!-- ##### ARG GstAsyncDiskSrc:size ##### -->
<para>
</para>
+<!-- ##### MACRO GST_META_FLAG_SET ##### -->
+<para>
+Set a flag in the meta data.
+</para>
+
+@meta: the meta data
+@flag: the flag to set
+
<!-- ##### MACRO GST_IS_SRC ##### -->
<para>
@GST_CAPS_ALWAYS:
@GST_CAPS_MAYBE:
+<!-- ##### MACRO GST_META_FLAG_IS_SET ##### -->
+<para>
+Check if a given flag is set.
+</para>
+
+@meta: the meta data to test
+@flag: the flag to test
+
<!-- ##### STRUCT GstPadClass ##### -->
<para>
</para>
+<!-- ##### MACRO gst_meta_new ##### -->
+<para>
+Create new meta data.
+</para>
+
+@type: the type of the meta data to create
+
<!-- ##### FUNCTION plugin_initialize ##### -->
<para>
@audiosink:
@format:
+<!-- ##### SECTION ./tmpl/spectrum.sgml:Long_Description ##### -->
+<para>
+Frequencies of a spectrum analysis.
+
+</para>
+
+
<!-- ##### SECTION ./tmpl/gstaudiosrc.sgml:Title ##### -->
GstAudioSrc
</para>
+<!-- ##### STRUCT MetaAudioSpectrum ##### -->
+<para>
+
+</para>
+
+@meta:
+@bands:
+@channels:
+@interleaved:
+@lowfreq:
+@highfreq:
+@steps:
+
<!-- ##### SECTION ./tmpl/plugin.sgml:Title ##### -->
plugin
projects / platform / upstream / gstreamer.git / commitdiff