struct GstMeta

struct GstMeta {
  GstMetaFlags       flags;
  const GstMetaInfo *info;
};

Base structure for metadata. Custom metadata will put this structure as the first member of their structure.

enum GstMetaFlags

typedef enum {
  GST_META_FLAG_NONE        = 0,
  GST_META_FLAG_READONLY    = (1 << 0),
  GST_META_FLAG_POOLED      = (1 << 1),

  GST_META_FLAG_LAST        = (1 << 16)
} GstMetaFlags;

Extra metadata flags.

GST_META_FLAGS()

#define GST_META_FLAGS(meta)  (GST_META_CAST (meta)->flags)

A flags word containing GstMetaFlags flags set on meta

GST_META_FLAG_IS_SET()

#define GST_META_FLAG_IS_SET(meta,flag)        !!(GST_META_FLAGS (meta) & (flag))

Gives the status of a specific flag on a metadata.

GST_META_FLAG_SET()

#define GST_META_FLAG_SET(meta,flag)           (GST_META_FLAGS (meta) |= (flag))

Sets a metadata flag on a metadata.

GST_META_FLAG_UNSET()

#define GST_META_FLAG_UNSET(meta,flag)         (GST_META_FLAGS (meta) &= ~(flag))

Clears a metadata flag.

struct GstMetaInfo

struct GstMetaInfo {
  GType                      api;
  GType                      type;
  gsize                      size;

  GstMetaInitFunction        init_func;
  GstMetaFreeFunction        free_func;
  GstMetaTransformFunction   transform_func;
};

The GstMetaInfo provides information about a specific metadata structure.

GstMetaInitFunction ()

gboolean            (*GstMetaInitFunction)              (GstMeta *meta,
                                                         gpointer params,
                                                         GstBuffer *buffer);

Function called when meta is initialized in buffer.

GstMetaFreeFunction ()

void                (*GstMetaFreeFunction)              (GstMeta *meta,
                                                         GstBuffer *buffer);

Function called when meta is freed in buffer.

GstMetaTransformFunction ()

gboolean            (*GstMetaTransformFunction)         (GstBuffer *transbuf,
                                                         GstMeta *meta,
                                                         GstBuffer *buffer,
                                                         GQuark type,
                                                         gpointer data);

Function called for each meta in buffer as a result of performing a transformation on transbuf. Additional type specific transform data is passed to the function as data.

Implementations should check the type of the transform and parse additional type specific fields in data that should be used to update the metadata on transbuf.

gst_meta_api_type_register ()

GType               gst_meta_api_type_register          (const gchar *api,
                                                         const gchar **tags);

Register and return a GType for the api and associate it with tags.

gst_meta_api_type_has_tag ()

gboolean            gst_meta_api_type_has_tag           (GType api,
                                                         GQuark tag);

Check if api was registered with tag.

gst_meta_register ()

const GstMetaInfo * gst_meta_register                   (GType api,
                                                         const gchar *impl,
                                                         gsize size,
                                                         GstMetaInitFunction init_func,
                                                         GstMetaFreeFunction free_func,
                                                         GstMetaTransformFunction transform_func);

Register a new GstMeta implementation.

The same info can be retrieved later with gst_meta_get_info() by using impl as the key.

gst_meta_get_info ()

const GstMetaInfo * gst_meta_get_info                   (const gchar *impl);

Lookup a previously registered meta info structure by its implementation name impl.