Gst.BufferForeachMetaFunc
A function that will be called from Gst.Buffer.prototype.foreach_meta. The meta field will point to a the reference of the meta.
buffer should not be modified from this callback.
When this function returns true, the next meta will be returned. When false is returned, Gst.Buffer.prototype.foreach_meta will return.
When meta is set to NULL, the item will be removed from the buffer.