Metadata for XML

NDI Metadata and XML

While NDI metadata is formatted as XML, there are some differences between XML used for NDI metadata frames and a more conventional stand-alone XML file. This page discusses how XML standards apply to NDI metadata frames.

XML Prolog

NDI metadata frames should not contain an XML prolog. Each NDI Metadata frame can be assumed to have the following prolog, indicating XML version 1.0 compliance and UTF-8 encoding.

<?xml version="1.0" encoding="UTF-8"?>

XML Syntax

NDI metadata frames should be "Well Formed" XML documents with correct syntax. Please check the following:

• Metadata should contain exactly one root element.

• XML elements must have a closing tag

• XML tags are case sensitive

• XML elements must be properly nested

• XML attribute values must be quoted

XML Root Element

As a "Well Formed" XML document, an NDI metadata frame can only have one root element. If there is a need to pass more than one XML element in an NDI metadata frame, the root element should be set to <ndi_metadata_group> and the required XML elements can be passed as children to this root element.

See the documentation for the <ndi_metadata_group> element for example usage.

XML Comments

XML comments are allowed but discouraged in NDI metadata frames.

XML Namespaces

XML namespaces are not supported in NDI metadata frames.

XML Element Names

With the exception of element names defined in this document, no XML element passed in a metadata frame to the NDI SDK should begin with the string ndi or ntk (or any permutation of capitalization, eg: Ndi).