International Organization for Standardization

Information technology – UPnP device architecture – Part 4-4: Audio Video Device Control Protocol – Level 2 – Audio Video Data Structures - Second Edition
 N ISO/IEC 29341-4-4

Annotation

Introduction

This document defines the layout of the AV Datastructure Template (AVDT) XML document. An AVDT document describes the format requirements and restrictions of various data structures used within the UPnP AV specifications. Although these data structures are defined very precisely in the appropriate service specification, in most cases, each data structure definition allows for a certain degree of variation in order to accommodate differences between individual devices.

The purpose of an AVDT document is to enable each device to describe (at run-time) its particular variation of these AV data structures. AVDT documents allow users of AV data structures (e.g. UPnP control points) to reduce the number of instances of those data structures that comply with the service specification but are not compatible with the device's particular capabilities. The ultimate goal of an AVDT document is to reduce those error conditions that are caused by control points creating instances of a data structure that exceed the static (known) capabilities of the device. Unfortunately, the AVDT mechanism will never eliminate all preventable error conditions, but it will help to reduce them by giving the client more information about the device's particular capabilities.

As described above, an AVDT document is a machine readable, implementation-specific variant of an AV data structure defined by one of the UPnP AV specifications. For a given device, each instance of that data structure must conform to both the specification definition AND the device's AVDT definition of that data structure.