13.1 Introduction

13.1. Introduction

The Decoding Order Number (DON) concept was introduced mainly to enable efficient multi-picture slice interleaving (see Section 12.6) and robust packet scheduling (see Section 12.7). In both of these applications, NAL units are transmitted out of decoding order. DON indicates the decoding order of NAL units and should be used in the receiver to recover the decoding order. Example use cases for efficient multi-picture slice interleaving and for robust packet scheduling are given in Sections 13.2 and 13.3, respectively. Section 13.4 describes the benefits of the DON concept in error resiliency achieved by redundant coded pictures. Section 13.5 summarizes considered alternatives to DON and justifies why DON was chosen for this RTP payload specification.