MDI – Media Delivery Index
Media Delivery Index is an open standard for use in quality assurance of IP video systems.
MDI is designed to address the problem of monitoring IP-encapsulated video signals in a live system.
The RFC (RFC 4445) for MDI details the technicalities of this in depth, but the issue of how this applies to real systems is more useful for many people, and that is the aim of this article.
The problem:
The fundamental problem when delivering IP encapsulated video across a network is that losing one IP packet results in multiple media packet loss.
UDP (User Datagram Protocol) based systems tend to encapsulate up to 7 188 (or 204) Byte Mpeg Transport Stream packets per udp packet. This means that losing one udp packet could result in 7 media packets being lost.
Loss of the media packets means that content is lost and the STB (set top box) or other end device must handle this as well as it can. Depending on the actual content of the packets (video, voice, data, stuffing) at the time, the impact will be different.
In an ideal world NO packets (IP or otherwise) would be lost across the...