The Moving Picture Experts Group

Event reporting

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MPEG-21 Event Reporting


MPEG doc#: N7217
Date: April 2005


Event Reporting in MPEG-21

The requirement for Event Reporting initially came from the critical need of rights-holders to be able to monitor the usage of copyrighted content in a commercial environment.  Up to now, only incomplete and incompatible solutions existed for reporting usage of content and MPEG-21 offered an ideal opportunity to standardize both the Event Reporting process, and the format.

Event Reporting within MPEG-21 provides a standardized means for “reportable events” to be specified, detected and acted upon.  Such a reportable event may relate either to the usage of a Digital Item (DI) by a Peer, or to the occurrence of Events related to the Peer itself.  For example, an Event that is related to the usage of a DI could be the rendering (or PLAYing) of resources associated with a DI.  Alternatively, an example of an Event that is Peer-related is when a Peer discovers (or connects to) another Peer, an action has no relation to the usage and/or manipulation of DI’s.

Key Concepts

In order to allow DI creators to specify reportable events, Event Reporting introduces the concepts of an Event Report Request (ER-R) and an Event Report (ER).  An ER-R is used to specify:

  • Conditions that must be fulfilled in order for the reportable Event to “occur”.
  • The syntax/format of the information is to be reported when the reportable Event occurs.  This information (or payload) is contained within an Event Report (ER).
  • The intended recipient(s) of the Event Report (Peers that need to be notified when the reportable Event occurs),
  • Parameters related to delivery of the Event Report (e.g. transport mechanism and protocol, delivery timing constraints, priority, etc.).

A General Event Reporting Model

A general (non-normative) model which reflects the functional aspects of ER-R handling and the subsequent creation of ER’s is shown in Figure 3.  It shows a set of functional blocks that together, can provide the overall Event Reporting functionality.  The general model of Event Reporting is as follows:

  • An Event Report Request (ER-R) is delivered to an MPEG-21 Peer. 
  • The ER-R is parsed and the Peer waits for Events to “occur”.  They are “trapped” by the Event Watchdog which then checks to see if the Events need to be reported on, according to the ER-R’s that the Peer has received.
  • When all of the Event conditions associated with an ER-R have been fulfilled, the Peer proceeds to construct an ER which includes the data fields specified in the ER-R.
  • The Peer then dispatches the resulting ER towards the ER-R’s specified recipient Peer(s).

Figure 1: General model of ER-R processing and ER generation


The standardization of Event Reporting within MPEG-21 is ongoing work, with the specification expected to reach International Standard in 2006.  It is driven by the original vision of MPEG-21, which foresaw a set of standards that together, provide a framework that enables commercial exploitation of digital multimedia items.  It is based upon a fairly simple yet powerful generic model that has been mapped towards the specifics of MPEG-21’s Digital Item concept.  The MPEG-21 Event Reporting specification provides a means for Digital Item creators to meter the usage of their creations which is an enabler for the healthy commercial future of digital multimedia.