CS4624 Ch7 - Time

Time-Based Media Representation

• Terminology
  
  
  • Synchronization = occurrence of simultaneous events
    
  • Orchestration = coordinating multimedia time-ordered presentations
    
  • Timeline = representation of time-ordering
    
  • Temporal access control (TAC) operations like reverse, fast-forward
    
  • Continuous media are sequences of discrete data elements that are played out contiguously in time.
    
  • Time instant
    
  • Time interval
    
  • Timed petri net (TPN)
    
  • Object composition petri net (OCPN), a form of marked graph, that can specify exact presentation-time playout semantics
    
  • Petri-Net-Based-Hypertext (PNBH), can have multiple outgoing arcs and so can represent nondeterministic and cyclic browsing
    
  • Jitter = individual difference in time between corresponding events (e.g., sequences of audio and video frames)
    
  • Skew = average difference in time of events that are supposed to be synchronized, computed as average over n intervals of frames
    
  • Dropouts = gaps in playout, such as when data is lost
    
  • Variable bit rate (VBR) compression such as results in MPEG