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
Hierarchy