The term multimedia usually implies that at least one of text ( structured/unstructured, hypertext, etc ), graphics (drawings), or image ( discrete media ) is associated with either audio or motion video information ( continuous media ).
Multimedia streaming is the overlapping the playout of the data at the receiver with the transmission by the sender.
A video stream consists of a sequence of images or frames.
A frame consists of a grid of pixels.
( Table 1 )
An audio stream consists of a sequence of audio samples.
Basic Terms Table 1. Hierarchy of multimedia content. Picture element Two-dimensional grid of pixels Sequence of frames over time Synchronized set of streams Set of multimedia sessions Pixel Frame Stream Session Presentation Definition Term
Multimedia Protocols MULTIMEDIA CONCEPTS Table 3. Multimedia protocols. Disadvantage Advantage Network Protocol · Complicated request mechanism · Receivers may experience random packet loss for small reservation · Reliable connection · Receiver can obtain different levels of service RSVP · No guarantee for QoS · Header is larger than UDP · More complicated that UDP · No support for congestion control · Support real-time transmission · Provide timing reconstruction, loss detection, security and content identification · Allows retrieval of very interesting network statistics RTP/RTCP · Many network firewalls block UDP data · Need error concealment for video packet loss · No support for congestion control · Cannot be played using popular stream players such as QuickTime · Suitable for streaming · Allows packet drops; if packets arrive late or damaged, streaming will continue · No retransmission needed UDP · Typically need large buffer to handle data rate variation · Loss recovery needs retransmission causing further jitter or skew · No support for multicast · Dominate protocol for data transfer of data over the Internet · Streaming through firewall · Reliable TCP