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Data stream characteristics for continuous media
The data stream characteristics in a multimedia system are related to any audio and video data transfer. Also the data stream characteristics are influenced by the compression during the data transfer. Its characteristics apply for distributed as well as local environment. So, data stream characteristics can be discussed here on the basic of three given properties or factors.
A. According to the time intervals between consecutive packets.
B. According to the variation of the amount between consecutive packets.
C. According to the continuity or connection between consecutive packets.
A. According to time intervals between consecutive packets
On the basic of this factor we find out three properties these are:
a) Strongly periodic data stream
If time intervals are of the same length between two consecutive t packets that is a constant, then the stream is called strongly periodic and in the ideal case the jitter has the value zero. For example: PCM coded speech in traditional telephone switching.
b) Weakly periodic data stream
If time intervals between two consecutive packets is not constant but are of periodic nature with finite period then the data stream is called weakly periodic.
c) A-periodic data stream
If the sequence of time intervals is neither strongly nor weakly periodic, instead the time period or time gap various between packets to packets during transmission then such data stream is called A-periodic data stream.
B. According to variation of consecutive packet amounts:
On the basic of these factors there are also three types of data stream, these are –
a) Strongly regular data stream
If the amount of data stays constant during the life time of a data stream, this feature is specially found in uncompressed digital data transmission, For example video stream of camera in uncompressed form, audio stream of CD.
b) Weakly regular data stream
If the amount of data stream varies periodically with time and not shows the behaviors of strongly regular data stream then it is called weakly regular data stream, For example compressed video stream.
c) Irregular data stream
If the amount of data is neither constant nor changes according to a periodic function, then the data streams are called irregular data stream. Transmission and processing of this category data stream is more complicated. Since data stream has a variable (bit) rate after applying compression methods.
C. According to continuity or connection between consecutive packets
On the basic of this factor their can be also 2 types or characters:
a) Continuous data stream
If consecutive packets are directly transmitted one after another without any time gap then such data streams are called continuous data stream, For example audio data use for B channel of Isdn with transmission rate for 64 kbps.
b) Unconnected data stream
A data stream with gaps between information units is called and unconnected data stream. The transmission of a connected data stream through a channel with a higher capacity treads gaps between individual packets, for example the data stream coded with JPEG method with 1.2 mbps on a FDDI network.