| Summary: | 碩士 === 國立臺灣大學 === 資訊管理學系 === 85 === A Rate/Retransmission Control Protocol for Real-Time MPEG Video
Transmission Over InternetAs the use of Internet becomes more
and more popular in information access, exchange and
distribution, the demand for real-time display or playback of
continuous media is ever increasing. Applications are such as
multimedia WWW (not just hypermedia), multimedia catalogs in
Electronic Commerce, and video-on-demand.Besides the benefits,
Internet, however, brings with it new problems or magnifies
certain existing problems in supporting real-time applications.
It is mainly because that Internet and its communication
protocols were not originally designed to support real-time data
transfer. As such, it suffers three major performance problems:
insufficient bandwidth, unpredictable transfer performance and
no support of quality of service.In this research, we propose an
innovative application-level control protocol called "Real-time
Rate/Retransmission Transfer Protocol" (R3CP) to cope with the
dynamic, unpredictable network transmission performance when to
real-time playback an MPEG video stream over Internet. The
protocol allows receiver to communicate with sender about its
data receiving state and how it would like sender to send the
data. The protocol includes three major schemes: a data
preloading scheme with reliable transfer to accommodate
transient dynamics of network delays and jitter; an adaptive
rate control scheme based on the receiver's receiving rate,
packet loss ratio and playback rate; and a look-ahead pre-
retransmission scheme which will check and retransmit missing
packets of an incomplete frame at least one round-trip time
ahead of its scheduled playback time. The first scheme using
reliable transfer mode to prevent the loss of important data, e.
g., MPEG sequence header. Because loss of any packets of the
important frames often causes significant degradation in
playback performance, the third scheme provides an effective
"in-time" retransmission. The entire protocol is based on the
use of the meta data file -a description of the data structures
of the video stream. The performance of the protocol was studied
via simulation. The results showed that the protocol has
significant improvement on playback performance compared to the
scheme has no control at all as well as the schemes with only
data preloading, especially in the Internet environments with
large packet loss.Keywords: continuous media, real-time ,MPEG ,
R3CP , real-time rate/retransmission control protocol , RTP,
meta data, preloading .
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