KEYWORDS: Video, Internet, Receivers, Prototyping, Local area networks, Multimedia, Video processing, Network architectures, Communication engineering, Signal to noise ratio
MPEG streaming over Mobile Internet leads to degradation of MPEG video quality. When a handoff of a mobile node (MN) occurs, it is quite difficult to guarantee seamless video quality due to the change of routing path towards the MN. In this paper, we propose a new scheme, MPEG streaming over Concatenation and Optimization for Reservation Path (CORP), to guarantee QoS of MPEG streaming service in the Mobile Internet. When a handoff of a MN occurs, the CORP extends the existing reservation path, which was established using RSVP between a server and a MN, to a new Base Station (BS) that the MN currently connected to, instead of making a new RSVP session between the server and the MN. To demonstrate practicality of the proposed scheme, we built a prototype system which provides the MPEG-1 Video and Audio on demand over Mobile Internet using Mobile IP and IEEE 802.11b wireless LAN. Our experiment shows that the proposed scheme significantly improves the peak signal-to-noise rate (PSNR) of MPEG streaming video. Also, we analyzed the video quality of our scheme with respect to TCP and UDP transport protocols.
Current video coding techniques have various features
to enable robust transmission of compressed video data over
noisy channels. Among them, the use of resynchronization markers
is an essential way to prevent spatial error propagation.
In this paper, we propose an optimal approach
for placement of resynchronization markers for
video communication over noisy channels.
Given the number of resynchronization markers assigned to
the current frame, we optimally decide the position of each marker
in a rate-distortion sense.
The proposed method takes into account
the channel condition and the expected distortion at the decoder, and
incorporates these informations into a rate-distortion framework.
Some assumptions and the Viterbi algorithm are employed in order to
reduce the complexity of the rate-distortion problem.
Various simulation results are shown to
justify the performance improvement achieved by the proposed method.
This paper presents a simple bitrate control method to percent the abrupt quality degradation after scene change. After scene change, the quality degradation occurs due to the poor temporal prediction between pictures before and after scene change. We predict the coding complexity of picture using the spatial variance before DCT and spectral flatness measure. From the predicted coding complexity, we show that the rate-distortion relation of image can be approximated to exponential function. When scene changes, picture target bit is adjusted in the direction to minimize the distortion in a GOP using the rate-distortion relations for each P-picture. Since the bit shortage could be occurred, proposed method extends the current GOP to the next. The algorithm can be applied to the existing MPEG codecs and real-time applications easily. Compared with the MPEG-2 TM5 rate control algorithm, proposed algorithm shows 0.5 to approximately 2.5 dB gain in PSNR and a small fluctuation in quality after scene change.
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