This paper describes a source controlled variable bit-rate (SCVBR) speech coder based on the concept of prototype waveform interpolation. The coder uses a four mode classification : silence, voiced, unvoiced and transition. These modes are detected after the speech has been decomposed into slowly evolving (SEW) and rapidly evolving (REW) waveforms. A voicing activity detection (VAD), the relati...

State of the art digital video compression produces bursty, variable bit rate video. The bursty nature of compressed video raises challenges in the design of video servers. In this paper, we first present a method for the efficient retrieval of bursty video data from the disk system to the memory of a digital video server. For a single video stream, the proposed retrieval schedule minimizes the...

For the performance analysis of ATM networks carrying Variable Bit Rate (VBR) MPEG video sequences there is a need for appropriate video traac models. In this paper, we discuss Markov chain models for this speciic type of traac with respect to several statistical properties and their ability to predict cell losses at buuers of ATM multiplexers. We intentionally selected a simple model class to ...

In this paper, we model the statistical behavior of real traces of MPEG-4 encoded variable bit rate (VBR) video data in a digital video server. As performance measures we calculate bounds for the user disk service rate and buffer size. According to our simulations, the Gamma Fractal Noise model for the increment process, which is self-similar, seems to be very close to the actual data behavior.

Video servers store digitized, compressed continuous media information on high-capacity secondary or tertiary storage [6]. The secondary storage devices allow random accessible and provide short seek times compared to tertiary storage. Video server design differs significantly from that of traditional data storage servers due to the large size of the objects stored and the real-time requirement...

Future high-speed computer networks are projected to carry a dizzying array of stored continuous media (CM) flows emanating from sources such as digital libraries and video servers. These flows are often variable bit rate in nature and are characterized by tight delay requirements. In order to guarantee such delay requirements, the network must reserve resources at the links of the path for the...

Recent work on JPEG compression for low bit-rate coding has shown that employing a JPEG coder within a sampling scheme where the image is downsampled prior to coding (and upsampled after the decoding stage) results in superior performance compared to standard JPEG coding. In this paper, we explore the use of optimal decimation and interpolation filters in this coding scheme. We shall first cons...

Digital Video Broadcasting for Handheld terminals (DVB-H) is assuming an ever growing importance for digital video transmission over wireless terminals. In such a context, Time Slicing has been implemented to achieve a better power saving and manage handover. Specifically, a generic user transmits bursts of data, interspaced by time periods in which no data are transmitted. In this paper, to im...

For admission control in real time multimedia systems, buuer space, disk bandwidth and network bandwidth must be considered. Most admission control mechanisms developed to date have been based on the CBR data model and have used a static period length. These mechanisms do not use system resources eeectively, since media data is usually encoded with VBR compression techniques. We propose an admi...

This memo discusses potential security issues that arise when using variable bit rate (VBR) audio with the secure RTP profile. Guidelines to mitigate these issues are suggested. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at in effect on the date of publication of this document. Please review these documents carefully, as ...