Multimedia systems

This thesis addresses a passive, economical strategy towards enhancing the security
feature of conventional plastic cards by embedding a set of electromagnetic (EM)
material that emulates an invisible "watermarking". It is an overlay strategy to prevailing
security measures.
Proposed method consists of incorporating (embedding) a set of metallic (foil-like) sheet
of high-mu material or high-conductivity metal, or a conducting-fiber interwoven fabric.
The test card when exposed to a suitable excitation of high frequency EM excitation
(with or without superimposing a static magnetic field), the plastic part yields a distinct
path-reluctance to the EM energy when compared to the embedded EM material section.
Sensing the resulting EM reaction with an appropriate circuit, delivers an output signal
depicting the presence of the embedded "watermarking" and any encoded signature in it.
The underlying concept is theoretically analyzed, relevant card-reading methods are
suggested and prototype (experimental) results are presented.

Recently, multimedia applications and their use have grown dramatically in
popularity in strong part due to mobile device adoption by the consumer market.
Applications, such as video conferencing, have gained popularity. These applications
and others have a strong video component that uses the mobile device’s resources. These
resources include processing time, network bandwidth, memory use, and battery life.
The goal is to reduce the need of these resources by reducing the complexity of the
coding process. Mobile devices offer unique characteristics that can be exploited for
optimizing video codecs. The combination of small display size, video resolution, and
human vision factors, such as acuity, allow encoder optimizations that will not (or
minimally) impact subjective quality. The focus of this dissertation is optimizing video services in mobile environments. Industry has begun migrating from H.264 video coding to a more resource intensive but compression efficient High Efficiency Video Coding (HEVC). However, there has been no proper evaluation and optimization of HEVC for mobile environments.
Subjective quality evaluations were performed to assess relative quality between H.264
and HEVC. This will allow for better use of device resources and migration to new
codecs where it is most useful. Complexity of HEVC is a significant barrier to adoption
on mobile devices and complexity reduction methods are necessary. Optimal use of
encoding options is needed to maximize quality and compression while minimizing
encoding time. Methods for optimizing coding mode selection for HEVC were
developed. Complexity of HEVC encoding can be further reduced by exploiting the
mismatch between the resolution of the video, resolution of the mobile display, and the
ability of the human eyes to acquire and process video under these conditions. The
perceptual optimizations developed in this dissertation use the properties of spatial
(visual acuity) and temporal information processing (motion perception) to reduce the
complexity of HEVC encoding. A unique feature of the proposed methods is that they
reduce encoding complexity and encoding time.
The proposed HEVC encoder optimization methods reduced encoding time by
21.7% and bitrate by 13.4% with insignificant impact on subjective quality evaluations.
These methods can easily be implemented today within HEVC.

In this thesis, we develop a set of programs in the MATLAB RTM Graphical User Interface environment, for use as an Interactive Digital Signal Processing Laboratory. The software toolbox consists of programs on selected topics covered in undergraduate Digital Signal Processing courses. Care is taken to give the user sufficient degrees of freedom to illustrate the effect of various parameter changes. Program code is left open and well documented to allow expansion.

Over the past ten years, Client/Server computing has had a powerful impact on the way businesses deal with information technology. Client/Server computing has enhanced user's productivity, revolutionized computer networking, and restructured the computer industry. Today, another new technology is poised to impact business computing in an equally dramatic way. Networked Multimedia computer applications will significantly affect users and network managers and have a tremendous impact on computing and network infrastructures. This thesis explores the areas of high speed networking for multimedia applications. Focusing primarily on the FDDI technology we model a high speed FDDI multimedia LAN model and developed typical multimedia traffic models to aid in case study of the FDDI HSMM-LAN networks. FFOL, the Follow On Standards currently in the ANSI standards committee, discuss Network Architectures that include a gigabit backbone network for FDDI and FDDI II networks, making them an attractive and cost effective option to the customer.

The home computer user represents a significant portion of the multimedia market. To the home user, multimedia is the ability to play, edit and even create movies (video and sound) on his home computer system. While there are many studies that concentrate on large multimedia servers which support hundreds (even thousands) of simultaneous users, there are very few that focus attention on the home computer configuration. This thesis presents the mechanisms for generating, compressing, transmitting and decompressing multimedia data as a framework for the long-term storage and retrieval of multimedia data on disk drives. After developing the framework, the thesis presents an in-depth design and analysis of a disk-based multimedia storage system, proposes a scheduling algorithm for data retrieval (DAN-SCAN) and presents the results of a simulation of the algorithm.

This thesis presents a survey of multimedia networks and the techniques to improve the capacity of video on demand systems. A survey was conducted and comparative evaluation was done to determine the multimedia capabilities of various networks. Video on demand is an electronic video rental system in which clients request and play videos on-demand. Video on-demand system can be implemented over an existing cable TV network or an upgraded ADSL network. The two techniques used to improve the capacity of video on-demand systems are segmentation and multicasting. Segmentation consists of dividing the video into several fixed length segments, and then transmitting the segments at regular intervals instead of transmitting the video continuously. With multicasting, more than one user requesting the same video are served by a single video stream. Multicasting further assumes that each subscriber has a limited storage space, so same video segments can be multicast to subscribers simultaneously even if the requests for a video are not synchronous.

Voice over IP (VoIP) is revolutionizing the global communications system by allowing human voice and fax information to travel over existing packet data networks along with traditional data packets. The convergence of voice and data in one simplified network brings both benefits and constraints to users. Among the several issues that need to be addressed when deploying this technology, security is one of the most critical. This thesis will present a combination of security patterns based on the systematic analysis of attacks against a VoIP network and the existing techniques to mitigate these attacks, providing good practices for all IP telephony systems. The VoIP Security Patterns which are based on object-oriented modeling, will help network designers to improve the level of security not only in voice but also in data, video, and fax over IP networks.

Multimedia applications incorporate the use of more than one type of media, i.e., voice, video, data, text and image. With the advances in high-speed communication, the ability to transmit multimedia is becoming widely available. One of the means of transport for multimedia in distributed networks is Broadband Integrated Services Digital Network (B-ISDN). B-ISDN supports the transport of large volumes of data with a low error rate. It also handles the burstiness of multimedia traffic by providing dynamic bandwidth allocation. When multimedia is requested for transport in a distributed network, different Quality of Service (QOS) may be required for each type of media. For example, video can withstand more errors than voice. In order to provide, the most efficient form of transfer, different QOS media are sent using different channels. By using different channels for transport, jitter can impose skews on the temporal relations between the media. Jitter is caused by errors and buffering delays. Since B-ISDN uses Asynchronous Transfer Mode (ATM) as its transfer mode, the jitter that is incurred can be assumed to be bounded if traffic management principles such as admission control and resource reservation are employed. Another network that can assume bounded buffering is the 16 Mbps token-ring LAN when the LAN Server (LS) Ultimedia(TM) software is applied over the OS/2 LAN Server(TM) (using OS/2(TM)). LS Ultimedia(TM) reserves critical resources such as disk, server processor, and network resources for multimedia use. In addition, it also enforces admission control(1). Since jitter is bounded on the networks chosen, buffers can be used to realign the temporal relations in the media. This dissertation presents a solution to this problem by proposing a Feedback-based Multimedia Synchronization Technique (FMST) to correct and compensate for the jitter that is incurred when media are received over high speed communication channels and played back in real time. FMST has been implemented at the session layer for the playback of the streams. A personal computer was used to perform their synchronized playback from a 16 Mbps token-ring and from a simulated B-ISDN network.

In the current communications age, the capabilities of mobile devices are increasing. The mobiles are capable of communicating at data rates of hundreds of mbps on 4G networks. This enables playback of rich multimedia content comparable to internet and television networks. However, mobile networks need to be spectrum-efficient to be affordable to users. Multimedia Broadcast Multicast Systems (MBMS) is a wireless broadcasting standard that is being drafted to enable multimedia broadcast while focusing on being spectrum-efficient. The hybrid video coding techniques facilitate low bitrate transmission, but result in dependencies across frames. With a mobile environment being error prone, no error correction technique can guarantee error free transmission. Such errors propagate, resulting in quality degradation. With numerous mobiles sharing the broadcast session, any error resilient scheme should account for heterogeneous device capabilities and channel conditions. The current research on wireless video broadcasting focuses on network based techniques such as FEC and retransmissions, which add bandwidth overhead. There is a need to design innovative error resilient techniques that make video codec robust with minimal bandwidth overhead. This Dissertation introduces novel techniques in the area of MBMS systems. First, robust video structures are proposed in Periodic Intra Frame based Prediction (PIFBP) and Periodic Anchor Frame based Prediction (PAFBP) schemes. In these schemes, the Intra frames or anchor frames serve as reference frames for prediction during GOP period. The intermediate frames are independent of others; any errors in such frames are not propagated, thereby resulting in error resilience. In prior art, intra block rate is adapted based on the channel characteristics for error resilience. This scheme has been generalized in multicasting to address a group of users sharing the same session. Average packet loss is used to determine the intra block rate. This improves performance of the overall group and strives for consistent performance. Also, the inherent diversity in the broadcasting session can be used for its advantage. With mobile devices capable of accessing a WLAN during broadcast, they form an adhoc network on a WLAN to recover lost packets. New error recovery schemes are proposed for error recovery and their performance comparison is presented.

The retrieval of digital images is hindered by the semantic gap. The semantic gap is the disparity between a user's high-level interpretation of an image and the information that can be extracted from an image's physical properties. Content based image retrieval systems are particularly vulnerable to the semantic gap due to their reliance on low-level visual features for describing image content. The semantic gap can be narrowed by including high-level, user-generated information. High-level descriptions of images are more capable of capturing the semantic meaning of image content, but it is not always practical to collect this information. Thus, both content-based and human-generated information is considered in this work. A content-based method of retrieving images using a computational model of visual attention was proposed, implemented, and evaluated. This work is based on a study of contemporary research in the field of vision science, particularly computational models of bottom-up visual attention. The use of computational models of visual attention to detect salient by design regions of interest in images is investigated. The method is then refined to detect objects of interest in broad image databases that are not necessarily salient by design. An interface for image retrieval, organization, and annotation that is compatible with the attention-based retrieval method has also been implemented. It incorporates the ability to simultaneously execute querying by image content, keyword, and collaborative filtering. The user is central to the design and evaluation of the system. A game was developed to evaluate the entire system, which includes the user, the user interface, and retrieval methods.