<p>The SASL project at the University of the Western Cape aims at developing a fully automated translation system between English and South African Sign Language (SASL). Three important aspects of this system require SASL documentation and knowledge. These are: recognition of SASL from a video sequence, linguistic translation between SASL and English and the rendering of SASL. Unfortunately, SASL documentation is a scarce resource and no official or complete documentation exists. This research focuses on creating an online collaborative video annotation knowledge management system for SASL where various members of the community can upload SASL videos to and annotate them in any of the sign language notation systems, SignWriting, HamNoSys and/or Stokoe. As such, knowledge about SASL structure is pooled into a central and freely accessible knowledge base that can be used as required. The usability and performance of the system were evaluated. The usability of the system was graded by users on a rating scale from one to five for a specific set of tasks. The system was found to have an overall usability of 3.1, slightly better than average. The performance evaluation included load and stress tests which measured the system response time for a number of users for a specific set of tasks. It was found that the system is stable and can scale up to cater for an increasing user base by improving the underlying hardware.</p>

In order to efficiently manage the large amounts of video data stored in a digital video archive, computerized management systems must be developed for storing and making the video available to users. In this thesis, we study tertiary storage technologies and storage architectures for storing and retrieving digital video in video archives. We evaluate serpentine tape as a storage medium for digital video. In order to increase the performance of storage systems using serpentine tape, we present and evaluate a detailed access-time model for serpentine tape and a novel scheduling algorithm for optimizing concurrent accesses to the tape. The scheduling algorithm is used for evaluating serpentine tape for storing images and video sequences. The main conclusion is that by using the access-time model and the proposed scheduling algorithm, it is possible to achieve significant improvements in initial latency, average access time, and the number of requests that can be served by a single tape drive. Tertiary storage technologies including magnetic tape and DVD are evaluated for use in digital video archives. The evaluation is performed using a simulator of the storage system of a video archive. The simulation model is based on the architecture of the Elvira~II video archive server. Different configurations for the storage system are evaluated with regards to performance and cost. In the evaluation different allocation strategies, access distributions, and user loads are studied. The effect of using a cache based on magnetic disks is investigated. The main conclusion is that the choice of architecture and storage technology for a video archive depends on the user generated load, the size of the requested video sequences, and the access distribution for the stored videos. It also depends on whether throughput, response time, storage cost, or cost per retrieved video is the main evaluation criterion. Furthermore, we show that a video archive based on DVD as the main storage technology outperforms a video archive using magnetic tape, and that including a relatively small disk cache in most cases improves the performance and reduces the total cost of the archive. The ideas and results presented in this thesis are also useful outside the video archive context. The strategies and results are beneficial for applications that require hierarchical storage management systems for managing large data volumes.

To encode, query and present the semantic content of digital video precisely and flexibly is very useful for many kinds of knowledge work: system analysis and evaluation, documentation and education, to name a few. However, that kind of video management is not a trivial matter. The traditional stratified annotation model has quite poor facilities for specifying the meaning – the structure and relationships – of the strata. Because of this, it may also be troublesome to present the annotations to the users in a clear and flexible manner. This thesis presents OntoLog, a system for managing the semantic content of video. It extends the stratified annotation model by defining the strata as objects and classes in ontologies, thereby making their semantic meaning more explicit and relating them to each other in a semantic network. The same ontologies are also used to define properties and objects for describing both the strata, individual video intervals and entire videos. This constitutes a very customisable, expressive and precise description model, without sacrificing simplicity and conceptual integrity. Arranging the annotation strata in a near-hierarchical network with specified semantics (classes, subclasses and instances) also enables reasoning about the annotations during query and browsing. In particular, it enables visual aggregation of traditional timeline-based strata graphics. Using this to create compact content visualisations, the OntoLog system is able to present tens of videos on screen at the same time, thus providing inter-video browsing. By judiciously disaggregating selected parts of the strata hierarchy, users can focus on relevant strata at their preferred level of detail – overview-and-zoom functionality for semantic annotations, in other words. The OntoLog system has been implemented in the form of six Java applications and web services – together covering annotation editing, browsing, analysis, search, query and presentation with various approaches – built on top of an RDF database founded on SQL. The system has been tested under realistic conditions in several real-world projects, with good results. A novel information gathering interface for OntoLog data, Savanta, has been created. This is based on an iterative interaction paradigm featuring inter-video browsing, filtering, navigation and context-sensitive temporal analysis of the annotations. In a comparative usability evaluation, Savanta is shown to outperform more traditional user interfaces for video search/browsing with regard to expressive power, straightforwardness and user satisfaction.

This thesis focuses on video watermarking robust against geometric attacks and video compressions. In addition to the requirements for an image watermarking algorithm, a digital video watermarking algorithm has to be robust against advanced video compressions, frame loss, frame swapping, aspect ratio change, frame rate change, intra- and inter-frame filtering, etc. Video compression, especially, the most efficient compression standard, H.264, and geometric attacks, such as rotation and cropping, frame aspect ratio change, and translation, are considered the most challenging attacks for video watermarking algorithms. In this thesis, we first review typical watermarking algorithms robust against geometric attacks and video compressions, and point out their advantages and disadvantages. Then, we propose our robust video watermarking algorithms against Rotation, Scaling and Translation (RST) attacks and MPEG-2 compression based on the logpolar mapping and the phase-only filtering method. Rotation or scaling transformation in the spatial domain results in vertical or horizontal shift in the log-polar mapping (LPM) of the magnitude of the Fourier spectrum of the target frame. Translation has no effect in this domain. This method is very robust to RST attacks and MPEG-2 compression. We also demonstrate that this method can be used as a RST parameters detector to work with other watermarking algorithms to improve their robustness to RST attacks. Furthermore, we propose a new video watermarking algorithm based on the 1D DFT (one-dimensional Discrete Fourier Transform) and 1D projection. This algorithm enhances the robustness to video compression and is able to resist the most advanced video compression, H.264. The 1D DFT for a video sequence along the temporal domain generates an ideal domain, in which the spatial information is still kept and the temporal information is obtained. With detailed analysis and calculation, we choose the frames with highest temporal frequencies to embed the fence-shaped watermark pattern in the Radon transform domain of the selected frames. The performance of the proposed algorithm is evaluated by video compression standards MPEG-2 and H.264; geometric attacks such as rotation, translation, and aspect-ratio changes; and other video processing. The most important advantages of this video watermarking algorithm are its simplicity, practicality and robustness.

Transmission of digital signals is today more frequently used than transmission of analog signals. One reason for this is that a digital signal is less sensitive to noise than an analog, another reason is that almost all signals today are handled in a digital format. This thesis describes the development of a system that receives digital video signals through FireWire. The standard for FireWire, which is a high performance serial bus, is under development. Today the standard of the bus supports transmission of data with a speed of up to 400 Mbit/s. In the future FireWire is supposed to transmit data with a speed of up to 3,2 Gbit/s. The thesis gives an introduction to the technique for FireWire and how it is implemented. It also includes a short description of digital video signals in DVCAM format.

This thesis focuses on video watermarking robust against geometric attacks and video compressions. In addition to the requirements for an image watermarking algorithm, a digital video watermarking algorithm has to be robust against advanced video compressions, frame loss, frame swapping, aspect ratio change, frame rate change, intra- and inter-frame filtering, etc. Video compression, especially, the most efficient compression standard, H.264, and geometric attacks, such as rotation and cropping, frame aspect ratio change, and translation, are considered the most challenging attacks for video watermarking algorithms. In this thesis, we first review typical watermarking algorithms robust against geometric attacks and video compressions, and point out their advantages and disadvantages. Then, we propose our robust video watermarking algorithms against Rotation, Scaling and Translation (RST) attacks and MPEG-2 compression based on the logpolar mapping and the phase-only filtering method. Rotation or scaling transformation in the spatial domain results in vertical or horizontal shift in the log-polar mapping (LPM) of the magnitude of the Fourier spectrum of the target frame. Translation has no effect in this domain. This method is very robust to RST attacks and MPEG-2 compression. We also demonstrate that this method can be used as a RST parameters detector to work with other watermarking algorithms to improve their robustness to RST attacks. Furthermore, we propose a new video watermarking algorithm based on the 1D DFT (one-dimensional Discrete Fourier Transform) and 1D projection. This algorithm enhances the robustness to video compression and is able to resist the most advanced video compression, H.264. The 1D DFT for a video sequence along the temporal domain generates an ideal domain, in which the spatial information is still kept and the temporal information is obtained. With detailed analysis and calculation, we choose the frames with highest temporal frequencies to embed the fence-shaped watermark pattern in the Radon transform domain of the selected frames. The performance of the proposed algorithm is evaluated by video compression standards MPEG-2 and H.264; geometric attacks such as rotation, translation, and aspect-ratio changes; and other video processing. The most important advantages of this video watermarking algorithm are its simplicity, practicality and robustness.

I detta examensarbete har olika sätt att implementera färgrymdskonverterare i multipel konstant multiplikationsteknik beskrivits med VHDL, syntetiserats och jämförts med avseende på effektförbrukning.

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This thesis consists of two parts. Part one includes the design procedure and implementation of the building blocks for an RF tuner module used in the Digital Video Broadcasting ¡V Terrestrial ¡]DVB-T¡^system. It contains the comparison of several RF tuner architectures, frequency planning, and link-budget analysis. Measurement results for the designed tuner operating in the frequency range from 50 to 860 MHz show that the maximum power gain ranges from 49 to 57.6 dB. The entire range for gain control is over 60 dB. In the maximum gain state, the noise figure ranges form 6.8 to 11.5 dB, the output third-order interception point¡]OIP3¡^ranges from 11.7 to 13.8 dBm, and the image rejection is over 50 dB. By applying the simplified single-carrier modulation signals, the tuner can pass the DVB-T system specifications with respect to the adjacent-channel and overlapping-channel protection ratios. In part two, an RFIC design for low-noise variable-gain amplifier that can be used in the RF front end of DVB-T system is presented. It operates from 100 to 900 MHz and dissipates 59.4 mW under a 3.3-V power supply. In the maximum gain state, measurement results for this RFIC show that the noise figure is less than 4 dB, the maximum gain is more than 14 dB, and the OIP3 is about 6.8dBm. The entire gain control range is over 40 dB.