L2C: Combining Lossy and Lossless Compression on Memory and I/O

In this paper we introduce L2C, a hybrid lossy/lossless compression scheme applicable both to the memory subsystem and I/O traffic of a processor chip. L2C employs general-purpose lossless compression and combines it with state of the art lossy compression to achieve compression ratios up to 16:1 and improve the utilization of chip\u27s bandwidth resources. Compressing memory traffic yields lower memory access time, improving system performance and energy efficiency. Compressing I/O traffic offers several benefits for resource-constrained systems, including more efficient storage and networking.We evaluate L2C as a memory compressor in simulation with a set of approximation-tolerant applications. L2C improves baseline execution time by an average of 50\%, and total system energy consumption by 16%. Compared to the lossy and lossless current state of the art memory compression approaches, L2C improves execution time by 9% and 26% respectively, and reduces system energy costs by 3% and 5%, respectively.I/O compression efficacy is evaluated using a set of real-life datasets. L2C achieves compression ratios of up to 10.4:1 for a single dataset and on average about 4:1, while introducing no more than 0.4% error

A network transparent, retained mode multimedia processing framework for the Linux operating system environment

Die Arbeit präsentiert ein Multimedia-Framework für Linux, das im Unterschied zu früheren Arbeiten auf den Ideen "retained-mode processing" und "lazy evaluation" basiert: Statt Transformationen unmittelbar auszuführen, wird eine abstrakte Repräsentation aller Medienelemente aufgebaut. "renderer"-Treiber fungieren als Übersetzer, die diese Darstellung zur Laufzeit in konkrete Operationen umsetzen, wobei das Datenmodell zahlreiche Optimierungen zur Reduktion der Anzahl der Schritte oder der Minimierung von Kommunikation erlaubt. Dies erlaubt ein stark vereinfachtes Programmiermodell bei gleichzeitiger Effizienzsteigerung. "renderer"-Treiber können zur Ausführung von Transformationen den lokalen Prozessor verwenden, oder können die Operationen delegieren. In der Arbeit wird eine Erweiterung des X Window Systems um Mechanismen zur Medienverarbeitung vorgestellt, sowie ein "renderer"-Treiber, der diese zur Delegation der Verarbeitung nutzt

System requirements and considerations for visual table of contents in PVR

With the introduction of non-tape-based digital video recorders also known as personal video recorders (PVR), consumers can expect alternative navigation methods to the well-known trick-play modes found on analog and digital tape-based systems. In this paper, we explore the system requirements and aspects of a visual table of contents (VTOC). A primary advantage of implementing a VTOC search mode is that it provides a much higher visual performance at high search speeds (50 times or higher) than the conventional search techniques. We present a solution for generating a video signal for visual search that is based on reusing MPEG-2 compressed video data. The video search signal is composed of a set of MPEG-2 compressed subpictures, resulting in a mosaic screen. An efficient strategy is introduced, that allows either full or partial reuse of the compressed sub-pictures via motion compensation of earlier reference sub-pictures to allow the generation of a new mosaic screen

User-activity aware strategies for mobile information access

Information access suffers tremendously in wireless networks because of the low correlation between content transferred across low-bandwidth wireless links and actual data used to serve user requests. As a result, conventional content access mechanisms face such problems as unnecessary bandwidth consumption and large response times, and users experience significant performance degradation. In this dissertation, we analyze the cause of those problems and find that the major reason for inefficient information access in wireless networks is the absence of any user-activity awareness in current mechanisms. To solve these problems, we propose three user-activity aware strategies for mobile information access. Through simulations and implementations, we show that our strategies can outperform conventional information access schemes in terms of bandwidth consumption and user-perceived response times.Ph.D.Committee Chair: Raghupathy Sivakumar; Committee Member: Chuanyi Ji; Committee Member: George Riley; Committee Member: Magnus Egerstedt; Committee Member: Umakishore Ramachandra

Image and Video Coding Techniques for Ultra-low Latency

The next generation of wireless networks fosters the adoption of latency-critical applications such as XR, connected industry, or autonomous driving. This survey gathers implementation aspects of different image and video coding schemes and discusses their tradeoffs. Standardized video coding technologies such as HEVC or VVC provide a high compression ratio, but their enormous complexity sets the scene for alternative approaches like still image, mezzanine, or texture compression in scenarios with tight resource or latency constraints. Regardless of the coding scheme, we found inter-device memory transfers and the lack of sub-frame coding as limitations of current full-system and software-programmable implementations.publishedVersionPeer reviewe

Cost-effective Hardware Design of a SPIHT Compression Algorithm

학위논문 (석사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 2. Jae Ha Kim.Set Partitioning In Hierarchical Trees (SPIHT) is one of most popular embedded coding algorithms applied for wavelet coding images. It allows progressive transmission of information and gives high coding efficiency. In addition, it can omit entropy coding of the bit stream by arithmetic code with only small loss in performance. Thus it offers a cheaper and faster hardware design. In this dissertation, a cost-effective design of a SPIHT-based algorithm is proposed. In this algorithm, an image is partitioned into 1x64 blocks, each of which is transformed by DWT to generate wavelet coefficients. The wavelet coefficients are coded by SPIHT to generate bit-stream. Due to the mismatch of the data structure between DWT and SPIHT, the large buffers are required. In order to reduce buffers, a new data structure of wavelet coefficients and partitioned SPIHT are proposed. A wavelet-based block is partitioned into small sub-blocks each of which is compressed independently. To minimize distortion due to the sub-block-based compression, a bit-allocation scheme is proposed. The proposed design is implemented in both software and hardware. Experimental results show that the proposed design reduces the buffer size while minimizing the degradation of the rate-distortion performance. It is proved that the proposed design outperforms previous designs in hardware cost.Chapter Ⅰ. Introduction 1 Chapter Ⅱ. Basic Architecture of the compression algorithm 5 Chapter Ⅲ. A Partitioned NLS Algorithm 17 Chapter Ⅳ. Adjustment of the target bit lengths for individual sub-blocks Chapter Ⅴ. Experimental Results 35 Chapter Ⅵ. Conclusion 48 References 50 Abstract 52 초록 53Maste