Browsing by Subject "Streaming technology (Telecommunications)"
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Item Bi-directional packing of compressed multimedia data for improved error resiliency(Texas Tech University, 2001-05) Srinivasan, AravindMost data compression schemes split the input signal into blocks and then produce a variable length code for each block. Since variable length codes are highly sensitive to channel errors that may occur during transmission, synchronization code words are often inserted between blocks to provide occasional resynchronization thereby adding more redundant bits of data. Error-resilient entropy coding (EREC) is a method of adapting existing schemes to give increased resilience to random and burst errors while maintaining high compression. This report proposes improvements to the EREC algorithm to increase its error resiliency. The objective is to pack code blocks in fixed-size slots, so that in the presence of bit errors, more data (blocks) can be recovered than is possible with the original EREC method of packing.Item Energy-aware embedded media processing: customizable memory subsystems and energy management policies(2004) Ramachandran, Anand; Jacome, Margarida F.The design of energy-efficient data memory architectures for embedded system platforms has received considerable attention in recent years. In this dissertation we propose a special-purpose data memory subsystem, called Xtream-Fit, targeted to streaming media applications executing on both generic uniprocessor embedded platforms and powerful SMT-based multi-threading platforms. We empirically demonstrate that Xtream-Fit achieves high energydelay efficiency across a wide range of media devices, from systems running a single media application to systems concurrently executing multiple media applications under synchronization constraints. Xtream-Fit’s energy efficiency is predicated on a novel task-based execution model that exposes/enhances opportunities for efficient prefetching, and aggressive dynamic energy conservation techniques targeting on-chip and off-chip memory components. A key novelty of Xtream-Fit is that it exposes a single customization parameter, thus enabling a very simple and yet effective design space exploration methodology to find the best memory configuration for the target application(s). Extensive experimental results show that Xtream-Fit reduces energy-delay product substantially – by 32% to 69% – as compared to ‘standard’ general-purpose memory subsystems enhanced with state of the art cache decay and SDRAM power mode control policies.Item Supporting rate adaptive multimedia streams on the Internet(2003) Weber, Steven Patrick; De Veciana, GustavoThis thesis investigates the feasibility of using rate adaptation, i.e., selective service degradation, as a mechanism for achieving various system level Quality of Service (QoS) targets on communication networks. In particular, we investigate how to optimally support rate adaptive multimedia streams on best-effort networks like the Internet. Optimal and practical mechanisms to maximize the client average QoS, de- fined in terms of a normalized time average received rate, are established. By scaling the arrival rate and link capacity, we obtain closed form expressions for asymptotic client average QoS. The optimal adaptation policy is identified as the solution to an integer programming problem which has an intuitive “sort by volume” inter- pretation. Our asymptotic analysis shows the optimal adaptation policy may yield performance improvements of up to 42% over baseline policies. We demonstrate that a static multi–class admission control policy can achieve the same asymptotic QoS as that of the optimal adaptation policy. This implies that dynamic adaptation may be unnecessary for large capacity networks with appropri- ate call admission. The multi–class admission policy, however, requires the stream load char- acteristics be both stationary and known a priori. To address this drawback we investigate a class of distributed algorithms where the frequency of rate adapta- tions depends on the stream “volume.” We show that these algorithms are able to achieve a QoS comparable to that achieved under the optimal adaptation policy, but without requiring knowledge of system wide parameters. Our simulations indi- cate our algorithm may yield performance improvements of up to 28% over baseline algorithms. Finally, we investigate using optimal adaptation in a networking environment supporting multiple service classes with distinct QoS guarantees. Our results confirm that rate adaptation, i.e., selective service degradation, is a viable means of achieving several different types of system level quality of service targets.