A very useful airborne-ground disaster surveying system (AGDSS) is being developed. The sensors of the surveying system consisted of a GPS receiver and some remote sensing instruments. The processed and compressed dat...
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A very useful airborne-ground disaster surveying system (AGDSS) is being developed. The sensors of the surveying system consisted of a GPS receiver and some remote sensing instruments. The processed and compressed data are transmitted to ground receiving stations directly. The AGDSS includes an optical sensor that is of large swath width, high resolution and produces a huge quantity of data. So it is very difficult to assemble the sensors, sample, compress and deal with the output data of the sensors in real-time. However, data splitting and compounding technology has been developed and it can solve the thorny problem. The distinguish feature of the data splitting and compounding technology is the multi-CPU parallel working method adopted. There are some advantages for the data splitting and compounding technology, so it is important to the real-time transmission system for huge amounts of data.
Subjective audio quality is currently obtained using expensive and time consuming listening tests that provide limited information. In this paper we show the different behaviors of several objective metrics designed t...
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Subjective audio quality is currently obtained using expensive and time consuming listening tests that provide limited information. In this paper we show the different behaviors of several objective metrics designed to match subjective results over different audio sequences for several audio distortions. In particular we extend these metrics to the case where distortions vary temporally and evaluate performance over two common time-varying distortions.
This paper considers the use of disk-based solution for network backup and studies how to restore data efficiently that can be made possible using disk-based backup solution. The study we conducted is based on the sto...
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ISBN:
(纸本)0780386477
This paper considers the use of disk-based solution for network backup and studies how to restore data efficiently that can be made possible using disk-based backup solution. The study we conducted is based on the storage media and restoration method. With the maturity of technology and cost falling, disks are becoming increasingly compelling as the backup media over magnetic tapes. The unique advantage of disk is that it is a random access media and it can apply such as possible compression algorithms to different versions of the same file during backup. In addition, restoration of data from disk can be much more convenient compared to tape. We consider in this paper browser/server approach, as well as client application/server approach. We also present a working system called "A-backup system" that offers new benefits such as efficient data restoration for disk-based network backup systems, benefits not possible before with tape based backup systems.
The session Initiation Protocol (SIP) is a widely used application-layer control protocol. The processing load of the SIP protocol is reportedly seen as one of the potential problems which may limit the range of its a...
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The session Initiation Protocol (SIP) is a widely used application-layer control protocol. The processing load of the SIP protocol is reportedly seen as one of the potential problems which may limit the range of its application although it has a number of advantages. Many research efforts have been made and have come up with various compression algorithms to reduce the packet size in order not to waste scarce bandwidth especially for wireless access networks. However, they increase the processing load at the same time. We propose a lightweight application-layer signaling protocol (lightweight-SIP) which reduces network bandwidth without sacrificing CPU performance by introducing a gateway which translates SIP into the proposed protocol. The gateway works as a cache for static and lengthy header fields of SIP messages. We expect the proposed protocol to be used by low-spec devices such as sensor nodes, less-expensive surveillance cameras and wearable computers so that it could reduce the energy consumption and lengthening the battery life or loosen requirements for the hardware specs.
We propose multi-level encoding and placement techniques to efficiently support the retrieval of video streams on a disk array at different resolutions. For the MPEG-1 compression algorithm, this encoding technique fi...
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We propose multi-level encoding and placement techniques to efficiently support the retrieval of video streams on a disk array at different resolutions. For the MPEG-1 compression algorithm, this encoding technique first partitions the parent video stream in the temporal dimension. Each frame in the sub-stream is then partitioned in the chroma dimension yielding a low-resolution and a residual component. The server stores blocks of a component on a disk and stores blocks of different components on consecutive disks in a round-robin manner. The lower the resolution level being maintained, the smaller is the number of disks accessed by each client.
Selective encryption is a technique to save computational complexity or enable new system functionality by encrypting only a portion of a compressed bitstream while achieving adequate security. Although suggested in a...
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Selective encryption is a technique to save computational complexity or enable new system functionality by encrypting only a portion of a compressed bitstream while achieving adequate security. Although suggested in a number of specific cases, selective encryption could be much more widely used in consumer electronic applications, ranging from mobile multimedia terminals to digital cameras, were it subjected to a more thorough security analysis. We describe selective encryption and develop a simple scalar quantizer example to demonstrate the power of the concept, list a number of potential consumer electronics applications, then describe an appropriate method for developing and analyzing selective encryption for particular compression algorithms. We summarize results from the application of this method to the MPEG-2 video compression algorithm.
The objective of this paper is to illustrate the details of optimization and real-time implementation of ITU's G.728 on C64x DSPs. First using pseudo codes provided by CCITTs published documents, we implemented th...
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The objective of this paper is to illustrate the details of optimization and real-time implementation of ITU's G.728 on C64x DSPs. First using pseudo codes provided by CCITTs published documents, we implemented the algorithm in C language. This implementation was performed for G and H (12.8 and 9.6 kbit/s) annexes. Next we optimized the written codes for implementation on DSP. At first stage, using different techniques based on DSPs' hardware characteristics, we rewrote and changed the most time-consuming parts of our codes in order to reduce their execution time. At second stage, we balanced the computational load of G.728 coder algorithm by splitting the Durbin's recursion for synthesis filter between different input speech vectors. In each stage, we verified the correctness of our implementation by testing our codes against testing vectors provided by ITU. Applying the above mentioned methods enabled us to optimize the C codes into 22.7 MIPS in worst case. At the end we also implemented the optimized codes in real-time on a DSK6416
The speed gap between CPU and memory is impairing performance. Cache compression and hardware prefetching are two techniques that could confront this bottleneck by decreasing last level cache misses. However, compress...
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The speed gap between CPU and memory is impairing performance. Cache compression and hardware prefetching are two techniques that could confront this bottleneck by decreasing last level cache misses. However, compression and prefetching have positive interactions, as prefetching benefits from higher cache capacity and compression increases the effective cache size. This paper proposes Compressed cache Layout Aware Prefetching (CLAP) to leverage the recently proposed sector-based compressed cache layouts such as SCC or YACC to create a synergy between compressed cache and prefetching. The idea of this approach is to prefetch contiguous blocks that can be compressed and co-allocated together with the requested block on a miss access. Prefetched blocks that share storage with existing blocks do not need to evict a valid existing entry; therefore, CLAP avoids cache pollution. In order to decide the co-allocatable blocks to prefetch, we propose a compression predictor. Based on our experimental evaluations, CLAP reduces the number of cache misses by 12% and improves performance by 4% on average, comparing to a compressed cache.
The bijective relationship between T-Code sets and finite strings discovered by Nicolescu and Titchener is of interest not only in coding, but also in information measurement and lately in content-based retrieval. The...
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ISBN:
(纸本)0780381858
The bijective relationship between T-Code sets and finite strings discovered by Nicolescu and Titchener is of interest not only in coding, but also in information measurement and lately in content-based retrieval. Their T-decomposition algorithm that accomplishes the mapping from the string to the T-code set was implemented in 1996 by Wackrow and Titchener. This paper introduces a new algorithm that permits faster T-decomposition. Initial experimental results are also given.
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