• Journal of Information Technology Applications and Management
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• v.12 no.1
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• pp.125-140
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• 2005

Nowadays, we have many embedded systems which store and process multimedia data. For multimedia systems using hard disks as storage media such as DVR, existing file systems are not the right choice to store multimedia data in terms of cost. performance and reliability. In this study we designed a reliable file system with very high performance for embedded multimedia applications. The proposed file system runs with quite simple disk layout to reduce time to initialize and to recover after power failures, uses a large data block to speed up the sequential accesses, incorporates a time-based indexing scheme to improve the time-based random accesses and boosts reliability by backing up the important meta data on a small NVRAM. We implemented the file system on a Linux-based DVR and verified the performance by comparing with existing file systems.

• ETRI Journal
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• v.32 no.5
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• pp.657-664
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• 2010

Many embedded multimedia systems employ special hardware blocks to co-process with the main processor. Even though an efficient handling of such hardware blocks is critical on the overall performance of real-time multimedia systems, traditional real-time scheduling techniques cannot afford to guarantee a high quality of multimedia playbacks with neither delay nor jerking. This paper presents a hardware-aware rate monotonic scheduling (HA-RMS) algorithm to manage hardware tasks efficiently and handle special hardware blocks in the embedded multimedia system. The HA-RMS prioritizes the hardware tasks over software tasks not only to increase the hardware utilization of the system but also to reduce the output jitter of multimedia applications, which results in reducing the overall response time.

• Korea Multimedia Society
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• v.7 no.4
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• pp.30-39
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• 2003

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.90-103
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• 2006

There are many file systems in various operating systems. Those are usually designed for server environments, where the common cases are usually 'multiple active users', 'great many small files' And they assume a big main memory to be used as buffer cache. So the existing file systems are not suitable for resource hungry embedded systems that process multimedia data streams. In this study, we designed and implemented a new file system which efficiently stores and retrieves multimedia data steams. The proposed file system has a very simple disk layout, which guarantees a quick disk initialization and file system recovery. And we introduced a new indexing-scheme, called the time-based indexing scheme, with the file system. With the indexing scheme, the file system maintains the relation between time and the location for all the multimedia streams. The scheme is useful in searching and playing the compressed multimedia streams by locating exact frame position with given time, resulting in reduction of CPU processing and power consumption. The proposed file system and its APIs utilizing the time-based indexing schemes were implemented firstly on a Linux environment, though it is operating system independent. In the performance evaluation on a real DVR system, which measured the execution time of multi-threaded reading and writing, we found the proposed file system is maximum 38.7% faster than EXT2 file system.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.460-471
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• 2004

Since the RTP is suitable for real-time data transmission in multimedia services like VoD, AoD, and VoIP, it has been adopted as a real-time transport protocol by RTSP, H.323, and SIP. Even though the RTP protocol stack for embedded systems has been in great need for efficient support of multimedia services, such a stack has not been developed yet. In this paper, we explain embeddedRTP which supports the RTP protocol stack at the kernel level so that it is suitable for embedded systems. Since embeddedRTP is designed to reside in the UBP module, existing applications which rely ell TCP/IP services can proceed the same as before, while applications which rely on the RTP protocol stack can request HTP services through embeddedRTp API. EmbeddedRTP stores transmitted RTP packets into per session packet buffer, using the packet's port number and multimedia session information. Communications between applications and embeddedRTP is performed through system calls and signal mechanisms. Additionally, embeddedRTP API makes it possible to develop applications more conveniently. Our performance test shows that packet-processing speed of embeddedRTP is about 7.5 times faster than that oi VCL RTP for multimedia streaming services on PDA in spite that its object code size is reduced about by 58% with respect to UCL RTP's.

• Journal of Korea Multimedia Society
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• v.8 no.5
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• pp.721-728
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• 2005

A virtual machine is a conceptual computer with a logical system configuration, made of software unlike physical systems made of hardware. Virtual machine technology for embedded systems is a requisite software technology for download solutions such as mobile devices, digital TVs, etc. At present, a research of virtual machines for embedded systems named EVM(Embedded Virtual Machine) is in progress. As a part of the research, we define the EFF(Executable File Format) as a file format for embedded systems. We also prove completeness of EFF by structurally mapping class file widely used to EFF.

• The KIPS Transactions:PartD
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• v.14D no.3 s.113
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• pp.311-318
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• 2007

A wearable computer has appeared as the next generation computer with the development of embedded system technique in our country, although it has not been applicable well since the hardware and software capabilities are limited for multimedia service. We have implemented a MPEG-4 video player to provide with such multimedia application service using the embedded systems. This paper illustrates the development of MPEG-4 video player operating on the wearable computer named WPS(Wearable Personal Station), the wristwatch PC developed at ETRI.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.6
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• pp.345-359
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• 2011

In high performance embedded systems, the use of multiple on-chip memories is an essential architectural feature for exploiting inherent parallelism in multimedia applications. This feature allows multiple data accesses to be executed in parallel. However, it remains difficult to effectively exploit of multiple on-chip memories. The successful use of this architecture strongly depends on how to efficiently detect and exploit memory parallelism in target applications. In this paper, we propose a technique based on a linear array access descriptor [1], which is generated from profiled data, to detect and exploit memory parallelism. The proposed technique tackles an array reorganization problem to maximize memory parallelism in multimedia applications. We present preliminary experiments applying the proposed technique onto a representative coarse grained reconfigurable array processor (CGRA) with multimedia kernel codes. Our experimental results demonstrate that our technique optimizes data placement by putting independent data on separate storage. The results exhibit 9.8% higher performance on average compared to the existing method.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.4
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• pp.245-255
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• 2009

Recently, embedded processor systems have been widely used in the field of information communication devices and increased its use range and influence. The embedded systems are offered variety of functions, and its operating systems have been developed to make them easy to repair and maintain. Especially embedded linux is very cheap and provide a lot of equipment drivers. Also we can set up our own system because the source code is opened. In this paper, we describe the implementation of Touch panel and TFT-LCD device driver that are widely used for multimedia application. We designed the system hardware by using Altera Nios II embedded system. And we implemented the device drivers of frame buffer, touch panel and i2s based on uClinux for multimedia application, and tested actual operations of the integrated system.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.183-193
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• 2003

The importance of XML data and their database supports in a mobile terminal system is on the increase. It leads to active research for embedded XML database systems. In order to handle in documents, DOM API should be supported. The existing DOM API is not suitable for the embedded system with limited resource because the DOM tree requires a large space on main memory. Considering poor resource of embedded systems, we present persistent DOM which is implemented on Berkeley DB and DOMdbm which manages it.