Multimedia File System Research Articles

Embedded NAND flash file system for mobile multimedia devices

In this work, we present a novel mobile multimedia file system, MNFS, which is specifically designed for NAND flash memory. Our design specifically addresses the needs of devices such as MP3 players, personal media players (PMPs), digital camcorders, etc. The file system has three novel features important in mobile multimedia applications: (1) predictable and uniform write latency, (2) quick file system mount, and (3) a small memory footprint. We implemented the proto-type file system on an embedded platform. In our experiments, MNFS exhibits uniform I/O latency for sequential write operation. It is mountable within 0.2 seconds and available with only 34 Kbytes of heap memory for a 128 Mbytes volume. The mounting time is 30 times faster compared to that of YAFFS, which is a well known file system for NAND flash memory, and the heap memory usage is only 5% of the YAFFS usage.

An efficient multimedia file system for NAND flash memory storage

Since the existing NAND flash memory file systems manage file data in page units, the memory usage increases greatly as the number and size of files increase, and the area to scan at the mounting time increases linearly as well. To resolve these problems, this paper suggests data management in segment units for more efficient processing of multimedia files to reduce memory usage and to improve reading and writing performance. In addition, it suggests a new index structure and garbage collection method for multimedia files to reduce the mounting time and to improve the wear-leveling effectiveness. This approach shows better performance for multimedia files than existing file systems in terms of reading, writing, memory usage, mounting time, and garbage collection.

Storage technique for real-time streaming of layered video

Scalable streaming technology has been proposed to effectively support heterogeneous devices with dynamically varying bandwidth. From the file system’s point of view, scalable streaming introduces another dimension of complexity in disk scheduling. Most of the existing efforts on multimedia file systems are dedicated to I/O scheduling algorithm and data placement scheme that efficiently guarantee I/O bandwidth. The important underlying assumption in these efforts is that most of the multimedia file accesses are simple playback operations and therefore are sequential. However, this workload characteristic is not valid in scalable streaming environment. In a scalable streaming environment, i.e., when only a subset of imagery is retrieved, the playback does not necessarily coincide with the sequential access on the file. The current file structure and the file system organization leaves much to be desired for supporting scalable streaming service. In this work, we propose a file system scheme, Harmonic Placement to efficiently support scalable streaming. The basic idea of Harmonic placement is to cluster the frequently accessed layers together to avoid unnecessary disk seeks. The data blocks are partitioned into two sets with respect to the layers: lower layers and upper layers. In Harmonic placement, the data blocks in the lower layers are placed with respect to their frame sequence and the data blocks in the upper layers are clustered according to the layers they belong to. We develop elaborate performance models for three different file system schemes: Progressive placement, Interleaved Placement and Harmonic Placement. We investigate the performance of the file server with different file system schemes. It was found that file system performance is very sensitive to the file organization scheme. When most of the service requests are for low-quality video (e.g., 128 Kbits/s ISDN), Progressive placement scheme supports twice as many sessions as the Interleaved placement scheme. When most of the service requests are for high-quality video (e.g., 1.5 Mbits/s MPEG-2 DVD quality), Interleaved placement can support twice as many requests as Progressive placement. In both cases, Harmonic placement scheme yields the most promising performance.

Fast-path I/O architecture for high performance streaming server

In a disk-network scenario where expensive data transfers are the norm, such as in multimedia streaming applications, for example, a fast-path I/O architecture is generally considered to be "good practice." Here, I/O performance can be improved through minimizing the number of in-memory data movements and context switches. In this paper, we report the results of the design and implementation of a high-performance streaming server using cheap hardware units assembled directly on a test card (i.e., NS card). The hardware part of our architecture is open to further reuse, extension, and integration with other applications even in the case of inexpensive and/or faster hardware. From the viewpoint of software-aided I/O, we offer Stream Disk Array (SDA) for scatter/gather-style block I/O, EXT3NS multimedia file system for large-scale file I/O, and interoperable streaming server for stream I/O.

Design considerations for the symphony integrated multimedia file system

A multimedia file system supports diverse application classes that access data with heterogeneous characteristics. In this paper, we describe our experiences in the design and implementation of the Symphony multimedia file system. We first discuss various methodologies for designing multimedia file systems and examine their trade-offs. We examine the design requirements for such file systems and argue that to efficiently manage the heterogeneity in application requirements and data characteristics, a multimedia file system should enable the coexistence of multiple data-type-specific and application-specific techniques. We describe the architecture and novel features of Symphony and then demonstrate their efficacy through an experimental evaluation. Our results show that Symphony yields a factor of 1.9 improvement in text response time over conventional disk scheduling algorithms while continuing to meet the real-time requirements of video clients. Finally, we reflect upon the lessons learned from the Symphony project.

Multimedia authoring and presentation techniques

Multimedia content is being increasingly used for presentations, be it in formal lectures and documents or informal home pages. Authoring a multimedia presentation involves describing spatial and temporal relationships governing the objects composing a document. While spatial relationships specify where (on the user’s screen) objects are to be presented, temporal relationships describe when and how objects presentations are to be synchronized. In a distributed environment, a multimedia presentation is carried out by retrieving and delivering objects according to their spatial and temporal relationships described by the author(s). In such environments, continuity of a presentation can be maintained by pre-fetching objects based on their temporal relationships and the system load (such as network traffic and server workload). Flexibility in temporal relationships can help in adapting to varying system loads and maintain continuity of presentation. Hence, the techniques used for authoring not only influence the aesthetics of presentations but also the efficiency. This special issue includes papers covering a wide range of multimedia authoring and presentation techniques: realtime authoring, web presentations, audio and video navigation/authoring, and databases for multimedia presentations. The first paper by Muller and Ottmann discusses a system that automates recording and replay of multimedia presentations. This system comprises an integrated text and graphics editor for preparing presentations as well as a recording component that captures in real-time the various streams of multimedia presentations. Named, Authoring on the Fly, the system has been extensively used over the MBone net. In the next paper, Borning et al. propose a constraint-based framework for laying out multimedia documents on the Internet. This framework can be used by both authors and viewers to exercise constraints on the page layout. The appearance of a document page during its presentation depends on the negotiation between the author and the viewer through the specified constraints. De Roure and Blackburn, in the third paper, present a system that allows content-based navigation of music, using melodic pitch contours. The system integrates hypermedia navigation and content-based retrieval techniques for this purpose. Navigation is supported by means of a link service along with a query process on a music database based on melodic pitch contours. This system incorporates techniques for storing and querying contours, and a set of componentbased navigational hypermedia tools. The fourth paper is on a video authoring system called Zodiac that employs an innovative edit history abstraction. This system, developed by Chiueh et al., facilitates video authoring by means of a powerful branching history model that allows users to organize the authoring process. Zodiac also carries out shot and boundary detection by analyzing the edit history. For its operations, Zodiac uses a multimedia file system, MMFS, and an internal buffer manager that handles transparent lossless compression/decompression. Adali et al., in the last paper, describe an architecture comprising a multimedia presentation algebra for creating interactive multimedia presentation databases. The multimedia presentation algebra can operate on presentation trees whose branches reflect different possibilities for delivering multimedia presentations. This algebra can be integrated into a query language that can support presentation database operations such as select and join. Based on these operations, the query language can be used as an authoring tool for multimedia presentations. In conclusion, this special issue carries several interesting approaches for multimedia authoring and presentations. We believe that the papers in this special issue will help the multimedia community to more easily make use of these widely spread results and will also stimulate further research in this topic.

Multimedia file systems survey: approaches for continuous media disk scheduling

We understand multimedia data processing as the handling of audio and video data together with traditional data like text and images. This multimedia data is to be stored with and by a multimedia file system which comprises one or more of the following three issues: (1) The file system can rely on various types of different physical storage devices; however, we usually encounter the same devices as in any other high performance computers; (2) the organization of files in a contiguous order and the data structuring with ropes and strands improves the throughput at the expense of additional management effort; (3) the main goal of traditional disk scheduling is to reduce the cost of seek operations, to achieve a high throughput, and to provide a fair disk access. In multimedia disk scheduling the main goal is to meet all deadlines of the time critical tasks. The buffer requirement should be kept low, and aperiodic requests should not starve, i.e. a balance between the time constraints and efficiency must be found. This paper presents a survey of these three issues, with the focus on disk scheduling. It shows how the traditional disk scheduling techniques ‘first come first serve’, ‘shortest seek time first’, SCAN and C-SCAN are enhanced or substituted by EDF, SCAN-EDF, ‘group sweeping scheduling‘, a ‘mixed strategy’ and a ‘continuous media file system’ approach.

Media synchronization in distributed multimedia file systems

Media synchronization in distributed multimedia file systems

The BBFS Filesystem Model

BBFS is a broadband filesystem research effort to support emerging applications that place intense demands on communications, computation, and data storage. Past research often addresses these needs with new special-purpose filesystems, such as transactional filesystems, replicated filesystems, real-time filesystems, and multimedia filesystems. A goal of BBFS is to be extensible so new mechanisms can be incorporated into a stable filesystem model.

Designing file systems for digital video and audio

We address the unique requirements of a multimedia file system such as continuous storage and retrieval of media, maintenance of synchronization between multiple media streams, and efficient manipulation of huge media objects. We present a model that relates disk and device characteristics to the recording rate, and derive storage granularity and scattering parameters that guarantee continuous access. In order for the file system to support multiple concurrent requests, we develop admission control algorithms for determining whether a new request can be accepted without violating the realtime constraints of any of the requests.We define a strand as an immutable sequence of continuously recorded media samples, and then present a multimedia rope abstraction which is a collection of individual media strands tied together by synchronization information. We devise operations for efficient manipulation of multi-stranded ropes, and develop an algorithm for maintaining the scattering parameter during editing so as to guarantee continuous playback of edited ropes.We have implemented a prototype multimedia file system, which serves as a testbed for experimenting with policies and algorithms for multimedia storage. We present our initial experiences with using the file system.