Multimedia Application Format for e-Learning
2006 . 03 ~ current
　
　

1. Introduction

As the use of the Internet keeps rising every year, digital multimedia contents also become abundant. In particular, to facilitate access to knowledge on those digital environments and to meet the needs of life-long learning, e-Learning has been a good alternative to conventional learning paradigms. As learning environments become ubiquitous, e-Learning methods should also be changed toward being portable, flexible and adaptive. Many researchers have studied e-Learning content structure and associated e-Learning metadata, but there still remain challenging issues.
　
1) Although e-Learning usually requires effective association and interaction of e-Learning resources and their metadata, there has been minimal research regarding the association and interaction.
　
2) e-Learning contents are typically composed of single media resource such as a single video, audio or text. If the e-Learning content needs to load multi-modal resources for effective learning, the multi-modal resources are hardly associated with the other resources. In particular, e-Learning contents with several multi-modal resources are often too big to be consumed in portable devices due to their limited storage or computational power.
　
3) Existing e-Learning contents have their own file formats and related metadata format dedicated to their specific applications. The absence of a standardized file format for containing media resources and e-Learning metadata often causes limited use of the e-Learning contents on different devices.
　
2. Multimedia Application Format for e-Learning
2.1 Multiemdia Application Format
MPEG-A, or the ISO/IEC 23000 standard, is recently added to the well-known standards developed by moving picture experts group (MPEG). MPEG-A aims to facilitate the swift development of innovative, standards-based multimedia applications and services for interoperable and augmented use of extensively prevailed multimedia data such as MPEG-2, MPEG-4, MP3 and JPEG. To meet this goal, the MPEG-A standard specifies MAFs. MAF offers selective borrowing current technologies not only MPEG standards, but also non-MPEG standards such as JPEG and JPEG2000. MAF presents a framework combining them into a single specification with relative metadata. A standard should specify the principle as little as possible while guaranteeing maximum interoperability. For this, MAF specifies how to combine metadata with media resources. MAF is derived from the ISO Base Media File Format. The ISO Base Media File Format proffers an efficient, flexible and extendible method to combine media resources. The basic file structure of the ISO Base Media Format is object-oriented and can be decomposed into a continuous object named Box, and all media data subsist in Box.
　
2.2 Multimedia Application Format for e-Learning
Fig. 1 Illustrates the structure of e-Learning MAF. Because the unified framework converts media resource files such as avi, mp3, JPEG into a unified e-Leaning file, e-Learning resource management systems could control the e-Learning files more efficiently. Information about media resources such as video, audio, image and text required by e-Learning content resides at trak in moov, and actual media resource data is in mdat. e-Learning metadata could allow users to consume e-Learning contents with enhanced functionalities such as easy and fast navigation using content-based retrieval. Proposed MPEG-7 e-Learning metadata locates at meta in moov, and additional spaces for contain existing e-Leaning metadata could locate in additional trak. Because of the additional space, proposed e-Learning MAF guarantees interoperability with other metadata for e-Learning. If a user has LOM metadata decoder, the user could consume LOM metadata which is located in trak.
　
Fig 1. Structure of MAF for e-Learning
　
3. MPEG-7 e-Learning metadata
The importance of metadata for e-Learning is in terms of the Semantic Web. Based on e-Learning metadata, e-Learning repositories can offer effective search for e-Learning contents. Currently several widely used e-Learning metadata exist including CanCore, IEEE LOM and GEM metadata. CanCore is educational metadata, and it is fully compatible with the IMS Learning Resource Metadata Information Model. CanCore has defined a sub-set of elements from IMS model for the purposes of the efficient and uniform description of digital educational resources. It is intended to facilitate effective interchange among learning objects. The IMS Global Learning Consortium developed IMS Learning Resource Meta-data, but it is being aligned with LOM. The schema had been superseded by the LOM. LOM, most widely used metadata for e-Learning, is defined by IEEE LTSC. LOM outlines the minimal set of attributes needed to allow learning objects (either digital or non-digital) to be managed, located and evaluated. It is based on DC metadata. GEM metadata is based on DC metadata with addition of education-specific elements. It consists of 8 GEM elements and 13 DC elements. We could intuitively understand the relation among e-Learning metadata through Fig. 3. Fig. 3 presents that DC metadata is the basic metadata for e-Learning because all metadata for e-Learning widely used are based on DC metadata. DC metadata is an international standard for cross-domain information resource description. The DC metadata have 15 descriptors that resulted from effort in interdisciplinary and international consensus building. It is intended to co-exist with metadata standards that offer other semantics. The 15 elements may appear in any order, and each element is optional and repeatable.
　
Most existing e-Learning metadata concentrate on effective and efficient search for contents. Although existing e-Learning metadata are enough to describe content itself efficiently search, there should be additional information to meet the users’ requirement about content-based retrieval. Because existing metadata for e-Learning could not support content-based retrieval, we define MPEG-7 e-Learning metadata which can describe not only information about content itself for efficient searching and acquisition but also semantic description for content-based retrieval. Proposed MPEG-7 e-Learning metadata is based on DC metadata for effective and efficient searching and acquisition of the e-Leaning content like existing e-Learning metadata. Moreover, it also describes semantic information about the content for content-based retrieval. MPEG-7 e-Learning metadata is described by MPEG-7 MDS. The MPEG-7 MDS is used to describe and annotate multimedia data. Because MPEG-7 is a standard for describing the multimedia content data that supports some degree of interpretation of the information meaning, which can be easily accessed by a device or a computer. MPEG-7 is not aimed at any one application in particular. The elements that MPEG-7 standardizes support as broad a range of applications as possible. MPEG-7 is a more systematic and well-structured description than other metadata for e-Learning. Only MPEG-7 could describe not only temporal segment structure but also hierarchical decomposition of multimedia contents. It has some advantages about accessing the elements and navigating them.
　
Fig 2. Structure of MPEG-7 e-Learning metadata
　
　
Sihyoung Lee, Seungji Yang, Yong Man Ro, Hyoung Joong Kim, -Learning Media Format for Enhanced Consumption on Mobile Application, Proceedings of the First International Workshop on Semanitc-enhanced Multimedia Presentation Systems (SEMPS 2006), pp.7-19, Dec. 2006
이시형, 양승지, 노용만, 김형중, 모바일 환경에서의 e-Learning을 위한 통합 미디어 시스템, 2006 신호처리합동학술대회
이시형, 양승지, 노용만, 김형중, e-Learning을 위한 MAF 기반 통합 미디어에 관한 연구, 2006 춘계 한국멀티미디어학회