MPEG-21 bitstream syntax description for scalable video codecs Chris Poppe Sam Lerouge Wesley De Neve Rik Van de Walle Davy De Schrijver Sravanthi Kolloju 2444637
Introduction • Cell phones and PDA s are capable of running video files • But both of them have dissimilar characteristics in terms of memory processing power and bandwidth. • So for every device there is need of using different bitstream for video broadcast.
Main Idea • Multichannel Publication Environment. • MPEG-21 Bitstream Syntax Description language (BSDL). • Creates high-level XML description of the structure of the bitstream.
Bitstream Syntax description language(BSDL) • MPEG-21 is build around one central concept called • “Digital Item (DI)” • BSDL belongs Digital Item Adaptation (DIA) • DIA consists of several tools like • Bitstream Syntax Description (BSD) • Bitstream Schema
Related Work • Another language used for multimedia representation is FLAVOR (Formal Language for Audio-Visual Object Representation. • FLAVOR code describes structure of a bit stream and this code can in turn be translated into C++ or Java. • FLAVOR which supports XML features is known as XFLAVOR. • MPEG video mark up language is a description language that has the same functionality of XFLAVOR .
Scalable video coding There are different types of video coding used for different applications • Fully scalable video coding MC-EZBC: This coding consists of all the information of original video stream. • Temporal scalability: Is used to achieve a video with lower frame rate. • Spatial scalability : Is used to achieve a video with lower resolution. • SNR scalability : Is used to achieve lower bitrate
Fully Scalable Video Coding • In this picture decomposition is done by dividing in to • low frequency frames and high frequency frames.
Structure of a MC-EZBC bitstream • The header consists of general information about the bitstream. • The general bitstream consists of header and payload. • Payload contains sizes of GOPs following the actual GOPs structure.
Bitstream to XML • Based on the bitstream BS Schema is generated. • The corresponding XML code is created by making use of • BintoBsd and BSSchema. • <?xml version=“1.0”> • <Bitstream namespace> • +<header> • +<NUMBER_GOPs> • +<GOPSIZE> • +<GOP> • +<GOP> • . • . • </Bitstream>
Adaptation of Temporal Scalability • By using temporal scalability a video with a lower frame • rate is obtained. • The lower frame rate is obtained by eliminating eight • high frequency frames in fully scalable video coding. • H frames can be eliminated by removing the highest • content tag in each GOP tag.
SpatialScalability • A lower resolution video frame is obtained by using Spatial Scalability. • This is obtained by eliminating highest subbands of each substream. SNR Scalability • A bitstream with a lower bit rate is generated with SNR • Scalability. • The encoding process in SNR scalability delivers a • compressed bit stream and also a file containing • information about the bit planes of different subbands.
Conclusion • Coding format-independent adaptation frame work for binary media resources is discussed. • To evaluate the performance of the BSDL framework, bitstreams encoded by two different coding schemata were discussed. • Various scalability methods are achieved by adaptive XML.
References • Vetro, A., Christopoulos, C., Ebrahimi, T.: From the guest editors – Universal multimedia access. IEEE Signal Process. Mag. 20(2), 16 (2003) • ISO/IEC 21000-7:2004: Information technology—multimedia framework (MPEG-21)—Part 7: Digital Item Adaptation (2004) • Mukherjee, D., Wang, H., Said, A., Liu, S.: Format-Agnostic adaptation using the MPEG-21 DIA framework. In: Proceedings of SPIE Annual Meeting 2004: Signal and Image Processing and Sensors. Denver, vol. 5558, pp. 351–362 (2004) • Devillers, S., Timmerer, C., Heuer, J., Hellwagner, H.: Bitstream syntax description-based adaptation in streaming and constrained environments. IEEE Trans. Multimedia 7(3), 463–470 (2005) • Burnett, I., Van de Walle, R., Hill, K., Bormans, J., Pereira, F.: MPEG-21: Goals and achievements. IEEE Multimedia 10(4), 60– 70 (2003) Amielh,M., Deviller, S.: Bitstream Syntax Description Language: • Application of XML-schema tomultimedia content adaptation. In: Proceedings of the 11th International WWW Conference. Honolulu, Hawaii (2002) • Duckett, J., Ozu, N., Williams, K., Mohr, S., Cagle, K., Graffin, O., Norton, F., Stokes-Rees, I., Tennison, J.: Professional XML Schemas. Wrox Press Ltd., Birmingham, UK (2001)