Complexity Optimized Video Codecs

Diploma Thesis from the year 2003 in the subject Communications - Miscellaneous, grade: 1,0, University of Rostock (Elektronik und Informationstechnik), language: English, abstract: Inhaltsangabe:Abstract:§We are facing an increasing bandwidth in the mobile systems and this opens up for new applications in a mobile terminal. It will be possible to download, record, send and receive images and videosequences. Even if we have more bandwidth, images and video data must be compressed before it can be sent, because of the amount of information it contains. MPEG-4 and H.263 are standards for compression of video data. The problem is that encoding and decoding algorithms are computationally intensive and complexity increases with the size of the video. In mobile applications, processing capabilities such as memory space and calculation time are limited and optimized algorithms for decoding and encoding are necessary. The question is if it is possible to encode raw video data with low complexity. Single frames e.g. from a digital camera, can then be coded and transmitted as a video sequence. On the other hand, the decoder needs to be able to handle sequences with different resolution. Thus, decoder in new mobile terminals must decode higher resolution sequences with the same complexity as low resolution video requires.§The work will involve literature studies of MPEG-4 and H.263. The goal is to investigate the possibility to encode video data with low complexity and to find a way for optimized downscaling of larger sequences in a decoder. The work should include§- Literature studies of MPEG-4 and H.263.§- Theoretical study how CIF sequences (352x288-pixel) can be downscaled to QCIF (176x144-pixel) size.§- Finding of optimized algorithms for a low complexity encoder.§- Implementation of such an encoder in a microprocessor, e.g. a DSP.§- Complexity analysis of processing consumption.§Prerequisite experience is fair C-programming, signalprocessing skills and basic knowledge in H.263 and MPEG-4 is useful.§New mobile communication standards provide an increased bandwidth, which opens up for many new media applications and services in future mobile phones. Video recording using the MMS standard, video conferencing and downloading of movies from the Internet are some of those applications. Even if the data rate is high, video data needs to be compressed using international video compression standards such as MPEG-4 or H.263.§Efficient video compression algorithms are the focus of this thesis. Very limited computational capabilities of the terminals require low complexity encoder and decoder. A low complexity encoder for usage with MMS has been developed. Furthermore, algorithms for computationally optimized downscaling of larger sequences in a decoder are discussed.§The results from the low complexity encoder have shown that compression rates up to 95% with suitable quality can be reached. A CPU with around 50MHz can encode digital video at frame rates of 10 to 15 frames/s. The compression standard is MPEG-4, which is well suited for computationally optimized encoding. Thus, efficient implementations of a MMS video encoder are possible. Based on literature studies, two algorithms for low complexity downscaling of CIF sized sequences to QCIF size have been proposed. Both algorithms must be evaluated in a practical test before the best approach can be determined.§Inhaltsverzeichnis:Table of Contents:§Abstractix§Acknowledgementsx§Contentsxi§List of Figuresxv§List of Tablesxvii§Acronymsxix§1.Introduction1§1.13G: The Future of Mobile Communication1§1.1.1From 1G to 3G1§1.1.2Multimedia Applications for 2.5G and 3G3§1.2Video Applications in New Mobile Terminals4§2.Basics of Image and Video Coding7§2.1Coding7§2.1.1Coding Fundamentals8§2.1.2Huffman Codes8§2.1...