Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/295
Title: DCT-based video downscaling transcoder using split and merge technique
Authors: Fung, Kai-tat
Siu, Wan-chi
Subjects: DCT-domain transcoder
Downscaling
Drift elimination
Transcoding
Video coding
Issue Date: Feb-2006
Publisher: IEEE
Source: IEEE transactions on image processing, Feb. 2006, v. 15, no. 2, p. 394-403.
Abstract: For a conventional downscaling video transcoder, a video server has firstly to decompress the video, perform downscaling operations in the pixel domain, and then recompress it. This is computationally intensive. However, it is difficult to perform video downscaling in the discrete cosine transform (DCT)-domain since the prediction errors of each frame are computed from its immediate past higher resolution frames. Recently, a fast algorithm for DCT domain image downsampling has been proposed to obtain the downsampled version of DCT coefficients with low computational complexity. However, there is a mismatch between the downsampled version of DCT coefficients and the resampled motion vectors. In other words, significant quality degradation is introduced when the derivation of the original motion vectors and the resampled motion vector is large. In this paper, we propose a new architecture to obtain resampled DCT coefficients in the DCT domain by using the split and merge technique. Using our proposed video transcoder architecture, a macroblock is splitted into two regions: dominant region and the boundary region. The dominant region of the macroblock can be transcoded in the DCT domain with low computational complexity and re-encoding error can be avoided. By transcoding the boundary region adaptively, low computational complexity can also be achieved. More importantly, the re-encoding error introduced in the boundary region can be controlled more dynamically. Experimental results show that our proposed video downscaling transcoder can lead to significant computational savings as well as videos with high quality as compared with the conventional approach. The proposed video transcoder is useful for video servers that provide quality service in real-time for heterogeneous clients.
Rights: © 2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.
Type: Journal/Magazine Article
URI: http://hdl.handle.net/10397/295
DOI: 10.1109/TIP.2005.863118
ISSN: 1057-7149
Appears in Collections:EIE Journal/Magazine Articles

Files in This Item:
File Description SizeFormat 
split-merge_06.pdf850.25 kBAdobe PDFView/Open


All items in the PolyU Institutional Repository are protected by copyright, with all rights reserved, unless otherwise indicated. No item in the PolyU IR may be reproduced for commercial or resale purposes.