Adaptive motion-vector resampling for compressed video downscaling

Digital video is becoming widely available in compressed form, such as a motion JPEG or MPEG coded bitstream. In applications such as video browsing or picture-in-picture, or in transcoding for a lower bit rate, there is a need to downscale the video prior to its transmission. In such instances, the...

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Bibliographic Details
Published in:IEEE transactions on circuits and systems for video technology 1999-09, Vol.9 (6), p.929-936
Main Authors: Bo Shen, Sethi, I.K., Vasudev, B.
Format: Article
Language:English
Subjects:
Applied sciences
Bit rate
Compressed
Computation
Discrete cosine transforms
Exact sciences and technology
Image processing
Information, signal and communications theory
Laboratories
Mathematical analysis
Motion estimation
MPEG encoders
Neural networks
Pixels
Quality of service
Signal processing
Spatial resolution
Telecommunications and information theory
Transcoding
Transform coding
Vectors (mathematics)
Video compression
Video sequences
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Description
Summary:Digital video is becoming widely available in compressed form, such as a motion JPEG or MPEG coded bitstream. In applications such as video browsing or picture-in-picture, or in transcoding for a lower bit rate, there is a need to downscale the video prior to its transmission. In such instances, the conventional approach to generating a downscaled video bitstream at the video server would be to first decompress the video, perform the downscaling operation in the pixel domain, and then recompress it as, say, an MPEG, bitstream for efficient delivery. This process is computationally expensive due to the motion-estimation process needed during the recompression phase. We propose an alternative compressed domain-based approach that computes motion vectors for the downscaled (N/2xN/2) video sequence directly from the original motion vectors for the N/spl times/N video sequence. We further discover that the scheme produces better results by weighting the original motion vectors adaptively. The proposed approach can lead to significant computational savings compared to the conventional spatial (pixel) domain approach. The proposed approach is useful for video severs that provide quality of service in real time for heterogeneous clients.
ISSN:1051-8215
1558-2205
DOI:10.1109/76.785730