Dissertation
Dissertation > Industrial Technology > Automation technology,computer technology > Computing technology,computer technology > Computer applications > Information processing (information processing) > Pattern Recognition and devices > Image recognition device

Rate -based transcoding of compressed video auxiliary spatial resolution conversion method

Author WangJie
Tutor GuoHongXing
School Huazhong University of Science and Technology
Course Computer System Architecture
Keywords Multimedia streaming adaptation Video Transcoding Convert video spatial resolution Active zero France
CLC TP391.41
Type Master's thesis
Year 2011
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In pervasive multimedia computing environment, due to the different receiving terminal has a different screen size, wireless video network before transmission needs to convert the video resolution. Spatial resolution transcoding is to solve this problem is an effective way. To reduce the amount of computation required in transcoding process reuse decoding compressed stream obtained when the original motion vector and the macroblock mode and other information. However, during the spatial resolution conversion, either the pixel domain transcoding, or compressed domain transcoding, the transcoding the video stream after the spatial resolution of inconsistencies, are difficult to effectively use the information obtained resulting video transcoding quality has dropped significantly. Therefore an urgent need to develop new video spatial resolution conversion method, the improvement of the video quality, while maintaining a relatively low computational complexity. The spatial resolution using video sub-sampling and video streaming bit rate reduction in the frequency domain equivalence, proposed a rate-based video transcoding auxiliary spatial resolution conversion (TARC) method. Spatial resolution transcoding traditional methods, which do not change during the transition when the first spatial resolution of the video, but directly by the decoder to decode the compressed video stream, and then use the motion vector obtained by decoding video and the macro-block mode, according to the Target bit rate corresponding to the spatial resolution of the video re-encoding, which uses rate-based transcoding the compressed video stream into first source spatial resolution corresponds to the target compressed video stream, and the re-sampling of the video sequence in the client Playback before implementation. On re-encoding the decoded video stream, the active portion of the inter-coded frame-frequency discrete cosine transform (DCT) coefficients set to zero, the implicit sub-sampling frequency domain implementation, while maintaining the same spatial resolution of the video signal , thus avoiding the motion vector and the macroblock mode synthesis problem of inaccurate. Moreover, since the active set to zero without the need for high frequency coefficients calculation and coding, and thus helps to reduce the amount of calculation and transmission bandwidth. Meanwhile, since the receiving end of resolution and bit rate type resampling frequency domain transcoding match the resolution of sub-sampling, which can effectively suppress aliasing resampling effects caused, video quality. The experimental results show that the use of this method can significantly improve the resolution of the converted video spatial rate-distortion performance. Spatial resolution with traditional video transcoding results compared to convert video PSNR (PSNR) can improve average about 2dB, and easy to implement arbitrary spatial resolution conversion ratio, which can adapt to better support multimedia streaming applications . This work was supported by the National Natural Science Fund Project \mechanisms (ID: 2010CDB01604) \

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