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- Efficient MV prediction for zonal search in video transcodingPublication . Marcelino, S.; Faria, S.; Assunção, P.; Moiron, S.; Ghanbari, M.This paper proposes a method to efficiently find motion vector predictions for zonal search motion re-estimation in fast video transcoders. The motion information extracted from the incoming video stream is processed to generate accurate motion vector predictions for transcoding with reduced complexity. Our results demonstrate that motion vector predictions computed by the proposed method outperform those generated by the highly efficient EPZS (Enhanced Predictive Zonal Search) algorithm in H.264/AVC transcoders. The computational complexity is reduced up to 59.6% at negligible cost in R-D performance. The proposed method can be useful in multimedia systems and applications using any type of transcoder, such as transrating and/or spatial resolution downsizing.
- Enhancement method for multiple description decoding of depth maps subject to random lossPublication . P. Correia; Marcelino, S.; Assuncao, P.; Faria, S.; S. Soares; C. Pagliari; E. da SilvaThis paper proposes a method to improve the quality of depth maps transmitted in multiple descriptions through multipath error prone networks. Whenever a single description is lost, the remaining ones are still able to provide a coarsely decoded version of the depth map. While in multiple description video, such coarse decoding is still acceptable for display, in the case of depth maps the additional decoding distortion propagates through the corresponding view synthesis. The proposed method is capable of enhancing low quality depth maps decoded from one single description, based on geometric information available in coarsely decoded slices, combined with higher quality depth values in adjacent slices decoded from both descriptions. In comparison with existing MDC decoders, the enhancement method achieves quality gains in synthesised views up to 1.69dB for packet loss rates of 10%.