Toshihiko Hata

Complexity-quality analysis of transcoding architectures for reduced spatial resolution

This paper presents a detailed complexity-quality analysis of various video transcoding architectures that perform spatial resolution reduction. In addition to a reference architecture, two additional architectures are considered. The reference architecture is a cascaded approach that decodes, down-samples and re-encodes the video. The first additional proposal, intra refresh architecture, compensates for various errors by converting select macroblocks to intra-coded blocks. The second proposal, partial encoder architecture, is similar to the reference, but simplifies the re-encoding process by not compensating for re-quantization errors. The optimization of several processing components, including the down-sampling operation, is presented. We have found that the two additional architectures provide a good trade-off in terms of complexity and quality compared to the reference.

Surveillance System with Object-Aware Video Transcoder

This paper presents an object-aware video surveillance system that is not only smart and friendly for users, but allows for transmission of the scene over limited bandwidth networks. The proposed system stores high-quality video data and associated object metadata, which includes ROI (region-of-interest) information. To satisfy bandwidth constraints and display important parts of the images fast and precisely, the stored images are efficiently transcoded in the compressed-domain based on the ROI information. At the receiver, effective display methods such as a mosaic style allow for an intuitive understanding of the important objects in the scene, as well as their movement over time

Fast region-of-interest transcoding for JPEG 2000 images

The paper presents a newly developed region-of-interest (ROI) transcoding method for JPEG 2000 images; it can be used for many progressive image/video streaming applications. The proposed method takes advantage of the empty packet property provided by the JPEG 2000 standard to elevate the priority of the ROI. Based on the user specified ROI information and progressive parameters, the developed transcoder extracts the selected ROI and background packets at the desired quality and suppresses the unselected packets to a low quality. Since the transcoder only performs a reorganization of the packets in the original coded bitstream, it does not involve any re-encoding operation. Compared to other ROI coding schemes in the literature, the proposed method has the advantages of lower complexity and faster processing. Therefore, it is very suitable for real-time applications.

Complexity-quality analysis of MPEG-2 to MPEG-4 transcoding architectures

This paper presents a detailed complexity-quality analysis of various MPEG-2 to MPEG-4 transcoding architectures that perform spatial resolution reduction. The optimization of several processing components is also presented.