Damian Karwowski

Coding of multiple video+depth using HEVC technology and reduced representations of side views and depth maps

During the last two decades, a new technology generation of video compression was introduced about each 9 years. Each new compression-technology generation provides halving of necessary bitrates as compared to the last previous generation. This increasing single-view compression performance is related to increasing compression performance of multiview video coding. For multiview video with associated depth maps, additional significant bitrate reduction may be achieved. The paper reports the original compression technology that was designed and developed at Poznań University of Technology in response to MPEG Call for Proposals on 3D Video Coding Technology. The main idea of this technique is to predict very efficiently the side views and the depth maps from the base view.

Bitrate distribution of syntax elements in the HEVC encoded video

The paper focuses on two problems: 1) analysis of bitrate contribution of I and B frames in encoded HEVC data stream, and 2) analysis of distribution of HEVC syntax elements in I and B frames. The relationship between sizes of I and B frames located at a different levels in hierarchical coding scheme was experimentally determined, as well as contribution of HEVC syntax elements in encoded streams of I, B0, B1, B2, and B3 frames. The results are presented in the paper. All presented results concern a wide range of QP values in a video encoder.

Improved context-based adaptive binary arithmetic coding in MPEG-4 AVC/H.264 video codec

An improved Context-based Adaptive Binary Arithmetic Coding (CABAC) is presented for application in high definition video coding. In comparison to standard CABAC, the improved CABAC works with proposed more sophisticated mechanism of data statistics estimation that is based on the Context-Tree Weighting (CTW) method. Compression performance of the improved CABAC was tested and confronted with efficiency of the state-of-the-art CABAC algorithm used in MPEG- 4 AVC. Obtained results revealed that 1.5%-8% coding efficiency gain is possible after application of the improved CABAC in MPEG-4 AVC High Profile.

Analysis of Frame Partitioning in HEVC

The paper presents analysis of frame partitioning in the next generation video coding standard HEVC. Complex study on frequency of the particular coding unit, prediction unit and transform unit sizes selection made by the encoder compliant with HEVC technology is included. General conclusions based on extensive experiments for HD video sequences are presented. Such knowledge may be the first step to the development of more efficient mode selection algorithms.

A large barrel distortion in an acquisition system for multifocal images extraction

This paper presents a new way to use the well-known distortions introduced by the fisheye lens (ultra-wide-angle lenses) and a well-known algorithms for the correction of distortion in order to obtain completely new functionality in supervision and monitoring of video. The suggested way to use the barrel distortion will result in a smoother zooming and allows to achieve the multiple images simultaneously with the same resolution but with a different viewing angle. This feature may vary greatly increase the effectiveness of surveillance application by providing a greater amount of visual data from one camera.

Encoding mode selection in HEVC with the use of noise reduction

This paper concerns optimization of encoding in HEVC. A novel method is proposed in which encoding modes, e.g. coding block structure, prediction types and motion vectors, are selected basing on noise-reduced version of the input sequence, while the content, e.g. transform coefficients, are coded basing on the unaltered input sequence. Although the proposed scheme involves encoding of two versions of the input sequence, the proposed realization ensures that the complexity is only negligibly larger than complexity of a single encoder. The proposal has been implemented and assessed. The experimental results show that the proposal provides up to 1.5% bitrate reduction while preserving the same video quality.

Homogenous HEVC video transcoding by transform coefficient removal

In this paper, a novel method of transcoding of HEVC encoded video is presented. The novel approach enables a very fast transcoding without the need for the image reconstruction. It is based on the principle of removing of the carefully selected coefficients from the bitstream. The removal of coefficients is done on the bitstream level and can easily be tailored to software as well as hardware implementations. The technique is able to provide a bitrate reduction in the order of up to 10%, with the image quality decrease of about 0.2–0.5dB.

Analysis of the complexity of the HEVC motion estimation

The paper presents analysis and comparison of complexity of selected algorithms of motion estimation used in video compression. With the use of own, highly optimized software implementation the authors explored complexity of the methods applied in the framework of the new High Efficiency Video Compression (HEVC) technology. The influence of many different factors on motion estimation complexity has been deeply studied, including the implementation technique, type of the algorithm, number of processor threads used, kind of metric of blocks similarity. The results obtained allowed to formulate guidelines and conclusions that may be useful for future implementation of motion estimation algorithms in context of HEVC encoders.

Computational Complexity Analysis of Adaptive Arithmetic Coding in HEVC Video Compression Standard

This paper presents computational complexity analysis of adaptive arithmetic coding (CABAC) in the emerging HEVC video compression technology. In particular, computational complexity of individual parts of CABAC (and the whole CABAC entropy codec in the HEVC video decoder) was measured from the point of view of video decoder side. Experiments were done using publically available HM reference software of the HEVC video codec and a set of test video sequences. The range of bitrates that can be processed in real time by CABAC entropy decoder were also evaluated for the considered in the paper implementation of CABAC.

Improved adaptive arithmetic coding for HEVC video compression technology

The paper presents Improved Adaptive Arithmetic Coding algorithm for application in forthcoming HEVC video compression technology. The proposed solution is based on standard CABAC algorithm and uses authors new mechanism of data statistics modeling that is based on CTW technique. The improved CABAC algorithm is characterized with better compression performance relative to standard CABAC. In the framework of HEVC encoder 1.6% - 4.5% bitrate reduction was obtained when using improved CABAC instead of the original algorithm.