Mahsa T. Pourazad

HEVC: The New Gold Standard for Video Compression: How Does HEVC Compare with H.264/AVC?

Digital video has become ubiquitous in our everyday lives; everywhere we look, there are devices that can display, capture, and transmit video. The recent advances in technology have made it possible to capture and display video material with ultrahigh definition (UHD) resolution. Now is the time when the current Internet and broadcasting networks do not even have sufficient capacity to transmit large amounts of HD content-Let alone UHD. The need for an improved transmission system is more pronounced in the mobile sector because of the introduction of lightweight HD resolutions (such as 720 pixel) for mobile applications. The limitations of current technologies prompted the International Standards Organization/International Electrotechnical Commission Moving Picture Experts Group (MPEG) and International Telecommunication Union-Telecommunication Standardization Sector Video Coding Experts Group (VCEG) to establish the Joint Collaborative Team on Video Coding (JCT-VC), with the objective to develop a new high-performance video coding standard.

An H.264-based scheme for 2D to 3D video conversion

An efficient 2D to 3D video conversion method which utilizes the H.264 motion estimation process is proposed. The relationship between motion and depth was approximated via our non-linear scheme, that is based on the characteristics of 3D visual perception. Performance evaluations show that our approach outperforms other existing motion-based depth map estimation technique by 1.84 dB PSNR via providing more realistic depth information for the scene. Subjective comparisons also confirm the efficiency of our method.

Heart Sounds Separation From Lung Sounds Using Independent Component Analysis

Heart beat is an unavoidable source of interference during lung sound recording. This disturbance is more significant at low and medium breathing flow rates. Removing heart sounds (HS) from lung sound recordings or vice versa is a challenging task but of great interest for respiratory specialists and cardiologists. In this study, to separate the two signals, a novel HS separation method based on independent component analysis (ICA) is developed. This method applies an ICA algorithm to the spectrograms of two simultaneous lung sound recordings obtained at two different locations on the chest and yields the independent spectrograms of the separated signals. Then, by implementing the inverse short time Fourier transform (ISTFT), the separated signals are reconstructed in the time domain. The method was applied to data of two healthy subjects. Analysis of the results as well as subjective inspections indicate the efficiency of the proposed method in terms of HS separation from lung sounds

Generating the depth map from the motion information of H.264-encoded 2D video sequence

An efficient method that estimates the depth map of a 3D-scene using the motion information of the H.264-encoded 2D-video is presented. The motion information of the video-frames captured via a single camera is either directly used or modified to approximate the displacement (disparity) that exists between the right and left images when the scene is captured by stereoscopic cameras. Then, depth is estimated based on its inverse relation with disparity. The low-complexity of this method and its compatibility with future broadcasting networks allow its real-time implementation at the receiver; thus 3D-signal is constructed at no additional burden to the network. Performance evaluations show that this method outperforms the other existing H.264-based technique by up to 1.98 dB PSNR, providing more realistic depth information of the scene. Moreover subjective comparisons of the results, obtained by viewers watching the generated stereo video sequences on a 3D-display system, confirm the superiority of our method.

Demystifying High-Dynamic-Range Technology: A new evolution in digital media.

High-dynamic-range (HDR) technology has attracted a lot of attention recently, especially in commercial trade shows such as the Consumer Electronics Show, the National Association of Broadcasters Show, the International Broadcasting Convention, and Internationale Funkausstellung Berlin. However, a great deal of mystery still surrounds this new evolution in digital media. In a nutshell, HDR technology aims at capturing, distributing, and displaying a range of luminance and color values that better correspond to what the human eye can perceive. Here, the term luminance stands for the photometric quantity of light arriving at the human eye measured in candela per square meter or nits. The color refers to all the weighted combinations of spectral wavelengths, expressed in nanometers (nm), emitted by the sun that are visible by the human eye (see Figure 1). The human eye can perceive a dynamic range of over 14 orders of magnitude (i.e., the difference in powers of ten between highest and lowest luminance value) in the real world through adaptation. However, at a single adaptation time, the human eye can only resolve up to five orders of magnitude, as illustrated in Figure 2. Dynamic range denotes the ratio between the highest and lowest luminance value. As reported in Table 1, there are different interpretations for dynamic range, depending on the application. For instance, in photography, dynamic range is measured in terms of f-stops, which correspond to the number of times that the light intensity can be doubled.

Content adaptive complexity reduction scheme for quality/fidelity scalable HEVC

There has been significant interest in developing a scalable version of the High Efficiency Video Coding (HEVC) standard. As expected, the HEVC scalable video version increases the complexity of the codec compared to the non-scalable counterpart. In this paper, we propose an adaptive early-termination interlayer motion prediction mode search that significantly reduces HEVC/SVCs coding complexity by up to 85.77%, while maintaining the overall bitrate.

Adaptive search range method for spatial scalable HEVC

Presently, the scalable extension of the HEVC standard (known as SHVC) is under development. One of the main issues with SHVC is its increased complexity compared to its non-scalable counterpart (i.e., HEVC). Reducing the complexity of SHVC is important, especially for real-time applications. In this paper, we propose an adaptive search range method that reduces the coding complexity of HEVC with spatial scalability by up to 30.27%, while maintaining the overall bitrate.

Compression of high dynamic range video using the HEVC and H.264/AVC standards

The existing video coding standards such as H.264/AVC and High Efficiency Video Coding (HEVC) have been designed based on the statistical properties of Low Dynamic Range (LDR) videos and are not accustomed to the characteristics of High Dynamic Range (HDR) content. In this study, we investigate the performance of the latest LDR video compression standard, HEVC, as well as the recent widely commercially used video compression standard, H.264/AVC, on HDR content. Subjective evaluations of results on an HDR display show that viewers clearly prefer the videos coded via an HEVC-based encoder to the ones encoded using an H.264/AVC encoder. In particular, HEVC outperforms H.264/AVC by an average of 10.18% in terms of mean opinion score and 25.08% in terms of bit rate savings.

A rate adaptation approach for streaming multiview plus depth content

Three-dimensional video has recently gained great popularity as it enhances the viewing experience. Streaming of 3D video over IP networks will soon become a common means of multimedia consumption, thanks to the recent standardization efforts such as MPEG-DASH and 3D-HEVC. To this end, rate adaptation techniques are required to overcome the unreliable nature of IP networks. In this paper, we propose a rate adaptation approach for streaming multiview plus depth (MVD) video by exploring the effects of the number of views and the quality of views on the quality of experience. Specifically, we show that concurrently decreasing the distance between virtual camera positions and reducing the number of views help maintain an acceptable perceptual quality level when the network resources are scarce.

A content adaptive complexity reduction scheme for HEVC-based 3D video coding

3D-HEVC is aiming at utilizing the advanced tools present in HEVC to efficiently code multiview video content. The computational complexity of this codec is significantly increased and is a challenge for real-time applications. In our study, we propose an adaptive early-termination inter and intra prediction mode search that reduces the 3D-HEVC coding complexity by utilizing the correlations between views, while maintaining the overall video quality.