Robust Video Steganography for Social Media Sharing Based on Principal Component Analysis

Most social media channels are lossy where videos are transcoded to reduce transmission bandwidth or storage space, such as social networking sites and video sharing platforms. Video transcoding makes most video steganographic schemes unusable for hidden communication based on social media. This paper proposes robust video steganography against video transcoding to construct reliable hidden communication on social media channels. A new strategy based on principal component analysis is provided to select robust embedding regions. Besides, side information is generated to label these selected regions. Side information compression is designed to reduce the transmission bandwidth cost. Then, one luminance component and one chrominance component are joined to embed secret messages and side information, keeping the embedding and extraction positions in sync. Video preprocessing is conducted to improve the applicability of our proposed method to various video transcoding mechanisms. Experimental results have shown that our proposed method provides strong robustness against video transcoding and achieves satisfactory security performance against steganalysis. The bit error rate of our method is lower than state-of-the-art robust video steganographic methods. It is a robust and secure method to realize reliable hidden communication over social media channels, such as YouTube and Vimeo.

Spectral Properties of Clipping Noise

One serious disadvantage of any multicarrier-modulation technique such as orthogonal frequency division multiplexing (OFDM) is its high peak-to-average-power ratio (PAPR) which might lead to signal clipping in several scenarios. To maximize the transmit data rate, it is important to take this non-linear distortion into account. The most common approach is based on the Bussgang theorem, which splits the distortion in a correlated part, represented by a linear damping factor, and uncorrelated additive noise. However, there are two aspects that are not correctly considered by the Bussgang theorem. Firstly, clipping noise shows a frequency-dependent power spectrum which depends on the clipping probability. Secondly, some of the clipping noise power is located outside of the transmission bandwidth, so that it does not influence the transmission quality. In this work, the Bussgang theorem is reviewed in detail and the exact power spectral density of the uncorrelated clipping noise is approximated to determine the signal-to-noise power ratio on every subcarrier separately. Although it is shown that the frequency dependence within the transmission bandwidth is relatively small, at least 36% of the uncorrelated noise power, depending on the clipping level, lays outside of the transmission band. Monte Carlo simulations validate that a simple expression for the power spectral density allows to calculate the symbol error probability of an OFDM transmission system that suffers from clipping. Furthermore, the newly found result can be used to optimize bit allocation tables in bit loading algorithms or to calculate the channel capacity.

Design of Complementary Hexagonal Metamaterial Based HMSIW Band-Pass Filter and Reconfigurable SIW Filter Using PIN Diodes

This paper is divided into two sections, in the first section, a new SIW and a half-mode SIW band-pass filters based on complementary hexagonal metamaterial cells (C-HMCs) are proposed. Firstly, the SIW is analyzed in case of using two C-HMC cells and in the case of using four of these cells. Secondly, the HMSIW tunable BPF is studied and optimized. The size of the half mode is reduced by almost 50%. This filter design has a very high insertion loss about -0.4 dB, and significant transmission bandwidth extending from 5.9 GHz to 6.5 GHz. In the second section of this paper, an electronically reconfigurable SIW band-pass filter is proposed. By implementing two PIN diodes in the gaps of the two C-HMC, the results of turning the diodes ON or OFF individually is a switching in the frequency center, between 5.8 GHz and 6.8 GHz. Also, a dual band with two frequency centers at (5.6 GHz and 7.4 GHz) is achieved by turning both of the diodes ON. In addition, the metamaterial properties of all the proposed filters are investigated and presented in this work.

Image Compression Techniques Using Linear Algebra with SVD Algorithm

In recent days, the data are transformed in the form of multimedia data such as images, graphics, audio and video. Multimedia data require a huge amount of storage capacity and transmission bandwidth. Consequently, data compression is used for reducing the data redundancy and serves more storage of data. In this paper, addresses the problem (demerits) of the lossy compression of images. This proposed method is deals on SVD Power Method that overcomes the demerits of Python SVD function. In our experimental result shows superiority of proposed compression method over those of Python SVD function and some various compression techniques. In addition, the proposed method also provides different degrees of error flexibility, which give minimum of execution of time and a better image compression.

Case Report: Women, Be Aware that Your Vocal Charisma can Dwindle in Remote Meetings

Remote meetings via Zoom, Skype, or Teams limit the range and richness of nonverbal communication signals. Not just because of the typically sub-optimal light, posture, and gaze conditions, but also because of the reduced speaker visibility. Consequently, the speaker’s voice becomes immensely important, especially when it comes to being persuasive and conveying charismatic attributes. However, to offer a reliable service and limit the transmission bandwidth, remote meeting tools heavily rely on signal compression. It has never been analyzed how this compression affects a speaker’s persuasive and overall charismatic impact. Our study addresses this gap for the audio signal. A perception experiment was carried out in which listeners rated short stimulus utterances with systematically varied compression rates and techniques. The scalar ratings concerned a set of charismatic speaker attributes. Results show that the applied audio compression significantly influences the assessment of a speaker’s charismatic impact and that, particularly female speakers seem to be systematically disadvantaged by audio compression rates and techniques. Their charismatic impact decreases over a larger range of different codecs; and this decrease is additionally also more strongly pronounced than for male speakers. We discuss these findings with respect to two possible explanations. The first explanation is signal-based: audio compression codecs could be generally optimized for male speech and, thus, degrade female speech more (particularly in terms of charisma-associated features). Alternatively, the explanation is in the ears of the listeners who are less forgiving of signal degradation when rating female speakers’ charisma.