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Compared with conventional encoding methods, Distributed Video Coding (DVC) has superiority in encoding speed. However, DVC is difficult to exhibit its advantages in fast video encoding in practical applications because it has the problem of insufficient compression ratio and no hardware accelerated chip support. In practical applications, how to effectively use general hardware resources with improved compression ratio is a significant challenge. By implementation, we realized an DVC encoder on Raspberry Pi device. In order to improve the compression ratio of DVC, we used a transform-domain DVC coding method based on frame difference, which can employ the correlation between neighboring frames to reduce the encoding cost of Discrete Cosine Transform (DCT) for those blocks with low motion amplitude, thereby reducing the bandwidth required for transmission of them. This method can improve the compression ratio without increasing excessive calculation in the encoding operation. In the implementation, we try to use Video Core (VC) chip of Raspberry Pi and OpenCV4 library for DCT calculation to speed up the DVC encoding process.

This paper proposes a software-defined network architecture for a radio spectrum monitoring system that aims to help regulate spectrum allocation and usage management for nationwide commercial or civilian wireless communication systems. The proposed software-defined network architecture provides radio spectrum monitoring with the ability to coordinate the demand for communication bandwidth between the control workstations and the monitoring stations, using software-defined radio devices. To evaluate the proposed architecture, a testbed is designed that incorporates two versions of the Dijkstra algorithm to route the monitored data over the simulated software-defined network. Several metrics are used to measure the transmission performance, including packet loss rate, packet jitter, throughput, path cost, and average link utilization. The results of applying the proposed software-defined network architecture to a radio spectrum monitoring system in order to fulfill high traffic load requirements with software-defined radio technologies are promising.

Traditional chaos-based encryption techniques use pseudorandom codes to implement encryption (e.g., XOR; exclusive or operation) directly, resulting in the violation of requirements for media compression formats for image transmission. In this study, a programmable spatial light modulator (SLM)-based optical wavelength filter was investigated for implementing a scrambling-based cryptographic scheme in WDM networks. A new chaotic tent/hologram mapping algorithm (THmA) and advanced THmA are proposed for triggering the programmable SLM-based filter array. Similarly, an approximately symmetric scheme was used to configure a scrambling SLM-based decryption scheme for performing decryption operations when the initial value and control parameters of the chaotic sequence as individual secret keys are communicated in advance over a private channel. The proposed scheme was evaluated using video application-layer experiments. The results revealed that compared with conventional reconfigurable schemes involving triggered registers and switches behind an AWG router, the number of code space sizes involved in the proposed cryptographic scheme increased by more than 1.31E + 89 times, thereby avoiding eavesdropping attacks in the physical layer. Furthermore, on the basis of the reduced peak signal-to-noise ratio of the encrypted videos and the unidentifiability of the videos to unauthorized users, the scrambling efficiency of the proposed scheme was sufficiently high.

In this paper, a prediction technique for the best coding unit (CU) partition tree is proposed to avoid the repeated computation on the variable-sized prediction units (PU) and transform units (TU) in high efficiency video coding (HEVC). In HEVC, many advanced coding tools are introduced to decrease the bit-rate of coded videos with higher visual quality. Of these tools, many seek to partition each CU in the incoming frame into a quad-tree structure of variable sized blocks while performing prediction and transform computations to obtain the optimal rate-distortion performance. During partition tree generation, the CU block and its four partitioned child-blocks need to become PU and TU for calculating the coding rate-distortion cost. This process requires more execution time from the processor because of highly repeated computations on PUs and TUs before finding the best quad-tree partition tree. The proposed prediction technique is based on edge information from the content of the considered CU and the depth information of partition tree from the co-located CU in the neighboring video frames for being able to adapt the reduction of computation time with the varying content in the incoming frames. When the CU is in a smooth frame, the information from the neighboring frames would dominate the prediction results of the partition tree; however, the edge information of the current CU mainly determines the partition tree. With the prediction technique, experiments on several benchmark videos show that the encoding time of HEVC can be reduced by 44.1 % at an acceptable degradation of coding efficiency.

To enhance the security of H.264/AVC streaming, such as that for Internet protocol television, over a passive optical network (PON), a dynamic reconfigurable coding---decoding scheme, based on a chaotic sequence, was demonstrated and characterised by pseudo randomness and a maximal period. Compared with conventional optical code-division multiple-access (OCDMA) PONs, without providing a dynamic reconfigurable mechanism and trigger timing, a secure mechanism was generated using a proposed chaos/maximal length sequence (M-sequence) mapping algorithm and embedded in a codebook to control an electrical controller (register). Because the state of the electrical controller (register) is used by the chaos/M-sequence mapping time sequence pattern to trigger a switch matrix and then vary the M-sequence signature address code for each authorised user, the scrambling and interleaving function of the encryption scheme was implemented in the OCDMA-PON physical layer for various M-sequence signature address codes to carry individual H.264/AVC transmissions of the same channel. The proposed chaos/M-sequence mapping algorithm provided similar pseudo randomness and higher variance effectiveness compared with a general uniform distribution of the pseudo-random, autocorrelation, and cross-correlation properties of the proposed time sequence. In addition, the scrambling and interleaving efficiency was determined to be sufficiently high by the reduced peak signal-to-noise ratio of encrypted videos and the produced unidentifiable videos for unauthorised users.

In this paper, an error concealment scheme for neural-network based compression of depth image in 3D videos is proposed. In the neural-network based compression, each depth image is represented by one or more neural networks. The advantage of neural-network based compression lies in the parallel processing ability of multiple neurons, which can handle the massive data volume of 3D videos. The similarity of neuron weights of neighboring nodes is exploited to recover the loss neuron weights when transmitting with an error-prone communication channel. With a simulated noisy channel, the quality of compressed 3D video, which is reconstructed undergoing the noisy channel, can be recovered well by the proposed error concealment scheme.

High Efficiency Video Coding (HEVC), which is the newest video coding standard, has been developed for the efficient compression of ultra high definition videos. One of the important features in HEVC is the adoption of a quad-tree based video coding structure, in which each incoming frame is represented as a set of non-overlapped coding tree blocks (CTB) by variable-block sized prediction and coding process. To do this, each CTB needs to be recursively partitioned into coding unit (CU), predict unit (PU) and transform unit (TU) during the coding process, leading to a huge computational load in the coding of each video frame. This paper proposes to extract visual features in a CTB and uses them to simplify the coding procedure by reducing the depth of quad-tree partition for each CTB in HEVC intra coding mode. A measure for the edge strength in a CTB, which is defined with simple Sobel edge detection, is used to constrain the possible maximum depth of quad-tree partition of the CTB. With the constrained partition depth, the proposed method can reduce a lot of encoding time. Experimental results by HM10.1 show that the average time-savings is about 13.4% under the increase of encoded BD-Rate by only 0.02%, which is a less performance degradation in comparison to other similar methods. All Rights Reserved © 2015 Universidad Nacional Autonoma de Mexico, Centro de Ciencias Aplicadas y Desarrollo Tecnologico. This is an open access item distributed under the Creative Commons CC License BY-NC-ND 4.0.

With regards to the nature of high intensive computation for motion estimation with an H.264/AVC encoder, this paper presents a parallel block-matching algorithm implemented on a general purpose graphics processing units (GPU) to speed up the execution of UAV video coding. Traditional parallel block-matching algorithms are primarily used to leverage the huge number of computational cores in graphic processing units, which can be used to compute the block-matching operation at each candidate position in a search range by an independent thread of kernel computation. In realistic scenarios, the time used to transfer pixel values among the various memory modules to fulfill the operation in a GPU system is much higher than the computation time used for computing each block-matching operation by the kernel threads. This leads to a performance improvement bottleneck for GPU algorithm design. The proposed algorithm exploits the characteristics of distinct memory modules on the data transfer speed for the block-matching algorithm and proposes a feasible mechanism to reduce the bandwidth of data transmission required for the parallel block-matching algorithms implemented on GPU system. With experiments on GPU systems, the proposed parallel block-matching algorithm gains up to 99% execution reduction of motion estimation compared to the host processor only motion estimation process.

The traditional chaotic-based enciphering technique uses pseudo-random codes to implement encryption directly (e.g., based on XOR – exclusive-or operation), which results in the violation of media compression format compliance for video streaming transmissions. In contrast to the conventional cryptography in application layers, the spatial light modulator-based (SLM-based) method uses a programmable optics wavelength filter and has been studied in order to implement a scrambling cryptography on WDM networks. In the suggested encryption scheme, we propose to use chaotic-based time series of secret keys because of their pseudo randomness and maximal period properties. The proposed scrambling SLM-based decryption is configured with an approximate symmetric scheme to perform the decryption when the initial conditions and control parameters of the chaotic sequence are communicated a priori on a private channel as individual secure keys. The experimental results showed that the proposed scrambling cryptography efficiency for video streaming is high enough to achieve secure transmission in the physical layer in terms of a peak signal-to-noise ratio (PSNR) and visual perceptual quality from the perspectives of authorized and unauthorized users. The scrambling performance of wavelength hopping is evaluated with entropy value analysis from the eavesdroppers’ perspective.

This paper addresses the problem of how to make efficient energy consumption on routing communications among the set of wireless sensor nodes deployed randomly in a large-scale manner. Tree-based routing topology is considered in the study with regarding to its simplicity of routing process. To minimize the energy dissipation of tree-routing, centralized coordination schemes are usually used to construct an optimal tree routing topology. In this paper, a distributed-based tree routing protocol is proposed not only to improve the scalability of the centralized tree routing schemes but also handle the balance consumption among the sensor nodes. With computer simulation, the effectiveness of the proposed routing scheme is verified and shown to be useful in large-scale wireless sensor networks.

This paper addresses the energy efficiency of data collection based on a concentric chain clustering topology for wireless sensor networks (WSNs). To conserve the energy dissipation of nodes spent in data routing, the paper attempts to take advantage of the two opportunities: (a) the impact of the relative positions of wireless nodes to the base station on the energy efficiency of the routing chain within each cluster; (b) the effect of the varying-sized chains on the selection rule of cluster heads (CHs). To establish an energy-efficient chain to connect all the nodes in a cluster, the paper proposes a principal vector projection approach, which takes into account both the position of each node and that of the base station, to determine the order to which a node can be linked into the chain in order to reduce the energy requirement of the chain. Since the CH selection rules in the concentric chains are mutually independent, solely based on their self-cluster sizes, the multi-hop path passing through all the CHs will consist of longer links and thus consume a significant fraction of the total energy. Thus, in order to suppress the effect of the unequal cluster sizes on decreasing the energy efficiency of the multi-hop path of CHs, the paper offers an average-cluster-size-based rule (ACSB) for each cluster in order to adapt the CH selection with both the number of active nodes in the current cluster and the average value of all cluster sizes. With these two proposed schemes, an adaptive concentric chain-based routing algorithm is proposed which enables nodes to collaboratively reduce the energy dissipation incurred in gathering sensory data. By computer simulation, the results demonstrate that the proposed algorithm performs better than other similar protocols in terms of energy saved and lifetime increased capabilities for WSNs which deploy random sensor nodes. Copyright © 2010 John Wiley & Sons, Ltd.

This study presents an automatic, fragile-watermarking-based scheme for monitoring the visual quality and authenticity of video streams broadcast by a communications satellite. In the proposed approach, watermark information is embedded in designated motion vectors within the frames of the original video stream prior to it encryption, modulation and transmission to the satellite. Following the reception of the video stream at a terrestrial monitoring system, the watermark information is extracted and compared to that embedded in the original frames. It is shown that by monitoring the mean square error (MSE) of the extracted watermark relative to the original version, reliable estimates of the visual quality of the transmitted video stream can be obtained. Furthermore, the experimental results indicate that the watermarking scheme successfully identifies various common forms of interference, namely recompression attacks, frame removals, frame substitutions, and so forth. Therefore, by monitoring the watermark extraction results on a continuous basis, the degree of signal interference can be automatically determined and an appropriate alarm signal generated to prompt the necessary response.