Kwong Huang Goh

Cost effective IP camera for video surveillance

IP cameras are key devices for a video surveillance system. This paper introduces a cost effective, power efficient and low profile IP Camera. The camera consists of a video preprocessing unit, an H.264 encoder, and an embedded streaming server. The video preprocessing unit is used for video data acquisition and format conversion; the H.264 encoder compresses the preprocessed data with H.264 baseline encoding tools; and the streaming server produces a continuous flow of data for the Internet video communication and surveillance applications. Both the encoder and the streaming server are implemented with the cost effective and power efficient Blackfin DSP and ARM9 processors. Key approaches for efficient usage of the DSP resources and main optimization methods for the encoding speed are presented in this paper. Performance tests and practical uses of the IP camera indicate that it is easy to use and able to deliver CIF or VGA size of real-time video clips directly to the Internet with high PSNR quality and low bitrates. Application of these IP cameras to the video surveillance systems may greatly lower the requirements for the network bandwidth, significantly improve the video quality, and efficiently enhance the system reliability accordingly.

An optimal smooth QoS adaptation strategy for QoS differentiated scalable media streaming

Due to the advance of technologies in multimedia compression and network communications, scalable media streaming services have been availed to provide QoS differentiated services for heterogeneous users. However, it is still a big challenge to support consistent end-to-end quality of services (QoS) for the users due to the dynamic feature of the Internet, and abrupt variability of the network resources may severally affect the client perceived QoS. In this paper, we address the issues of smooth QoS adaptation for scalable streaming services. We propose an Optimal Smooth QoS Adaptation (OS-QA) strategy which allocates the server resource adaptively to cope with the variability of network bandwidth and protects the service quality of different quality classes under dynamic resource constraints. We analyze the quality variation caused by resource fluctuation and proposed OS-QA to minimize the average QoS variance under the resource constraints. Simulations are conducted to compare our proposed method with other QoS adaptation methods, and performance is analyzed in terms of QoS variance and PSNR. Results show that our proposed method is able to gracefully adapt the QoS and protect the client perceived QoS by minimizing the QoS variance under dynamic network resource constrains.

An Adaptive Thresholding Technique for the Detection of All-Zeros Blocks in H. 264

In H.264 video coding, there are a substantial number of 4x4 blocks becoming all-zeros after transformation and quantization. This is a waste of computational resources because these skipped blocks do not require forward transform and quantization. We proposed a very effective early detection of fast skipped block detections based on the theoretical derivation of H.264 integer transform and quantization. The experimental results show that the algorithm can detect 9.71%-43.35% more zero blocks than Yongs method.

Pattern selection for error-resilient slice interleaving based on receiver error concealment technique

Video communication is often afflicted by packet loss over unreliable networks. To alleviate the quality degradation in the situation of packet loss, this paper proposes a novel error resilient slice interleaving method for compressed video packetization. Each packet is constructed by interleaving independently decodable slices of the coded video bit-stream in consecutive frames. The optimal interleaving pattern for minimizing the overall distortion of the decoded video, subject to a delay constraint, is determined based on the error concealment technique employed at the user end. Compared with traditional error-resilient methods, this scheme greatly improves the overall performance without requiring an increase in bit-rate. Experimental results on different video sequences demonstrate the effectiveness of the proposed approach.

Efficient rate-quantization model for frame level rate control in spatially scalable video coding

This paper addresses the quantization parameter (QP) selection problem in H.264 spatially scalable video coding (SVC). For frame level rate control in SVC, it is important to have an accurate QP selection scheme such that the target bit rate of each coding layer will be achieved. In this paper, we present an adaptive rate-quantization (R-Q) model to select the appropriate QP for each inter frame in spatial enhancement layers according to the target bit rate. The proposed algorithm introduces an efficient coding complexity estimation method by taking into consideration the inter-layer dependency between different spatial layers. Based on the coding complexity information, the R-Q model parameters can be adaptively updated. Experimental results demonstrate that compared to the traditional method, the proposed method provides better estimation accuracy for bit rate in terms of target bits mismatch error and thus it is very desirable for H.264/SVC rate control applications.

Slice error concealment based on size-adaptive SSIM matching and motion vector outlier rejection

Consecutive corrupted MBs or slice errors are commonly seen in modern video transmission systems. Temporal error concealment is an effective approach to reduce the impact of errors. Conventional temporal error concealment techniques recover slice errors on a MB basis. We propose a new novel temporal scheme for slice error concealment based on a size-adaptive region basis. Size-adaptive region boundary matching can significantly reduce the misalignments or side mismatches that are commonly seen in MB-based approaches. Instead of using MSE or MAE as the matching criteria, We propose a matching criterion based on structural similarity (SSIM). Our proposed matching criterion can achieve better structural alignments and better visual perceptual quality. We also propose a method to detect motion vector outliers at the last stage of the error concealment scheme, which can further improve the visual quality of the concealed videos. Our proposed scheme conceals slice errors with good accuracy as well as low computation complexity, and it can be applied for real-time applications.

A distance-based slice interleaving scheme for robust video transmission over error-prone networks

Video transmission over wireless networks suffers from packet loss due to either temporary packet drop or fading-induced bit errors. To ensure that the quality of the decoded video is not overly affected by the channel unreliability, the video applications have to provide sufficient robustness. In this paper, a novel slice interleaving algorithm is proposed for compressed video packetization. Each packet is constructed by interleaving independently decodable slices of the coded video bit-stream in a group of frames. We group slices into packets according to the maximum minimal distance of these slices. The scattered pattern guarantees that each lost slice has, as many as possible, spatial and temporal neighbors that belong to other correctly received packets. This scheme greatly strengthens the error concealment performance compared with traditional methods. Experimental results demonstrate the superiority of the proposed algorithm.

MP4 File Creator for SVC Adaptive Video Streaming

With the advances in the Internet and mobile networks, consumers now wish to enjoy their live and on-demand multimedia contents anytime, anywhere and across any device. Scalable Video Coding (SVC) provides a very attractive solution to achieve this goal. However, SVC streams themselves are not stream-able by a streaming server. The SVC streams must be stored in a proper file format to facilitate packet-based streaming. MP4 files are designed to contain timed media for streaming purposes. An MP4 file contains media sample data, sample timing information, and sample packetization information, among which sample times are the most important information. In this paper, we take advantage of the unique SVC hierarchical B-pictures coding structure and propose to use a fixed initial delay ((GOP/2)*duration) for SVC composition times instead of parsing the whole file to find out the proper initial delay. We also propose that sample times of the full SVC streams should be obtained firstly, and then the sample times for SVC sub-streams are simply matched from the sample times of the full SVC streams, instead of calculating sample times for each sub-stream, for both single-RTP-stream and multiple-RTP-stream packetization modes. This paper also highlights and addresses some other key implementation issues of the MP4 creator for SVC adaptive video streaming.

Real-time software MPEG-2 TO H.264 video transcoding

The paper describes a fast MPEG-2 to H.264 transcoder by leveraging the MPEG-2 metadata set to reduce the computational complexity of the H.264 encoding process. With the proposed fast transcoding algorithms, our software-based transcoder can perform real-time transcoding a MPEG-2 movie from a DVD disc (at D1 resolution and full frame-rate) and simultaneously performing RTP/UDP streaming of the H.264 video with AC-3 audio over IP networks using only a 1.6 GHz PC notebook. We can achieve about 20-30% faster than the full re-encoding method even at the same target bit-rate and without visible quality degradation. Benchmarking with existing software systems has shown similar results.

Error-resilient slice interleaving for robust video transmission over bursty loss channels

Video communication can be severely afflicted by burst packet loss over unreliable networks. In this paper, we present a novel error resilient slice interleaving strategy for improving the robustness of video transmission over bursty loss channels. The interleaving pattern is designed to distribute the burst packet loss intelligently in a scattered pattern to guarantee that each lost slice has, as many as possible, spatial and temporal neighbors that are correctly received. This scheme can greatly strengthen the error concealment performance compared with traditional methods. Experimental results on different video sequences demonstrate the effectiveness of the proposed approach.