CHAPTER 14 - Video Coding Technology

Video communication requires sufficient resources to obtain the desired image quality. Availability of bandwidth and screen resolution from different devices on the client end, as well as compression techniques used for transmission also significantly influence to the video quality. Even though the H.264/AVC video compression standard and its scalable extension is known as Scalable Video Coding (SVC) was introduced and successfully addressed the challenge, some weaknesses persist especially for high-resolution video transmissions. The size of the bitstream generated by the SVC standard for ultra-high resolution video compression can only be met if transmitted on a network with a large bandwidth. The Scalable High-Efficiency Video Coding (SHVC) were introduced to overcome problems in the SVC standards. The new video compression standard is proven to reduce bandwidth requirements by up to 46.41 % compared to the SVC standards for the same video quality. This study introduces the performance analysis of SHVC standard video transmission as compared to SVC standard. Both compression standards are transmitted and emulated through network emulator called Mininet-Wifi to get the real transmission picture. The client-server video transmission scheme with different bandwidth and various client position are set in the experiment scenario. It is found that transmission time, packet loss, and video reconstruction quality on scalable video transmission with SHVC standard is better than scalable video transmissions with SVC standard.

Current digital video applications require delivery of digital video content to different clients over heterogeneous networks. These clients may have different system resources and bandwidth capabilities. Thus, delivering of digital video data compressed at specific spatial resolution, quality levels, frame rates and encoding those video data at specific bit rates according to the client resources and the available network is essential. The characteristics of current video transmission system pose many problems for video delivery and scalable video coding is a highly attractive solution. This thesis investigates the existing video coding standards, especially the newest H.264/advanced video coding and its scalable extension: scalable video coding. In this thesis, we address two issues related to the state-of-the-art scalable video coding: 1) computational complexity reduction; and 2) video coding efficiency enhancement. In the first part of this thesis, we address the complexity issue of spatial, signal-to-noise ratio (SNR), temporal and combined scalable video coding. Our goal is to find a good tradeoff between computational complexity and video coding efficiency. We first establish the need to reduce computational complexity for current H.264/advanced video coding and scalable video coding framework. We then evaluate the mode distribution correlations between the base layer and its enhancement layers for different video scalabilities. After the exhaustive search over all possible block partitions is performed at the base layer, the number of candidate modes for luma and chroma blocks in a macroblock that take part in rate distortion optimization calculation at enhancement layers could be greatly reduced based on the correlations. Finally, adaptive fast mode decision schemes for spatial, SNR and temporal scalable video coding are presented. Our schemes could achieve consistent and significant computational complexity reduction with negligible loss in objective and subjective video quality and insignificant increments in bit rate consumption. The second part of this thesis is to provide a solution for the problem of high computational complexity of scalable video decoders. An adaptive encoding algorithm is proposed to reduce decoder complexity in coarse grain SNR scalable video coding.

Multidimensional Signal, Image, and Video Processing and Coding

Scalable video coding (SVC) has been standardized as an extension of the H.264/AVC standard. This paper proposes a practical real-time transport protocol (RTP) packetization scheme to transport SVC video over IP networks. In combined scalability of SVC, a coded picture of a base or scalable enhancement layer is produced as one or more video layers consisting of network abstraction layer (NAL) units. The SVC NAL unit header contains a (DID, TID, QID) field to identify the association of each SVC NAL unit with its scalable enhancement layer without parsing the payload part of the SVC NAL unit. In this paper, we utilize the (DID, TID, QID) information to derive hierarchical spatio-temporal relationship of the SVC NAL units. Based on the derivation using the (DID, TID, QID) field, we propose a practical RTP packetization scheme for generating single RTP sessions in unicast and multicast transport of SVC video. The experimental results indicate that the proposed packetization scheme can be efficiently applied to transport SVC video over IP networks with little induced delay, jitter, and computational load.

Video compression plays an important role in video signal processing, transmission and storage. Since the available bandwidth for transmission is very limited, Multimedia Applications such as video conferencing, video on demand, video telephony and remote sensing are not possible without compression. A lot of video compression techniques have been developed and the video signal transmission has followed at data rates below 64kbps. Wavelet transform based motion compensated video codec performs better compression in order to meet the rate and distortion constraint in video transmission for the available bandwidth than the block based techniques, which are followed in standard video transmissions such as H.261 and H.263. But the efficiency of those technique's depends on the way in which it estimates and compensates the object motions in the video sequence. Wavelet based embedded image coder is quite attractive in modern multimedia applications. Wavelet transform, bit plane coding and other techniques make embedded image coder practical and also provide efficient compression. In this paper, we have proposed a novel video coding using swarm intelligence in dual tree complex wavelet transform for video coding. The 3-D DDWT is an attractive video representation because it isolates motion along different directions in separate subbands. However, it is an over-complete transform with redundancy, which is going to be eliminated by choosing optimal subbands with the help of PSO. The proposed video codec does not require motion compensation and provides better performance than the 3D SPIHT (Embedded type)codec, both objectively and subjectively, and the coder allows full scalability in spatial, temporal and quality dimensions.

This paper investigates how Scalable Video Coding (SVC) can benefit from different Forward Error Correction (FEC) and transmission schemes in mobile broadcast systems. Simulation are performed in DVB-H (Digital Video Broadcasting - Handheld) systems. In DVB-H, a differentiation in robustness for the different SVC layers can be achieved at the link layer using intra-burst MPE-FEC (multi-Protocol Encapsulation FEC). The paper evaluates the gain that can be achieved with the MPE-FEC using equal (EEP) and unequal error protection (UEP), and the performance improvements of an SVC layer-aware FEC (LA-FEC) approach that can be implemented in DVB-H either at the link layer with MPE-iFEC (inter-burst MPE-FEC) or at the application layer with AL-FEC. LA-FEC improves the SVC base layer robustness generating parity information across existing dependencies within the SVC video coding structure. Laboratory measurement results using a TU6 channel model show that the performance of an SVC service in DVB-H can be significantly increased by a proper link layer FEC scheme. It is shown that using SVC in combination with LA-FEC and a proper transmission scheduling does not only give a better performance in terms of PSNR and amount of video outages compared to a single layer service at the same service bit rate, but also gives an additional lower quality layer which can be used for applications like conditional access.

Selective protection can exploit dependency coding properties to effectively perform partial protection on scalable video coding (SVC) bitstreams since protecting frames in lower scalability layers affects visual quality of the reconstructed frames in higher scalability layers. In this paper, we propose a selective protection scheme that maximizes protection effects by the minimum number of encoded frames to be protected in the SVC bitstream domain. We first model the SVC dependency coding structure as a directed acyclic graph which is characterized with an estimated visual quality value as the attribute at each node. In addition, a visual quality estimation model is proposed based on the proportions of intra-predicted and inter-predicted MBs, amounts of residues, and estimated visual quality of reference frames. The proposed selective protection scheme traverses the dependency graph to find optimal protection paths that can give the maximum visual quality degradation. Experimental results show that, compared to the existing protection schemes, the proposed selective protection scheme reduces computation complexity in the number of protected frames, the amount of protected data, and the protection time saving. The SVC file format specification supports the carriage of selectively protected bitstreams based on the concept of our selective protection in dependency coding structure of SVC.

In this paper, we first propose a new parallel video coding framework, considering three important factors: parallel strategy, computational complexity and task scheduling. Then combining the characteristics of scalable video coding (SVC), a novel parallel encoding structure for temporal and quality scalabilities is introduced to obtain a high speedup of parallel SVC. Since the data dependencies in SVC are complex and time variant, the scheduling of parallel SVC is extremely difficult. In order to find the optimal scheduling solution, directed acyclic graph (DAG) is exploited to model the dependencies of encoding tasks, and the complexities of the encoding tasks which are accurately estimated by the Kalman filter to weight the scheduling tasks. Finally, two heuristic scheduling algorithms are also proposed to achieve a high encoding speed of parallel SVC. Experimental results show that the speedup of our parallel method was higher (about 60%) than previous work. Using the proposed method, high definition (HD) SVC videos can be encoded in real time.

H.264 Scalable Video Coding (SVC) is an extension to the Advanced Video Coding (AVC) H.264 standard which provides efficient scalability functionalities on top of the high coding efficiency of H.264/AVC. SVC allows for temporal, spatial, and quality scalability of the output video stream, encoding the video information into an H.264/AVC base layer and a series of enhancement layers which incrementally improve the quality, increase screen resolution and/or frame rate. SVC is particularly suited for mobile TV reception, since the received video quality is adaptable to variable reception conditions and heterogeneous receiver capabilities. However, mobile TV Digital Video Broadcasting (DVB) standards such as DVB-H and DVB-SH were designed prior to the introduction of SVC, and therefore the underlying transmission protocols are not optimized for scalable video delivery. In this overview paper, we review recently proposed solutions for SVC stream adaptation on the underlying DVB-H/SH protocols, and point out novel technical solutions that are currently under consideration for the next generation mobile broadcasting standard DVB-NGH.

Scalable Video Coding (SVC) is a new video coding standard with high efficiency and scalability. The digital right management (DRM) system for SVC should exploit the scalability and be easy to operate. Currently, there is no such a key management scheme for DRM system of SVC. Hence in this paper, a hierarchical key management scheme is proposed. Corresponding to the three scalabilities of SVC (temporal, spatial and quality), we introduce a key management scheme with symmetric cryptographic algorithm and three-dimensional key derivation. This approach is proved to prevent various types of attackers, and the communication efficiency is higher than direct key distribution scheme.

In Scalable Video Coding (SVC), motion estimation and inter-layer prediction play an important role in elimination of temporal and spatial redundancies between consecutive layers. This paper evaluates the performance of widely accepted block matching algorithms used in various video compression standards, with emphasis on the performance of the algorithms for a didactic scalable video codec. Many different implementations of Fast Motion Estimation Algorithms have been proposed to reduce motion estimation complexity. The block matching algorithms have been analyzed with emphasis on Peak Signal to Noise Ratio (PSNR) and computations using MATLAB. In addition to the above comparisons, a survey has been done on Spiral Search Motion Estimation Algorithms for Video Coding. A New Modified Spiral Search (NMSS) motion estimation algorithm has been proposed with lower computational complexity. The proposed algorithm achieves 72% reduction in computation with a minimal (<1dB) reduction in PSNR. A brief introduction to the entire flow of video compression H.264/SVC is also presented in this paper.

The development of Scalable Video Coding (SVC) has been directed to serve a wide range of terminals over heterogeneous networks with the same encoded bit stream. SVC provides an elegant solution to adapt the video content, as it allows terminal and/or gateways accessing only a sub-part of the stream, without affecting the semantics of the source video signal. This paper describes adaptation mechanisms based on SVC, focusing on the implementation in the context of the IST project ENTHRONE. A particular emphasis is placed on adaptation techniques based on SVC NAL unit header extension, and on innovative RTP packet loss handling mechanisms, specifically conceived to handle losses in scenarios where SVC to SVC and SVC to H.264/AVC adaptation is performed and layered multicast cannot be used.

Emerging ubiquitous multimedia services are expected to be available anytime, anywhere, and using different computing devices. Video compression is necessary for transmission of digital video over today's band-limited networks, or for storage constrained applications. This paper gives a short overview over previous video coding standards and analyzes in more detail H.264, which is the latest international video coding standard. Since scalable video coding (SVC) provides the capability of reconstructing lower resolution or lower quality signals from partial bitstream, it is a good paradigm to the streaming video application for ubiquitous multimedia service. Hence, we also discuss several coding techniques and frameworks for SVC including fine granular scalability (FGS).

Due to the advancement of multimedia and its requirement of communication over the network, video compression has received much attention among the researchers. One of the popular video codings is scalable video coding, referred to as H.264/AVC standard. The major drawback in the H.264 is that it performs the exhaustive search over the interlayer prediction to gain the best rate-distortion performance. To reduce the computation overhead due to exhaustive search on mode prediction process, this paper presents a new technique for inter prediction mode selection based on the fuzzy holoentropy. This proposed scheme utilizes the pixel values and probabilistic distribution of pixel symbols to decide the mode. The adaptive mode selection is introduced here by analyzing the pixel values of the current block to be coded with those of a motion compensated reference block using fuzzy holoentropy. The adaptively selected mode decision can reduce the computation time without affecting the visual quality of frames. Experimentation of the proposed scheme is evaluated by utilizing five videos, and from the analysis, it is evident that proposed scheme has overall high performance with values of 41.367 dB and 0.992 for PSNR and SSIM respectively.

MPEG is currently developing a new scalable video coding (SVC) standard which should provide compression efficiency similar to current non-scalable video coding standard. The extension of H.264/AVC hybrid video coding using motion-compensated temporal filtering (MCTF) is a current solution. This paper presents a dynamic group of picture (GOP) structure to improve the quality of the SVC coded video by using variable GOP sizes along the video sequences without the restriction of the fixed GOP size or the limited adaptive GOP size. The dynamic GOP structure keeps temporal importance information of frames in the encoded video, which helps in coding efficiency and provides better user perception. An effective GOP size determination method is also proposed in this paper. The proposed scheme has been validated by experimental results.