Scalable and Robust Video Compression

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.

This paper describes the design and implementation of a multimedia home gateway for threescreen television (3STV) service. The proposed in-home wireless network uses scalable video coding (SVC) and unequal error protection with Raptor forward error correction (FEC) for maximizing the quality of experience (QoE) over the variable-bandwidth, error-prone wireless network. The gateway incorporates (a) dynamic SVC layerswitching, which enables the server to perform selecting appropriate layers from SVC bitstreams, (b) adaptive Raptor FEC, which controls the overhead of Raptor FEC according to packet loss rate (PLR), (c) an efficient combination of (a) and (b), and (d) slice group-based selective streaming in the overall gateway architecture. The paper explains the home gateway architecture as well as experiments for performance evaluation as compared to that of traditional SVC streaming. In the experiments conducted, gains in video quality vary from 2 to 5dB in peak signal-to-noise ratio (PSNR), with corresponding subjective improvements. Overall reductions of bit rate at the input to the home gateway vary from 28% to 36% <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> .

This paper describes a three-screen television system using a block recovery rate (BRR)-based unequal error protection (UEP). The proposed in-home wireless network uses scalable video coding (SVC) and UEP with forward error correction (FEC) for maximizing the quality of service (QoS) over error-prone wireless networks. For efficient FEC packet assignment, this paper proposes a simple and efficient performance metric, a BRR which is defined as a recovery rate of temporal and quality layer from FEC assignment by analyzing the hierarchical prediction structure including the current packet loss. It also explains the SVC layer switching scheme according to network conditions such as packet loss rate (PLR) and available bandwidth (ABW). In the experiments conducted, gains in video quality with the proposed UEP scheme vary from 1 to 3 dB in Y-peak signal-to-noise ratio (PSNR) with corresponding subjective video quality improvements.

This paper develops a new adaptive scanning methodology for intra frame scalable coding framework based on a subband/wavelet(DWTSB) coding approach for MPEG-4 AVC/H.264 scalable video coding (SVC). It attempts to take advantage of the prior knowledge of the frequencies which are present in different higher frequency subbands. We propose dyadic intra frame coding method with adaptive scan (DWTSB-AS) for each subband as traditional zigzag scan is not suitable for high frequency subbands. Thus, by just modification of the scan order of the intra frame scalable coding framework of H.264, we can get better compression. The proposed algorithm has been theoretically justified and is thoroughly evaluated against the current SVC test model JSVM and DWTSB through extensive coding experiments for scalable coding of intra frame. The simulation results show the proposed scanning algorithm consistently outperforms JSVM and DWTSB in PSNR performance. This results in extra compression for intra frames, along with spatial scalability. Thus Image and video coding applications, traditionally serviced by separate coders, can be efficiently provided by an integrated coding system.

Random linear network coding with ladder-shaped global coding matrix for robust video transmission

Fixed length entropy codes (FLC) have been employed as an alternative to the usual variable length codes (VLC) in video codecs. The effect of a transmission error in an FLC coded stream does not propagate beyond the corrupted codeword because of its fixed parsing structure. This paper presents a new decoding algorithm for FLC compressed video streams that fully exploits the error resilience properties of FLC codes combined with spatial synchronization points. While maintaining the compression efficiency of VLC coded video streams, the proposed solution is a novel idea to combat the consequences of transmission errors and it is totally compatible with more traditional solutions such as error concealment and forward error correcting codes.

Scalable video coding (SVC) has aroused a wide interest in the areas of video coding and transmission technology, since it provides desirable features for heterogeneous error-prone network environments. The layered video structure allows not only adaptation to the available bandwidth but also a device adaptation capability via multiple decodable sub-streams. In this paper, we focus on SVC Medium- Grain Scalability (MGS) and investigate the end user's quality of experience (QoE) in error-prone transmission conditions. We describe our error detection and concealment implementation on the JSVM 9.15 reference decoder and assess its effectiveness through several quality indicators. Results show an improvement of the proposed concealment strategy when compared to the standard Frame Copy (FC) and Interpolation, in terms of Peak Signal-to-Signal Noise Ratio (PSNR) and Structural Similarity Index Metric (SSIM) quality metrics. This improvement is evident in the case of concealment on quality enhancement layers, since video fluidity is preserved assuring an acceptable QoE to the end users.

IPTV (Internet Protocol Television) provides interactive function, which greatly improves subjective experience of users. However, IP network is a best-effort network and does not guarantee a reliable connection, which makes video transmission based on IP network prone to problems. This paper focuses on the relationship between packet loss and video perception quality in IPTV transmission. Through subjective evaluation experiments, the influence of different packet loss rate and packet loss distributions (burst loss and random loss) are quantitatively studied. Experimental results show: When packet loss rate is the same, video with burst loss has a better quality than one with random loss. The proportion of burst loss in total packet loss increases, and subjective perception quality increases exponentially. Based on experimental results, this paper also designs an objective evaluation model of video quality based on packet loss rate and packet loss distribution.

In October 2007 ITU-T and MPEG organizations published the Scalable Video Coding (SVC) specification as an addendum to the H.264 standard. Basically SVC enables H.264 video encoders to support temporal, spatial and SNR scalability. This new functionalities lead to more flexibility on bandwidth management and robustness against packet losses. It is therefore more suitable for heterogeneous multimedia applications like IPTV and mobile networks. However implementations of SVC specification are still limited due the augmented computational complexity. One of the most critical SVC algorithms is the motion estimation module, which allows identification of extra intra and inter-layer redundancies. The great computation demand of this module is responsible for the large SVC encoder latency time, restraining its use in real-time applications. We propose in this paper a new motion estimation approach specially designed to reduce memory accesses and data comparisons in order to increase performance. Experimental results prove significant gains in speed (up to 6 times faster) with small effects on quality (less than 0.2 dB).

In this paper, a prescription-based error concealment (PEC) method is proposed. PEC relies on pre-analyses of the concealment error image (CEI) for I-frames and the optimal error concealment scheme for P-frames at encoder side. CEI is used to enhance the image quality at decoder side after error concealment (by spatial interpolation or zero motion) of the corrupted intra-coded MBs. A set of pre-selected error concealment methods is evaluated for each corrupted inter-coded MB to determine the optimal one for the decoder. Both the CEI and the scheme indices are considered as the prescriptions for decoder and transmitted along with the video bit stream based on a reversible data embedding technique. Experiments show that the proposed method is capable of achieving PSNR improvement of up to 1.48 dB, at a considerable bit-rate, when the packet loss rate is 20%

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.

Adaptable system based on Scalable Video Coding for high-quality video service

This paper presents an MPEG-4 video codec, called MoVa, for video coding applications that adopts 3G-324M. We designed MoVa to be optimal by embedding a cost-effective ARM7TDMI core and partitioning it into hardwired blocks and firmware blocks to provide a reasonable tradeoff between computational requirements, power consumption, and programmability. Typical hardwired blocks are motion estimation and motion compensation, discrete cosine transform and quantization, and variable length coding and decoding, while intra refresh, rate control, error resilience, error concealment, etc. are implemented by software. MoVa has a pipeline structure and its operation is performed in four stages at encoding and in three stages at decoding. It meets the requirements of MPEG-4 SP@L2 and can perform either 30 frames/s (fps) of QCIF or SQCIF, or 7.5 fps (in codec mode) to 15 fps (in encode/decode mode) of CIF at a maximum clock rate of 27 MHz for 128 kbps or 144 kbps. MoVa can be applied to many video systems requiring a high bit rate and various video formats, such as videophone, videoconferencing, surveillance, news, and entertainment.

Bit-depth scalability compatible to H.264/AVC-scalable extension

Mobile Ad-hoc Networks (MANETs) usually suffer from high packet loss and high link failure rates. These challenges usually increase congestion on some links while other links are almost free. In this paper, we propose a novel mechanism to enhance QoS in multipath routing protocols in MANETs based on the InfiniBand (IB) QoS architecture. The basic idea of our approach is to enhance the load balancing and thus reduce congestion on overloaded links. This mechanism has enabled us to (1) give critical applications higher priority when routing their packets across the network, (2) effectively manage frequent connections and disconnections and thus reduce link failures and packet loss rates, and (3) reduce the overall power consumption as a consequence of the previous gains. We have tested the scheme on the (IBsim) simulator and achieved significant improvements in QoS parameters compared to two well- known routing protocols: AODV and AOMDV.