Peter Amon

File Format for Scalable Video Coding

This paper describes the file format defined for scalable video coding. Techniques in the file format enable rapid extraction of scalable data, corresponding to the desired operating point. Significant assistance to file readers can be provided, and there is also great flexibility in the ways that the techniques can be used and combined, corresponding to different usages and application scenarios.

Real-Time System for Adaptive Video Streaming Based on SVC

This paper presents the integration of scalable video coding (SVC) into a generic platform for multimedia adaptation. The platform provides a full MPEG-21 chain including server, adaptation nodes, and clients. An efficient adaptation framework using SVC and MPEG-21 digital item adaptation (DIA) is integrated and it is shown that SVC can seamlessly be adapted using DIA. For protection of packet losses in an error prone environment an unequal erasure protection scheme for SVC is provided. The platform includes a real-time SVC encoder capable of encoding CIF video with a QCIF base layer and fine grain scalable quality refinement at 12.5 fps on off-the-shelf high-end PCs. The reported quality degradation due to the optimization of the encoding algorithm is below 0.6 dB for the tested sequences.

Cross-layer architecture for scalable video transmission in wireless network

Multimedia applications such as video conference, digital video broadcasting (DVB), and streaming video and audio have been gaining popularity during last years and the trend has been to allocate these services more and more also on mobile users. The demand of quality of service (QoS) for multimedia raises huge challenges on the network design, not only concerning the physical bandwidth but also the protocol design and services. One of the goals for system design is to provide efficient solutions for adaptive multimedia transmission over different access networks in all-IP environment. The joint source and channel coding (JSCC/D) approach has already given promising results in optimizing multimedia transmission. However, in practice, arranging the required control mechanism and delivering the required side information through network and protocol stack have caused problems and quite often the impact of network has been neglected in studies. In this paper we propose efficient cross-layer communication methods and protocol architecture in order to transmit the control information and to optimize the multimedia transmission over wireless and wired IP networks. We also apply this architecture to the more specific case of streaming of scalable video streams. Scalable video coding has been an active research topic recently and it offers simple and flexible solutions for video transmission over heterogeneous networks to heterogeneous terminals. In addition it provides easy adaptation to varying transmission conditions. In this paper we illustrate how scalable video transmission can be improved with efficient use of the proposed cross-layer design, adaptation mechanisms and control information.

Performance Analysis of Inter-Layer Prediction in Scalable Video Coding Extension of H.264/AVC

Scalable video coding (SVC) is a good approach for video services over heterogeneous networks. To achieve efficient video broadcasting systems, a good understanding on the performance of coding tools in SVC is necessary. In this paper, the efficiency of inter-layer prediction tools in SVC extension of H.264/AVC is thoroughly investigated by simulations. First, it is shown that inter-layer prediction is more efficient for fast/complex sequences than for slow/simple scenarios. Second, among the three inter-layer prediction methods, inter-layer residual prediction contributes most gains in simulations suggested by SVC standardization group. Nevertheless, all of them are comparatively less efficient for sequences with many details in the environment of spatial scalability. In addition, medium-grain quality scalability (MGS) outperforms coarse-grain quality scalability (CGS): MGS is able to provide up to 1 dB gain over CGS while keeping an even higher flexibility. However, MGS introduces a relatively large PSNR fluctuation which impacts visual quality.

Automatic adaptation of streaming multimedia content in a dynamic and distributed environment

The diversity of end-terminal and access network capabilities as well as the dynamic nature of wireless connections pose significant challenges to providers of multimedia streaming services. In this paper, we present a system based on MPEG-21 Digital Item Adaptation (DIA) technologies that automatically adapts scalable multimedia resources, like upcoming MPEG-4 Scalable Video Coding (SVC) streams, in a generic and transparent way to the user and session context. This context includes terminal and network capabilities as well as user characteristics. A server side adaptation engine reacts to context changes by dynamic decision taking and accordingly modified bitstream adaptation. Furthermore, novel concepts are presented that facilitate multimedia adaptation in a distributed fashion along the delivery path.

Pixel-based averaging predictor for HEVC lossless coding

This paper presents an intra-frame prediction scheme designed for lossless coding using HEVC. The proposed coding method comprises a pixel-wise prediction based on original samples. It is realized as a separate intra prediction mode, which replaces the PLANAR mode. In order to perform the prediction, a four-sample template around the pixel that is to be predicted is compared to the respective template of a four-pixel neighborhood. For each reference template, the sum of absolute differences (SAD) is determined. A table look-up of the SAD value gives the respective weighting factor for each neighborhood pixel. The predictor for the current pixel is calculated as the weighted average of the neighborhood pixels. In comparison to the unmodified HEVC Test Model HM-9.1 configured for lossless coding by disabling/bypassing transformation, quantization, and in-loop filters, the proposed method provides average bitrate savings up to 10.88% for intra-only coding at similar computational complexity.

Lagrange multiplier selection for rate-distortion optimization in SVC

The Lagrangian multiplier based rate-distortion optimization (RDO) has been widely employed in single layer video coding. During the development of scalable video coding (SVC) extension of H.264/AVC, it was directly applied in a multilayer scenario. However, such an application is not very efficient since the correlation between layers is not considered in the Lagrange multiplier selection. To improve the overall performance, in this paper a new selection algorithm is presented for RDO in SVC. Simulations show that the proposed method outperforms the recent SVC reference software. With a tiny computational cost, average gains of 0.22 dB and 0.35 dB were achieved in the tests of four-layer quality scalability and three-layer spatial scalability, respectively.

Sample-based Weighted Prediction with Directional Template Matching for HEVC lossless coding

The recently introduced High Efficiency Video Coding (HEVC) standard is currently further investigated for potential use in professional applications. The considered Range Extensions should on the one hand introduce higher bit depths and additional color formats, and on the other hand the coding efficiency of HEVC for high fidelity compression as well as lossless compression is to be improved. In this paper we investigate and improve the recently introduced Sample-based Weighted Prediction (SWP) for HEVC lossless coding. Although being very efficient for natural video content, the SWP algorithm can be further improved for screen content by using a directional template predictor in cases where the SWP algorithm yields worse prediction. The mainly introduced predictor improves the lossless coding results by up to 9.9% compared to the unmodified HEVC reference software for lossless compression.

Adaptive quantization parameter cascading for hierarchical video coding

Quantization parameter (QP) cascaded hierarchical prediction structures have been proved as efficient techniques in hybrid video coding. However, the current QP cascading method is empirical and not adaptive. The reason for the higher coding efficiency of this method has not been fully explored so far. In this paper, the rate-distortion performance of QP cascaded hierarchical video coding is first analyzed with dependent rate-distortion function. Then the optimal offset in linear QP cascading scheme is derived theoretically. It is shown that the widely accepted empirical QP cascading method is actually an approximation to the theoretical solution in fast movement environment. For slow sequences, an average gain of 0.43 dB can be achieved by the combination of two proposed adaptive algorithms.

Model based analysis for quantization parameter cascading in hierarchical video coding

Originally, hierarchical prediction structures were proposed to achieve temporal scalability. Soon after, it was realized that with a proper quantization parameter cascading (QPC) scheme the general performance can be significantly improved by hierarchical coding. However, the theory behind the gain has not been explored so far. In this paper, the QPC in hierarchical coding is investigated by model based emulations. From the analysis, it is noticed that a parameter ß which represents the error propagation in a group of pictures greatly affects the performance of QPC in hierarchical coding. Based on ß, a simple adaptive QPC algorithm is designed. Simulations verify the efficiency of this algorithm: a gain up to 0.89 dB is obtained over the most recent SVC reference software.