Polyphase Downsampling Research Articles

Spatial-frequency HEVC multiple description video coding with adaptive perceptual redundancy allocation

Multiple description coding (MDC) approaches improve the error-resilient performance of video transmission by introducing redundancy. The existing multiple description video coding (MDVC) schemes are rarely designed for particular coding structure of HEVC, and the characteristics of the human visual system (HVS) are seldom considered. In this paper, a spatial-frequency multiple description video coding with adaptive perceptual redundancy allocation framework, named SF-PMDVC, is proposed for HEVC. For descriptions generation, after polyphase down-sampling in spatial domain, a transformation based on integer discrete cosine transform (DCT) is expended to adapt to the flexible coding unit partitioning process in HEVC, and the frequency coefficients are segmented and mapped to reduce the bitrate of each description. To further improve the performance of MDVC, an adaptive perceptual redundancy allocation strategy based on visual saliency is proposed, which improves the coding efficiency adapting to the visual perception. Experimental results show that the proposed scheme improves the error resiliency of HEVC by achieving superior objective and subjective reconstructed video quality as compared to the state-of-the-art MDVC methods for HEVC.

A New Polyphase Down-Sampling Based Multiple Description Image Coding.

Multiple description coding (MDC) is an efficient source coding technique for error-prone transmission over multiple channels. In this paper, we focus on the design of a new polyphase down-sampling based MDC (NPDS-MDC) for image signals. The encoding of our proposed NPDS-MDC consists of three steps. First, we perform down-sampling on each N×N image block according to the quincunx down-sampling pattern. Second, we propose a new transform and apply it to the down-sampled pixels to produce the side descriptions. Third, we develop an error compensation algorithm to reduce the compression distortion occurring on the down-sampled pixels. In our scheme, the side decoding is performed posterior to image interpolation with reference to the down-sampled compressed pixels. Moreover, the central decoding is achieved by interlacing the side descriptions. We also propose a compression-constrained central deblocking algorithm to further improve the efficiency of the central decoding. The experimental results indicate that our proposed MDC scheme offers clearly superior performance, especially at high bit rates, as compared to the state-of-the-art methods for various types of images.

Low-complexity redundancy insertion in multiple description coding

Multiple description coding has recently been proposed as a joint source and channel coding to solve the problem of robust image transmission over unreliable network, and it can offer a variety of tradeoff between signal redundancy and transmission robustness. In this letter, a novel pre-and post-processing method with flexible redundancy insertion for polyphase downsampling multiple description coding is presented. The proposed method can be implemented as pre-and post-processing to all standards for image and video communications, with obvious advantages. Simulation results show that this approach can reduce the computational complexity while provide a flexible redundancy insertion to make the system robust for any packet loss situation over different networks.

Improved Redundant Picture Coding Using Polyphase Downsampling for H.264

This paper presents an improved redundant picture coding method that efficiently enhances the error resiliency of H.264. The proposed method applies polyphase downsampling to residual blocks obtained from inter prediction and selectively encodes the rearranged residual blocks in the redundant picture coding process. Moreover, a spatial-temporal sample construction method is developed for the redundant coded picture, which further improves the reconstructed picture quality in error prone environments. Simulations based on JM11.0 were run to verify the proposed method on different test sequences in various error prone environments with average packet loss rates of 3%, 5%, 10%, and 20%. Results of the simulations show that the presented method significantly improves the robustness of H.264 to packet loss by 1.6 dB PSNR on average over the conventional redundant picture coding method.

Polyphase Downsampling Based Multiple Description Coding Applied to H.264 Video Coding

This paper presents a video coding method that improves error resilient functionality of H.264 with good coding efficiency. The method is based on PD (polyphase downsampling) multiple description coding. The only changes to H.264 are inserting PD before the DCT process and having new data partitioning NAL units. A coded slice is sent on 3 data partitioning NAL units. A header NAL unit contains motion vectors and block modes. Each of the other two NAL units contains a description generated by PD multiple description coding. The experimental results on all 9 of the test sequences of JVT SVC show that the proposed method gives 0.5 to 5 dB enhancement over the existing H.264 FMO checker board mode with motion vector based error-concealment.

Multiple description video coding for scalable and robust transmission over IP

In this paper, we address the problem of video transmission over unreliable networks, such as the Internet, where packet losses occur. The most recent literature indicates multiple description (MD) as a promising coding approach to handle this issue. Moreover, it has been shown also how important the use of motion compensation prediction is in an MD-coding scheme. This paper proposes two architectures for multiple description video coding, both of them are based on the motion compensation prediction loop. The common characteristic of the two architectures is the use of a polyphase down-sampling technique to create the MDs and to introduce cross-redundancy among the descriptions. The first scheme, that we call drift-compensation multiple description video coder (DC-MDVC) appears very robust when used in an error-prone environment, but it can provide only two descriptions. The second architecture, called independent flow multiple description video coder (IF-MDVC), generates multiple sets of data before the motion compensation loop; in this case, there are no severe limitations in the selection of the number of descriptions used by the coder.