Khaled Helmi El-Maleh

Encoder-assisted adaptive video frame interpolation

In low bandwidth video coding applications, frame rate is reduced to increase the spatial quality of the frames. However, video sequences that are encoded at low frame rates demonstrate motion jerkiness artifacts when displayed. Therefore, a mechanism is required at the decoder to increase the frame rate while keeping an acceptable level of spatial quality. In this paper, we present a new method to perform video frame interpolation by sending effective side information for frame rate up conversion applications. The proposed scheme encodes the skipped frames lightly by sending motion vectors and an important information map which indicates to the decoder the type of interpolation method to perform. We also propose a novel overhead reduction method to keep the side information cost low. Experimental results show that the proposed algorithm outperforms decoder-only frame rate up conversion methods and gives better performance in terms of PSNR and visual quality over encoding at full frame rate without frame skipping.

Real-Time Region-of-Interest Video Coding Using Content-Adaptive Background Skipping With Dynamic Bit Reallocation

In this paper, we propose a low-complexity content-adaptive background skipping scheme for region-of-interest (ROI) video coding in real-time wireless video telephony applications. Based on the real-time content information of the current and previous frames, such as foreground shape deformation, foreground and background motion, and background texture complexity, the proposed algorithm dynamically decides whether to skip non-ROI macroblocks of current frame and reallocate saved bits to ROI and coded non-ROI. In this work, we proposed and compared three bit reallocation strategies, and the one predicting the future events using a Bayesian model is found the most efficient. Experimental results indicate that the proposed scheme significantly outperforms other methods by up to 2.5 dB

Upfront intra-refresh decision for low-complexity wireless video telephony

An adaptive intra-refresh (IR) technique is proposed for low-complexity video encoding on resource-constrained wireless platforms. The IR decision is made upfront without requiring any pre-encoding, which significantly reduces the complexity and power consumption in real-time communication. To allow upfront mode decision, a novel closed-form solution is provided requiring no algorithmic iteration or exhaustive searches. The IR scheme adapts to multiple factors including the content texture information, the frame-to-frame pixel-value variation, and the estimated channel loss probability. The macroblock-based refresh can be performed using various patterns (i.e., cyclic, random etc.). Experimental results demonstrate superior performance of the adaptive scheme over fixed schemes at all channel loss rates

Joint Adaptive Background Skipping and Weighted Bit Allocation for Wireless Video Telephony

In this paper, we propose a novel region-of-interest (ROI) video coding algorithm for wireless video telephony applications. In order to improve the visual quality of the ROI, the proposed approach reallocates bits from non-ROI macroblocks to ROI by adaptively skipping non-ROI and using an optimized weighted bit allocation scheme to bias the bit allocation. To the best of our knowledge, this work is the first effort to develop an optimized rho-domain bit allocation scheme for ROI video coding. Experimental results indicate that the proposed approach significantly outperforms other methods by up to 2 dB

Temporal Quality Evaluation for Enhancing Compressed Video

This paper proposes a metric to quantify the effect of the video frame loss according to their impact toward perceived temporal quality. This metric utilizes information obtained from pixel domain and particularly aims at measuring the temporal video quality degradation caused by both regular and irregular frame loss. As one application, the proposed temporal quality metric is used to evaluate the benefit of adaptive thresholding in frame skipping algorithms at the encoder. Temporal quality metric shows high prediction accuracy compared to subjective quality evaluation. Furthermore, it is shown by the experimental results that proposed temporal quality metric precisely differentiates between different frame skipping approaches and can be effectively used to evaluate them. With the help of the proposed quality metric, encoders can be designed to drop frames effectively with minimal perceptual video quality degradation.

Efficient video data recovery for 3G-324M telephony over WCDMA networks

In this paper, we propose a novel cross-layer decoder design that efficiently recovers more video data in the presence of transmission errors for 3G-324M video telephony over WCDMA networks. The proposed method requires collaboration of the video decoder and multiplexing protocol. In particular, it considers loss characteristics of WCDMA channels and modifies demultiplexer to provide additional information to assist video decoder to locate the error position. Then, the video decoder performs error concealment only on the lost macroblocks (MBs), instead of all the MBs in a video slice. The simulation results show that the proposed method can reduce the number of concealed MBs by 22-27% and improve video quality by 0.3-0.7 dB, depending on the video contents and block error rates.

Design and implementation of content-adaptive background skipping for wireless video

This work presents a low-complexity system implementation of a novel content-adaptive background skipping scheme for region-of-interest (ROI) video coding in mobile video phone applications. To improve the overall perceptual quality, the proposed approach reallocates bits to ROI macroblocks by adaptively skipping the non-ROI and using a weighted bit allocation scheme. The skip decision for the non-ROI is adaptively determined by the content information of the video, such as foreground shape deformation, foreground motion, background motion and background texture complexity. Experimental results demonstrate that the proposed scheme outperforms traditional schemes by up to 2 dB

The Quality of Multimedia: Challenges and Trends [From the Guest Editors]

One of the most visible consequences of progress in multimedia has been an increase in quality of the products and services offered. Nowadays, there is no longer only a question of which features are to be included in multimedia applications but also how well they contribute to the quality of user experience.

A Multi-Mode Video Object Segmentation Scheme for Wireless Video Applications

This paper presents a new multi-mode video object segmentation scheme to automatically segment head-and-shoulder objects from a video sequence. The proposed system supports two modes of segmentation: intra-mode and inter-mode. The intra-mode segmentation integrates skin detection, facial feature localization and verification, object shape approximation, split-and-merge region growing, and object region selection and guarantees good performance of the proposed segmentation scheme. The inter-mode object segmentation makes use of background modeling and subtraction to take advantage of temporal correlation of video frame while increasing the robustness of the segmentation and speeding up the performance. The main contributions of the proposed method includes: (i) a robust and efficient background modeling in inter-mode object segmentation, (ii) a facial feature verification and a multi-face separation algorithm in intra-mode segmentation. The performance of the algorithm is illustrated by simulation results carried out on various head-and-shoulder video sequences.

Quality of multimedia experience

Reference EPFL-ARTICLE-177930doi:10.1186/1687-5281-2012-5View record in Web of Science Record created on 2012-06-08, modified on 2017-05-10