Andrea Lorenzo Vitali

Polyphase spatial subsampling multiple description coding of video streams with H264

In this work, we propose a multiple description (MD) coding system for video streams. In particular, our scheme originates four descriptions from the spatially downsampled polyphase components of the original frames. Each description is compressed independently with the recent H264/AVC video coding standard, it is packetized and sent over an error prone network. In case of errors in one or more descriptions, appropriate concealing is applied at the receiver, before insertion of the corrected frames into the corresponding receiver frame buffers. We propose and compare different concealment solutions and a post processing stage to attenuate visual effects related to MD coding. We analyze the trade off between robustness to channel errors and coding efficiency, comparing the proposed technique with single description (SD) video coding with H264/AVC. Experimental results validate the effectiveness of the proposed scheme.

Development of a wireless low-power multi-sensor network for motion tracking applications

This work presents a novel wireless and low power Attitude and Heading Reference Systems network based on low-cost MEMS (Micro Electro-Mechanical System) sensors, developed for motion tracking systems. Biomedical and rehabilitation purposes as well as gaming and consumer electronics may be the potential applications of this network. The paper aims to describe the hardware architecture, the embedded sensor fusion algorithm and the motion tracking system.

Performance analysis of the scalable video coding standard

The emerging Scalable Video Coding extends the H.264/AVC video coding standard with new tools designed to efficiently support temporal, spatial and SNR scalability. This paper gives a comprehensive overview of the new features of the SVC standard, providing at the same time an evaluation of their Rate-Distortion performance as well as of the computational complexity.

A novel Qi-standard compliant full-bridge wireless power charger for low power devices

In this paper a Qi-standard compliant compact wireless power charger system, composed of a wireless power transmitter and a wireless power receiver, is presented. The developed system aims to be compliant with the latest revision of Wireless Power Consortiums directives and uses a full-bridge resonant inverter as the main power transmitter architecture. The wireless power transmitter and receiver have been designed with ultra low power and high efficiency electronics components thereby maximizing the overall power transfer efficiency.

Real-Time Multiple Description Video Streaming over QoS-Based Wireless Networks

We consider the problem of robust video streaming over networks that support QoS differentiation, such as the 802.11e wireless network infrastructure. We consider the benefits obtained matching the H.264 data partitioning (DP) mode with such a QoS-based interface. We compare this solution with an innovative scheme which combines a multiple description (MD) coding framework with a QoS-based network. Results are reported using both a simple IID channel model and a more realistic wireless network, simulated using the OmNet++ network simulator.

Comparison Between Multiple Description and Single Description Video Coding With Forward Error Correction

Video streaming over packet switched best-effort networks is a challenging topic, due to low latency, scalability and fault tolerance requirements. Many techniques can be used to deal with delay, loss and the time-varying nature of best-effort networks. In this paper we compare two techniques to improve the performance of video streaming, i.e., a multiple description (MD) scheme based on spatial polyphase downsampling, and a single description (SD) scheme where robustness to packet loss is increased using forward error correcting (FEC) codes. We consider both a single channel scenario and a multiple channel (or multi-path) scenario. We span a large set of channel conditions, to consider the high packet loss probabilities common in wireless communication systems. A H.264/AVC video coding standard with advanced error concealment capabilities is used. Experimental results show that MD can be competitive in practical scenarios with more flexibility and less complexity than the SD+FEC scheme

neMEMSi: One step forward in wireless attitude and heading reference systems

This work presents neMEMSi, a novel MEMS based inertial and magnetic system-on-board with embedded processing and wireless communication capabilities, providing an ultra low-power and easy to use Attitude and Heading Reference System (AHRS). Main target applications are navigation systems and inertial based motion tracking technologies. The paper describes the architecture of neMEMSi and provides an evaluation of the performance in terms of key features of state-of-the-art AHRS.

Low-complexity standard-compatible robust and scalable video streaming over lossy/variable bandwidth networks

We propose a robust and scalable transmission scheme based on multiple description coding (MDC). Each description is encoded using a standard video codec such as MPEG-2 or H.264. This scheme provides equal or better robustness with respect to other solutions such as forward error correction (FEC), at lower system complexity; also, it provides scalability by selectively dropping descriptions.

Frame-based multiple-description video coding with extended orthogonal filter banks

We propose a frame-based multiple-description video coder. The analysis filter bank is the extension of an orthogonal filter bank which computes the spatial polyphase components of the original video frames. The output of the filter bank is a set of video sequences which can be compressed with a standard coder. The filter bank design is carried out by taking into account two important requirements for video coding, namely, the fact that the dual synthesis filter bank is FIR, and that loss recovery does not enhance the quantization error. We give explicit results about the required properties of the redundant channel filter and the reconstruction error bounds in case of packet errors. We show that the proposed scheme has good error robustness to losses and good performance, both in terms of objective and visual quality, when compared to single description and other multiple description video coders based on spatial subsampling. PSNR gains of 5 dB or more are typical for packet loss probability as low as 5%.

MP3 Audio Quality for Single and Multiple Encoding

The results of several measurements of audio quality of single and multiple MPEG-Layer 3 encodings will be presented. Subjective and objective tests have been done. A comparisons between the scores of the objective difference grade (ODG) and the subjective difference grade (SDG) prove a more accuracy of the PEAQ method at higher bit-rate. The recent versions of the LAME encoder and PEAQ software based on the ITU recommendation have been used, in association with the ITU standards for the execution of the Subjective test for small impairments.