Enrico Masala

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The popularity of DASH streaming is rapidly increasing and a number of commercial streaming services are adopting this new standard. While the benefits of building streaming services on top of the HTTP protocol are clear, further work is still necessary to evaluate and enhance the system performance from the perspective of the end user. Here we present a(More)
This paper evaluates the performance of video streaming in inter-vehicular environments using the 802.11 ad hoc network protocol. We performed transmission experiments while driving two cars equipped with 802.11b standard devices in urban and highway scenarios. Different sequences, bitrates and packetization policies have been tested. The experiments show(More)
The H.264/SVC video codec extends the H.264/AVC standard with scalability features. In this paper we introduce a traffic prioritization algorithm suitable for the transmission of both H.264/SVC and H.264/AVC video over 802.11e ad hoc wireless networks. The proposed algorithm exploits the traffic prioritization capabilities offered by 802.11e to provide(More)
We present a new cross-layer ARQ algorithm for video streaming over 802.11 wireless networks. The algorithm combines application–level information about the perceptual and temporal importance of each packet into a single priority value, which drives packet selection at each retransmission opportunity. Hence, only the most most perceptually important packets(More)
We present a new algorithm to dynamically identify perceptually important regions in pictures of a video sequence. For each macroblock, the distortion that its loss would cause at the decoder is computed. High-distortion macroblocks are then grouped together into slices to be protected with forward error correction or to be sent as “premium” packets. We(More)
The paper aims at evaluating a number of Quality of Service (QoS) indices of a real-time video transmission over an 802.11 ad hoc wireless network. Video is coded according to the state-of-the-art ITU-T H.264 encoder and its transmission is simulated by means of the ns network simulator. Objective quality measurements are presented. Moreover, the impact of(More)
This paper focuses on optimizing real-time intervehicle video communications from an image analysis perspective. Differently from traditional multimedia communication schemes which are typically optimized to maximize perceptual quality as perceived by human users, in this work we propose a new packet importance estimation method designed to capture the(More)
Controlling the group of picture (GOP) size in distributed video coding (DVC) is a difficult but important task since it has a direct impact on the coding performance. This paper presents a framework to adaptively control the size of GOPs in a Wyner–Ziv encoder by means of encoder-side decisions based on support vector machines (SVM) that uses simple(More)
This work addresses the implications of using the Time-Division Unbalanced Carrier Sense Multiple Access (TDuCSMA) coordination function to support triple-play services. Firstly, the theoretical background of TDuCSMA is reported, presenting its advantages and discussing its full compliance with the IEEE 802.11 standard. Secondly, a prototype of TDuCSMA is(More)
This paper presents an analysis-by-synthesis technique to evaluate the perceptual importance of multimedia packets for ratedistortion optimized streaming. The proposed technique, instead of relying on a priori information, computes the distortion that would be caused by the loss of each single packet, including the effects of error propagation and(More)