Search

This paper suggests a standalone Arabic Reading Machine using TTS (Text-to-speech) and OCR (Optical Character Recognition) software built in a user friendly way for Visually Impaired People. In the Arab world, the assistive reading technology for visually impaired people use either computer or mobile phone software, which both require the help of another person. The type of reading machines has already been developed for Latin languages and research about it has been very active since the mid 1950's. An important progress has been made, and many reading machines now provide smooth and reliable speech. Although, reading machines are the most visually impaired friendly reading assistive devices, since their hardware is specifically designed for visually impaired people, they are not yet commercialized for Arabic as it requires further work on the integration of two different systems, namely OCR (Optical Character Recognition) and TTS (Text-to-speech) systems. To answer this issue an Arabic standalone reading machine designed specifically for visually impaired people with convenient control is suggested. Also, the system of existing Latin reading machines is analyzed in details, along with existing OCR and TTS software.

Notification is a service which addresses devices and users with messages or applications to be executed immediately or at specific time. Notification is important for delivering emergency, warnings and other timed messages. Recently introduced mobile broadcast is an ideal candidate for notification services due to its constant availability and potential for simultaneous addressing of very large user groups. Mobile devices also have connectivity to non-broadcast networks which allows for extended notification relying on user interaction, bringing its scope to applications requiring a response mechanism, e.g. for voting. In this paper, extensions to include notification service into the data transport system called IP Datacast (IPDC) used in the DVB-H mobile television standard are presented. The notion of notification services is first overviewed and the notification service elements complementing IPDC in DVB-H are described. Next the notification protocols and message formats are defined and the default notification channels are explained. The presented notification system reflects the current standardization status within the DVB and introduces extensions and new functionalities.

In this work, we present a distortion-based erasure code for realizing unequal error protection in video delivery services. Prior to transmission, the resulting distortion caused by packet erasure is estimated for each of the video packets. This Information Is used to protect the video packets with higher distortion values strongly, whereas video packets with very low distortion values are not worth being protected. We present a local search algorithm that delivers near-optimal parity codes which minimize the expected overall distortion at the receiver. Furthermore, we suggest the deployment of our FEC erasure code at video proxies located at the edge to access networks with high packet erasure rates (e.g. mobile networks). This helps detecting and correcting packet losses efficiently, by tailoring the error protection code characteristics to the observed packet erasure rate of the receiver. Our erasure code is a parity code and relics solely on XOR-operations for encoding and decoding; hence, it shows very high efficiency compared to other more sophisticated codes. Simulation results show that our introduced erasure code outperforms the classical Reed-Solomon erasure codes in terms of perceived video quality, while running considerably faster.

In this work, we develop a framework for the estimation of distortion caused by packet loss. Video traffic carried over the Internet is often subject to congestion leading to packet loss and late arrivals. Depending on the characteristics of the transported video sequence and on the location of the lost packet data, the effects on the perceived video quality may vary considerably. We develop a practical model for the estimation of the distortion, introduced through some packet loss. We then deduce a metric for prioritizing video packets of a video flow for streaming over networks, based on the expected loss distortion in the perceived video quality. The evaluation of our model shows high accuracy in estimating video quality deterioration.

Streaming video over the best effort Internet raises some challenging issues. The available bandwidth and packet transmission delays are often subject to severe changes. As a consequence, a significant ratio of video packets is dropped by network routers because of lack of capacity on congested links. The impacts of video packet drops on the observed quality at the receiver may vary from unnoticeable to unacceptable. This is due to the different values of each video packet for the decoding process at the receiver. Classical queueing disciplines do not have the ability to distinguish between different packet values. It is not unusual that a packet of higher value is dropped in favor of lower valued packet. The value of a packet is measured in terms of the induced distortions when the packet is not received correctly. In this study, we introduce an application specific queueing system, which drops packets in a size-distortion optimized manner. Out of all packets present in the queue, the system selects the packets to be dropped in order to meet a queue size constraint while minimizing the overall distortion if necessary. Improvements in video quality for the receiver and an efficient utilization of the available bandwidth have been observed through different simulations.

We propose an approach for the deployment of video proxy caching for robust video transmission over lossy networks. Video packets are classified by the server according to their valuableness for the decoding process and the perceived video quality. This can be easily realized using a framework for objective video quality measurement along with the frame prediction type. When deployed within the network, e.g. in intermediate multicast routers or proxy caches, this technique helps achieving great quality improvements. By identifying the most important video packets and caching them for short time, retransmission request can be processed quickly, while saving precious time and bandwidth over retransmissions issued by the server. An analytical model as well as experiments have been developed and carried out to show the gain in video quality at the receiver side, that can be achieved through selective video packet caching and retransmission.