Abstract
In this contribution, an evaluation of the effectiveness of Application Layer-Forward Error Correction (AL-FEC) scheme in video communications over unreliable channels is presented. In literature, several AL-FEC techniques for reducing the effect of noisy transmission on multimedia communication have been adopted. Recently, their use has been proposed for inclusion in TV over IP broadcasting international standards. The objective of the analysis performed in this paper is to verify the effectiveness of AL-FEC techniques in terms of perceived Quality of Service (QoS) and more in general of Quality of Experience (QoE), and to evaluate the trade-off between AL-FEC redundancy and video quality degradation for a given packet loss ratio. To this goal, several channel error models are investigated (random i.i.d. losses, burst losses, and network congestions) on test sequences encoded at 2 and 4 Mbps. The perceived quality is evaluated by means of three quality metrics: the full-reference objective quality metric NTIA-VQM combined with the ITU-T Rec. G.1070, the full-reference DMOS-KPN metric, and the pixel-wise error comparison performed by using the PSNR distortion measure. A post-processing synchronization between the original and the reconstructed stream has also been designed for improving the fidelity of the performed quality measures. The experimental results show the effectiveness and the limits of the Application Layer protection schemes.
Highlights
In the last years, communication architectures based on TCP/IP suite have been widely adopted, mainly due to the spreading of Internet
Since the basic TCP/IP framework is based on a besteffort paradigm, many efforts have been spent in designing additional mechanisms able to handle the Quality of Service (QoS)
We demonstrate that the adoption of an objective model allows to automatically determine the parameters of the video quality ITU metric, without requiring expensive and time-consuming subjective experiments
Summary
Communication architectures based on TCP/IP suite have been widely adopted, mainly due to the spreading of Internet. Video over IP can offer a wide range of added-value services: video telephony, videoconferences, and TV broadcasting over IP are few examples of them. These services pose severe constraints on both data integrity and temporal delays. Since the basic TCP/IP framework is based on a besteffort paradigm, many efforts have been spent in designing additional mechanisms able to handle the Quality of Service (QoS). They include protocols designed for real-time multimedia streaming, like RTP/RTCP and TP++, [1,2], as well as mechanisms for error recovery at
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