This paper presents an Unequal Error Protection (UEP) scheme for audio streaming over IP networks. The sender simulates packet loss by employing the same error concealment scheme as the receiver for each audio frame. The perceived quality of such an estimated frame is compared to that of a lower bit rate version. Whenever the quality of the estimated frame is below a given threshold relative to a lower bit rate version, the frame is error protected by sending the low bit rate version in addition. Simulations have been performed using MPEG-4 Advanced Audio Coding (AAC) encoding, Perceptual Evaluation of Audio Quality (PEAQ) as quality measurement tool, and the Gapped data Amplitude and Phase EStimation (GAPES) algorithm as error concealment. Results show that by adjusting the threshold level for when frames are error protected, the quality improvement vs. redundancy can be quantified.
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