  This paper introduces a redundancy adaptation algorithm for an on-the-fly
erasure network coding scheme called Tetrys in the context of real-time video
transmission. The algorithm exploits the relationship between the redundancy
ratio used by Tetrys and the gain or loss in encoding bit rate from changing a
video quality parameter called the Quantization Parameter (QP). Our evaluations
show that with equal or less bandwidth occupation, the video protected by
Tetrys with redundancy adaptation algorithm obtains a PSNR gain up to or more 4
dB compared to the video without Tetrys protection. We demonstrate that the
Tetrys redundancy adaptation algorithm performs well with the variations of
both loss pattern and delay induced by the networks. We also show that Tetrys
with the redundancy adaptation algorithm outperforms FEC with and without
redundancy adaptation.
