请教英文注释？？

szuczz

本人在看iLBC(rfc3951)语音编码，对下面这两句话不知如何理解才正确，请教各位：
1.At the same time,the described algorithm enables fixed bit rate coding with a quality-versus-bit rate trateoff close to state-of-the-art.  (Page 4)
其中quality-versus-bit 和state-of-the-art不知如何注释？？？
2.Also,a white noise floor is added to the autocorrelation function by multiplying coefficient zero by 1.0001.  (Page 10)
其中a white noise floor 和by multiplying coefficient zero by 1.0001也不知如何理解？？
谢谢！！！
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