R128GAIN: An EBU R128 compliant loudness scanner Reply #200 – 2011-01-31 11:28:40 Quote from: C.R.Helmrich on 2011-01-30 14:21:54In addtion, the major issue, which is mentioned there, is that the "exact" conversion constant when using the formula[blockquote]RG(dB) = constant - R128(LUFS)[/blockquote]depends on the loudness of the material you use to measure that constant. As you confirmed yourself, the best-fit conversion involves a slope different from 1:QuoteThe optimum slope of -0.81 indicates a dependency on loudness. This can be explained by the loudness dependent level difference between the near maximum frame power (Replay Gain) and the long term power average (ITU-R BS.1770). Due to dynamic range processing and limiting this difference tends to get smaller for louder music. This observation is supported by an experiment where in the Replay Gain procedure the near maximum frame power analysis was replaced by a long term power average. Then the least squares fit between this modified Replay Gain and the ITU-based loudness has indeed a slope of -1.While a loudness dependent coefficient makes the two data sets match more closely, that's not what should be used here.One algorithm or the other is a closer match to human perception. Assuming that R128 is closer to human perception, then using a loudness dependent conversion factor will give a poorer result!Cheers,David.