normalization in Audio Catalyst

Hi George,
I too was confused by the AC options when I started to rip for my empeg. Now I find the AC options for 'Variable Bit Rate' and 'Normalisation' very useful. This is the way I believe it works:

Normalisation will adjust (bring up or down) the output level of the entire track by the same amount. To do this, AC will listen to the entire track and find the peak recording level and, if this falls within the boundaries that make normalisation worthwhile, adjust the volume of the entire recording equally. I like to think about this as the binary representation of floating point numbers: I imagine that normalisation leaves the fraction alone (content remains unchanged) but adjusts the exponent (the multiplier i.e. volume) of the frames such that the peak equals the percentage of max output that you set.

I now have this normalisation option on all the time when I rip for the empeg player and have noticed that most new CD remain untouched: they don't need adjustment: almost all are mastered in a such way that max output is at 98% or 99%. Older stuff, however, is sometimes put on CD at much lower levels, and therefore sounds less loud too. To listen to these CD's you'd need to adjust the volume of your head unit / pre-amp. Normalisation will allow to bring such older recordings up to the same volume level as the new stuff, so that you won't have to adjust the volume of your empeg player (as much) between tracks. In theory you ask AC to normalise to any level, so you can also normalise recordings down to say 70% or 50%, but I see no benefit in doing this. During play-back you'd need to amplify these more / introduce more distortion.

My understanding of Richard's 'Volume Adjust' is that it looks ahead to see if the output level of what's going to be played next is significantly different from what's currently playing and, if so, smoothes out the differences. As a result, low volume passages are turned up a bit and when if finds sudden increases in output level, it quickly turns down the volume to avoid clipping. (I don't know if Richard manipulates the empeg volume, of the output level data in the recording. I would think the latter.)

In this way Richards utility complements normalisation: AC's normalisation will smooth out differences between recordings, but leaves the soft/loud differences in tact. Richard's 'Volume Adjust' will smooth out the differences, such that the low passages are not lost in the back ground noise.

Henno
mk2 6 nr 6