RG and adjusting preamp to prevent clipping
Reply #3 – 2008-10-12 12:37:16
I saw that option but won't that make tracks kind of jump in volume? As a purist, I guess you'll be more likely to use Album Gain, so it would be the whole album that's scaled down to ensure the Album Peak doesn't exceed 1.000, so my answer is... ...Yes, but only those few that would have clipped AFTER applying the Replay Gain (which is usually negative and will bring the resulting peak below 1.000 most of the time. For old recordings and dynamic recordings such as classical, you may find zero or positive Replay Gain that would cause this. For most rock & pop, I'd think it unlikely. The calculation is simplest in decibels (addition rather than multiplication of gain factors): Convert Album Peak (e.g. 1.234567) into dB: 20*log(1.234567) = +1.83dB Add this to Album Gain (e.g. -8.90 dB): +1.83 + (-8.90) = -7.07 dBFS = peak value relative to full scale after applying gain Add RG Pre-amp setting (e.g. -6.02 dB to approximate the original 83 dB SPL calibration) and Volume Control setting (usually 0.00 dB): +1.83 - 8.90 - 6.02 - 0.00 = -13.09 dBFS = peak value relative to full scale after all RG is applied in FB2K's playback chain unless you turn on clipping prevention, which would limit positive results to 0 dBFS. So, if the sum of Album Gain and Album Peak (converted to dBFS) is positive, FB2K will apply the negative of that gain to prevent clipping if you've turned on clipping prevention. I'd suggest that a negative pre-amp might be best for the true purist. 83 dB SPL, or preamp of -6 dB or so, isn't a bad target, though it will be much quieter than Windows' own sounds and sounds on many websites unless you find a way of applying a negative gain to all other sounds.I'd rather just make everything the same volume to prevent it from clipping in the first place. What I'm not sure about is what to set the preamp in order to do that. I haven't thought about non-rg-scanned sources... Well, you now have the formula for each album, but I don't know how to collect the values for a whole collection into a spreadsheet to find the maximum peak after apply Album Gain. I usually set my non-RG pre-amp to somewhere in the range of -7.0 dB to -9.0 dB. I've moved away from purism, and I don't bother with clipping prevention now. I'm happy to set only a modest target volume (89 dB is fine for me) and use Advanced Limiter , which looks ahead in the buffer (hence 'Advanced') and won't touch my sound unless an upcoming peak would actually exceed full scale, where it will apply soft limiting around the area to rein it in without any very unpleasant distortion. In most circumstances when Album Gain clips at 89 dB target (zero pre-amp), there's something like the culmination of a crashing orchestral crescendo which is quite noise-like and will mask the harmonic distortions so that they're not annoying (probably the case whether peaks are clipped or limited). Advanced Limiter actually sounds pretty good with a bit of positive pre-amp and positive gain applied, so I'm not too worried about audio quality during the rare and brief occasions when it will be called upon in normal use.