I probably should have had this settled in my mind long ago, but -- how necessary is it to level match when you are comparing a lossless track, to its mp3 counterpart?By way of investigation, I compared foobar2k's reported replaygain and track peak values for the same track encoded (LAME 3.98) as V2 (195kbps VBR) and at 320 kbps CBRlossless:Track gain -1.08Track Peak 0.938171195kbps VBR:+0.110.954459320kbps CBR:+.100.934477The track peak differences are negligable, but whence comes the >1db difference in RPG gain of lossless vs. lossy? Does this mean that one should level match according to those RPG values when doing an ABX?
If they're encoded from the same source I see no reason to level match, *if* the encoder is not intentionally changing the volume. I understand LAME does this at least in some ABR modes to lower the amount of clipping.1dB of ReplayGain difference between lossy and lossless is surprising. The ReplayGain calculation isn't perfect of course, but that's more than I'd have expected. Are you sure the same ReplayGain *algorithm* was used in both cases? (original ReplayGain vs R128?)
Level matching within +/- 0.1 dB is the general rule. No level match and I will personally guarantee you will get proper identification if you are paying attention, even if you are comparing two copies of the same file but with the level shift.
I guess the question of interest is the choice of criteria for matching. Back in the days before phase disruptive things like perceptual coders even peak level was good enough. Today, if nothing else use average RMS or the closest thing to it that your software supports.
Black Cow .wav Left RightMin Sample Value: -30296 -30143Max Sample Value: 29222 30742Peak Amplitude: -.68 dB -.55 dBPossibly Clipped: 0 0DC Offset: -0.003 -0.007Minimum RMS Power: -91.32 dB -85.37 dBMaximum RMS Power: -9.34 dB -10.29 dBAverage RMS Power: -22.68 dB -22.37 dBTotal RMS Power: -21.18 dB -20.9 dBActual Bit Depth: 16 Bits 16 Bits 195VBR Left RightMin Sample Value: -30151.38 -31275.73Max Sample Value: 29373.31 30374.21Peak Amplitude: -.72 dB -.4 dBPossibly Clipped: 0 0DC Offset: -0.003 -0.007Minimum RMS Power: -91.67 dB -85.63 dBMaximum RMS Power: -9.35 dB -10.3 dBAverage RMS Power: -22.68 dB -22.37 dBTotal RMS Power: -21.19 dB -20.91 dBActual Bit Depth: 32 Bits 32 Bits 320CBR Left RightMin Sample Value: -30620.92 -30537.32Max Sample Value: 29536.84 30406.43Peak Amplitude: -.59 dB -.61 dBPossibly Clipped: 0 0DC Offset: -0.003 -0.007Minimum RMS Power: -91.82 dB -85.46 dBMaximum RMS Power: -9.34 dB -10.29 dBAverage RMS Power: -22.68 dB -22.37 dBTotal RMS Power: -21.18 dB -20.9 dBActual Bit Depth: 32 Bits 32 Bits
I find there is too great a tendency to treat RG figures as the absolute and perfect metric for loudness matching. It definitely is not. That said I don't think level matching using RMS is a good idea either. The ideal thing to do is determine if the encoder scaled and by how much and use this to calibrate the two signals.
Do you have foo_hdcd or use foo_dsp_effect for de-emphasis?
But what about lossless vs lossless -- say, comparing two remasters (for either audible difference, or for preference)? No encoder scaling involve there. Should one even bother trying to level match when there's different EQ? To the extent I've done such comparisonsm, I've always used replaygain values to 'match' them.
(Sorry about the formatting -- i have never been able to recall how to get tables to format correctly in BB code).
RG does not apply any psychoacoustic magic, other than using a less-than-state-of-the-art equal-loudness curve which hardly constitutes psychoacousitc magic.
foobar2000 always uses postprocessing plugins such as foo_hdcd on playback and during RG calculation. But these plugins work only for lossless files, not MP3. That's why I asked about the presence of foo_hdcd, foo_dsp_effect, ...
Without going into a prolonged discussion about it...1) Is "RG w/ EBU R128" different from R128Gain?2) If yes to 1), is RG w/ EBU R128 just RG with a different equal-loudness curve?Just a yes or no will suffice.
This is not " just RG with a different equal-loudness curve", even though it can be a simplified way to explain it.
Before you start, remember the loudness calculation is 10log10(value) minus 0.691. The result is in LUFS*, which is just a dB scale. Calling it LUFS* makes it clear that all the other stages have also been done. Remember this - you'll need to apply it several times below.
Quote from: 2Bdecided on 08 February, 2013, 07:06:24 AMBefore you start, remember the loudness calculation is 10log10(value) minus 0.691. The result is in LUFS*, which is just a dB scale. Calling it LUFS* makes it clear that all the other stages have also been done. Remember this - you'll need to apply it several times below.dB is 10*log10(value) if the value represents power. It it is voltage (the usual) then use 20*log10(value) because dB represents relative power, which is the square of relative voltage.