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level matching when comparing lossy to lossless
krabapple
post Feb 7 2013, 19:42
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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 CBR

lossless:
Track gain -1.08
Track Peak 0.938171

195kbps VBR:
+0.11
0.954459

320kbps CBR:
+.10
0.934477

The 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?

This post has been edited by krabapple: Feb 7 2013, 19:42
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greynol
post Feb 7 2013, 21:03
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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. wink.gif

This post has been edited by greynol: Feb 7 2013, 21:05


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[JAZ]
post Feb 7 2013, 22:57
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QUOTE (greynol @ Feb 7 2013, 21:03) *
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. wink.gif


I can't answer just with a yes/no, but I'll be quick.

Both, RG and R128 are two things: A reference standard for transmitting loudness estimation of a signal, and an algorithm to calculate it.

So, RG w/R128 means using the RG "tag" standard, but analyze with the R128 algorithm to estimate the loudness.

This is not " just RG with a different equal-loudness curve", even though it can be a simplified way to explain it.

This post has been edited by [JAZ]: Feb 7 2013, 22:57
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greynol
post Feb 7 2013, 23:11
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QUOTE ([JAZ] @ Feb 7 2013, 13:57) *
This is not " just RG with a different equal-loudness curve", even though it can be a simplified way to explain it.

If R128 also differs in the block size used for RMS calculation, in statistical processing, different reference signal used for calibration (ignoring a possible change in level if only trivial), or any other detail in the algorithm besides using a different equal-loudness curve, then the answer to my second question would be no. While it wasn't readily apparent, I'm only interested in the algorithm, not in how the tagging is performed.

So is that a yes or a no?

This post has been edited by greynol: Feb 7 2013, 23:18


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Kees de Visser
post Feb 8 2013, 11:24
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For critical work I still prefer to adjust for equal loudness by ear. Feed one channel of version A and B to both ears and adjust the level for minimal lateralization while swapping L/R in the monitor chain (headphones or speakers).
If A and B are very similar (and time aligned), "nulling" can work too, by reversing the polarity of one of them and adjusting the level to obtain a minimum difference signal.
Although this method can be pretty fast, it's not suitable for large numbers of files smile.gif

Many years ago I had a special analog monitoring pre-amp built with 4 separate inputs and individual variable input gain, polarity switch and L/R output routing. With a bit of experience levels can be matched in less than a minute. I'm sure this can be done with most modern DAW's with a mixing desk.
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Posts in this topic
- krabapple   level matching when comparing lossy to lossless   Feb 7 2013, 19:42
- - lvqcl   The difference between lossless original and LAME...   Feb 7 2013, 20:01
- - Garf   If they're encoded from the same source I see ...   Feb 7 2013, 20:03
|- - krabapple   QUOTE (Garf @ Feb 7 2013, 14:03) If they...   Feb 7 2013, 20:28
- - Arnold B. Krueger   QUOTE (krabapple @ Feb 7 2013, 13:42) I p...   Feb 7 2013, 20:12
- - greynol   QUOTE (Arnold B. Krueger @ Feb 7 2013, 11...   Feb 7 2013, 20:32
|- - krabapple   QUOTE I find there is too great a tendency to trea...   Feb 7 2013, 20:46
|- - greynol   QUOTE (krabapple @ Feb 7 2013, 11:46) But...   Feb 7 2013, 20:59
- - krabapple   Here's what I get when I run the three tracks ...   Feb 7 2013, 20:37
|- - db1989   QUOTE (krabapple @ Feb 7 2013, 19:37) (So...   Feb 7 2013, 20:59
- - greynol   Thanks for the data. I believe those average RMS ...   Feb 7 2013, 20:41
- - lvqcl   Do you have foo_hdcd or use foo_dsp_effect for de-...   Feb 7 2013, 20:48
|- - krabapple   QUOTE (lvqcl @ Feb 7 2013, 14:48) Do you ...   Feb 7 2013, 20:51
- - lvqcl   foobar2000 always uses postprocessing plugins such...   Feb 7 2013, 20:56
|- - krabapple   QUOTE (lvqcl @ Feb 7 2013, 14:56) foobar2...   Feb 7 2013, 22:23
- - greynol   Without going into a prolonged discussion about it...   Feb 7 2013, 21:03
|- - [JAZ]   QUOTE (greynol @ Feb 7 2013, 21:03) Witho...   Feb 7 2013, 22:57
|- - greynol   QUOTE ([JAZ] @ Feb 7 2013, 13:57)...   Feb 7 2013, 23:11
|- - Kees de Visser   For critical work I still prefer to adjust for equ...   Feb 8 2013, 11:24
- - db1989   foobar2000 uses libebur128 since v1.1.7, so a diff...   Feb 7 2013, 21:15
- - 2Bdecided   If I understand it correctly, EBU R128 / ITU BS.17...   Feb 8 2013, 13:06
|- - DonP   QUOTE (2Bdecided @ Feb 8 2013, 07:06) Bef...   Feb 8 2013, 14:18
|- - 2Bdecided   QUOTE (DonP @ Feb 8 2013, 13:18) QUOTE (2...   Feb 8 2013, 14:56
- - 2Bdecided   I do not use automatic (RG/R128) loudness matching...   Feb 8 2013, 13:15
- - greynol   I'm glad that is all spelled out, though you c...   Feb 8 2013, 16:58
- - 2Bdecided   It's made me realise that I ought to do a tabl...   Feb 8 2013, 17:56
- - lvqcl   QUOTE (krabapple @ Feb 7 2013, 23:28) QUO...   Feb 8 2013, 23:19


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