Thank you very much for the response. I have been reading about the 'Loudness Wars' recently, and I was hoping that DR128 was doing something to deal with the dynamic range compression. I couldnt really tell from the sticky, the jargon was over my head.
Once music has been mastered in a compressed way, there's really nothing to be done about the compression on the back end (R128 volume leveling can't help with that). However, because R128 is a broadcast standard, it may help with the loudness wars eventually. If broadcasters use R128 volume leveling faithfully, compression will no longer provide a "loudness advantage": compressed music will just sound compressed, not loud. So in time, mastering engineers may "get the message" and ease off compression. But meanwhile, we're stuck with it.
I wish to use the information the Analyse Audio has gleaned.
For example, where for any given Album, I have a number of old mp3s of original recordings, or perhaps a flac of a modern CD remix that has been subjected to the loudness war compression and has a low crest factor DR, or even a recent HiRes 24/96 flac with nice high crest factor DR.
Now, please tell me how I can use it.
How can I use the non-crest factor information to help me discern which recordings are worthy of keeping and which duplicates are a waste of space and should be deleted. How can I interpret the Analyse Audio results, esp the LU readings.
If you're comparing different versions of the same recording, you would use the R128 readings the same way you use the crest factor DR readings. Look at each version's R128 DR and compare them across (apples to apples). A recording with a higher R128 DR is less compressed than a recording with a lower R128 DR. You can't necessarily compare a crest factor DR to an R128 DR straight across because they are measuring different things (as described above). For example, I have three CD versions of Yes's
Close to the Edge (an album with three songs):
Album Version Song#1 Crest R128 Song#2 Crest R128 Song#3 Crest R128
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Version 1 11 13 11 12.3 11 5.3
Version 2 11 12.7 11 13.5 9 5.5
Version 3 11 12.9 11 12.4 10 4.6
As you can see Crest Factor DR and R128 DR do not agree, especially on the third track, and that's to be expected because they're measuring different things. Crest factor compares average volume level to peak volume level, R128 compares the 95th percentile for loudness to the 10th percentile for loudness.
In the second version of the third track, the R128 peak level for that track is +0.6 (which means clipping), and looking at the waveform in Audacity, I can see a handful of narrow spots where the track clips. But the spots where the volume is at or near peak make up a fairly small portion of the track's running time (they are a handful of fairly narrow dynamic peaks). For crest factor DR, all that matters is the actual peak, so it compares the actual peak to the average volume level of the music and gets a "9" db result. R128 dynamic range ignores the peak and looks at the 95th percentile for volume (the volume level that 95% of the song is less loud than) on the theory that a handful of very small peaks should not set the dynamic range, and so it discards that information and arrives at a smaller number "5.5" dB. The 10th percentile for loudness forms the bottom of the R128 DR range (rather than the average level for crest factor), and that will often lead to R128 DR ranges that are wider than crest factor ranges, but, in this case, there aren't many quiet moments in this song, so I think the difference here is mostly at the top.
Which one is more accurate? It depends on what your criteria are. If you consider extremely narrow dynamic peaks to be an important part of the picture, then R128 may sometimes give you a misleadingly narrow impression. If you instead want to get a sense of how dynamic "most of the song" is, crest factor DR may give you a misleadingly good impression (in this case because of a handful of clipped peaks). Personally I look at both and try to understand why when they disagree.
All that being said, I don't think DR (either one) is the be all end all of musical quality. As it happens, I prefer the second version of the album shown above to the other two. It has a better R128 DR for two tracks, but a worse one for the 18-minute centerpiece track that makes up half the album. DR isn't a perfect way to separate the sheep from the goats, it's just more information.