I've been playing a random rock list for large chunks of today; this dredged up all sorts of stuff I hadn't heard in ages, and some I'd probably never heard!
I had "Smart" volume adjustment enabled; and I noticed that some tracks were considerably quieter than most. On looking at a couple, I saw adjustment values of -20dB! How could ReplayGain get it so wrong, I wondered... Later, I inspected some of these tracks (in foobar2k, though mp3tag would do just as well). The RG values looked much more reasonable; so why was SqueezeCenter making such huge reductions? Then I noticed that all of the affected tracks also had ITUNNORM tags... and I was immediately suspicious. (A search of the forums for ITUNNORM threw up 'this thread' (http://forums.slimdevices.com/showthread.php?t=42932&highlight=ITUNNORM), which suggests recent changes in SqueezeCenter might have something to do with this. But I'm suspicious of ITUNNORM itself anyway...) A long time ago, I'd tried turning on SoundCheck in iTunes. I'd done my damnest to keep iTunes away from my "real" music library, as I knew it had a penchant for scribbling all over files. Even now, to transfer music to my iPod, I generate a fresh set of mp3s on a separate drive, and import those into iTunes. Nonetheless, iTunes had somehow managed to scrawl over some of my real files anyway (that is, at least some 700+ mp3s - thankfully it doesn't go near flac). My experiences with SoundCheck led me to abandon it rather quickly: for unknown reasons, instead of levelling volume on the iPod, it made some tracks inaudibly quiet and others deafeningly loud. Perhaps the SoundCheck values (and the ITUNNORM tag) were somehow miscalculated? Perhaps that's why some files are far too quiet on the Squeezebox? (Only some WMA files - whose RG tags are ignored - were too loud, and even they weren't as loud as the loud SoundChecked files had been on the iPod.) Using the extended tags button on mp3tag, I removed (blanked) the tag "COMMENT ITUNNORM" on one of the affected albums. I used Browse Music Folder to refresh it in SqueezeCenter - and lo and behold, SC's RG value now matched the track gain tag. Time to get rid of those pesky ITUNNORM tags, then. But how to do this on a folder containing some 16,000 files? Well, loading all 16,000 into mp3tag (by letting it loose on the top-level folder) took about 5 minutes. At this point, I suppose I could've selected the lot, pushed the Extended Tags button, and deleted the ITUNNORM tag as above; but for some reason I didn't think of doing it that way. (I'm not sure how long it would've taken, had mp3tag decided to write to all the files that didn't have the tag as well...) Besides, what I did gave me a chance to see the scale of the problem. At first, I simply sorted the Comment column. This did throw some iTunes-muddied tracks to the fore: some comments contained long strings of digits, sometimes preceded by "iTunes". Every track with these kinds of comments that I tested with "Extended tags..." also had a "COMMENT ITUNNORM" tag. Unfortunately, a few random tests showed that this wasn't a sufficient condition: some tracks without such comments also had the ITUNNORM infection. What I wanted to do was to add a column to mp3tag to show the value of any ITUNNORM tags... this turned out to be possible, but it took several goes to get it right. Here's a quick description of one way to do it: - right-click on mp3tag's column headings, and select Customise columns; - click on the name (not checkbox) of a column near where you want to add the new column, and click New; - in the boxes on the right hand side, call the column whatever you want; in the Value box, put: %COMMENT ITUNNORM% (note the space). Click on OK. Sorting on this column (clicking on the heading) popped all the non-empty ITUNNORM values to the top of the list (well, probably the bottom at first - click again to reverse the order). This gave me a rough idea of which tracks, and which albums, had been tainted by iTunes, before I selected them all then used Extended Tags to blast ITUNNORM away. One SqueezeCentre rescan later, and the RG values (at least those tested so far) look more reasonable. Clearly, not something to do if you do want to keep SoundCheck values in your library; but that certainly wasn't my case. -- Brian -- Brian Ritchie ------------------------------------------------------------------------ Brian Ritchie's Profile: http://forums.slimdevices.com/member.php?userid=2319 View this thread: http://forums.slimdevices.com/showthread.php?t=45277 _______________________________________________ ripping mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/ripping
