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Thread: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

  1. #1

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    Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    I am trying to use the Replay Gain utility to normalize my music in iTunes (files are lossy aac in a .m4a container). The Replay Gain Utility says that it can write the iTunes tag but the volume values are not showing correctly in iTunes. For an example track, I get the values below from the dBPowerAmp utility:

    Album Gain = +0.14 dB
    Track Gain = -2.26 dB
    ITUNNORM = 000003C7 000003C7 00000973 00000973 00024CA8 00024CA8 00007FFF 00007FFF 00024CA8 00024CA8
    iTunes says the volume = -1.0 dB (ie when I import this track it is doing the sound check analysis)

    Now I created an action within MP3Tag to write the ITUNNORM value based on the album gain value. It gives the following:

    ITUNNORM = 000003C8 000003C8 000003C8 000003C8 000003C8 000003C8 000003C8 000003C8 000003C8 000003C8
    iTunes says the volume = +0.1

    Is it possible to get this bug in the Replay Gain utility fixed? I was hoping to batch convert my entire song library of 25,000+ to save me a ton of time and effort and now that does not look like that will work.

  2. #2
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    http://id3.org/iTunes%20Normalization%20settings

    3C8 in all tag values is not correct.

    I believe the first 2 numbers are used by iTunes, so 3C7 and 3C8 are pretty much identical. The +0.1 might be based on the previous calculation of -1.0dB
    Last edited by Spoon; 10-15-2019 at 10:11 AM.

  3. #3

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    I can't say that I know what all the numbers in the ITUNNORM field mean but I can unequivocally say that the Replay Gain Utility IS NOT writing the values in a way that iTunes is actually using them.

    The +0.1 is because iTunes only displays one decimal point on the number (actual number is +0.14). I have tested this now for two days and I can tell you the mp3Tag action IS working (at least with AAC m4a files, still have not figured out MP3. iTunes runs it's sound check procedure every time when I import files that I have used the dBPowerAmp Replay Gain Utility even though I have it set to write iTunes tags. Note that I have set Replay Gain to write the album value to iTunes.

  4. #4
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    You are running the latest iTunes?

  5. #5

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    I am running version 12.10.1.4

    I can't get iTunes to recognize the COMMENT ITUNNORM field at all for mp3 files not matter if I use the dBPowerAmp Replay Gain Utility or MP3Tag to write the field. I don't understand why all of this has to be so hard...I just want to normalize the volume of my music.

  6. #6

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    So this issue is really annoying me. I managed to get AAC files to work with foobar2000 v1.4.8 but still can't get MP3 files to work. However, as far as I can tell it appears to be writing the fields the same as dBPowerAmp so I don't understand why one works and not another. I also managed to get a single MP3 file to work with foobar2000 but have not been able to get any others. I also can't really find any difference in the file that worked vs. all of the others that have not (tried about 30 other files).

    I tried using iVolume in the past with album gain and default 90 dB setting but it does not seem to work nearly as well as Replay/Gain. I know some will say it is the same thing but I assure you that it's not. I have one album that iVolume was adding a crazy +15 dB (caused clipping) but Replay/Gain would only add +8dB. I had another that iVolume added +2.5 dB (caused clipping) when Replay/Gain reduced -0.3 dB. As you can see from these two examples, there is no setting I could do that would provide a happy medium for these (2) albums. The really confusing thing is that iVolume appears to be writing to the same field. I'm stumped and hoping that someone can comment on why this is happening...

  7. #7
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    I import my mp3 library into iTunes. The ReplayGain tags in these files are created using the dBpoweramp ReplayGain DSP setting set to Track, Album & iTunes Album Normalization.

    After reading this thread, I decided to have a quick look at the Volume values in my Songs in iTunes. I sorted all Songs in iTunes by Date Added and noticed that all Songs I imported into iTunes before 11/02/2018 show correct Volume values. However, all Songs imported after 24/02/2018 show incorrect Volume values, similar to the issue you have posted here. I would add, that I am unable to determine the iTunes release versions I had installed on the dates I have specified, although I tend to keep iTunes updated regularly.

    So, I suspect you have highlighted a problem, although it is my suspicion that the problem possibly exists with changes made in iTunes releases after 11/02/2018, in the way that those releases handle imported mp3 files with SoundCheck values.

    Hopefully, Spoon and/or PeterP can shed more light on this issue.

    I would also be very interested in feedback on this issue from garym, as I believe he creates his mp3 library with RG values in a similar manner.

  8. #8
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    Ok will look into this.

  9. #9

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    So I have been experimenting further and the issue is very strange. If I take a flac rip and convert it to MP3 in dBP using the Replay Gain converter to write the iTunes tags, then everything seems to work. However, if I take a file that I only have in mp3 and therefore can't re-encode, then iTunes re-analyzes the file after I have used the Replay Gain converter to write the tags. I don't understand why this would matter but am wondering if how the files are tagged could affect how iTunes reads the tags (ie version of idv3)?

  10. #10
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    Hold the mouse over the file, dBpoweramp will show the ID3 Tag version

  11. #11

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    IDv2.3 for one of the MP3 albums that won't work. IDv2.4 for another. IDv2.4 for the album that did work using foobar2k. Therefore probably not really relevant...it was just a thought as I try to understand why it won't work for some files...

  12. #12
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    FYI, all my mp3 files are ID3v2.3, as recommended.

  13. #13
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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    Quote Originally Posted by mville View Post

    I would also be very interested in feedback on this issue from garym, as I believe he creates his mp3 library with RG values in a similar manner.
    I'd suspect the itunes changes as well. I'll have to play with this when I get some time (won't be soon). I haven't imported any mp3 files into itunes since before Nov 2018, so haven't likely noticed this. I've become very lazy with my iThings, simply using Spotify for streaming (or temporarily downloading Spotify albums to iThings). And for playback of any of my own files I have transferred to iThings, I'm using foobar2000 mobile, which uses the ReplayGain tags themselves I recall (rather than soundcheck).

  14. #14

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    I messed around with this a bit last night again. I had one album with 52 tracks and the Replay Gain information worked for 33 tracks of the 52. When I look at how the COMMENT ITUNNORM data is written it appears that all the numbers between the tracks are the same except for the parts which I have highlighted in bold below. If I have to guess, something in the way these numbers are generated causes it not work sometimes in iTunes but I don't understand enough about how they are generated to figure out why.

    Track where writing album Replay Gain to COMMENT ITUNNORM worked:
    000000E1 000000E1 00000234 00000234 00024CA8 00024CA8 000018D2 000018D2 00024CA8 00024CA8

    Track where writing album Replay Gain to COMMENT ITUNNORM did not work:
    000000E1 000000E1 00000234 00000234 00024CA8 00024CA8 0000695E 0000695E 00024CA8 00024CA8

    Another track that worked:
    000000E1 000000E1 00000234 00000234 00024CA8 00024CA8 000015F2 000015F2 00024CA8 00024CA8

  15. #15

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    Re: Replay Gain Not Writing iTunes SoundCheck Tags Correctly

    I did not see any further updates to this so I started experimenting again figuring it must be something in the way that dBPowerAmp and other programs are writing the tag. I manipulated iVolume so that it was writing the same volume as I was getting from dBPowerAmp. Here is how the ITUNNORM tags were written:

    dBPowerAmp: 0000023A 0000023A 00000591 00000591 00024CA8 00024CA8 00007C24 00007C24 00024CA8 00024CA8 (imports as -0.7 dB for SoundCheck)
    iVolume: 0000023D 0000023D 00000599 00000599 0000BD60 0000BD60 00000000 00000000 0000D0C8 00009138 (imports as +2.4 dB for SoundCheck)

    As you can see, the first (4) hex sets of numbers almost the same and really are just rounding differences. The last (6) sets of hex numbers are completely different so I don't know what is going on there. The funny thing is that if I copy the hex numbers from iVolume tag to the dBPowerAmp file using MP3Tag, the SoundCheck value that comes up in iTunes does not change. So I then took it a step further and took the original file after dBPowerAmp did it's replay/gain calculation that had not been touched at all by MP3Tag and opened it in a hex editor. I then made the COMMENT ITUNNORM tag the same as what was written by iVolume and when I imported that file into iTunes it gave the right value.

    So, given all of this I now know that dBPowerAmp IS NOT converting the Album Gain correctly to the hexidecimal numbers that iTunes uses. Using the same hex editor, I simply made all of the hex numbers the same 0000023A and iTunes showed the correct volume when I imported the tag (note that I did this because that is how MP3Tag writes the values for m4a files and that works). I'm not sure what all the different numbers are supposed to mean but it doesn't appear to matter. I also know from this experiment that MP3Tag IS NOT truly writing the COMMENT ITUNNORM tag as a comment which is why it did not work when I copied the COMMENT ITUNNORM field that iVolume wrote to a virgin track.

    I hope this helps and that the Replay/Gain module can be fixed so that it works correctly so that there is a batch way of handling this from now on using the EBU R128 standard.

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