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[e-head]

Just noticed this by chance using mp3tag.

I don't know if it has something to do with my settings, but... when you tell MC to do an audio analysis on your files, the COMMENT ITUNNORM tag gets erased (other COMMENT tags are untouched). I'm not sure if this is intentional or not.

I don't see why itunes normalization and MC's can't coexist together. Both should ignore the others tags.

The only issue with this I can see is when transferring files to an iPod. I assume MC actually changes the DB level in the mp3 itself (considering the iPod won't use any replay gain values other than it's own). I can see how the normalization could get applied twice, but I think it's not too much to ask the iPod users to turn off sound check on their iPods if they want to use MC's replay gain (MC users seem to be a smart bunch).

Having both is nice. Someone might want to use MC's when playing files on their computer, and use iTunes when playing files on their pod. Sound check on an iPod is nice because you can turn it on and off, e.g., when listening to a full album. I assume MC's replay gain cannot be turned on/off from the iPod.


My other problem with this is some people (like me) probably go through a transition where they are trying out MC, and are continuing to use iTunes as well. It's sort of a pain to get iTunes to redo the audio analysis on all your files.

[e-head]

Alright... more observations on the COMMENT tag. At this point I pretty much consider this a (rather serious) bug. Assuming you have file tagging enabled:

If you uncheck "store in file tags" for the COMMENT field, MC will wack the COMMENT field whenever you change any of the other tags. Note, this is totally unique to the COMMENT field as far as I can tell. If you uncheck "store in file tags" for ARTIST or ALBUM, MC will leave the existing tag alone when making changes to other tags. The COMMENT tag is treated differently for some reason.

This may not seem like a big deal, but other programs use the COMMENT field for their own unique tags, just like MC does. Sound Check on iTunes relies on this tag.

Now, if you have "store in file tags" checked for the COMMENT field, all is STILL not well. An existing COMMENT tag will be preserved, however any "COMMENT SOMETHING_HERE" tag will get deleted. This goes for the COMMENT ITUNNORM tag.

I hope this is not a conscious attempt to sabotage other software, or power users custom tags.


Are there any plans to do something about this, as I feel a little uneasy using MC to tag my files in the meantime.

[JimH]

Anything is possible, but it would be news to us if our player removes any iTunes tags.   

Has anyone else seen any problems with iTunes tags?

[Matt]

In certain cases, we clean up unknown comment fields when saving the comment to the ID3v2 tag.  This isn't right for the files you are describing.

Could you email a sample MP3 that contains a comment that is being removed to matt at jriver dot com?

Thanks.

[Alex B]

Anything is possible, but it would be news to us if our player removes any iTunes tags.   

Has anyone else seen any problems with iTunes tags?

Sorry Jim, but e-head is correct. At least the COMMENT ITUNNORM and COMMENT ITUNPGAP ID3v2 tags are written as "comment frames with descriptive headers" similarly like MC's custom tags. MC has never been able to preserve foreign ID3v2 comment frames when it writes its own tags. If a comment tag and its value are not in the database they will be erased on a tag write. MC preserves all other foreign custom tags like TXXX frames, but the actual comment tags are exception to this.

The only issue with this I can see is when transferring files to an iPod. I assume MC actually changes the DB level in the mp3 itself (considering the iPod won't use any replay gain values other than it's own). I can see how the normalization could get applied twice, but I think it's not too much to ask the iPod users to turn off sound check on their iPods if they want to use MC's replay gain (MC users seem to be a smart bunch).

MC does not change the audio audio files' volume level. It writes ID3v2 replay gain tags to the files (and reads them on import if they already exist). For playback volume leveling MC uses the replay gain values from the database.

The iPod does not have a tag reader at all. Everything works through its database. MC writes compatible sound check values to the iPod database if the files have replay gain info in MC's library.

Alright... more observations on the COMMENT tag. At this point I pretty much consider this a (rather serious) bug. Assuming you have file tagging enabled:

If you uncheck "store in file tags" for the COMMENT field, MC will wack the COMMENT field whenever you change any of the other tags. Note, this is totally unique to the COMMENT field as far as I can tell. If you uncheck "store in file tags" for ARTIST or ALBUM, MC will leave the existing tag alone when making changes to other tags. The COMMENT tag is treated differently for some reason.

You are correct. This must have been changed at some stage during MC12 development -  probably by accident. I just tested MC11.1 and it preserves all existing comment frames (foreign or not) if the tag writing is disabled for the main Comment field. I have always believed that MC12 behaves similarly.

[Alex B]

In certain cases, we clean up unknown comment fields when saving the comment to the ID3v2 tag.  This isn't right for the files you are describing.

Actually always, if the comments are foreign. You can try any iTunes tagged MP3 file.

[e-head]

MC does not change the audio audio files' volume level. It writes ID3v2 replay gain tags to the files (and reads them on import if they already exist). For playback volume leveling MC uses the replay gain values from the database.

Thanks. I was wondering how this worked. I thought maybe it just changed the mp3's as it transferred them to the iPod, but the way you describe it is even better. You can turn it on or off like normal, with the added benefit that you get a better algorithm (the sound check algorithm is supposedly inferior).

Anyway... this comment thing is still troublesome. I emailed a mp3 file to the stated address. This behavior is easily reproducible with any tag editor, however. I use mp3tag. Just create a tag like "COMMENT FOOBAR" and give it a value. It will get wiped the next time you write any tags to the file.

[Matt]

In build 511 and later:
Fixed: Foreign comment tags could be unnecessarily removed from the ID3v2 tag during tag saving.

Thanks for the help.