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Author Topic: how to detect and delete custom mp3 tags?  (Read 2696 times)

rjm

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how to detect and delete custom mp3 tags?
« on: March 03, 2012, 04:15:34 pm »

Hoping there's an mp3 expert that can help me.

A long time ago I ripped some CDs with MusicMatch Jukebox which created some custom tags like Mood, Situation, etc. I've also seen many other strange custom tags created by other applications. For example, iTunes has an Track Count tag (used to specify Track n of m). MC sees some of these tags and does not see others.

1) What is the best way to detect the presence of, and completely delete all of these non-core tags (not just clear their contents)?

2) Same question for default custom tags created by MC. For example, I have in the past wanted to remove the podcast feed URL tag created by MC (which is the only way to change a podcast downloaded by MC into a regular audio track). This was really hard. Only method I could find was to use a 3rd party tag editor with a nuke all tags feature. This was much too aggressive and I am seeking a more elegant solution.

3) Same question for custom user tags (created by me) in MC.

Thanks for you help.
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rick.ca

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Re: how to detect and delete custom mp3 tags?
« Reply #1 on: March 03, 2012, 05:46:05 pm »

Quote
Only method I could find was to use a 3rd party tag editor with a nuke all tags feature. This was much too aggressive and I am seeking a more elegant solution.

Why "much too aggressive"? It seems like a simple and effective way to ensure all tags are written consistently and exactly the way you want them (i.e., according to the field settings in MC).
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #2 on: March 03, 2012, 05:51:55 pm »

Good point.

1) do you know if MC will put artwork back in original quality after I nuke all?

2) do you have opinion on best tool for batch nuke all tags operations?
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rick.ca

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Re: how to detect and delete custom mp3 tags?
« Reply #3 on: March 03, 2012, 06:16:16 pm »

1. Yes.

2. MP3Tag seems capable enough. Make sure the tags you want removed are selected in Options.
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #4 on: March 03, 2012, 06:58:10 pm »

Thanks.

Just to be certain, do you know if MC puts back an exact binary copy of the artwork, or a re-compressed jpg approximation? I do not know how MC stores thumbnails in its cache.

By the way, the reason I did not like nuke for podcast conversion was that I could not use Update Tags from Library and had to re-enter everything from scratch. Update Tags should work nicely for music.
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rick.ca

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Re: how to detect and delete custom mp3 tags?
« Reply #5 on: March 03, 2012, 10:32:26 pm »

Quote
Just to be certain, do you know if MC puts back an exact binary copy of the artwork, or a re-compressed jpg approximation? I do not know how MC stores thumbnails in its cache.

It stores an exact copy of the original cover. If the original cover isn't found, nothing is saved. Thumbnails aren't involved. If you have any doubt whether the original cover exists in all cases, you should Save cover art to external location specified in Options before nuking the tags.
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #6 on: March 03, 2012, 11:53:55 pm »

Not sure I completely understand but will do some tests first and may be back with another question. Thanks for your help.
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vagskal

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Re: how to detect and delete custom mp3 tags?
« Reply #7 on: March 04, 2012, 01:52:15 am »

It sounds like you have MC set to write the content of MC fields to the file tags. If so, begin with deleting all unwanted file tags/MC fields in MC. Select all files and in the tag action window, set to show all tags with values, empty the tags you want to delete. Then you can remove the MC fields in the settings.

Thereafter you can use MP3Tag to find and delete the rest of the unwanted tags:

In settings make sure read all tag versions is set for mpeg and that write only the tag version and charset you prefer is set (ID3v2.3 and ISO charset, for example) and that delete is set to delete all tag versions EXCEPT the one you prefer. EDIT: Attached a screenshot to illustrate.

Load all files into the program, select them all, and choose save (this will ensure you have your preferred tag version written to the files)

Then, while all files are still selected, choose delete tag (and you should only have the preferred tag version in your file tags; embedded cover art is in my experience not affected)

Now, while all files are still selected, choose the Extended tag panel. There you can see what tags are in your files. Just choose delete for the ones you want to delete and click OK

As a precaution, if the fields in MC are as you want them and set to write to file tags, select all files in MC and choose update tags from library.

You may want to try this out first on some test files.

There is unfortunately nothing you can do about MC writing unnecessary Tool info to your file tags.
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #8 on: March 04, 2012, 09:49:30 am »

Thanks kindly vagskal. I am out of town and will do some tests when I return next week. I will report back here how it worked.
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #9 on: March 27, 2012, 12:43:08 pm »

It stores an exact copy of the original cover. If the original cover isn't found, nothing is saved. Thumbnails aren't involved. If you have any doubt whether the original cover exists in all cases, you should Save cover art to external location specified in Options before nuking the tags.

Did some experiments. If I copy cover art to clipboard from one track, and then paste cover art from clipboard to another track, I observe the imbedded cover arts have the same resolution but different sizes which suggests MC is changing the compression, and since I use lossy jpg artwork, this might suggest a change in quality.

Anyone understand what is going on here?
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MrC

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Re: how to detect and delete custom mp3 tags?
« Reply #10 on: March 27, 2012, 12:47:28 pm »

Did some experiments. If I copy cover art to clipboard from one track, and then paste cover art from clipboard to another track, I observe the imbedded cover arts have the same resolution but different sizes which suggests MC is changing the compression, and since I use lossy jpg artwork, this might suggest a change in quality.

Anyone understand what is going on here?

When you paste a copy of an image, MC has to recompress.  Copy the link instead, and MC will use the referenced file.
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #11 on: March 27, 2012, 02:21:53 pm »

Thanks.

When I add cover from file does MC use it unchanged, or does it recompress?
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MrC

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Re: how to detect and delete custom mp3 tags?
« Reply #12 on: March 27, 2012, 02:40:54 pm »

Unchanged.

The clipboard copy is where the decompress/compress occurs.  I think Alex B or jmone posted about this somewhere.
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rjm

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Re: how to detect and delete custom mp3 tags?
« Reply #13 on: March 27, 2012, 03:02:04 pm »

Thanks. Very glad to know I have not been screwing up after tagging 4000 albums!
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