odd values in some tags (how to fix?)

Hello, I have almost completed my library organization thanks to the great mp3tag (and of course thanks to you), but I have noticed there are some files with odd values in tags:
A lot of files have no LENGTH tag (right click on file and "Tags..."), and show 00:00 in length field on mp3tag and player, but they can be played fine (I use musicbee and wmp11). Those files usually have no bitrate or mode (mode field is empty, no "Stereo" or else) info in mp3tag. But many other files don't have length tag but show wrong length on mp3tag and player, and they can only be played till the player expects the end, even if there is song remaining, or don't play at all.

Are there any way to fix these values without re-ripping?

Also I realized that when I cut the tags of a group of files there appear other tags under them, cut tags are not empty. May be I cut id3v2 and ID3v1 tags are showing?
In mp3tag settings I have only enabled reading and writing ID3·v2, and removing id3v1 and APE. I'd like to have only id3v2.3 tags, so what should I do?
1- Select the file and use "remove tags". This will not remove id3v2 tags as this option is unselected or will it remove all tags?
2- Select files, cut tags, then remove tags, and finally paste cut tracks?

I thought right click on files, select "tags.." and remove unwanted fields would be enough, but I see it's not.

I wish somebody can help, thanks for your time.

By the way, Do you share your music library tags with any online service like cddb?
I think it would be nice that other people can do in seconds what I did in too many hours, once tried to share with cddb, but I think it is complicated and a bit useless, as adding or removing a tag will chage file's CRC and so it will no be a so automatic process.

any way to set a mp3 time tag?

you cannot edit the length field. of if you do you get a second one which will not be evaluated.
I am afraid that your VBR tag or mp3-stream is broken.
But there is help although not within mp3tag.
I have gathered good results using the freewares foobar2000 and mp3val which both are able to repair the files. foobar seems to do it even better.
So let one of these deal with your weird files and see if anything turn out to be better.

PS: in foobar you have to load a folder and then right-click on a list item to see the function "utilities > repair ..." in the context menu.

Good luck.

Don't bother about this field. It's usually created by rippers but it's completely useless (players are figuring out file length by themselves rather than making use of that frame).

I don't know why but it's definetly not connected with lack of LENGTH field. More likely some encoding issues.

Nope, can't be. Mp3tag copies frame values from tag which is currently read. If there is more than one type of tags in a file and if Mp3tag is configured to read them then one type takes precedance over the others and it's values are copied. The order is (from the one with highest priority): APE, ID3v2, ID3v1.

It won't remove ID3v2.

You don't have to remove tags. After you cut them, they are gone. So just cut & paste.

thanks for the answers.

At last I used the "tags..." menu to remove all tags I don't need as it seems the safest option and it shows all fields at once.

About the files messing with length, I'll give a try to foobar.