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deckard
I frequently get mp4 files from friends who strictly use MAC/iTunes.

I've read here that Mp3tag will not write leading zeros in Mp4 tags because the format does not support them. I also read that a custom "track" field was added at some point to accommodate this but then removed because iTunes choked on it.

I am curious then, as to why I have some Mp4 files that HAVE leading zeros in the track numbers and other don't. The ones that do can be written/converted back and forth and they retain the leading zeros, but there are some which will not, even though Mp3tag does not indicate there was a problem writing the data. The only difference I can see between the files is either the encoder or the version of iTunes listed, but even that is not consistent. The tag field ONLY shows "MP4 (MP4)" in both cases.

I have tried deleting the tags completely. Doesn't matter. The ones that can have leading zeros still can and the ones that can't still can't. Can someone explain why this is or if there is a work-around? Would it be possible to give the option of using the custom "track" field or not with a check box?

Few more questions:

- Can an ID3v2 tag be written to an Mp4 file?

- Will there be any support for other file types (.wav .aif, etc.)?
I am able to write tags to these file types in Tag&Rename, and they read fine in other apps, but I have no idea how that application is doing it.

- Will Mp4 be added to the options dialog so it can be checked unchecked for reading/writing?

Thank you for your time. This is a wonderful program that I've only recently discovered and it's already saved me a lot of headache getting things in order!

Florian
QUOTE (deckard @ Oct 30 2010, 16:29) *
Can someone explain why this is or if there is a work-around?

Unfortunately not. I've never encountered such files and still think that track numbers can be numeric only with MP4.

QUOTE
Can an ID3v2 tag be written to an Mp4 file?

No

QUOTE
Will there be any support for other file types (.wav .aif, etc.)?

Not at the moment.

QUOTE
Will Mp4 be added to the options dialog so it can be checked unchecked for reading/writing?

No, because it's the only tag format that is supported for MP4.

QUOTE
Thank you for your time. This is a wonderful program that I've only recently discovered and it's already saved me a lot of headache getting things in order!

That's great! Thanks for the feedback smile.gif
deckard
Hey - Thanks for getting back to me. Would you like me to send you one of the MP4 files that accepts leading zeros? Smallest one I have is around 8MB. Please let me know when you have a moment. Thanks again!
Florian
Yes, you can upload one file to e.g. http://drop.io and send me the URL to support@mp3tag.de

Kind regards
Florian
deckard
Hey - drop.io is going through some changes and no longer allows free uploads. I used sendspace instead. You should have the link in your email now. Thanks!
deckard
OK just realized the file I linked you is an m4a. Since it showed up as (MP4) in the tag field, I didn't bother to look at the extension... I guess there's the answer, although I thought they were basically the same with the exception of copy-protection (which this file does not have).
Florian
It's a file that contains a Nero Digital tag which supports leading zeros for MP4 files and is displayed by Mp3tag.

Kind regards
Florian
deckard
If you have the ability to read it, can it be written via the same method or with some custom settings?
deckard
I recently downloaded some m4a files from the iTunes store and noticed that some of them showed leading zeros in Mp3tag. There didn't appear to be any Nero tags in the files, so I started deleting the extended tags one by one until the leading zeros disappeared.

Turns out, if the field TOTALDISCS exists (these were set to "1"), then Mp3tag will allow you to have leading zeros in the track numbers. As soon as I deleted this field, the leading zeros disappeared.

Not sure why this is, but I figured I'd pass on the info.
dano
If you write only TOTALDISCS without DISCNUMBER you'll get nero tags.
So your leading zero is because of nero tags again.
deckard
QUOTE (dano @ Jan 22 2014, 13:10) *
If you write only TOTALDISCS without DISCNUMBER you'll get nero tags.
So your leading zero is because of nero tags again.


Ha! Was going to ask about that - I didn't realize TOTALDISCS was in fact a Nero tag...

Based on Florian's original answer, I though there was some other hidden field written exclusively by Nero software that could only be seen with a HEX editor or something like that (like iTunes account info).

Is there any problem with using TOTALDISCS in an M4A file?

Thanks for the info!
dano
TOTALDISCS is part of the DISCNUMBER tag. Instead of displaying
DISCNUMBER=1/4 you get

DISCNUMBER=1
TOTALDISCS=4

If you don't fill DISCNUMBER then the program cannot write a proper DISCNUMBER tag and it creates the nero tag.
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