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Author Topic: Does writing larger Tags change the file?  (Read 6191 times)

oldnewbie

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Does writing larger Tags change the file?
« on: October 16, 2013, 09:31:37 am »

Hello,
I am using Media Jukebox 14.0.166

When I change or add the cover art (embedded) and it is larger than what was previously in the tag, it takes longer than a simple change of a text field/value (the length of time also seems to vary from flac to mp3s).
This makes me wonder (and concerned) that it may not only add the new image but also rewrites (or even re-encodes) the whole file; this in turn makes me wonder if a simple thing as adding cover art of changing some tags will result in a change in quality (or length, or corruption) of the file in any way (since I don't know if re-encodes are used and what encoder is used)...
I hope this is not the case and my music is safe, but the speed difference in changing tag info has me wondering why there is such a difference. This also sometimes but more seldom, occurs when the art is smaller than what previously there.

I also hope that Media Jukebox (as well as Center) utilizes id3 Tag writing and settings which are compatible with most software (from iTunes, foobar to windows media player and most automobile systems) and does not corrupt the files themselves because there was a previous tag written by another program. I think id3v2.3 is currently most supported while v2.4 is not. (I read somewhere in the changelogs with Media Center  or Jukebox that there used to be a file corruption when certain tags were written I hope that is all cleared now with MJ 14).

I also noticed when I add cover art from one mp3 to another file (Copy first file) the copied artwork shows up as larger in the new mp3 than the in the original, surprisingly also if I overwrite the art in the original file with its copy.

If there is a quality issue with larger changes in the tag, will the same apply to simple text changes (or adding values to previously empty fields or even adding custom fields) also change the file / quality?

Does all this impact flac as well as mp3 files, or is it safer to work with changes in one type of file or the other?

I am a bit worried because I just got through re ripping the collection, and this time also with flac, I used db-Poweramp with accurate rip which also wrote the original tags; now hope that there are no compability issues and that I finally have great quality rips with no hiccups.

Thanks for clarifying this issue with the tags/quality...
oldnewbie
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Arindelle

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Re: Does writing larger Tags change the file?
« Reply #1 on: October 16, 2013, 01:23:38 pm »

Quick response ...

Don't worry, your music will be fine :) Metadata modifications/additions do not affect quality. There is no "safer" file format to work with. However Flac will support more tagging fields than a wav or mp3 file .. the important tag info like track artist album artist, genre etc will be supported in virtually all players. Extended informational fields may just not appear, is all.  Just backup up your music and your library frequently, keep an archive of same in a safe place and you'll be fine

Longer response ...

if you are writing tag fields (can be optional) to your files from JRiver, like your initial rip from dbPoweramp you are indeed embedding data in the file itself. This is Metadata, and does nothing to the quality of the actual music  or media residing in the principal part of the file. It is normal if you embed large images or small ones that the file size would change.

Both jriver and dbpoweramp support id3 tags. One thing to note though is that good tagging programs have a much more flexible structure and many more "default" fields. Not all of these fields can be imported to itunes. Also the handling of fields to include things like multiple genres is not supported in itunes (or at least not very well^^) .... the fields separators are different . But that's not a big deal as you can retag in bulk even in iTunes ... I would recommend tagging in flac, then converting to mp3 (which will embed the tags from the flac files). dbpower amp also offers the possibility to rip to multiple file formats at the same time should you want to do it that way.

If you are really concerned about archiving you could initially rip an archive copy (before re-tagging) in addition to your playback flac mp3 files.  I think that's a bit much personally, as you will be backing up your flac files on a regular basis, as well as your library and keeping an archive of all this in a secure place.

Interesting article here from a hard core archivist http://www.computeraudiophile.com/content/309-computer-audiophile-cd-ripping-strategy-and-methodology/ if its of interest to you.
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oldnewbie

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Re: Does writing larger Tags change the file?
« Reply #2 on: October 16, 2013, 03:39:18 pm »

Thank you for the quick response.

I know that normally there should be no harm when editing tags, but (from my understanding) in the case of major changes (say cover art that is 1MB or greater or going the other way, from a large cover to a small say 50 KB one) the whole tag needs to be rewritten because the padding room in the tag is not big enough. Correct me if I am wrong. (I don't know if that means the whole file needs an actual re encode if this happens)
When you do this with a bunch of files at once (a whole album) I noticed that MJ hurries through this but still takes quite some time for certain files (mp3 and flac differ); I hope during this process nothing bad happens to the actual file or audio (quality, artifact, size, length, corruption - wise).

Since it takes quite a bit longer to change a cover art tag than a text tag, can I be sure that this is a safe process? Are the whole files bein re encoded or just the tags?


Also, I just now for the first time saw that an embedded cover art that I copied out of the file (460KB) with MJ got smaller in size (not pixel dimension) when pasted to another file (171KB); as I reported earlier, the opposite usually happens when I do this (copy and paste cover art from within audio files all with MJ tools). Quite strange...
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oldnewbie

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Re: Does writing larger Tags change the file?
« Reply #3 on: October 17, 2013, 10:30:42 am »

Can anyone verify that files are not reencoded, and that the audio quality is not tampered with, when the whole tag needs to be rewritten (due to large size increases in the tag such as embedding a huge cover art image) for both flac and mp3?

Any explenations for the speed difference in writing cover art tag info to flac vs. mp3?

And any ideas why there is a size difference in the cover art when using: Cover Art > Copy to Clipboard and then >Paste From Clipboard with the embedded art? Most times this results in bigger (KB not dimension) embedded pics but sometimes smaller ones. You can even do it multiple times to get an even bigger effect.
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Matt

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Re: Does writing larger Tags change the file?
« Reply #4 on: October 17, 2013, 11:00:08 am »

Tagging does not alter the audio in any way.

You might consider upgrading to MC19 so you have the latest tagging support.
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Matt Ashland, JRiver Media Center
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