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Author Topic: Tagging of flac-files in MC, nonstandard?  (Read 2292 times)

flac.rules

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Tagging of flac-files in MC, nonstandard?
« on: May 16, 2010, 07:15:14 am »

Does MC tag flac-files differently than for instance foobar2000 or the flac-encoder? When i take flac-file and change some tags with MC, and then compare the original with the changed file with Winmerge, it seems like there is a bigger difference than just the tag-data in the changed tags. However its is difficult to say, as most of the change content is mumbo-jumbo in winmerge (probably binary data). The problem is further complicated by the fact that MC writes Tool name and tool version tags. Is there a a way to turn of the writing of these tags? I don't like to have those unnecessary tags in general, and in this particular case it makes it more difficult to compare tag-writing between programs.
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flac.rules

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #1 on: May 16, 2010, 07:34:54 am »

Seems like the difference mainly is the tracknumber, with flac-encoder and foobar, tracknumber is set too "01", with MC, tracknumber is set to "1" Is there a reason for this difference?
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Alex B

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #2 on: May 16, 2010, 10:05:04 am »

Oh dear, actually I think this is a waste of time, but I'll try to reply to each point.

1. Subject: Which standard?
2. Comparing: Why do you do that? Do you have a problem that needs to be fixed?
3. "mumbo-jumbo binary data": The Vorbis comments are human readable. Use a hex editor for inspecting them (an exception: cover art is binary).
4. Tool name & version: You can't turn them off. Do they really bother you? Sometimes the version info has been useful when a tagging problem has been cured.
6. Track number:
- Strictly speaking 01, 02, 03, etc are not numbers.
- MC uses the field as a pure numeric field (in the database and in the physical file tags).
- Also foobar does that when it writes tags to the files. The physical tags it writes in the files do not contain leading zeros (at least not by default). Its display may show the zeros, but I think that is configurable.
- What is "flac-encoder"?
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flac.rules

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #3 on: May 16, 2010, 10:32:46 am »

1. Presumably there is some standard governing how tags are written, de-facto or otherwise. I am not that familiar with flac-tags though, thats why the heading is written as a question, not a statement.
2. Yes, in fact i had some problems with it. But the reason i began with the comparison is that its not that uncommon for media progrs to change audio-data when writing tags. Before i let loose programs on my files i try to do my best to keep such problems from occurring.
3. I now the comments are readable, but the comments seemed to be the same (except tool name and version), however winmerge seemed to indicate a change in the beginning of the file in addition to the things written in the tags, that change was indicated as "mumbo-jumbo" in winmerge, which might indicate there is also a change in binary data? The tags themselfs are readable in plain text.
4. I like to control myself what data is written and not written to the tags, I sure its useful for someone, for me its just unnecessary tags i would rather be without
6 I tested again with foobar, it does not seem to change the numbering of the track, MC changes it from 01 to 1 when wrting the tag, foobar does not.
The flac-encoder is the tool for encoding flac-files. The one you download from http://flac.sourceforge.net/download.html
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Dirhael

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #4 on: May 16, 2010, 11:10:26 am »

If what you're worried about is changes in the audio data, using tools such as winmerge etc. is a complete waste of time and energy. There's a reason FLAC files includes MD5 checksums of the raw PCM data :) A simple flac -t audiofile.flac will verify if anything about the audio have changed from the original encoding, or if you're using fb2k, you can use the "verify integrity" function from the utilities right-click menu.
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Alex B

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #5 on: May 16, 2010, 11:46:49 am »

1. There is no official standard that would specify details like the track number format.

The following links pretty much explain the situation:
http://en.wikipedia.org/wiki/Vorbis_comment
http://en.wikipedia.org/wiki/Ogg#Metadata
http://wiki.xiph.org/Metadata
http://wiki.xiph.org/VorbisComment
http://xiph.org/vorbis/doc/v-comment.html

Regarding a de facto standard, some typical field names are proposed by Xiph.org (a quote from the last link above):

Quote
Field names

Below is a proposed, minimal list of standard field names with a description of intended use. No single or group of field names is mandatory; a comment header may contain one, all or none of the names in this list.
TITLE
Track/Work name
VERSION
The version field may be used to differentiate multiple versions of the same track title in a single collection. (e.g. remix info)
ALBUM
The collection name to which this track belongs
TRACKNUMBER
The track number of this piece if part of a specific larger collection or album
ARTIST
The artist generally considered responsible for the work. In popular music this is usually the performing band or singer. For classical music it would be the composer. For an audio book it would be the author of the original text.
PERFORMER
The artist(s) who performed the work. In classical music this would be the conductor, orchestra, soloists. In an audio book it would be the actor who did the reading. In popular music this is typically the same as the ARTIST and is omitted.
COPYRIGHT
Copyright attribution, e.g., '2001 Nobody's Band' or '1999 Jack Moffitt'
LICENSE
License information, eg, 'All Rights Reserved', 'Any Use Permitted', a URL to a license such as a Creative Commons license ("www.creativecommons.org/blahblah/license.html") or the EFF Open Audio License ('distributed under the terms of the Open Audio License. see http://www.eff.org/IP/Open_licenses/eff_oal.html for details'), etc.
ORGANIZATION
Name of the organization producing the track (i.e. the 'record label')
DESCRIPTION
A short text description of the contents
GENRE
A short text indication of music genre
DATE
Date the track was recorded
LOCATION
Location where track was recorded
CONTACT
Contact information for the creators or distributors of the track. This could be a URL, an email address, the physical address of the producing label.
ISRC
ISRC number for the track; see the ISRC intro page for more information on ISRC numbers.

2. If you have a problem post a detailed report in the current release thread. The developers may be able to do something.

3. The Vorbis Comment block in FLAC files is separate from the audio stream (http://flac.sourceforge.net/format.html). A tagging program may change it in many ways. Even if the field values are apparently identical in two separate FLAC files, the two Vorbis Comment blocks may differ from each other.

If you are worried about the audio content you can verify FLAC files with dedicated tools that can check the audio data. Flac.exe can do it (use the -t switch) or you can use the separate verifier tool that is included in the official flac installer (http://downloads.sourceforge.net/flac/flac-1.2.1b.exe). You can also use Foobar's File Integrity Verifier component.

4. No comments.

6. (Oops, I missed "5")  I tested this before posting my reply. I used foobar's automatic numbering tool in "properties". Actually, you can write "0" in the file tag if you include the zero manually, but foobar doesn't automatically add a zero if you type only the number.


EDIT

Dirhael replied while I was writing my reply.
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flac.rules

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #6 on: May 16, 2010, 12:37:52 pm »

2 The problem is caused by the writing of tracknumbers without the zero. Its not a bug with MC per se. Its a choice done by the developers, thats the reason for my question in post 2.

6. But foobar does not change the tracknumber tag if its already written, if i use the official encoder, and it writes 01, and i write a new tag with foobar the tracknumber stays the same, but with MC it also changes the tracknumber to 1.

Thanks for the tip about verifying integrity from both you and dirhal btw, I was not aware of that. I rarly use foobar2000 for other things than tagging flac.

The end result is that I probably have nothing to worry about audiowise, that i would rather that MC didn't change the tracknumber-tag when other tags are written, however its not that big of a deal, and that i would rather have the choice that MC does not write the Tool-version tags, however the latter is a slightly different topic, might just add it in the suggestion thread.
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Alex B

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #7 on: May 16, 2010, 01:52:28 pm »

MC prioritizes its database. The database can handle various formats - also formats that cannot store tags. The physical file tags are secondary. MC does its best to keep the physical file tags synced. When MC writes tags it writes all fields from the database. It doesn't remove foreign tag fields from the files, but if a field value exists in the database the corresponding file tag is written.

Some other programs (e.g. foobar) have a different philosophy and use the file tags as the only or primary metadata storage place. When you change a field value only that file tag is altered.

Regarding flac.exe, it writes whatever is specified in the command line. It doesn't have any tagging intelligence. You can specify -T "TRACKNUMBER=the first track of this album" and it'll write the text string.

EDIT

You may already be aware of this, but you can disable tag writing in the field specific settings. So if your track numbers are already written in your preferred style you can protect them. MC will still be able to write other tags.

Tools > Options > Library & Folders > Manage Library Fields > Track # > Data > untick: Store in file tags (when possible)
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flac.rules

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Re: Tagging of flac-files in MC, nonstandard?
« Reply #8 on: May 16, 2010, 05:32:26 pm »

Yeah, thats true, the encoder takes the input it is given, I guess the program writing the tracknumbers that way is my ripper (EAC). Thanks for the tips about tag writing, I was aware of it in a way, I just didn't think about it. fortantly MC is blessed with a lot of options to customize stuff :) To bad it seems like i cant make the adjustment to "tool version" and "tool name" in the same place in the options though.
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