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Metadata/tag mapping between FLAC, mp3, and UPnP/DLNA, Is there a standard? What does fb2k do?
2Bdecided
post Jul 31 2013, 13:52
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This is not just a foobar2k question - please don't move this thread to the fb2k forums.


tl/dr: Does anyone know of a standard or quasi-standard of how metadata can be mapped between various tagging schemes (Vorbis comments, ID3, UPnP/DLNA, etc)?



Having tried to figure out sensible filenames, I realised that I don't know what I'm doing with tags either. I rip to FLAC, and convert to mp3. Because I use the mp3s more, I usually find tag errors in the mp3s first, but flac2mp3 has the potential to makes it easier to keep both collections in-sync.

The problem is, I want to understand what's happening (and what "should" happen) to the tags on their way from FLAC (Flac tags = Vorbis comments), to mp3 (ID3v2.3 or ID3v2.4) to a UPnP/DLNA server.

Knowing that the tags have a good probability of working and making sense whatever mp3 player or DLNA renderer I might use in the future is important. I don't want to keep messing around with them. Hence my desire to understand how they work and map.


I've found some useful information on-line, but not the whole story:

mp3tag has a helpful list...
http://help.mp3tag.de/main_tags.html

fb2k has a list of displayed tag names vs id2v3+4 mp3 tags...
http://wiki.hydrogenaudio.org/index.php?ti...ID3_Tag_Mapping
...and a list of ways it now knowingly breaks the standard...
http://wiki.hydrogenaudio.org/index.php?ti...y_1.1.6_changes

The description of Vorbis comments starts here...
http://wiki.xiph.org/index.php/VorbisComment
...with the list here...
http://xiph.org/vorbis/doc/v-comment.html
...newer additions here...
http://wiki.xiph.org/Field_names
...and a useful guide here...
http://age.hobba.nl/audio/mirroredpages/ogg-tagging.html

I can't find an on-line list of how fb2k maps Vorbis Comments to ID3. Is there one?

In dBpoweramp, if I dive deeply into the menus, there are options for changing how tags are mapped and named on screen. I can't find an on-line list that states what the defaults are.

Asset UPnP, Serviio, and some other DLNA/UPnP servers have options to try to make things work properly with various clients. My stuff tends to be thrown at Twonky and I had no idea what it was doing but found this on line...
http://www.twonkyforum.com/mediawiki/index...Twonky_Database

I've heard of (but not tried) MinimServer which tries to make the tags needed for classical music work properly.

The intricacies of making various things work is played out in full on the Linn forums, though thankfully they share some of the things they have created.


That's all I can find. Anyone have any other useful links?


Is there a "standard", or does everyone just try to figure it out for themselves?

It would also be nice to find documentation of the compatibility and quirks. e.g. for multiple values, do you add multiple tags or one tag with a specific delimiter etc. and e.g. what works on various players.

If anyone spots any flying pigs, feel free to mention that as well wink.gif .

Cheers,
David.

This post has been edited by 2Bdecided: Aug 8 2013, 11:37
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2Bdecided
post Sep 4 2013, 10:58
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ReplayGain developer


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Posts: 5062
Joined: 5-November 01
From: Yorkshire, UK
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Nothing new to add, but found relevant comments at line 3455 of this...
https://github.com/robinbowes/flac2mp3/blob.../lib/MP3/Tag.pm
...bemoaning the difficulty of knowing exactly what you are mapping when you map the track artist.

Also line 77 onwards here...
https://github.com/robinbowes/flac2mp3/blob...ter/flac2mp3.pl
...shows mapping used by flac2mp3. Line 113 onwards lists the names associated with each TXXX frame. Copying ReplayGain peaks when transcoding without noting the fact is unorthodox. Loss of TRACKTOTAL and DISCTOTAL is visibly annoying on many players. I guess when the "right" mapping is properly defined it can go into this code.
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marc2003
post Sep 4 2013, 18:40
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QUOTE (2Bdecided @ Sep 4 2013, 10:58) *
Loss of TRACKTOTAL and DISCTOTAL is visibly annoying on many players.


i'm not sure loss is the right word? if converting flac>mp3, they should be added to the tracknumber (TRCK) and discnumber (TPOS) fields.

from id3.org (which appears to be down but i used google's cache)

QUOTE
TRCK
The 'Track number/Position in set' frame is a numeric string containing the order number of the audio-file on its original recording. This may be extended with a "/" character and a numeric string containing the total numer of tracks/elements on the original recording. E.g. "4/9".


if your player/converter software doesn't make use of this, poke them with a sharp stick. tongue.gif

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Posts in this topic
- 2Bdecided   Metadata/tag mapping between FLAC, mp3, and UPnP/DLNA   Jul 31 2013, 13:52
- - 2Bdecided   I've found a similar thread on the mp3tag foru...   Aug 12 2013, 11:03
- - marc2003   QUOTE but when you're trying to figure out exa...   Aug 12 2013, 11:39
- - 2Bdecided   Thanks marc2003 - I hadn't found that. Googli...   Aug 12 2013, 15:18
- - marc2003   QUOTE Unless I'm missing something, axone.js o...   Aug 12 2013, 15:30
- - 2Bdecided   That's great, thank you. Thank you for taking ...   Aug 12 2013, 17:01
- - Rescator   You might want to take a peek at http://www.mp3tag...   Aug 12 2013, 23:52
- - db1989   Did you totally miss the bits in the OP where he s...   Aug 13 2013, 00:02
- - Rescator   *doh* I did see a mention of QUOTE mp3tag has a h...   Aug 13 2013, 00:24
- - 2Bdecided   Yes, I'm using mp3tag - though I wish I'd ...   Aug 13 2013, 09:39
- - 2Bdecided   I was/am hacking something together on the HA wiki...   Aug 14 2013, 11:04
- - 2Bdecided   Here is my attempt. It is not finished yet! I ...   Aug 14 2013, 17:24
|- - Rescator   QUOTE (2Bdecided @ Aug 14 2013, 18:24) He...   Aug 14 2013, 18:40
|- - tuffy   QUOTE (Rescator @ Aug 14 2013, 11:40) See...   Aug 14 2013, 20:07
|- - marc2003   QUOTE (Rescator @ Aug 14 2013, 18:40) Foo...   Aug 14 2013, 23:18
- - 2Bdecided   Well, we're either great minds or fools becaus...   Aug 14 2013, 22:48
- - Rescator   QUOTE (marc2003 @ Aug 15 2013, 00:18) QUO...   Aug 15 2013, 02:07
- - 2Bdecided   It's the first time I've typed a HA wiki p...   Aug 15 2013, 18:26
|- - Rescator   QUOTE (2Bdecided @ Aug 15 2013, 19:26) I...   Aug 15 2013, 19:01
|- - marc2003   QUOTE (2Bdecided @ Aug 15 2013, 18:26) I ...   Aug 16 2013, 03:59
|- - 2Bdecided   QUOTE (marc2003 @ Aug 16 2013, 03:59) QUO...   Aug 16 2013, 10:36
- - 2Bdecided   OK, well I might get chance to add+fix some bits t...   Aug 15 2013, 22:29
- - 2Bdecided   While I'm collecting resources... Some explan...   Aug 16 2013, 14:40
- - 2Bdecided   There are two things that I think would make it mu...   Aug 16 2013, 22:08
|- - Rescator   QUOTE (2Bdecided @ Aug 16 2013, 23:08) Ha...   Aug 17 2013, 15:12
- - 2Bdecided   Any progress? Should I pick it up where I left it,...   Aug 27 2013, 17:23
|- - Rescator   QUOTE (2Bdecided @ Aug 27 2013, 18:23) An...   Aug 28 2013, 18:31
- - 2Bdecided   Thanks Rescator. I like the sections, and agree wi...   Aug 29 2013, 11:45
- - 2Bdecided   Nothing new to add, but found relevant comments at...   Sep 4 2013, 10:58
|- - marc2003   QUOTE (2Bdecided @ Sep 4 2013, 10:58) Los...   Sep 4 2013, 18:40
|- - JJZolx   QUOTE (marc2003 @ Sep 4 2013, 10:40) if y...   Sep 4 2013, 20:48
|- - 2Bdecided   QUOTE (marc2003 @ Sep 4 2013, 18:40) i...   Sep 5 2013, 10:04
- - marc2003   just read the bit i quoted. it's useful to som...   Sep 4 2013, 21:19
- - Sapagrino   Hello. I have been following this thread and recen...   Sep 27 2013, 13:31
- - 2Bdecided   Yes please! Haven't made any progress on ...   Sep 27 2013, 17:32
- - Sapagrino   Great. I can't seem to figure out how to uplo...   Sep 27 2013, 23:17
- - 2Bdecided   Start a thread in the dedicated uploads forum.   Sep 30 2013, 09:52
- - Rescator   Made a tiny tweak, the tables columns are now sort...   Oct 11 2013, 23:31


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