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APEv2 tags in MP3, aimed: generally, at implementation, in rel.w/ foobar2000, vs. ID3v2.4
Tigermess
post Dec 29 2011, 19:30
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Recent topics on ID3v2.4 and APEv2 implementation in foobar2000 (like this and that and others) raise the chase between ID3v2.4 and APEv2 tags. I'd like to start this topic as a branch of first mentioned topic, concerning APEv2 tags in MP3 files.

I want to choose optimal type of tags for MP3s with which I'll stick for few following years. ID3v2.3, ID3v2.4 and APEv2 are in the game. For long I've been tagging ID3v1+ID3v2.3, recently I started to like idea of multifields but after the discussions above I'm not sure what tag type is the best (selfishly enough for my needs). I'd appreciate multifields but I still want to keep best possible compatibility with most used SW/HW. In this matter after some googling and searching I have some questions about APEv2 and will be glad if you could help, especially if you were dealing with similar questions yourselves.

Q1: Are APE tag names standardized anyhow??
HA wiki says:
QUOTE
Just like Vorbis comment it defines some standard fields, but it also defines some formats for those fields (like what a date should look like).
I couldn't find it. Does any informal standard or recommendation exist? If not, default settings of most used players are standards enough - do iTunes, Winamp, foobar2000, Media Monkey or any hardware players have something in common? Basic field names - ARTIST, ALBUM, TITLE are obvious but others may be tricky. Shall I use spaces between words, no spaces or underscores? (e.g. ALBUM ARTIST is preffered by foobar2000 and Winamp, ALBUMARTIST is pref. by Mp3tag, nevertheless some people use ALBUM_ARTIST. ENCODED BY, ARTIST SORT NAME are other examples). Is more proper YEAR or DATE? DISC or DISCNUMBER? In this regard I see a benefit of imperfect yet precise ID3v2 recommendations specifying which field shall contain which kind of information.

Q2: Is APEv2 designed to contain pictures??
The implementation of pictures in APEv2 tag is very poor. foobar2000 doesn't support it yet (Peter said cautiously it will be done at some point, in Winamp it's in TO-DO state as well (I haven't tried latest version, correct me if I'm wrong), only Mp3tag can save pictures in APE tag. I stumbled upon these statements in APE tag FAQ, probably by Frank Klemm himself:
QUOTE
(ii) What's the point in storing binary data in a tag? I don't think storing images in files is a good idea (and Klemm seems to agree that 'long' tags is not a good idea).

(x) I store images and other goodies in the tags. There's no reason to be afraid of 30kb of extra data with a modern computer...
  • images should never be added to an audio file.
  • if the data is important for the audio-visual representation, an additional container format should be used to store data and relations between the data. A well designed example is the MPEG-4 system stream. Tags should be tags and not the worst possible concept of a container format.

and quote from APE tag format description:
QUOTE
It is strongly recommended that the data size be stored in the tags. The size should normally be in the roughly one kilobyte, never more than 8 kilobytes.

From these statements it looks like images and binary data in general are not welcome in APE format and it isn't designed for it. ID3v2 is having direct support for images and it is supported by many software and hardware players. Is there any problem with pictures in APE tags?

Q3: Is APEv2 suitable to be embedded into MP3?
I'm not sure how's APE in MP3 technically achieved. Are APE tags in MP3 saved on the same level as ID3 tags, or do they use some wrapper or ID3 tag as container? I assume MP3 doesn't define ID3 as the only and proper tag scheme, but it probably has requirements on embedding non-audio (in this case metadata) frames. Does APE meet those requirements?
From the description of APE tag at wikiaudio.org:
QUOTE
The foobar2000 player can also tag MP3 files with APEv2 tags instead of ID3 tags, because they are considerably easier to write and more flexible.However, because ID3 was designed with the MP3 format in mind and APEv2 was not, there are some complications. For example, the string APETAGEX signals the start of an APEv2 tag, but the string TAG signals the start of an ID3v1 tag. If the TAG in APETAGEX ends up where an ID3v1 tag is expected, it may be read incorrectly. ID3 also has an “unsynchronization scheme” to ensure players do not try to play the tag data as audio; APEv2 has no such scheme, and APEv2 tags may result in errors or static at the end of files.

I use MP3val as a favourite tool to validate and repair all types of common errors in MP3 files. One of the most frequently reported error is "Garbage in the end of file". I checked test files tagged with few basic APE tags and they passed, however the statement above reveals that in rare cases APE tag will look like garbage in the end of file and will be ignored or removed by tools such as MP3val. Is it safe to use APE tags in MP3s? Any experience with misinterpreted APE tags or knowing current state of quote above are welcome.

The topic is as long as it can be. Thanks to those who were able to read it until here. In the times when I didn't know much about it, I was cutting MP3 off all tags and reimported them just to make sure that nothing else than ID3 frames I choose will not be there. Now I understand the benefits of APE tags, only the answers on the questions above aren't clear to me. Supposed answers: 1. No, 2. Yes, 3. Yes are in contradiction with excerpts I pasted.
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rodrigomartinho
post Dec 29 2011, 20:26
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Hi again Tigermess. As I stated in the other topic, I had already made up my mind towards apev2 tags, but I didn't consider all these questions you have put.

First, some links. You probably have seen them though:

APEv2 specification
APE Tags Header
APE Tag Item
APE key
APE Item Value
Ape Tags Flags

Comments:

Q1: The 4th link has some defined keys. But you can assign any name you want. With the mp3tag mapping functionality, I wouldn't bother with this. If in any time in the future you want to change your standardization, you can just change the mapping an re-save the tags. This can be done in batches, so wouldn't take much time nor much work. Since some time ago I started backing up my tags in text files. With such a file, it is also possible to change the import mask and reimport the tags.

Q2: As you can see in the 6th link, the tag flags has a string for defining if it contains text or binary data. So the answer is yes. If it is poorly designed and may lead to problems I can't say. I started yesterday to change my id3 tags to apev2, and untill now everything worked fine. But I only tested 6 album untill now, and only saving tags in mp3tag and playing in foobar. The first album I tested is encoded in 96 kbps, with average 2,3 MB per track. I put 433 KB of binary data (covers) in each file and played with no problems in foobar. All files I tested have the ape tags in the end of the file.

But, since some time ago (before all this discussion), I was saving both id3v2.4 and apev2 in my files. Since ape has the precedence in foobar, I may assume I have had a long period of tests with ape tags, with a collection of thousands of files. It always worked as expected, so I didn't even notice the precedence of ape tags untill that was pointed out to me in mp3tag forum. But, again, all playback was done only in foobar.

Q3: I didn't understand the question well. But, as you stated, the tag starts with APETAGEX and ends with TAG. I confirmed that in a hex editor. It can induce problems with id3v1, but I don't use it since long time ago and don't plan to use again.

As I keep playing my apev2 tagged files, I come back with the results. I didn't plan to make tests in other players apart foobar, but maybe it would be good for this discussion.

Regards,

Rodrigo Martinho.
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Tigermess
post Dec 29 2011, 23:42
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I've seen about 5 links from your post but not APE key!! Thanks! That's great for the start, from now I can be aware how close are my tags to the recommended tags - and then reasonably guess compatibility with software supporting APE in MP3. If we can define tags as we want, why we don't name them in Czech and Brazil Portuguese? smile.gif I suppose everyone wants to be at least basically compatible, and when I do that, I want to do that properly. Unfortunately there aren't keys for Album Artist or Encoder but at least I see some logic... spaces in label names are okay.

(side note to your previous Topic, Rodrigo: even APE doesn't expect multiple strings in Title, what a mess :-)))

Q2: ok binary flag is fine. Just don't understand the statements @ FAQ & format description. First I was thinking that it was about APEv1 and not v2 but then I found that it was from the time when v2 was out. Fear of long tags might be related to problems with streaming and lenght of gap between tracks. It can happen that APE is not designed for large/binary tags even if it allows them and ID3v2 handles them better. One of the formats may have lesser gaps between the tracks and less problems with streaming. Yet thanks for results of your test run.

Q3: ID3v1 is compatibility saviour. I play my music on parties, use it in car stereo, my mobile phone or MP3 player borrowed from my sister and I am planning to purchase multimedia centre to a living room.. probably none of these devices knows APE. I will need both APEv2 and ID3v1 to cooperate. First part of question was technical, I'm not educated in this matter, I was just curious if APE tags reside in MP3 "legally" and basically the same as ID3 (just different type of tags/metadata), or, because they were originally designed for APE files, are in MP3 by some kind of hack which perfectly works but uses grey points in specification, goes beyond recommended values etc. I am interested because of stability - e.g. may a player, which is very old and reads only ID3v1 tags but MP3 handling has properly implemented (no bugs), have problems with skipping APE tag, or can't it wrongly consider as a part of audio stream?

Nice list wink.gif
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Tigermess
post Dec 30 2011, 00:50
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I've found something to Q2. Florian, Mp3tag dev himself mentioned never more than 8KB rule as a obstacle for implementing embedding images into APEv2. And also that Mp3tag discards all binary data. 1.3 years later the embedding was done, without explaning how come that for years the rule was held and now it was breached. A demand for embedded pictures had certainly its role; if the rule itself was proven wrong, surpassed by technological improvement or simply ignored is hard to tell.

More, there's mention about two ways of embedding - "Godfather", which is against rules, and "JRMC", the proper one. I suppose Mp3tag uses the right one.
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benski
post Dec 30 2011, 02:49
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I'd be happy to finish the implementation of album art APEv2 in Winamp if someone can provide reliable test files.
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rodrigomartinho
post Dec 30 2011, 06:32
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QUOTE (Tigermess @ Dec 29 2011, 20:42) *
I've seen about 5 links from your post but not APE key!! Thanks! That's great for the start, from now I can be aware how close are my tags to the recommended tags - and then reasonably guess compatibility with software supporting APE in MP3. If we can define tags as we want, why we don't name them in Czech and Brazil Portuguese? smile.gif I suppose everyone wants to be at least basically compatible, and when I do that, I want to do that properly. Unfortunately there aren't keys for Album Artist or Encoder but at least I see some logic... spaces in label names are okay.

I already have my way of naming tags, but if we go further in this and want to make a new one, that maybe can serve for others, I'm in. At present I don't use spaces, but underlines in my custom tags (album_artist, date_of_reference, recording_info and VBR_mode).

QUOTE (Tigermess @ Dec 29 2011, 20:42) *
(side note to your previous Topic, Rodrigo: even APE doesn't expect multiple strings in Title, what a mess :-)))

What do you mean? It is working for me in foobar. As far as I am concerned, every frame may have multiple values. It only doesn't support multiple keys, so multiple values must be in the same key, separated by a special character I don't remeber now (maybe NULL).

QUOTE (Tigermess @ Dec 29 2011, 20:42) *
Q2: ok binary flag is fine. Just don't understand the statements @ FAQ & format description. First I was thinking that it was about APEv1 and not v2 but then I found that it was from the time when v2 was out. Fear of long tags might be related to problems with streaming and lenght of gap between tracks. It can happen that APE is not designed for large/binary tags even if it allows them and ID3v2 handles them better. One of the formats may have lesser gaps between the tracks and less problems with streaming. Yet thanks for results of your test run.

Those files I mentioned, with about 20% of binary data (433 KB of cover arts) are playing gapless in foobar.

QUOTE (Tigermess @ Dec 29 2011, 20:42) *
Q3: ID3v1 is compatibility saviour. I play my music on parties, use it in car stereo, my mobile phone or MP3 player borrowed from my sister and I am planning to purchase multimedia centre to a living room.. probably none of these devices knows APE. I will need both APEv2 and ID3v1 to cooperate. First part of question was technical, I'm not educated in this matter, I was just curious if APE tags reside in MP3 "legally" and basically the same as ID3 (just different type of tags/metadata), or, because they were originally designed for APE files, are in MP3 by some kind of hack which perfectly works but uses grey points in specification, goes beyond recommended values etc. I am interested because of stability - e.g. may a player, which is very old and reads only ID3v1 tags but MP3 handling has properly implemented (no bugs), have problems with skipping APE tag, or can't it wrongly consider as a part of audio stream?

I may go with you in this and start saving id3v1 too. Since id3v1 should be in start and apev2 in end of file, shouldn't be a problem. Tests needed though.

About what Florian said, this was long time ago. It doesn't seem to me we should rely on that. It's been already 4 years now that he implemented binary data on ape.

This post has been edited by rodrigomartinho: Dec 30 2011, 06:40
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rodrigomartinho
post Dec 30 2011, 06:39
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QUOTE (benski @ Dec 29 2011, 23:49) *
I'd be happy to finish the implementation of album art APEv2 in Winamp if someone can provide reliable test files.

What do you mean by "reliable test files"?
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Tigermess
post Dec 30 2011, 13:09
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QUOTE (benski @ Dec 30 2011, 02:49) *
I'd be happy to finish the implementation of album art APEv2 in Winamp if someone can provide reliable test files.

Great news. What about these samples? I admit there are not many mp3s... Alex B could create them.

QUOTE (rodrigomartinho @ Dec 30 2011, 06:32) *
I already have my way of naming tags, but if we go further in this and want to make a new one, that maybe can serve for others, I'm in. At present I don't use spaces, but underlines in my custom tags (album_artist, date_of_reference, recording_info and VBR_mode).

Non-binding standards would be nice. We all solve similar problems as software developers do too. Maybe I'll try to push that later. With all respect to your naming scheme - from what I've seen now on very limited range of software (fb2k, Mp3tag, Winamp), two prefer spaces between words, one puts the words together - if you still can change it, I'd rather stick with one of those schemes. If you have any reasons to keep it - habits, friends - no problem :-)


QUOTE (rodrigomartinho @ Dec 30 2011, 06:32) *
QUOTE (Tigermess @ Dec 29 2011, 20:42) *
(side note to your previous Topic, Rodrigo: even APE doesn't expect multiple strings in Title, what a mess :-)))

What do you mean? It is working for me in foobar.

It's not a big deal. In the table, column "Recommended format of value" - Artist, composer, comment and others have one of the recommended values "List of UTF-8 strings" i.e. multiple strings. Title has only single string recommended. It was not against you, I was just surprised that multiple titles are missing in recommendation. It's the same behaviour which foobar2000 has now with ID3v2.4 - no multivalues allowed in a title.
Btw how do you plan to tag single-file rips of albums? Will you write all song names to the title? And all track numbers as multivalue too?

QUOTE (rodrigomartinho @ Dec 30 2011, 06:32) *
I may go with you in this and start saving id3v1 too. Since id3v1 should be in start and apev2 in end of file, shouldn't be a problem. Tests needed though.

In fact you won't even notice it, APE tag will always have priority and ID3v1 is saved in the background. The tags are imperfect but at least will be some... it will serve you well. Just beware, ID3v1 is in the end of file too, its written right after APEv2 tag - that's the reason for warning about possible confusion between TAG as a starting string for ID3v1 tag and APETAGEX as delimiter for APEv2. I hope if there were real problems, we already knew that, however ID3v2 is definitely safer - as ID3v2 is the one positioned in the beginning of the file.
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Gumboot
post Dec 30 2011, 14:05
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QUOTE (Tigermess @ Dec 29 2011, 23:50) *
1.3 years later the embedding was done, without explaning how come that for years the rule was held and now it was breached. A demand for embedded pictures had certainly its role; if the rule itself was proven wrong, surpassed by technological improvement or simply ignored is hard to tell.


If you want to define a format where the maximum length of a field needs only 11 bits to encode, then you do not allocate 32 bits to that field. Simple as that.

Looking over the format it appears that APEv2 is generally safe from false sync markers (which would break MP3 compatibility) provided you do not have any field or tag length greater than about 56kB and you do not embed any binary data (like cover art). APEv3 would need to reserve a couple of bits in the flags field (and keep them zero) to keep that level of safety.

There are greater lengths that are safe to encode, and there is binary data which is safe to encode, but beyond the constraints above things could get hairy.

This post has been edited by Gumboot: Dec 30 2011, 14:06
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rodrigomartinho
post Dec 30 2011, 15:03
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QUOTE (Tigermess @ Dec 30 2011, 10:09) *
QUOTE (benski @ Dec 30 2011, 02:49) *
I'd be happy to finish the implementation of album art APEv2 in Winamp if someone can provide reliable test files.

Great news. What about these samples? I admit there are not many mp3s... Alex B could create them.

The question is only about copyright-free mp3 files? If it is so, it's easy to find some, isn't it?

QUOTE (Tigermess @ Dec 30 2011, 10:09) *
QUOTE (rodrigomartinho @ Dec 30 2011, 06:32) *
I already have my way of naming tags, but if we go further in this and want to make a new one, that maybe can serve for others, I'm in. At present I don't use spaces, but underlines in my custom tags (album_artist, date_of_reference, recording_info and VBR_mode).

Non-binding standards would be nice. We all solve similar problems as software developers do too. Maybe I'll try to push that later. With all respect to your naming scheme - from what I've seen now on very limited range of software (fb2k, Mp3tag, Winamp), two prefer spaces between words, one puts the words together - if you still can change it, I'd rather stick with one of those schemes. If you have any reasons to keep it - habits, friends - no problem :-)

I put underlines exactly because foobar uses space and mp3tag uses words together. I needed an "album_artist" tag that was different from "albumartist" (mp3tag) and "album artist" (foobar), since these for me mean "band". So I used underlines for other tags too. But I can change them, except for "album_artist".

QUOTE (Tigermess @ Dec 30 2011, 10:09) *
QUOTE (rodrigomartinho @ Dec 30 2011, 06:32) *
QUOTE (Tigermess @ Dec 29 2011, 20:42) *
(side note to your previous Topic, Rodrigo: even APE doesn't expect multiple strings in Title, what a mess :-)))

What do you mean? It is working for me in foobar.

It's not a big deal. In the table, column "Recommended format of value" - Artist, composer, comment and others have one of the recommended values "List of UTF-8 strings" i.e. multiple strings. Title has only single string recommended. It was not against you, I was just surprised that multiple titles are missing in recommendation. It's the same behaviour which foobar2000 has now with ID3v2.4 - no multivalues allowed in a title.
Btw how do you plan to tag single-file rips of albums? Will you write all song names to the title? And all track numbers as multivalue too?

Oh, I didn't notice that. But, different from id3, these are just recomendations, not limitations, and any frame should work with multiple values. As you know, multiple values in titles was the main reason I got into this discussion!
About single-file rips, I don't use them, so I got little experience on it. As far as I know they need a cuesheet to get properly tagged. When I get such files, I usually tear the files apart.

QUOTE (Tigermess @ Dec 30 2011, 10:09) *
QUOTE (rodrigomartinho @ Dec 30 2011, 06:32) *
I may go with you in this and start saving id3v1 too. Since id3v1 should be in start and apev2 in end of file, shouldn't be a problem. Tests needed though.

In fact you won't even notice it, APE tag will always have priority and ID3v1 is saved in the background. The tags are imperfect but at least will be some... it will serve you well. Just beware, ID3v1 is in the end of file too, its written right after APEv2 tag - that's the reason for warning about possible confusion between TAG as a starting string for ID3v1 tag and APETAGEX as delimiter for APEv2. I hope if there were real problems, we already knew that, however ID3v2 is definitely safer - as ID3v2 is the one positioned in the beginning of the file.

It just came to me now that after I properly mapped the discnumber tag in apev2 to just "disc", my previous setup of saving both apev2 and id3v2.4 should work between foobar and mp3tag. I'll test it again. And maybe it will work with other combinations, such as apev2 + id3v2.4 + id3v1, or apev2 + id3v2.3 + id3v1. I'll test that too and, if works indeed, it would be possible to have a scheme where complete tags work in foobar (apev2) and incomplete but largely supported tags would work in software that doesn't handle apev2. This would be the best of both worlds and seems this is our goal.
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rodrigomartinho
post Dec 30 2011, 17:27
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QUOTE (rodrigomartinho @ Dec 30 2011, 12:03) *
It just came to me now that after I properly mapped the discnumber tag in apev2 to just "disc", my previous setup of saving both apev2 and id3v2.4 should work between foobar and mp3tag. I'll test it again. And maybe it will work with other combinations, such as apev2 + id3v2.4 + id3v1, or apev2 + id3v2.3 + id3v1. I'll test that too and, if works indeed, it would be possible to have a scheme where complete tags work in foobar (apev2) and incomplete but largely supported tags would work in software that doesn't handle apev2. This would be the best of both worlds and seems this is our goal.


I made some further tests that clarified some more things.

1. About saving more than 1 tag in a file
I saved apev2 + id3v2.4 + id3v1 in some files. As you stated, id3v2.4 was at the beginning, apev2 at the end and 1d3v1 after apev2. But apev2 didn't end as expected with a "TAG", but with a "APETAGEX". Example of end of a file from HexEditor:
CODE
APETAGEXÐ...Å.......... ................COMPOSER.Pixinguinhap.......MUSICIANCREDITS.Pixinguinha:.Donga:.(...)PUBLISHER.Sinter SLP-1038........BAND.A Velha Guarda........DISC.1/1APETAGEXÐ...Å..........€........TAGQue Perigo....................A Velha Guarda................A Velha Guarda................1955..............................ÿ


2. I tested these files with varied combinations of tags with the other audio software I have:

- Windows Media Player: doesn't read id3v2.4 nor apev2. Reads id3v2.3 and id3v1, even with apev2 present.
- iTunes: doesn't read apev2. Reads id3v2.4, even with apev2 present.
- VLC: Seemed to partially read apev2.

3. I seems that now I am finally aware of the problems about saving tags on files that have more than one tag type both in mp3tag and foobar. Apev2 and vorbis comments doesn't have any pre-definition for frame names. So, whatever you choose, both in mp3tag and foobar, is written in the file. But id3 is different. It has pre-defined frame names (TIT2, TPE1, etc), but none software uses them. Instead, they use a mapping between these frame names and more intelligible names, but these intelligible names aren't the same between mp3tag and foobar. So, TPE4, for instance, is MIXARTIST in mp3tag and REMIXED BY in foobar. This isn't a problem when you have only id3 tags. You save MIXARTIST in mp3tag, it writes TPE4 in file, foobar reads TPE4 in file and shows you REMIXED BY. If you change this tag, foobar will save in TPE4, so everything works between them, even if they show a different name.

This doesn't happen if you have id3 and ape tags in the same file. In the same example as above, when you save MIXARTIST in mp3tag, it will save TPE4 in id3 and MIXARTIST in ape. When foobar reads this file, it reads both tags and shows all frames, despite which tag type it is from, in the properties window. So it will show REMIXED BY (the TPE4 frame read from id3) and MIXARTIST (read from ape and shown unchanged). If you save this tags in foobar, it will create the TXXX MIXARTIST in id3 (since this isn't the name it expects for TPE4) and the REMIXED BY in ape. It was this kind of duplication (principally noted in DISCNUMBER) that was bothering me. Now that I finally understood it, I can see that, apart the unnecessary replication of frames, there isn't much to worry about this. And, since mp3tag has a mapping function, but foobar doesn't, it is possible to have full compatibility between frame names if one uses exclusively the foobar names, mapping them in mp3tag. This will be my next test.

Just a final comment. It would be great if mp3tag and foobar let you edit the internal mapping they do between id3 frame names and "intelligible names". If this was possible, one could choose his preferable standardization of tag names and edit it in this table. Then, apev2 and vorbis comments, which doesn't have pre-defined frame names, would also use this standard the user had chosen. All the problems described here would be gone. Mp3tag has already tried something is this path, with its mapping function, but it would be much easier if, instead of mapping the "internal intelligible names" to "chosen names for each file type", we could change the mapping between "internal intelligible names" and "id3 names".

This post has been edited by rodrigomartinho: Dec 30 2011, 17:39
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db1989
post Dec 30 2011, 17:32
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I am fairly sure that APEv2 and ID3v2 are mutually exclusive, i.e. disruptive of each other. Hence foobar2000 and other applications offering them on their own or with ID3v1, but not in combination. This may explain some of your observations.
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rodrigomartinho
post Dec 30 2011, 22:18
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QUOTE (db1989 @ Dec 30 2011, 14:32) *
I am fairly sure that APEv2 and ID3v2 are mutually exclusive, i.e. disruptive of each other. Hence foobar2000 and other applications offering them on their own or with ID3v1, but not in combination. This may explain some of your observations.

In mp3tag you can save id3v1, id3v2 and apev2 all in the same file. Once you have done it, foobar will edit them, but with the problem stated in my previous post.
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db1989
post Jan 1 2012, 23:10
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I didn’t say that they can’t be added; I said that perhaps they shouldn’t! And, if such is the case, that may explain your findings.

This is based upon the fact that foobar2000 doesn’t allow the user to write both types of tag to one file, and my presumption that there’s a good reason for this choice.
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rodrigomartinho
post Jan 2 2012, 13:35
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QUOTE (db1989 @ Jan 1 2012, 20:10) *
I didn’t say that they can’t be added; I said that perhaps they shouldn’t! And, if such is the case, that may explain your findings.

This is based upon the fact that foobar2000 doesn’t allow the user to write both types of tag to one file, and my presumption that there’s a good reason for this choice.


Yes, foobar really doesn't allow to write both id3v2 and apev2 in the same file. But it allows to write id3v1 and apev2. And, if there already are id3v2 and apev2 in any file, it can edit both.
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rodrigomartinho
post Jan 2 2012, 13:43
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QUOTE (rodrigomartinho @ Dec 30 2011, 14:27) *
This doesn't happen if you have id3 and ape tags in the same file. In the same example as above, when you save MIXARTIST in mp3tag, it will save TPE4 in id3 and MIXARTIST in ape. When foobar reads this file, it reads both tags and shows all frames, despite which tag type it is from, in the properties window. So it will show REMIXED BY (the TPE4 frame read from id3) and MIXARTIST (read from ape and shown unchanged). If you save this tags in foobar, it will create the TXXX MIXARTIST in id3 (since this isn't the name it expects for TPE4) and the REMIXED BY in ape. It was this kind of duplication (principally noted in DISCNUMBER) that was bothering me. Now that I finally understood it, I can see that, apart the unnecessary replication of frames, there isn't much to worry about this. And, since mp3tag has a mapping function, but foobar doesn't, it is possible to have full compatibility between frame names if one uses exclusively the foobar names, mapping them in mp3tag. This will be my next test.


I tested it and, as expected, when properly mapped in mp3tag, it works consistently. The only exception is MUSICIANCREDITS, since foobar doesn't read this id3 frame (TMCL). Obviously this would occur with any unsupported frame. So, as far as one uses any frame that isn't supported by foobar, it is impossible to have full compatibility editing tags both in mp3tag and foobar and the unsupported frame will be duplicated.
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benski
post Jan 3 2012, 01:54
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Winamp assumes that an APEv2 tag might come between an ID3v2.4 "appended" tag and an ID3v1 tag. The reason for this is because MP3Gain will create files such as these if there is a pre-existing appended ID3v2.4 tag.
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Tigermess
post Jan 4 2012, 00:25
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Gumboot, thanks. I liked your argument about 11 and 32 bits :-) And Rodrigo for gapless playback test as well. I suppose there's no need to doubt about quality of APE tags anymore. Nobody addressed Q3 but it!s more my laziness than anything else standing behind it - I'll have a look at MP3 specs myself.

Rodrigo, if you find time, post your further observations, I'll gladly read it. Looks like we were dealing with similar issues. I began to compare tag "standards" and their implementation in popular software; for this purpose I did a table. The table can be downloaded here. I still need to add at least Vorbis standards and Winamp default mappings (the more the better), then I can decide how to label fields for most compatibility across various tag types and SW. Feel free to enhance it (I didn't have time to upload it to googledocs though, just offline version for now).

I will be busy in following 3 weeks so sorry if I won't make early replies; but don't hesitate to discuss anything that comes on your mind about APE tags; after that I'll finally choose my tagging scheme.
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rodrigomartinho
post Jan 4 2012, 01:31
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QUOTE (Tigermess @ Jan 3 2012, 21:25) *
I began to compare tag "standards" and their implementation in popular software; for this purpose I did a table.

Hehehe, I had done a similar one long time ago and started to work on it again recently. Take a look. I didn't get the time to compare it with yours though, nor translate it fully. I'll do that later.
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Tigermess
post Jan 4 2012, 02:34
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I speak a little bit portuguese, no need to translate :-) Your table is very comprehensive!! And very good in its ID3v2 part. Mine tries to focus on comparison. Well, nice share... it's complete list of fields which fb2k and mp3tag recoginze, I will have a use for that.
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rodrigomartinho
post Jan 4 2012, 02:40
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QUOTE (Tigermess @ Jan 3 2012, 23:34) *
I speak a little bit portuguese, no need to translate :-) Your table is very comprehensive!! And very good in its ID3v2 part. Mine tries to focus on comparison. Well, nice share... it's complete list of fields which fb2k and mp3tag recoginze, I will have a use for that.

Its a complete list of both id2v2.3 and id3v2.4 frames. And it points which ones I use, and which user defined I created. Seems all this discussion should end with such a table with a list of tags and names we have agreed it's the best practice.

This post has been edited by rodrigomartinho: Jan 4 2012, 02:41
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Tigermess
post Feb 13 2012, 10:49
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Today I noticed that Soulsearchingsun updated Foobar2000:ID3 Tag Mapping, thanks for the good job :-)

In last two weeks I updated table with Winamp, few rare MusicBrainz recommendations, added more fields and made my pick fields I am going to use (it's about thirty blink.gif). ATM I have about 300 various files to tag (cd rips, netlabels music, sets, live and radio shows...), I want to test it and then I will put it out.

Rodrigo, I found out there's no problem editing ALBUM ARTIST both in Foobar and Mp3tag when I made proper mapping in Mp3tag - even without underscore between the words smile.gif I suppose you already know.. you gave me the notice about possibility of field remapping in Mp3tag and its perfectly achieveable just with that.
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rodrigomartinho
post Feb 25 2012, 16:13
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As far as I have tested it, the mapping in mp3tag works fine. I just use album_artist because I am using albumartist (in mp3tag) and album artist (in foobar) for their previous usage: band. For that, there is an option in foobar that makes it map tpe2 to band, as it was in previous releases.

When you finish your table, send it. I will take a look and see what could be of value for me. Maybe we could end with the same standard. You are using tpe2 for album artist, not band, right?

This post has been edited by db1989: Feb 25 2012, 20:36
Reason for edit: removing unnecessary full quote of above post
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rodrigomartinho
post Mar 5 2012, 02:07
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QUOTE (Tigermess @ Feb 13 2012, 07:49) *
Today I noticed that Soulsearchingsun updated Foobar2000:ID3 Tag Mapping, thanks for the good job :-)

In last two weeks I updated table with Winamp, few rare MusicBrainz recommendations, added more fields and made my pick fields I am going to use (it's about thirty blink.gif). ATM I have about 300 various files to tag (cd rips, netlabels music, sets, live and radio shows...), I want to test it and then I will put it out.

Rodrigo, I found out there's no problem editing ALBUM ARTIST both in Foobar and Mp3tag when I made proper mapping in Mp3tag - even without underscore between the words smile.gif I suppose you already know.. you gave me the notice about possibility of field remapping in Mp3tag and its perfectly achieveable just with that.


I made a little edition to my table. All frames you use are in my standard, except for those in red: TXXX{MEDIA}, TXXX{FILE} and TXXX{ORIGFILENAME}. What do you want to use them for?

My list is very big, but in fact I usually use only a few of them. I put all those for the cases when I get some files where the tagger puts other tags which I usually wouldn't use, but may be good to keep. So, when I export the tags for a text file (for backup), I export all the frames on the list on the 2nd tab of my file.

I didn't make any changes, and I use mostly id3v2.4 frames, except for: ALBUM_ARTIST (I use TPE2 for band), RECORDING_INFO (for information about the recording sessions), DATE_OF_REFERENCE (the date I choose for using in renaming operations, usually the same as YEAR or RELEASETIME), VBR_MODE (for renaming operations automation) and the replaygain frames.

It seems to me the only diference between my standard and yours is the TPE2. You use it for album artist, right? I will keep it as band. It was the way it was designed, and it is very useful for classical music.

I thought about puting some frames from MusicBrainz in my scheme, but I didn't do it. It is a very good tool, but most of the albums I tag aren't there. If you are studing it, I may take a look on it later.

I'm finishing this work for the moment, sticking with this scheme and saving id3v1, id2v2.4 and ape tags. Here is my updated table.

Now I will start the tagging of my files, all over again...
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Tigermess
post Apr 8 2012, 14:00
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How did it go? I got stuck in the beginning, I couldn't get to tag a file for approx. 7 weeks wacko.gif

Oh I know why you can't use ALBUM ARTIST... it's okay then! I rarely tag classical music nonetheless it's important to me too and maybe I'll have to deal with the same issue - using TPE2 at its original purpose. I'll get back into a game and find out. Today as I got to it I'm busy with various types of compilations and how to properly distinguish between them. So far I've identified 5 different types of compilations which deserve individual approach. I will upload the table ASAP - I am noting that among my to-do tasks right now.
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