4.4.2 Tags and the iPod
Tag information is essential to the operation of the iPod. To take full advantage of your iPod, you must understand how tag information is used.
The most common misunderstanding about the iPod is how audio files are stored and organized on board. Many people assume that the iPod works like a normal hard disk where you can create arbitrary folders and store your audio files in whatever folder you like. This is incorrect. Apple did not design the iPod this way.
Virtual Folders and "A Database of Music"
The best way to think of your iPod is as a database of music. When you transfer audio files to the iPod, they are all stored in a single storage area. The filenames they had when on your computer are discarded, and they are stored using internal id numbers. You access your audio files on-board the iPod and through Anapod using virtual folders, or views, that the iPod constructs using tag information. The Audio Tracks, Artists, Albums, and Genres folders are therefore all dynamically constructed from the tag data associated with your audio files.
Given this design, it is not possible to "create" new folders per se. For example, people often ask how to create a new album. Well, you cannot create a new album and move files into it. Instead, what you would do is select some of your existing files and change the album field in their tags. This would have the effect of "creating" a new album.
The Tag Database
Another iPod design characteristic important to note is that it does not read tag information directly from within the audio files stored on your iPod. Tag information is often stored at the end of multi-megabyte music files, making reading tags a slow process. When dealing with several thousand audio files on a iPod, reading through every file to build the tag database is simply not practical. Instead, the iPod maintains a separate database of tag information alongside the audio file storage. Each entry in the database is a complete set of tag data and is associated with one of the files stored on the iPod. The iPod uses this database so it doesn't have to continually read through all of the audio files.
This database is only updated when you transfer a new file to the iPod, explicitly edit a tag on-board the iPod, or delete a file. During a transfer, the transfer software is responsible for reading the tag information out of the source audio file on the computer, and handing that data to the iPod along with the file. The iPod then puts that tag information into its database and associates that entry with the newly transferred file.
This scheme has several advantages. First, as mentioned above, it saves the iPod from having to repeatedly parse through all the thousands of files on-board to gather all the tag information. Second, it shifts the burden of parsing all the different tag formats from the iPod to the software running on the computer. This is important because software running on the computer has signficantly more processing power and resources than what is available on the iPod to read new and more complicated tag formats of the future. This way, the iPod firmware need not be updated when new tag formats arise.
Given this tag database design, Anapod is responsible for reading tag information and passing it to the iPod. The next section discusses Anapod's specific tag reading capabilities.
Organizing Tags on Your Computer
This overall design is surprising to some people at first. The most significant implication is that you should have the tags in all your audio files properly filled out before transferring them to your iPod, otherwise they will look a mess once on there. Although this requires some investment of time up-front, most people find that in the long run it makes managing a large collection of music much, much easier.
4.4.3 Anapod Tag Reading and Generation
When transferring a file to a iPod, Anapod must read the tag information from the source audio file on the computer and pass it along with the file data to the iPod. This section describes how Anapod does that.
ID3 Tags
ID3 is the tag format for MP3 files. Anapod is capable of reading both ID3 V1 and ID3 V2 tag formats. For each file, Anapod will first attempt to read the V2 tag. If it does not exist, Anapod will read the V1 tag.
Filling-In Missing Tag Information
To successfully transfer a file to the iPod, Anapod must provide at least the Artist, Album and Title, because these are the fields the iPod uses to uniquely identify an audio track. If Anapod cannot either read all three of them from the tag or guess them from the filename, they must be filled in manually by you or filled in with boilerplate information.
Normally, if Anapod cannot fill the three fields for a file during transfer, it will pop-up a dialog box asking for you to manually fill in the information. Anapod Explorer has several options to alter this default behavior. They can be found on the "iPod" tab in the Configuration dialog.
First, Anapod can be configured to skip files whose tag information cannot be automatically determined. Check the "Auto-skip files with incomplete ID3 tags" option to enable this. You can examine the transfer log afterwards to find which files did not transfer due to incomplete tags and fix them later. Second, Anapod can fill the missing fields with boilerplate text. Check the "Auto-complete ID3 tags with missing fields" option to enable this and provide the text you want Anapod to fill with in the box below it.
