One way to approach the problem of managing personal digital audio and premium content is to provide an alternative technical solution and let the market come up with the implementations.

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by Rick Winterton, senior software engineer, Intel Corp.

Music sales and ownership of personal multi-media content is at an all time high. Worldwide sales of music CDs last year exceeded 11 million U.S. dollars. That dollar amount does not include the sales of individual track downloads over the Internet. For the first time in December 2004, the purchase of online music exceeded the sales of physical media purchases. The sale of audio content in 2005 is estimated to be a 20 million dollar business. The volume of content alone makes content management a daunting task. Now add in the complexity of the number of different types of rendering devices and different audio formats and the task becomes even more complex. The format of the downloaded audio content ranges from MP3, WAV, WMA, MP3Pro, AAC and AAC-2. Devices such as desktop computers, laptops, personal digital assistants (PDAs), mini audio players, and cell phones are all popular ways of rendering music. Ease of use and distribution is key to this expanding market.

So how would you answer the question: what is the best way to manage personal audio and premium content on an individual basis? Admittedly, using the word "best" makes this question impossible to answer. A better way to approach the problem is to provide an alternative technical solution and let the market come up with the implementations. This paper addresses an alternative way to manage audio content and presents the advantages and disadvantages of this technique. Before going into the proposed technique, it is important to understand some background on the other current techniques so a comparison may be drawn.

Identifying content
How do people manage digital audio content today? Most of the content is managed by tagging the content with ID3 tags or something similar. MPEG layers I, II, III have no native way of identifying the content so the ID3 tagging scheme was developed. The original layout ID3v1 is defined as follows:

Song Title	30 Characters
Artist	30 Characters
Album	30 Characters
Year	4 Characters
Comments	30 Characters
Genre	1 byte

ID3 V1 Standard

As you can see, in the first version of ID3, the content type and size are very limited, so ID3v2 was developed. This specification provided a significant improvement over the old specification, such as moving the information to the front of the media content and adding variable length fields and a wide variety of optional content frames (over 50), as shown in the following table:

Album/Show/Movie	Beats per minute
Composer	Content type
Copyright message	Playlist delay
Encoded by	File type
Title/song name	Initial key
Original media type	Original filename

ID3 V2 Standard

However just because this information is "standardized" in the ID3 specification, it doesn’t mean we have interoperability. The actual implementation is far from interoperable. In fact, the tagging information from one content vendor to another content vendor may be completely different. For example, some media players place the album art in the same folder or "container" and uniquely tag the art by a cryptic name (usually a global unique identifier—GUID). Others embed the art directly into the content making the file size bigger, which is a drawback in some cases for players that do not have the capability to display the art. The advantage is that the art moves with the content if the content is moved from folder to folder.

Tagging the file by the content provider is one tool of content management; however, this technique falls short if the content is converted from one form or moved from one location to another. For example if you purchase a WMA-audio encoded file, you probably need to convert the file from WMA to MP3 because your hand-held device plays only MP3-encoded files. The MP3 player manufacturer probably provided a file converter but it might not do the migration of tags to the new format appropriately. Or another scenario might be that you moved one file from one folder to another and lost the album art association.