Mary Sheridan, our stalwart president and ace presenter, kept us entertained as usual by responding to "how to" questions relating to MS Windows for the first 30 minutes of the evening’s meeting.

Next, the standard announcements and official organizational business were addressed for five minutes including the announcement of the slate of TPCUG officers for 2001 to be elected at the November meeting. See the President’s message in this newsletter for the list.

Then Mary introduced the author of The MP3 and Internet Audio Handbook, Marty Fries, who co-authored the book with his brother Bruce Fries.

Marty entertained the group with his excellent presentation on the ins and outs of the audio compression technology known as MP3 that has recently opened up the music delivery marketplace and provided a new medium of personal listening opportunities. Marty was definitely in command of his topic and came across as a cool devotee of his passion for music in general and the enhancements provided by MP3 technology in particular. The presentation was like "easy listening" but contained an enormous wealth of technical information relating to MP3. What now follows is my attempt to capture a number of technical nuggets of information recorded as best I could from Marty’s excellent presentation. For those anxious for more technical definition, Marty’s book has just gone through a reprint and should again be readily available at all the major booksellers.

Marty, a long time band musician by his own admission, also confessed that his interest in things digital commenced with the Commodore 64 and Apple PC’s. Marty started out by passing around the group a small compact electronic device known as an MP3 Player. Portable MP3 players range up to 64 MB’s of memory. The MP3 compression technology is perfectly legal, notwithstanding the raging Napster legal controversy pitting the recording industry against independent musicians. Typical compression factors achieved by MP3 approach 1 to 10 and can be compared loosely to zip compression that eliminates space and zeros.

The technical discussion started with the factoid that a standard audio CD contains 760MB of data and provides 74 minutes of audio. The laser CD path covers 1.6 kilometers of recording. This equates to 1.1 MB per minute. The Nyquist theorem, sometimes known as the Shannon theorem, states that the sampling rate must be at least two times the highest natural frequency, which for human audio perception equates to 1.4 MB per second, or 44.1 kilohertz. A typical five-minute song, therefore, requires 50 MB. Also, typically 5 MB is about the maximum practicable amount of data that can be downloaded over a 56 KB per second modem.

MP3 technology mostly overcomes this problem by virtue of the compression achieved. The human frequency range of hearing is from 20 Hz to 20 kHz. The compression algorithm divides this range into 30 bands and eliminates the definition of those bands with a volume level lower in dynamic range than the brain’s detection level. Sixteen bit encoding provides a dynamic range up to 90 dB. This equates to 6 dB per bit or voltages ranging from one milli-volt to one volt. Other types of compression have been developed and are also known by their acronyms, such as WMA, AAC and AZT3. However, MP3 has now permeated the marketplace. With a 128 KB per second bit rate, MP3 is found to have a most acceptable audio quality. A full orchestral recording is by far the most musically complex collection of sounds and, even so, a compression ratio of 7 to 8 is readily achievable.

A standard MP3 player with 64 MB of memory can play back over one hour’s worth of high quality music. Memory itself has taken on a number of highly compact forms such as flash memory, the Sony stick, or the smart media chip. With any of these memory forms the MP3 players tend to be extremely light and, therefore, very portable.

Marty then conducted a live test for our captive audience, who were asked to distinguish between uncompressed audio, as from a CD, and the MP3 recordings. MP3 recordings were demonstrated at a number of recorded bit rates, and we were asked to determine from the audio quality rendered if they were compressed or not. These tests were conducted using a Ricky Lee Jones song that contained a significant level of musical complexity. This demonstration was conducted using the Win Amp MP3 player software. The test was repeated for a number of variable bit sampling rates that automatically varied according to the musical complexity. Bit rates of 80 to 200 kilohertz were witnessed. The streaming Internet "Real Audio" uses a 32-kilohertz bit rate, by way of comparison. At the lower bit rates a loss of sharpness or muddiness of sounds was detectable when compared to the audio CD rendition of the same song. The use of a variable bit rate further improves the compression ratio by 2:1 compared to the fixed bit rate sampling rates.

The presentation now proceeded into a less technical realm of MP3 recorded music. "Music Match Juke Box" was touted as the equivalent of a 300 CD disc changer! The software not only catalogs and allows the user to pre-select a large number of songs to be downloaded to a MP3 player but also stores information for readout on the player display, such as the song title and artist and any other information so desired.

A number of MP3 player models were presented and included the Genica, the Nomad and the JB Works. Prices range from $150 to $900. Excellent 64 MB MP3 players were obtainable by means of Internet sales for $250.

For further details on all of the above and for technical validation, the reader is directed to the web site, http://www.MP3handbook.com. Overall this session was one of the best and most enjoyable presentations ever made at our monthly TPCUG meetings. Thanks again to our presenter, Bruce Fries, who signed copies for us of his book, available for $20. Two copies were donated for our door prize that netted $46 for our general fund. u