About Sound Files

Digitizing

• All my music starts out as real live analog signals, including real drums, bass, guitar, piano, and voice. The only exception is synth tracks. Getting it into the computer realm takes some doing. I used a Power PC 6100 I purchased in April 1995 to digitize music. Note that I used to use a Mac SE (here's and old file describing how I used to digitize music).
• CDs are simple: put a CD into the internal CD drive, launch the "AppleCD Audio Player" (comes with System 7.5), launch SoundEdit16 (more about that program later), press record, then play the appropriate track.
• Cassettes require me to attach an external deck to my Mac using a cable with a 1/8" stereo connector at one end and the appropriate connector(s) at the other. The rest of the process is the same.
• DATs and vinyl (haven't had to do the latter yet, but that media seems to be making a comeback...) I simply dump to cassette, then proceed as above.

Playback

• SoundEdit16 plays back the AIFF files well, but for some strange reason, the WAV files play back at slow (half?) speed when I download them over the net through Netscape on my Mac. I need to test them on my '486.
• SoundMachine is the best public domain software for the Mac, as far as I know. Read this document, from the San Diego Area Music pages for more info on playing back the sounds you find here and elsewhere on the net.
• RealAudio is a great solution to the sound download-delay problem with it's audio-on-demand method. The player is supposed to be bundled into a release of Netscape this December, and I'm working on getting a copy of their server for this server.
• New note, October 2000: MPEG3 (aka "MP3") has taken over, thanks to my UCSD colleague Michael Robertson's company MP3.com...I now recommend people simply digitize 30 to 60 seconds of a given track to MPEG3, and let people download and listen. *Don't* digitize the entire track unless you are willing to "give it away." The MPEG3 format is close enough to CD quality that most people can't tell the difference. Make sure you put nice fade ins and fade outs on your samples!

Digital Recording Software

• I use a software tool called SoundEdit16 on my Macintosh computers to digitize music. The key variables are sample rate (typically 22.05 or 44.1KHz), sample bits (8 or 16), compression (I haven't used any, yet), and stereo vs. mono. Also, there is no single accepted sound format. Mac people like AIFF files, Windows/DOS people like WAVE files, and UNIX-heads like AU. MPG2 is also making some noise (pun intended). I save to AIFF and WAV, as I've found most Unix people can, worst-case, handle format translation.
• See how old that last note is? Still talking about MPEG2...now MPEG3 is the standard, and "MP4.com" and a bunch of other "MP*.com" addresses are already registered. I'll bet the Motion Picture Engineering Group changes their name soon in reaction to this popular onslaught.
• I've found that mono, 8-bit, 22KHz samples sound quite good on most playback systems. Some hiss is apparent, but the SNR (signal-to-noise ratio) is quite good, and you can hear most of the subtleties of the music. You do lose some bandwidth (frequency response) and any stereo imaging. A 32-second sample takes up about 650K of disk, and takes about 30 seconds to download across the net on a busy day. That's a 1:1 download time:sample length ratio, which seems to be OK for songs up to about 5 minutes. Longer samples are going to take some real-time playback techniques (like RealAudio software), so no symphonic movements for now (remember, that's what drove the LP record format!).
• "CD-quality" samples can be had by digitizing music at 44.1KHz, 16-bit, stereo. The resulting files (depending on the quality of your playback equipment, connecting cables, and computer used to digitize) are as good as a DAT or CD, and if someone downloads these files and can dump them to a DAT or CD, they've got studio-quality downloads. The files are about 8 times as big as the technique above, and this it takes about 4 minutes to download a 30-second sample.
• My solution is to offer 30-second samples at the lower-quality sampling rates, and put CD-quality full-length sound files right next to them. That way, a user can sample songs quickly, and if they like what they hear and are willing to wait a bit, they can get a full-length top-quality version. Of course, I put up 3-5 minute songs this way, which means I'm asking the user to wait 24-40 minutes to get these songs. I will make this fact clear on the pages, so users don't inadvertently start a long download. I assume users who want quality samples will put up with the download time I'll be applying this solution to all my sound files soon.