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Extension Mention - PC Sound Files

Sfortunatamente, questa pagina è disponibile solo in inglese.

It's easy to get overwhelmed with the multiplicity of audio file types, each with a different extension - .wav, .mid, .kar, .mp3 to name just the more common ones. It gets much clearer if you group these as digitized vs. synthesized formats, and how they relate to the physics of sound.

In digitized sound, the bit instructions tell the connected speakers, instant by instant, to oscillate or 'sound wave produce' in certain ways. The digitized sound is stored in files called WAVE files, with .wav extension. Just like a graphics bitmap, digitized .wav files vary with resolution. Resolution involves monaural vs. stereo, sound bit samples (4-bit up to 16 bit CD-ROM audio resolution which affords 2 power 16, or 65,536 information combinations), and finally sample rate (how often the computer samples the stream of analog sound to store a digital sample - 11kHz or 11,000 times per second like AM radio, 22kHz like FM radio, or 44 kHz like CD-ROM audio).

A middle-of-the-road level is 8-bit mono 22 kHz. The .wav file to store one minute of music at this resolution is 1.3 MB. True CD-ROM quality digitized (16-bit stereo 44 kHz) uses up 10.6 MB of hard drive to store one minute. So what do you do when composing and recording a ten minute single, much less try to store your new album and its draft versions on your PC? Switch to synthesized sound, of course.

Synthesized sound doesn't tell a speaker second by second how to oscillate, but instead gives instructions like "play a B flat for five seconds and make it sound like the instrument Saxophone". That sounds mighty like a MIDI instruction. In fact, MIDI is the standard format for PC based synthesized sound (see previous article on this web site). MIDI format files are stored with extension .mid or .midi. In a MIDI file, you can store a whole hour's worth of music in only 1 MB!

MIDI was originally developed to record, manage, and play back music synthesizers. Depending on the sound board's capabilitiy, MIDI can define upwards of 128 instruments, 47 percussions, with 32 note polyphony. You can find various pianos, string instruments, horns, guitars, sitars, kotos, vibraphones, drums - even helicopter sounds, birds, and gunshots.

Even better, if you want to sing along, you can embed text song lyrics in the right spots of the instrumentation, to display and sing to in a MIDI file. To make things clearer, the unwritten convention is to name a lyrics-containing .mid file, instead a .kar file. Yes, it stands for Karaoke - see first article in this series. vanBasco's Karaoke player supports up to four lines of karaoke lyrics for great singing versatility.

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