Wav file tone generation library.

[agraham]

Unlike some versions of Basic Basic4PPC does not implement a Beep statement that can specify the frequency and duration of a tone. These libraries, one each for desktop and device, let you write a wav file of the required frequency and duration. They also provide playback of any wav file with some additional options not available to the Basic4PPC Sound facility.

I knocked these libraries up for a specific use in another thread but thought that I would post them here complete with demo app and help file in case they are of use to anyone else.

[Zenerdiode]

I've been using the Wav library in one of my apps for calibrating our mechanical timers - if the user is too slow it gives five low tones, too fast five high tones and within range, a continuous mid tone. Very useful.

Then fiddling a bit with the demo application, agraham's note about having the sampling 2.5 times the desired frequency is quite important. For example, if you keep the default rate of 11025samp.s-1; play a tone of 6kHz and 8kHz. The 8kHz tone sounds appreciably lower than the 6kHz tone. A good example of Quantization. That's probably why CD audio is sampled at 44.1kHz.

Using 44100 with the library produces the correct tone.

[agraham]

Originally Posted by Zenerdiode

A good example of Quantization.

To be pedantic is actually Aliasing