Playing digitized sound files on the HP48G/GX

[Pierre95]

Hello,

There are utilitizes which convert 8 bits mono .wav file into a format playable onto the HP 48G(X) calculator.

As far as I know, those utilitizes converts each byte of the sound file into a '1' or a '0', according to the current byte's value. Basically when the value is above 127 it is considered as a '1', otherwise a '0'.

The resulting file is then played by toggling the internal speaker in accordance to the value of each bit.

The advantage is that it takes 8 times less memory than the original .wav file. The sound quality is however extremely low.

So my question is: did someone try to implement a PWM replay routine which would produce a duty cycle in accordance to the original .wav file current byte? The frequency will remain fixed and be that of the .wav file sampling rate but for each byte there will be a specific duty cycle which may produce fairly better sound quality. I don't think it will eat too much processing power as compared to existing playback routines. It will however take 11000 bytes per second for a 11KHz sampling rate.