[LAD] SysEx data-conversion woes: nibbles and complements (Microwave 2)

[Jeanette C.]

May 13 2021, Fons Adriaensen has written:

> On Thu, May 13, 2021 at 09:14:47AM +0200, Jeanette C. wrote:
>
>> Only the wave data (128 bytes):
>> https://www.dropbox.com/s/q5rcm3cvtfp8cdu/pure_wave_data.dat
>
> I get a 'smooth' waveform whch makes be believe the result is correct,
> but it certainly is not a sine wave. No fundamental F1, very strong
> 4 * F1, 6 * F1, 11 * F1.
>
> How does it sound ?
Many, many thanks, Fons! I can't exactly say how it sounds, because I
don't have a listing of waveforms within wavetables. But there is a list
of all spectra, as images, I think this is it:
http://www.carbon111.com/300waves.pdf

What did you do to combine the nibbles into the final sample? I tried
something like:
char sysex_string[128];
signed char samples[64];
... // fill string
for (int item = 0;item<64;item++)
{
   sample[item] = (sysex_string[item /2])^0x80 + (sysex_string[(item / 2) +1]
     <<4);
}
I also tried by ^'ing the finished value with 0x80. Perhaps somewhere I
got the correct sample, but because I expected the sine, I didn't
believe my own code. :)

Best wishes,

Jeanette

>
> -- 
> FA
>
>
>
>

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