[iiwusynth-devel] Optimization

[markus.nentwig]

Hello,

 

first of all, thanks for iiwusynth - it works very well. I found a 12 MB Rhodes EP-soundfont, which just blows away any synthesizer-fake-Rhodes I have ...

 

Some notes (should be 'some patches', maybe after the weekend :-)

 

- Compiler optimization: After upgrading to the latest GCC version, I managed to compile with -O3 -funroll-loops -mcpu=i686 -march=i686.

At least the -O3 is needed for handling full polyphony (on a P III 700). Not sure about the i686 options, though.

With previous compiler versions, strange behaviour resulted from -O3 (the root key of each sample was missing, but that's a compiler bug).

 

- Bug: There should be a pitchbend default value for each Midi channel. Currently pitch bend starts with +/- 0 for each generator, instead of the real position of the pitch bend wheel.

 

- Filter: The filter -is- commented out at the moment? I'm not sure, I didn't manage to set the filter. I'll try to find some time in the weekend to understand the code...

 

- Equalizer: I have implemented a 10 band equalizer in C, that works just fine (http://millisampler.sourceforge.net). It's based on a 'recipe' from a DSP application note.

The CPU load with all 10 bands on is around 10 % on my machine. Turning off bands (gain = 0 dB) reduces the load proportionally.

While I don't think that it could be included in iiwysynth in a way compatible with the standard, It might be useful as a 'master effect', which is

only controlled via command line parameters. Any opinions?

 

-Sysex: Iiwusynth locks up, when sysex messages are transmitted.

 

Regards

 

Markus

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