[Stk] problems implementing polyphony...

[Stephen Sinclair]

I also messed around a little with a program used to time a bunch of
calls to HevyMetl::tick().  It was indeed slower than e.g. Clarinet.
I couldn't get to the bottom of it, but for what it's worth removing
the calls to setFrequency() made it about twice as fast.  Removing
those and all calls to tick() (for ADSR and wave objects) made it like
10 times faster.

Not sure why this stuff would be slow, as I traced through and
couldn't find an unexpected amount of indirections and virtual calls.
I had a quick look at assembly output to see about inlining but had
trouble immediately making sense of it.  I think there were some
"call" instructions in there, but it didn't seem like a lot of them.
I would want to step through the assembly with a debugger but don't
really have time for that right now.

I played around with removing the std::vectors, and also removing the
indirection of the arrays (e.g. making them arrays of ADSR instead of
ADSR*), and also using link-time optimisation, none of which seems to
really help.

Steve

On Tue, Sep 18, 2012 at 10:39 AM, Tristan Matthews
<le.businessman at gmail.com> wrote:
> 2012/9/17 Rumi Humphrey <rumi at refresh.vu>:
>> I think you can get your (modified for momu) FM class to compile if you
>> comment out this line in FM.h:
>>
>> virtual StkFrames& tick( StkFrames& frames, unsigned int channel = 0 ) = 0;
>>
>> I'm not exactly sure why that is or how to use tick with frames i think the
>> MoMu version of STK might implement it differently or something.
>>
>> Unfortunately though doing this and using arrays instead of vectors didn't
>> seem to help performance that much at least not on my ipod touch. I'm still
>> only able to get one voice to play using HevyMetl.
>
> How does your hardware handle denormal floats? The FM class contains a
> TwoZero filter,
> which I believe can lead to denormals. You could try adding a small DC
> offset the samples
> before they are input to the TwoZero filter.
>
> This article has some background, as well as how to test denormal
> computation on your hardware:
> http://stackoverflow.com/questions/9350810/denormalized-floating-point-in-objective-c
>
> The only other thing I might try is changing StkFloat from double to float.
>
> Best,
> Tristan
>
>>
>> On Sep 17, 2012, at 7:27 PM, Patrick J. Collins wrote:
>>
>> Hmmm..  So after I put replaced the FM files with those two that you
>> provided, building failed first because of:
>>  #include "SKINI.msg"
>>
>> Claiming that file was not found...  I changed it to what it was
>> previously:
>>
>>  #include "Skini_msg.h"
>>
>> Then the .cp failed with:
>>        if ( nOperators_ == 0 ) {
>>            oStream_ << "FM::FM: Number of operators must be greater than
>> zero!";
>>            handleError( StkError::FUNCTION_ARGUMENT );
>>        }
>>
>> Saying "use of undeclared identifier oStream_"...  So I changed that to
>> errorString_ as it was before...
>>
>> Then finally after doing that, the build fails at a point in my own code
>> where I am doing:
>>
>>  // in my .h:
>>    HevyMetl *instrument[4];
>>
>>  // in my .mm:
>>    voicer = new Voicer();
>>    instrument[0] = new HevyMetl();
>>    instrument[1] = new HevyMetl();
>>    voicer->addInstrument(instrument[0]);
>>    voicer->addInstrument(instrument[1]);
>>    voicer->silence();
>>
>> ...  It's failing at "new HevyMetl()" saying "Allocating an object of
>> abstract class type 'HevyMetl'"...
>>
>> Patrick J. Collins
>> http://collinatorstudios.com
>>
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>>
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>
>
>
> --
> Tristan Matthews
> web: http://tristanswork.blogspot.com
>
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