[Stk] .tick() and callback function

[Gary Scavone]

Hi everyone,

I'll just point out something relevant to Emile's example ... the  
StkFrames class provides an indexing operator.  So, you can directly  
fill the StkFrames buffer along the lines of:

   frames[index] = *inputsamples;

Further, the StkFrames buffer is simply an malloc'ed vector, so you  
can get a pointer to the buffer as:

   StkFloat *ptr = &frames[0];

and then work with pointer arithmetic if you like (though you then  
need to keep track of your location and limits more carefully).

Regards,

--gary

On 16-Jan-09, at 10:47 AM, Emile Vrijdags wrote:

> I'm not an expert here, but I think I might have something useful to  
> say
> about your problem.
> My guess is you specify how the input can be read while initializing
> your rtaudio object with a call to openstream
>
> http://ccrma.stanford.edu/software/stk/classRtAudio.html#a7
>
> One of its parameters specify how many channels are read and which one
> is the starting channel.
> I only use the outputbuffer in my project with 2 channels. With me  
> these
> two channels are interleaved, which means that 1 sample of the  
> channel 1
> is put on the stream then 1 sample of the next channel ... until all
> channels are used, and then you go and put sample nr2 of channel 1 on
> the stream and so on. So I guess this works the same for input.
> The input can be read pointerlike in the callbackfunction: (as
> explanatory pseudo-code-like  illustration, not compiled, could  
> contain
> errors, it resembles working output code I have written)
>
> Stkfloat* inputsamples = (StkFloat *) inputBuffer
>
> Stkfloat sampleChan1, sampleChan2;
> StkFrames frames(buffersize,2,true); //buffersize from the
> callbackfunction parameters
>
> for(unsigned int i=0; i < buffersize; ++i)
> {
>    ...
>    sampleChan1 = *inputsamples;
>    ++inputsamples;
>    sampleChan2 = *inputsamples;
>    ++inputsamples;
>    frames[2*i] = SampleChan1;
>    frames[2*i+1] = SampleChan2;
>    //of course this can be written much shorter
> }
>
> filewvout.tick(frames); //magically a filewvout object appears here :)
>
>
>
> Hope this explanes some things (without to many errors) and gets you  
> on
> your way, awaiting a more educated answer
>
> Emile Vrijdags
>
>
>
> Beinan Li schreef, op 16/01/2009 1:57:
>> Hi,
>>
>> Might be an obvious one but I'm confused..
>> I'm trying to monitor mic input and save everything to a wave file
>> before an interrupting signal
>> like CTRL-C. So what I do is to use the call-back function and try to
>> use a FileWvOut object.tick()
>> to take the void* inputBuffer, which is first interpreted as a
>> StkFloat. But I notice that .tick() takes
>> StkFrame as input parameter.
>>
>> So my questions are:
>>
>>   1. How to "tick" the data (inputBuffer) in this case?
>>   2. What if my input is multichannel in this case?
>>
>> Thanks!
>>
>> Beinan
>>
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