Instrument

Class Variables

• float _start is the starting time (in seconds) of the scheduled INSTRUMENT note. This is set by the rtsetoutput function.
  
  
• float _dur is the duration (in seconds) of the scheduled INSTRUMENT note. This is set by the rtsetoutput function.
  
  
• int cursamp is the current sample being computed. The user must increment this in the sample-computing loop:

  MYINSTRUMENT::run()
  {
  	int i;
  
  	...
  
  	for (i = 0; i < chunksamps; i++)
  	{
  		...
  
  		cursamp++;
  	}
  }
  

  cursamp will range from 0 to nsamps-1 during note execution.
  
  
• int chunksamps is the number of samples ("frames") to be computed during each RTcmix scheduler "chunk". The INSTRUMENT::run() method is called once for each scheduler "chunk" for every note executing at a given time.
  
  
• int endsamp is (I think) the ending sample number. I'm not sure if this is an absolute number from the very start of RTcmix running, or just from the beginning of the note (in which case it is equal to nsamps). Someday I'll find out, I'm sure.
  
  
• int nsamps is the number of samples ("frames") to be executed for the entire note. This is usually set by the rtsetoutput function.
  
  
• double inputsr is the sampling rate of the input soundfile or input device (in samples/second).
  
  
• int inputchans is the number of input channels for the input soundfile or input device.
  
  
• int outputchans is the number of output channels for the output soundfile or output device.
  
  
  
  There are a bunch of other variables associated with the Instrument object, but I'll be blamed if I can recall or ascertain what they all do. Aaah! I'm old! See the Instrument.h and Instrument.C files in the RTcmix/rtstuff directory for a complete look at these.

  Three useful variables, however, that are not class vars of the Instrument, but are very useful in INSTRUMENT design:
  
  

• float SR -- the output sampling rate (in samples/second) set by the directive in the scorefile.
  
  
• int NCHANS -- the number of channels in the output (should be the same is outputchans set by the directive in the scorefile.
  
  
• int RTBUFSAMPS -- the number of samples ("frames") in each RTcmix buffer (should be the same as chunksamps, I believe). This can be set by the directive in the scorefile, although it is an optional parameter. The default value varies depending on the computing platform.
  
  

int Instrument::CurrentFrame()


returns the current sample (frame) being computed. This is the value of the variable cursamps.


int Instrument::FramesToRun()


returns the number of samples (frames) to compute in each invocation of the Instrument::run() method. Usually this is the value of the variable chunksamps.


int Instrument::NSamps()


returns the total number of samples (frames) to run for the note. This is the value of the variable nsamps.


int Instrument::InputChannels()


returns the number of input channels for the input device (specified in the rtinput scorefile directive). This is the value of the variable inputsr.


int Instrument::OutputChannels()


returns the number of output channels for the output device (specified in the rtsetparams scorefile directive). This is the value of the variable outputsr.


void Instrument::increment()


increments the value of cursamp, used to keep track of how many samples (frames) have been executed. Equivalent to ++cursamp.


void Instrument::increment(int amount)


increments the value of cursamp by amount, used to keep track of how many samples (frames) have been executed. Equivalent to cursamp += amount.


float Instrument::getstart()


returns the start time (in seconds) of the INSTRUMENT note. This is the value of the variable _start.


float Instrument::getdur()


returns the duration (in seconds) of the INSTRUMENT note. This is the value of the variable _dur.

Examples