Testing Out a New STK Project

In the preceding section, we built the STK library and all the demos, and we tried out one of them (Physical.bat). In this section, we will create a new STK project and go through the steps of compiling, linking, and trying it out. Debugging programs using gdb is introduced in Appendix B.

The file stk/myproj/README briefly describes the simple examples in its subdirectories. Let's focus for now on the echo example:

$ cd ~/stk/stk/myproj/echo
$ ls -F
Makefile  echo.cpp  test.wav
$ make echo
echo g++ -g -Wall -I../../include/  ...
g++ -g -Wall -I../../include/ ...
g++ -g -Wall -I../../include/ ... \
  echo.cpp  ../../src/libstk.a -lpthread -lm -lasound -o echo
$ \echo 2
$ sndplay echo.wav

The sndplay program is installed with the Planet CCRMA distribution (snd-utils package). It works whether the jack audio server is running or not.

Figure A.2 lists the complete makefile for this example. As we see, most of the actual work is done in Makefile.proj in the parent directory. All we need in this makefile is the program name, any program arguments (the number 2 in this case), and the names of any additional object files to be compiled and linked with the main program (including the .o extension in each filename, separating filenames with space).

MAIN = echo
ARGS = 2
OFILES = 
include ../Makefile.proj

/* echo.cpp - simple test program for echo simulation. 
   Compatible with STK version 4.2.1.

   Usage:

     echo 2

   Plays the input soundfile (hard wired to test.wav) summed 
   with itself delayed by 2 seconds. You thus hear two 
   instances of the input sound separated by the echo delay.
   If not specified, the echo delay defaults to 1 second.  
   It can be any nonnegative real value.
*/
   
#include "FileWvIn.h"
#include "FileWvOut.h"
#include "Delay.h"
#include <stdlib.h> // for atof()
#include <math.h> // for floor()

int main(int argc,char *argv[])
{
  Delay *delayLine;    
  FileWvIn input("test.wav"); 
  FileWvOut output(argv[0]); // Writes main.wav
  double del = 1.0;
  if (argc>1) { del = atof(argv[1]); }
  long delsamps = (long)floor(del*Stk::sampleRate()+0.5);
  delayLine = new Delay(delsamps,delsamps);
  long nsamps = input.getSize();
  for (long i=0;i<nsamps;i++)   {
    StkFloat insamp = input.tick();
    output.tick(0.5*insamp + 0.5*delayLine->tick(insamp));
  }
  for (long i=0;i<delsamps;i++)   {
    output.tick(0.5*delayLine->tick(0));
  }
  return(0);
}

Figure A.3 lists our example program, echo.cpp. Below is a description of how the program works:

• The first three lines include header files for three STK modules:
  • FileWvIn, which reads sound files,
  • FileWvOut, which writes sound files, and
  • Delay, which implements a digital delay line.
  In general, any time you want to use a class from the STK library, you need to include the header-file for that class so that its messages become defined in your program.
• Including standard C header files such as stdlib.h and math.h is routine C programming. To find out which C header file ne