2: Building the AGain example

This 2nd tutorial will explain how to build the AGain plugin demo which comes with the VST SDK. We will be using MinGW and Scons (which you should have up and running after reading the previous tutorial) to do the job. AGain is a pretty unexciting plugin which just adjusts the gain applied to an input signal and sends it to the output, however, you will be able to do a lot more interesting stuff once you understand the basic framework of the source files in this example. This is what the plugin and interface look like in VSTHost.

I personally like to leave the SDK folder in the root of my c:\ drive and then build plugins in a different folder, for example “My Documents\VSTdev” or something similar but this is up to you. The first step is to copy the AGain directory and its contents to your development directory and then in this copied directory make a plain text file named SConstruct with no extension. Load this file up in your preferred text editor and then paste in the following build script.

# Scons build script for ADelay demo in VSTsdk v2.4
#
# bmoviehorror - Feb 2009

#Adjust the following line to suit your setup
vstPlugName = 'again'
vstSDKDir = 'C:\\vstsdk2.4'

#This line tells the compiler where the sdk is so it can find the necessary include files
env = Environment(CPPPATH= vstSDKDir, tools=['mingw'])

#This line sets some optional compiler flags
#  -Wall shows all warnings during the build
#  -O3 MAkes the output dll highly optimised (fast)
env['CCFLAGS'] = ['-Wall -O3']

#The shared library command makes scons build a dll under windows.
#At this stage we specify all the source files in the project.
env.SharedLibrary(vstPlugName, [
          vstPlugName+'.cpp',
          vstSDKDir+'\\public.sdk\\source\\vst2.x\\audioeffect.cpp',
          vstSDKDir+'\\public.sdk\\source\\vst2.x\\audioeffectx.cpp',
          vstSDKDir+'\\public.sdk\\source\\vst2.x\\vstplugmain.cpp'])

Hopefully there are enough comments in there to make each stage clear. Those readers who are familiar with the make tool can accomplish the same this with the following script. It is a lot longer and less intuitive than the SCons script in my opinion. The original can be found at http://schmid.dk/wiki/index.php/VST_Plug-ins

# change this to the location of your unpacked VST SDK:
VSTSDKDIR = ../vstsdk2.4

CPP       = g++.exe
OBJ       = PLUGINNAME.o $(VSTSDKDIR)/public.sdk/source/vst2.x/vstplugmain.o $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffect.o $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffectx.o
LIBS      = -L. --add-stdcall-alias -lole32 -lkernel32 -lgdi32 -luuid -luser32 -mwindows --no-export-all-symbols --def PLUGINNAME.def
CXXINCS   = -I"$(VSTSDKDIR)/pluginterfaces/vst2.x" -I"$(VSTSDKDIR)/public.sdk/source/vst2.x" -I"$(VSTSDKDIR)" -I"$(VSTSDKDIR)/vstgui.sf/vstgui" -I.
BIN       = PLUGINNAME.dll
CXXFLAGS  = $(CXXINCS) -DBUILDING_DLL=1 -mwindows -O3
RM        = rm -f

.PHONY: all clean

all: PLUGINNAME.dll

clean:
        ${RM} $(OBJ) $(BIN)

DLLWRAP   = dllwrap.exe
DEFFILE   = libPLUGINNAME.def
STATICLIB = libPLUGINNAME.a

$(BIN): $(OBJ)
        $(DLLWRAP) --output-def $(DEFFILE) --driver-name c++ --implib $(STATICLIB) $(OBJ) $(LIBS) -o $(BIN)

PLUGINNAME.o: PLUGINNAME.cpp
        $(CPP) -c PLUGINNAME.cpp -o PLUGINNAME.o $(CXXFLAGS)

$(VSTSDKDIR)/public.sdk/source/vst2.x/vstplugmain.o: $(VSTSDKDIR)/public.sdk/source/vst2.x/vstplugmain.cpp
        $(CPP) -c $(VSTSDKDIR)/public.sdk/source/vst2.x/vstplugmain.cpp -o $(VSTSDKDIR)/public.sdk/source/vst2.x/vstplugmain.o $(CXXFLAGS)

$(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffect.o: $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffect.cpp
        $(CPP) -c $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffect.cpp -o $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffect.o $(CXXFLAGS)

$(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffectx.o: $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffectx.cpp
        $(CPP) -c $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffectx.cpp -o $(VSTSDKDIR)/public.sdk/source/vst2.x/audioeffectx.o $(CXXFLAGS)

Anyhow, back to our build. Using your console application, navigate to the AGain directory in your development directory and give the following command

scons

If all goes according to plan you will see the following output in your command window. If scons exits with an error or build terminated warning, then please carefully read over tutorial #1 again.

scons: Reading SConscript files ... c:\Python26\Lib\site-packages\scons-1.1.0\SCons\Platform\posix.py:38: DeprecationWarning: The popen2 module is deprecated. Use the subprocess module. import popen2 c:\Python26\Lib\site-packages\scons-1.1.0\SCons\Tool\msvs.py:37: DeprecationWarning: the md5 module is deprecated; use hashlib instead import md5 scons: done reading SConscript files. scons: Building targets ... g++ -o again.o -c "-Wall -O3" -IC:\vstsdk2.4 again.cpp again.cpp:27:15: warning: multi-character character constant g++ -o C:\vstsdk2.4\public.sdk\source\vst2.x\audioeffect.o -c "-Wall -O3" -IC:\vstsdk2.4 C:\vstsdk2.4\public.sdk\source\vst2.x\audioeffect.cpp g++ -o C:\vstsdk2.4\public.sdk\source\vst2.x\audioeffectx.o -c "-Wall -O3" -IC:\vstsdk2.4 C:\vstsdk2.4\public.sdk\source\vst2.x\audioeffectx.cpp g++ -o C:\vstsdk2.4\public.sdk\source\vst2.x\vstplugmain.o -c "-Wall -O3" -IC:\vstsdk2.4 C:\vstsdk2.4\public.sdk\source\vst2.x\vstplugmain.cpp g++ -shared -o again.dll again.o C:\vstsdk2.4\public.sdk\source\vst2.x\audioeffect.o C:\vstsdk2.4\public.sdk\source\vst2.x\audioeffectx.o C:\vstsdk2.4\public.sdk\source\vst2.x\vstplugmain.o -Wl,--out-implib,libagain.a -Wl,--output-def,again.def Creating library file: libagain.a scons: done building targets.

Success! The plugin .dll will now be located in the same directory as your SConstruct file and is ready to load into a vst host. If you want to clean up all of the files generated in the build, including the output .dll, issue the following command . . .

scons -c

If you wish to rebuild the sources again then re-issue

scons

If the plugin has built successfully, then now would be a good time to really understand how the plugin is functioning. Head on over to Euphoria Audio and look at this tutorial http://www.euphoriaaudio.com/tutorials/vstexample/vstexample1.php .Once you understand how this works then have a go at modifying the source to crossfade between the input signal and noise or something similar. Another good resource is the tremolo example at Euphoria Audio http://www.euphoriaaudio.com/tutorials/tremolo/tremolo1.php . Once comfortable with these simple demos we will move on to building the ADelay example which comes with the sdk and its big brother Surrounddelay, which has a custom GUI.

Have fun and see you in tutorial 3!