256a-fall-2017/hw1

Homework #1: Cookin' with Low-level Audio

Due date: 2017.10.3 11:59:59pm, Tuesday.

Let's get cookin'.

Specification (part 1 of 4): Real-time Audio

• create a program that is capable of real-time audio input/output
• give it name (e.g., sig-gen; creative names are always welcome)
  • start with this basic boilerplate: HelloSine
• next, add real-time audio support, using the RtAudio Library (version 4.0.10 or later, included in the boilerplate)
  • even though it's useful to briefly look through the package, the only files you'll need are:
    • RtAudio.h (the header file for RtAudio, it contains the class definitions)
    • RtAudio.cpp (the implementation)
    • RtError.h (header containing various error handling constructs for RtAudio)
  • it may be useful to browse the RtAudio documentation and the example programs in the RtAudio distribution
• implement the callback function to generate the expect number of samples per call for a sine wave at 440Hz
• the overall behavior when you run the program should be a continuous sine tone at 440hz...
• to quit: press enter

See Signal generator hints if needed.

Specification (part 2 of 4): Waveforms

• modify your program to take command line arguments and generate different signals, depending on the command line flag you specify:

    sig-gen [type] [frequency] [width]
        [type]: --sine |  --noise | --impulse | --pulse
        [frequency]: (a number > 0, not applicable to noise)
        [width]: pulse width (only applicable to pulse)

• where the flags correspond to the following signals:
  • --sine : sine wave
  • --noise : white noise
  • --impulse : impluse train, the frequency should determine the impulse train's fundamental period
  • --pulse : rectangular pulse wave, the width ([0.0-1.0]) controls the pulse width (e.g., width=.5 should result in a square wave)

• it might be a good idea to output the usage (as show above), if insufficient or incorrect parameters are given
• you'll need to implement a simple command line parser, with basic error checking (e.g., what to do when invalid/irrelevant parameters are provided?)
• you'll also need to organize your code a bit, to selectively generate the request signal

See Signal generator hints if needed.

Specification (part 3 of 4): One Ring to Modulate Them All

• Next, add another command line flag:
  • --input : mic/line input (make sure input is enabled in the RtAudio initialization)
• if specified, this flag tells the program to take the mic/line input and and multiply it against the signal being generated, and output the result;
• test it by talking into it and listening to the result...

Specification (part 4 of 4): add ChucK!

• Lastly, add ChucK as a module to your program
• download charles boilerplate project that includes ChucK as library and API
• in host/charles.cpp, add in your existing code from earlier parts
• study chuck.h in core/ -- it contains the chuck API you'll use to add ChucK as a module
• make the following modifications to charles.cpp (after you've brought in your code, and verified it still compiles/works):
  • instantiate a ChucK object
  • set parameters
  • initialize the ChucK object (init())
  • compile a chuck program (created as a string, according to the specification from the command line)
  • start ChucK
  • very importantly, drive chuck from your callback function
• add the --chuck flag to your program. when it is passed in, you should generate and use a chuck program for the sig-gen functionality, rather than what you wrote in earlier parts
  • sine
  • pulse wave
  • white noise
  • impulse train
  • ring modulating

Note

• have fun with it!!!
• comment your code!
• choose your own coding conventions - but be consistent
• you are welcome to work together, but you must do/turn in your own work (you'll likely get more out of it this way)
• some considerations:
  • how to organize the code for the various types of signals?
  • how much error-checking and error-reporting on the command line arguments?

Hints for ChucK Code

ChucK code for reference

You may want to use a stringstream or other string formatting techniques to construct ChucK programs on-the-fly

Deliverables

turn in all files + readme through coursework

• 1) Create a zip/tar file and put all the files in there. The required files are:
  • source code to the project (*.h, *.cpp, makefile, etc.)
  • a short README text section that:
    • instructions on building the project (for example, anyone in the class should be able to download
    • conveys your ideas/comments in constructing each program
    • describes any difficulties you encountered in the process
    • lists any collaborators
• 2) upload zip/tar file to Canvas!