View source for Testing audio output

== Recording/Analyzing Signals ==

* Easiest: just write a binary output file using standard file I/O. For simplicity, you can directly write out the audio output within the audio callback or copy the buffer and write the file on a separate thread so the file writing doesn't hold up the audio callback.

The [http://audacity.sourceforge.net/ Audacity] audio editor can "Import Raw" audio. Select the correct format and import. Audacity is installed on all CCRMA machines or can be downloaded for free [http://audacity.sourceforge.net/ here]. You will automatically view the time domain signal. To see the frequency response, you can select a portion of audio and click Analyze->Plot Spectrum.

* Bit Harder: Use  [https://ccrma.stanford.edu/software/stk/classstk_1_1FileWrite.html STK]-a wavefile writer found withint the [https://ccrma.stanford.edu/software/stk/ Synthesis ToolKit ]

* Bit Harder: Use [http://www.mega-nerd.com/libsndfile/ libsndfile](C library for reading and writing files containing sampled sound) to write an output file. Use Audacity or other audio editor/analyzer.

* Bit Harder: Write your own wavefile reader/writer. Use Audacity or other audio editor/analyzer.

==Reference Signals==

When creating signal generators yourself, you will want to compare your audio output to reference signals. Here are a few audio programing languages/environments that might be useful.

*[http://chuck.cs.princeton.edu/ Chuck]-audio programming language (suggested for ease-of-use)

*[http://puredata.info/ Pure Data]- a graphical audio programming language

*[http://www.audiosynth.com/ SuperCollider]-audio programming language

* Bit Harder: use [http://www.mega-nerd.com/libsndfile/ libsndfile](C library for reading and writing files containing sampled sound) to write an output file

* If you want to do some serious digital signal analysis/processing: use [http://www.mathworks.com/products/matlab/ matlab] or its open source counterpart [http://www.gnu.org/software/octave/ octave]

== Sample Chuck Code==


    // Comment/uncomment the different oscillators to hear each 

    SinOsc s => dac;
    //TriOsc s => dac;
    //SqrOsc s => dac;
    //PulseOsc s => dac;

   .2 => s.gain;

    while( true )
    {
        440.0 => s.freq;
        100::ms => now;
    }

    // Use this for impulse

    //Impulse i => dac;
    //while( true ) {
    //    1.0 => i.next;
    //    100::ms => now;
    //}

    // Use this for noise 

    //Noise n => dac;
    //.2 => n.gain;
    //while( true )
    //{
    //    100::ms => now;
    //}

    

Download and install.  From there you'll need to create a small bit of code to make the same output signals.