Music 220A - Fall '04

HW1 Survival Guide

How to run unBird.scm

• Copy unBird.scm into your directory
• Open Snd from terminal -- Snd &
• Snd -> view -> show listener
• (load "unBird.scm")
• (go)
• Now you can modify and try running unBird.scm
• To see the spectrogram, Snd -> Options -> transform options -> sonogram.
  In order to show the frequencies of peaks, transform options -> single transform and choose "peak."

FAQ: unBird.scm

Use of the frequency envelope

I specified my frequency to sweep from 3700 to 700, like
(bird beg .03 3700 700 .05 descending main-amp)
and it does not go as low as 700 Hz. Why?

• freq, freq-env and freqskew works in this way: freq-env is scaled with freqskew, then
  added to freq. In this case, "descending" envelops is scaled with 700, then added to 3700 Hz.
  Therefore you'll see the sweep from 4400 to 3700. If you need a sweep from 3700 to 700,
  (bird beg .03 700 3000 .05 descending main-amp)
  should work.

Debugging Tips

The nested parentheses are too messy.

• Emacs has very useful options for debugging. Open emacs by typing emacs yourfile.scm & on the terminal. Go to "options" in the pull-down menu, and check the boxes "syntax highlighting" and "paren match highlighting." You'll see the scheme statements colored, and if you set the cursor at open or close parentheses, you'll see the matching parenthesis highlighted with nice green color. Click "save options" in the "options" pull-down menu, so that you don't have to repeat the customization.
  The other useful options are found at the Scheme pull down menu, such as indent region and comment/uncomment out region.


• Xemacs gives plenty of options too. Explore the "Options" pull-down menu to customize as you like. Don't forget to click "Save options to init file." This creates the init.el and custom.el files in your ~/.xemacs/ directory, which you can edit directly.

Miscellaneous but useful things

Please try these two commands in the terminal:

sndinfo your_soundfile
sndplay your_soundfile

Snd offers an option to tell the frequency and the amplitude of a spectram.
Go to the top pull-down menu, choose options -> transform options.
Click on "peaks" in the right colomn.

Broken links in your HW website

You first have to test the page with a browser. If it complains that file is not found, follow the instruction below.

• 1: Remove the wave file from your ~/Library/Web/220a/ directory, using "rm" command.
• 2: Make sure that your sound file is in /usr/ccrma/snd/220a-2004/your_login/ directory
• 3: In the terminal, type

  chmod 744 /usr/ccrma/snd/220a-2004/your_login/your_soundfile.wav  
  ln -s  /usr/ccrma/snd/220a-2004/your_login/your_soundfile.wav ~/Library/Web/220a/ 
  

• 4: Either in OpenOffice or Mozilla composer, select and edit the hyperlink. One of the following two should work.
  
  your_soundfile (Filename only, without path)
  http://ccrma-www.stanford.edu/~your_login/220a/your_soundfile (formal internet notation)

I cannot listen to my soundfile from outside CCRMA

Possibly your soundfile is in a different format than .wav (microsoft wave file) format,
which is the de facto standard for many computers.
Open the soundfile with Snd, and Edit -> Edit Header, and choose header - wave. Then Save.