11.3 Utility Functions

In the course of developing the envelope viewing application in MATLAB, I wrote several utility functions for general tasks like reading a sound file, reading a partial file and the like. As these can be useful for other people as well, I will document them here. They can be found in  schwarz/src/viewenv/util.

11.3.1 Reading Sound Files

loadsf.m: Uses a pipe for fromsf to write a stream of samples to, reads samples from the pipe. The sampling rate is obtained by calling querysf. If the file does not exist, an error message is printed and the call exits.

Usage:

    [sig, sr] = loadsf (filename)

Loads the (IRCAM sf or aiff) sound file into the vector sig, returns the sampling rate in sr.

Further extensions (if there is the need for it):

• Pass an argument to select the baviour in case of an error.
• Pass command line arguments for fromsf as a string to access all of its funtionality (select channels to read, specify the section of the audiofile to be read, etc.).

11.3.2 Reading Format Files

MEX-file loadpartials.c

11.3.3 Reading SDIF Envelope Files

11.3.4 Miscellaneous

• Conversion from amplitude values to decibel (dB.m).
• Conversion between sample position and time position (samptosec.m and sectosamp.m).
• Find the identifying handles of several Matlab user interface objects given their names (tags) (findt.m).