CS 3733 Operating Systems

Assignment 2: Audio

Part I: Due February, 16 1998 at midnight; Part II: Due March 13, 1998 at midnight

Audiotool
- Use the audiotool to record and play back some video clips of your voice.
- Experiment with different settings of the volume.
- Record your speaking of individual numerical digits (from 0 to 9) in ten different files.
Play back
- Download the audio object implementation given in Program 3.4 and the associated include file audiolib.h
- Add the function get_play_buffer_size() to audiolib.c. This function finds the appropriate blocksize for writing to the audio device. Use Example 3.27 of PUP as a model.
- Add the function play_file() to audiolib.c as described on page 133 of PUP. The function should remove the audio header before writing the file to the audio device.
- Write a main program that takes an arbitrary number of file names as command line arguments and plays those files consecutively.
- Evaluate how your program sounds when it plays the digit files that you recorded to speak a number.
Part II: Due Friday, March 13, 1998 at midnight
- Correct all of the problems that I indicated were in your assignment 1.
- Add the following two functions to the audiolib.c library:
  - The play_open_file plays the indicated file on audio device. It assumes that the audio device has already been opened. The prototype for this function is:
```
              int play_open_file(int fd)
```
    The function returns the total number of bytes output or -1 if an error occurs on the audio device.
  - The record_to_open_file reads the audio device and writes the results to the open file that has been passed as a parameter. It assumes that the audio device has already been opened. The prototype for this function is:
```
              int record_to_open_file(int fd) 
```
    The function returns the total number of bytes output or -1 if an error occurs on the audio device. It uses an error or end-of-file on fd to terminate the program.
- Write separate main programs to test play_open_file and record_to_open_file. Each of these main programs should take a command line argument that is the name of the file to pass to the function. The main programs will open the disk file and the audio device before making the function call. The execution of the main program to test the record_to_open function will have to be terminated manually be entering a CTRL-C.
- Hand in all source code and lint output. Pay particular attention to not making the mistakes mentioned in the FAQ for Part I. I will take off extra points for these mistakes.
Revision Date: 3/1/98