Frequently Asked Questions

1. What are the shell commands for recording and playing sounds?
rec for recording through microphone and play for playing sound through speakers. Sox can also be used. More information on these can be found using the man command.

2. How do I know if my microphone is properly connected and ready to receive sound signal?
After connecting the microphone and speakers to the CPU, try sending a test voice signal through the mic. If the microphone is properly connected and is ready to receive signals, you can hear the echo of your voice through the speakers.

3. I have tried both rec and sox for recording. But when I play it back, it is blank.
Check for the mic settings. Go to System --> Preferences --> Volume control. Go to File-->Change Device. Select HDA Intel (Alsa Mixer). Go to Capture tab and make sure that mic line is enabled and is not muted. Keep the slide bar at top level. Also go to Options tab and select the appropriate input source. After this do the test as in FAQ 2 to ensure that the mic is ready to recieve signals.

4. The number of samples I transmit is not same as the number of samples received in the recieved file.
The default sampling rates of rec command in the terminal and play command in scilab are not the same. So we need to explicitly specify the sampling rates to ensure that the number of samples is same in transmitted and received files. Also the bits corresponding to silence periods have to be removed in the recieved file before processing.

5.When I run my Scilab code, I get the error message 'Stack size exceeded'. What should I do?
It means that one or more variable(s) in your program has data that exceeds the pre-alloted value of the size of stack. The solution is to increase the size of the stack to a reasonably high value using the stacksize() command. More information about the command can be found in Scilab Help .