How can I make an audible Beep in Dart? - dart

Question

I have searched on [DartLang and Beep] and have found only various HTML5 solutions that require a sound file. I would like to do a as basic and as universal a "Bell" sound as possible without using a sound file. (I'm using Ubuntu and there is a System beep function that reports the following when I call it with -h:
Usage:
beep [-f freq] [-l length] [-r reps] [-d delay] [-D delay] [-s] [-c] [--verbose | --debug] [-e device]
However, again, I just want to do this in as simple and universal a way as possible.
There is also this clue:
7 00/07 07 07 BEL (Ctrl-G) BELL (Beep)
...but nothing I could think of doing with the print() function would cause a beep.
Thanks in advance!

Answer 1

I don't know why are you doing this, but it really depends on whether you want this to work on the browser or on the console.
If you want to do this on the console, try this:
main() {
print(new String.fromCharCodes([0x07]));
}
It beeps for me at least on Windows. It should work if the terminal supports it (and it's not disabled by the user and so forth).
If you want to do this on the browser, you should play a sound file.
Here's a free beep sound: http://www.freesound.org/people/SpeedY/sounds/3062/
A very simple example on the browser:
new AudioElement("path/to/beep.wav")
..autoplay = true
..load();

Answer 2

You can use the Audio API to generate tones. For example, the following Dart code will generate a beep lasting 50 ms when you hit a key.
import 'dart:html';
import 'dart:web_audio';
import 'dart:async';
void main() {
final num LENGTH = 50;
var ac = new AudioContext();
window.onKeyUp.listen((KeyboardEvent ke) {
print("press a key");
OscillatorNode oscillator = ac.createOscillator();
oscillator
..type = "sine"
..frequency.value = 1000
..connectNode(ac.destination, 0, 0)
..start(0);
var timer = new Timer(const Duration(milliseconds: LENGTH), () {
oscillator.disconnect(0);
});
});
}
Possibly, there is a better way to terminate the generated tone than to set a timeout - perhaps by using an event listener (I'm still pretty new to the API; hopefully someone who knows more can edit the above code) - but the result is an audible beep, without any sound files... on a browser that supports the Audio API, that is.

Answer 3

If you are writing a console application, you can print '\a' which is an ASCII bell character.
This might not play a sound on all terminals. For instance, GNU screen may instead make the screen colors invert momentarily and print the message "Wuff, Wuff!!" instead of playing a sound. Various terminal emulators will allow you to disable ASCII bells, and the specific sound played might be modified in system settings.
Also, this won't work in the browser. For that, you'll have to use a sound file.