Bug 498608

Description of problem:

If multiple alert-triggering events occur too close in time, the alert sound is only played upon the first event, whereas no alert sound is played for the remaining alert-triggering events.

Consider the case of two successive alert-triggering events. If the delay between the two alert events is longer than the duration of the alert sound, two distinct alert sounds are played. If, however, the second alert event is triggered before the sound for the first alert event has finished playing, no alert sound for the second alert event is played. If more than two event-triggering events occur within a time window shorter than the duration of the alert sound, only one alert sound is played. This is bad because all alerts but the first one essentially vanish.

In a situation where an alert is triggered every time a given key is pressed, pressing the key twice must lead to two alert sounds, no matter how quickly the two keypresses are done. This way, the user receives feedback on each of the two keypresses. Issuing a single alert sound would leave the user without feedback about the second keypress.

In order to combine the two alert sounds, two solutions come to my mind:
1. the first alert sound is interrupted and the second alert sound is played immediately afterwards
2. the second alert sound is superimposed to the first one
Note that when the system beep was used for alerts (prior to the introduction of libcanberra (*), I think), solution 1 was in place. The first beep would be interrupted to give way to the second beep. The user would (sloppily speaking) hear "Bee-beeeeep" and hence receive the information that two separate beeps had been issued.

(*) Thanks to bug 498594, this situation can currently be observed by turning the desktop effects on.


Version-Release number of selected component (if applicable):

As in the 2009-04-30 rawhide. In particular:
libcanberra-0.12-1.fc11.x86_64
pulseaudio-0.9.15-11.fc11.x86_64
alsa-lib-1.0.19-3.fc11.x86_64


How reproducible:

always


Steps to Reproduce:

1. Ensure desktop effects are disabled (see bug 498594) and that the sound theme is set to
"Default"
2. Open a gnome-terminal window
3. Push the "down" arrow very quickly two times within the gnome-terminal window to trigger two consecutive alert events
4. Keep the "down" arrow pressed to trigger a large number of consecutive alert events


Actual results:

In step 3, a single alert sound is heard.
In step 4, the alert sound is played periodically, with the period equal to the duration of the alert sound.


Expected results:

In step 3, two alert sounds be heard (either with the first one being interrupted to give way to the second one, as in solution 1, or with the second one superimposing on the first one, as in solution 2).
In step 4, multiple alert sounds be heard (again, either according to solution 1 or to solution 2), with the speed at which new alert sounds are started being equal to the keypress repeat speed specified in the keyboard preferences.