In my message, archived here http://lists.squeakfoundation.org/pipermail/vm-dev/2007-October/001595.html I mentioned that it seems that once a sound has played, the image keeps sending silence to the sound device.
This keeps the CPU quite busy, as seen both by the OS (load average) and the interpreter (slower benchmarks).
I've had a little more time to dig into this, and it seems this is expected behaviour: it is toggled by the "soundStopWhenDone" preference, and read in SoundPlayer>>playLoop. It seems that this is off by default (i.e. sound never really stops, once started). Switching it to "on" solved my problem.
So now I'm curious. Why was it built this way? And why do released images have this preference off?
For most modern hardware, this isn't an issue, but for slower hardware (e.g. mine), or for power-lean systems (e.g. the OLPC) I think it could be.
Andrew
Andrew Gaylard wrote:
So now I'm curious. Why was it built this way? And why do released images have this preference off?
Purely historical coincidence. Things used to work more smoothly on Mac OS 7-9 if we kept sending silence instead of turning the whole soundsystem on and off. I added the preference since on Windows ('95 and '98) access to the sound device is exclusive so having had Squeak play a sound once would make it inaccessible for other apps.
I don't think any of these concerns are valid any longer.
Cheers, - Andreas
Thank you, Andrew,
For most modern hardware, this isn't an issue, but for slower hardware (e.g. mine), or for power-lean systems (e.g. the OLPC) I think it could be.
The soundStopWhenDone preference is set to on in the OLPC Etoys image, FYI. When the user switches away from Etoys, we also shutdown the sound system.
-- Yoshiki
vm-dev@lists.squeakfoundation.org
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Andreas Raab -
Andrew Gaylard -
Yoshiki Ohshima