Re: [2.4.17/18pre] VM and swap - it's really unusable

Chris Friesen
2002-01-10T19:33:09Z

Rob Landley wrote:

> And a sound card with only 1mS of buffer in it is definitely not useable on
> windoze, the minimum buffer in the cheapest $12 PCI sound card I've seen is
> about 1/4 second (250ms). (Is this what you mean by "hardware fun"?) Even
> if the app was taking half that, it's still a > 100ms big gap where the OS
> leaves it hanging before you get a dropout. (Okay, some of that's watermark
> policy, not sending more data to the card until half the buffer is
> exhausted...) What sound output device DOESN'T have this much cache?

Imagine taking an input, doing dsp-type calculations on it, and sending it back
as output. Now...imagine doing it in realtime with the output being fed back to
a monitor speaker. Think about what would happen if the output of the monitor
speaker is 1/4 second behind the input at the mike. Now do you see the
problem? A few ms of delay might be okay. A few hundred ms definately is not.

> Now VIDEO is a slightly more interesting problem. (Or synchronizing audio
> and video by sending really tiny chunks of audio.) There's no hardware
> buffer there to cover our latency sins. Then again, dropping frames is
> considered normal in the video world, isn't it? :)

If I'm trying to watch a DVD on my computer, and assuming my CPU is powerful
enough to decode in realtime, then I want the DVD player to take
priority--dropping frames just because I'm starting up netscape is not
acceptable.

Chris

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