[pulseaudio-discuss] [alsa-devel] pulseaudio eats 19% CPU power in Fedora 12

[Dan Kegel]

[crossposts removed]

On Mon, Apr 19, 2010 at 7:48 AM, Lennart Poettering <mznyfn at 0pointer.de> wrote:
>>         current latency: 444.25 ms
>>         requested latency: 31.25 ms
>
> So, this is interesting: the client requested 30ms (which is needlessly
> low, but that's another question),

I'm interested in that other question.    What is a reasonable latency
to request?   In video games, especially ones streamed from
remote servers (e.g. OnLive), latency is a huge issue; the
network latency is unavoidable, so their client app is likely
to be very keen to have minimal locally-caused latency.

http://www.gamasutra.com/view/feature/3725/measuring_responsiveness_in_video_.php
suggests that gamers will start noticing if the time from pressing
a button to the time they hear a sound is above 70 to 100ms.
Let's say the network latency to the game server is 20ms (can't ask
for much lower),
and that the streaming codecs have a latency of 10ms on each end (likewise).
The time from a button push to hearing a sound would then be 20ms up +
10 ms encode + 20 ms down + 10 ms decode = 60ms.  That
leaves all of 10 to 40 ms for local audio latency.
So, in what way is requesting 30ms unreasonable in that scenario?
- Dan