[orca-list] Latency reduction: get a snappier orca without removing pulse.

[Nolan Darilek <nolan thewordnerd info>]

Hello.

I was a bit annoyed with the solution for getting snappier response 
times from orca that involved removing pulseaudio from my ubuntu system. 
Like it or not, and I've done enough research to realize that there's 
quite a large "not" contingent out there, it looks as if pulse is here 
to stay. I didn't have a huge issue with the latency, but I wondered if 
it could be improved and I think I may have. Things seem slightly 
snappier, but it'd be good to have some independent 
testing/confirmation. If this works, it's so much easier than disabling 
pulse.

1. Configure speech-dispatcher to use the pulse backend. This should be 
fairly straight-forward and is configured via 
/etc/speech-dispatcher/speechd.conf or ~/.speech-dispatcher/speechd.conf 
[1].

2. Add your user to the pulse-rt group as shown:

$ adduser <username> pulse-rt

3. Log out and in so your user is in the group.

If you're a member of pulse-rt, pulseaudio doesn't drop privileges and 
allows for real-time scheduling. This, for me, seems to offer a slightly 
snappier response time. Granted, it wasn't all that bad before, but it 
seems even better now.

Can anyone else confirm this? Looking forward to trying it on my Eee 
later to see how much things improve there.

Update: Wow, the more I play with this, the more impressed I am. There 
used to be a slight delay between pidgin's outbound IM chime and the 
speaking of the message. Now it's almost instantaneous and flat review 
is a lot snappier. This seems like a much better solution than gutting 
my system. Note that it does have security implications since pulse is 
presumably still running with elevated privileges.

1 I wonder if the ubuntu speech-dispatcher package should configure 
itself to use the pulse backend by default? Granted, alsa is the SD 
default, but the configs don't work as shipped, and if ubuntu is going 
to default to pulse then perhaps it should ship a SD config with the 
same default. Unless anyone thinks this sounds like a horrible idea, 
I'll file a bug in launchpad, since it's not something that needs 
resolution upstream.