scratch team mailing list archive

[Derek O'Connell <doc@xxxxxxxxxxxxxxxxx>]

Hi all, I have been updating myself on PA issues. Last time I looked
(~December) Lennart Poettering had disappeared on holiday while quite a
few people were having problems on Karmic with the Simple_API (which I
use in the Scratch plug-in). The problem boils down to default latency
being ~2s, much too long for most app's, and not easily controlled via
Simple_API (my attempts failed at least). The volume meter set a low
latency in order to display the current sound level/s so that's why
things improved for other app's when it was running.

The problems were created by an internal change to the PA API
(supposedly one single flag setting!) between 9.04 / 9.10 and the good
news is that it's impact is at least now recognised. There seems to be
some new suggestions about how to get around the problem, including a
patch to set latency via an env var. So tomorrow I will see how far I
can get with them. The bad news is there seems to be new problems
introduced by the version of PA to be used in Lucid. Fingers crossed
they get sorted soon.

Re GStreamer, the hope was/is that a GSt based plugin for Scratch would
avoid these issues but thinking about it there is no guarantee since GSt
itself relies on plugin's to interface with whatever sound server is in
use. On Ubuntu that will still be PA out-of-the-box. PA can of course be
shut down and bypassed but the ideal solution is one that avoids forcing
what may be *novice* users from having to reconfigure their system just
to run Scratch (auto shutdown/start-up of PA is not an option for other
reasons). So it makes sense to me to concentrate on working around
current PA issues before considering GSt, although GSt is still
attractive for the other options it brings to the table, as well as
isolating Scratch from specific sounds systems, ie, more platform/distro
independence.

Btw, I don't claim to be an expert on any of the above, more like too
stubborn to know when to give up ;-) So if anyone else has expertise/
info/ advice I'm happy to hear it.

-D