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Re: emacspeak, alsa and other sound applications

Hi Peter,

just wondering if you have experienced the same issue regarding
latency if you use a different speech server, such as espeak.

One of the issues which may impact on your latency is the need for
outloud to use the dmix alsa plugin and the unusual sample rate of
11025 generated by the outloud libs rather than more common 44100 or
48000. I'm guessing this would involve more processing in order to mix
the signal with other sound signals.

Many modern sound cards do incorporate multiple channels, so it could
be possible to create a .asoundrc file which sets up one channel just
for outloud and one for your other app. The only problem with this is
that becuase cards tend to differ quite a bit, it will be difficult to
define one asoundrc file which will work on a majority of platforms
i.e. would need to be tweaked for each one.

The above two points are just guesses. What you really need to do is
some profiling to determine exactly where the latency issue is coming
from. Without this information, you can never really be sure you have
fixed the problem. While a pain to setup, it will at least give you a
solid basis to decide if the problem is just with your app and
emacspeak, a specific emacspeak speech server such as outloud or if it
is likely to be a more general issue and only noticeable now because
emacspeak is creating just the right conditions and you could see the
same problem with other apps that may also run at the same time.


On Thu, Sep 15, 2011 at 10:01 AM, Peter Rayner < >
<prayner@unimelb.edu.au> wrote:
> This is not exactly an emacspeak problem although there might be an
> emacspeak solution so I hope it isn't too off topic.
> I'm writing an application (let's call it soundscape) for sonifying 2d
> graphics with the use of a touchpad or graphics tablet. This requires
> relatively low latency so the output responds to the position of your
> finger. Other requirements for me are that it runs under gnome, that
> it must not interfere with emacspeak (currently running the 32-outloud
> server) and it must run on a laptop (i.e
> one soundcard). Without emacspeak it works fine. With emacspeak
> running I can't tune the buffer sizes to get the latency down far
> enough. I don't know how much of this I can fix by having emacspeak
> and soundscape talk to different ALSA plugin devices given that
> they're talking to the same underlying hardware. The recent addition
> of the ALSA_DEFAULT environment variable for the outloud speech server
> makes this possible but my experiments so far haven't helped, probably
> a comment on my ignorance of the alsa architecture.
> My question to the alsa users list came up blank so I'm now hoping
> someone has had a similar enough problem with emacspeak to suggest a
> solution.
> thanks in advance for any help
> Peter
> --
> Peter Rayner
> room 343
> School of Earth Sciences, University of Melbourne, 3010, Vic, Australia
> tel: work: +61 (0)3 8344 9708; fax: +61 (0)3 8344 7761
> mobile +61 402 752 379, skype: petermorag
> mail-to: prayner@unimelb.edu.au
> and
> http://www.climmod.com
> mail-to: Peter.Rayner@climmod.com
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Tim Cross
Phone: 0428 212 217

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