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Re: Updates To Outloud Alsa Server

The difference you notice between espeak and outloud could be due to
the different architectures used and libraries involved.

When you ask espeak to synthesize the text, you pass the text off to
it and it takes care of both the synthesis and the subsequent
rendering via the sound system. Depending on how espeak has been
compiled, this could also involve portaudio or pulseaudio or just
plain alsa.

With outloud, its a little different. You pass the text to be
synthesized to outloud, which creates the wave sound data, which is
passed back to the calling program, which is then responsible to
sending it to the sound system etc. This is why the outlloud code has
to deal with lower level also library calls and the espeak server does

This difference may also explain the difference in responsiveness. I
suspect that espeak is possibly sending small chunks to the sound
system, making it slightly more responsive to being intgerrupted. It
could also be that as more of the processing is handled by the espeak
library, the higher level script is able to be more responsive than it
is with outloud where it is also handling the management of the sound
output at a much lower leve.

I really don't understand all the nitty gritty details of Also and may
have all the details confused. However, I do know from looking at the
code and having worked with the espeak server etc, that the underlying
architecture of the two systems are quite different and making
comparisons between the two is likely to be misleading.

I would be interested if anyone has any good pointers that explains
the alsa architecture with a bit more clarity and overview than what
is avilable via the existing documentation. While I can use the API
and sort of understand much of it, I can't say I really understand how
it all hangs together!


On 4 March 2012 05:50, Alastair Irving <alastair.irving@xxxxxxxxxxx> wrote:
> On 03/03/2012 18:24, T. V. Raman wrote:
>> This is not a threading issue -- it is probably triggering
>> because of the virtualization layer you mentioned.
> I appologise for my ignorance but why should virtualisation make a
> difference with outloud but not espeak?
> Alastair
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