[alsa-devel] somebody ever see ALSA applied in robotics ?

[Alex Austin]

You may be better off working with JACKd than straight-up ALSA.
Also, you may want to look into PureData for your app. I've never used it
though. Can anyone else chime in on this?

- Alex Austin
(651) 238-9273

"...and then I visited Wikipedia ...and the next 8 hours are a blur."


On Fri, Dec 19, 2008 at 3:50 PM, Ronald <raalst at gmail.com> wrote:

> Hi, all,
>
> I'm trying to develop a system which can determine the direction(s)
> sound comes from.
> In the end, it will be put in an R/c submarine, on a gumstix linux board
> (see  http://www.subcommittee.com for my hobby)
>
> But for now, I develop in air, with ubuntu.
> all I want is to record using both the mic channel and the  line in
> (where another 2 mics are attached with a small preamp),
> and I want to record while emitting a chirp, analyzing echo's.
> the concept has been shown to work. see for instance
> http://eddiem.com/projects/chirp/chirp.htm
>
> I am assuming that since all this goes via the same sound card, the same
> crystal is used, and samples from mic and line in are
> essentially synchronized (I only need it to be sync-ish for < 0,1 sec..)
>
> Now I have read a lot of ALSA tutorials and such like, but I'm lost.
> a lot is about humans consuming nice harmonics, sharing and mixing,
> which is not applicable to my case.
> I have the nagging feeling OSS is a better fit for my case, but OSS is
> apparently on a 60 day licence now.
>
> And, I am a newbie coder. no surprise there ;-)
>
> So, these are my questions :
>
> - Do I need to combine mic and line-in into one device using the
> config file ? do I get a 3 channel device then ? does a plug-in add
> latency ?
>
> - can I sync the transmission of a short chirp with the start of the
> recording on these 3 channels ? is starting them close after each other
> in the program OK, or is there possibly large latency caused *after* I
> call the API ? the "real" sync'ing will be the (first) recording of the
> chirp once it leaves the speaker, so it isn't critical, but I would like
> to know because it might save a few bytes useless samples.
>
> - Does anybody out there have any links, code snippets or general
> published info on how to apply ALSA to the robotics field ?
>
> Ps I have read the el-cheapo hack with multiple soundcards, and while a
> very good idea, I cannot use it in the boat later on..
>
> thanks for any input you might have.
>
> Regards,
> Ronald van Aalst
>
>
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