[Sugar-devel] TA with sensors

[Walter Bender]

Thanks for this background.

I think that the try/exception mechanism is adequate for our needs. It
will be otherwise trivial for me to add the sensor features to the
main branch of TA... I'll add it to the next release.

I wonder if there is a mechanism we can call upon (Sugar should
perhaps provide this) that will tell us that we are being sent to the
background so that we can only reinitialize when we go away and come
back? It seems that for every call to the sensor, it is a large
overhead to incur...

-walter

On Fri, Jan 2, 2009 at 2:25 PM, Arjun Sarwal <arjunsarwal at gmail.com> wrote:
> Hello Walter,
>
> Thank you for the new year wishes. Best wishes to you too for the new
> year! (hope you received my card too)
>
> A few points regarding adding sensor support
>
> * Calls to Alsamixer to set the DC mode on/off will result in an
> exception on one's normal laptop. This is because the DC mode controls
> don't exist in the Alsamixer of a normal laptop (even sugar emulation
> makes calls to the laptop's default alsamixer)
>
> * I had put in initializations before each call to the sensor because
>  - user may switch to another Activity  in between a session of Turtle
> Art -- the other Activity  may use the laptop's sound device. The
> other Activity may alter the sound device settings.
>  - unless a call for sensor input is being made, I didn't want to keep
> the capture device active.
> The capture device can be thought to be in a state of 'recording
> sound' when one is getting sensor input data, hence only one
> Activity/program can have access to it at one time.
> However, any suggestions you may have on the above implementation
> would be very welcome.
>
>
> * If it helps, I am summarizing approximately the changes  I made in
> TurtleArt to add sensor support and some relevant lines to look at
> within the TA with Sensors code that I had made for the earlier (non
> SVG version of TAwithSensors):
> Referring to the  version of the online git tree ('Initial import')
> (http://dev.laptop.org/git?p=users/arjs/TurtleArtwithSensors;a=tree;h=3f22f9f86d60f6160268c52009273eba82dba465;hb=3f22f9f86d60f6160268c52009273eba82dba465)
>
> - audiograb.py as an additional file was included completely
> - talogo.py :
> (note that lines 8 and 9 in this version of git tree would need to be
> changed to
> from numpy.oldnumeric import *
> from numpy.fft import *  )
> lines 8,9,11,12 were added
> lines 366 onwards till the end have been added
> -tasetup.py: lines 47 to 51 to account for the additional sensor
> blocks in the UI
>
> As you can see from the code of talogo.py , the approach involves a
> lot of painful starting the whole gstreamer pipeline, getting one
> sample then stopping the pipeline. An overkill for getting just one
> sample, but there is no way unless python alsa audio is included in
> the build system. The approach with python alsa audio is work in
> progress here (
> http://dev.laptop.org/git?p=users/arjs/TurtleArtwithSensors;a=tree )
>
> I want to work on incorporating sensor support into the SVG version of
> TA that you have made, but my current day job isn't leaving me any
> time these days to do anything else. I will get to it as soon as I get
> the opportunity, but if in the meanwhile you get a chance to do it -
> it'd be great.
>
> Please let me know if I can help further.
>
> Kind Regards
> Arjun
>
> On Fri, Jan 2, 2009 at 3:18 AM, Walter Bender <walter.bender at gmail.com> wrote:
>>
>> I've begun folding TA with sensors into TA. I use an exception to
>> catch the calls to set DC Mode in Alsamixer, so it seems to run fine
>> on my normal laptop using the mic input. But when I look at the logs,
>> it seems that there is a lot of initialization that happens with every
>> call to the sensor. Is that all necessary? Can we just check for
>> changes after the first time?
>>
>> -walter
>>
>>
>>
>>        # test to see if DC Mode is enabled
>>        try:
>>            self.dcmode = Mixer('DC Mode Enable')
>>            self.bias = Mixer('V_REFOUT Enable')
>>            self.has_dcmode = True
>>        except:
>>            print "DC Mode unavailable"
>>            self.has_dcmode = False
>>
>>
>>
>> Walter Bender
>> Sugar Labs
>> http://www.sugarlabs.org
>
>
>
> --
> Arjun Sarwal
>



-- 
Walter Bender
Sugar Labs
http://www.sugarlabs.org