Re: iio and jack - 1MHz sample rate success

[Christian Gagneraud <chgans@gna.org>]

On 12/02/14 20:36, Matt Flax wrote:
>
> I have implemented the jack2 iio driver and have done a couple of tests.
>
> In a preliminary finding, waiting for more time to test and re-test, I
> have had success.
> I don't see any overruns reported (when setup properly), and I haven't
> put a signal through the system to highlight any un-reported overruns.
> Next week I will look into this more.

Hi Matt,

This is a very interesting usage of the linux-iio framework. Can you say 
a bit more about your analog front-end? Did you use an audio IC, or 
SPI/I2C ADC? If so which one.

Thanks,
Chris


>
> Firstly I would like to say that writing a driver for jack2 is a little
> difficult because there is not much documentation ... at least I
> couldn't find simple information. Some inline src doc would be good ...
> mind you, I could have put more into my driver as well :)
>
> On the system with IIO devices I ran :
> jackd -iio
>
> I then setup and ran netjack on both computers.
>
> On the other computer I used :
> jack_capture -c 2 -p system:capture*
>
> ... wahlah ... it worked ! with an MTU of 1500. Thats 2 channels @ 1 MHz
>
> Everything reporting 1MHz sample rates and so on a so forth, no xruns
> and the wav file looked like what I expected ...
>
> When I tried to record 4 channels @ 1 MHz, I had to increase the MTU to
> 6000 to get rid of xruns on the ARM core. But still ... 4 channels @
> 1MHz over a network ... pretty good start !
>
> I would like to integrate my both of my iio branchs into the jack1 and
> jack2 repos, but for now I have forked the jack2 repo here :
> https://github.com/flatmax/jack2/tree/iio
>
> I have some questions for other developers of jack2.
> is it necessary to use :
>      JackDriver::CycleTakeBeginTime();
> and
>      JackDriver::CycleTakeEndTime();
>
> ?
>
> thanks
> Matt
> p.s. Don't forget that these findings are very preliminary and things
> need to be neatened up, debugged more and so on and so forth.
>
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