iio and jack - 1MHz sample rate success

iio and jack - 1MHz sample rate success

[Matt Flax]

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.

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.

Re: iio and jack - 1MHz sample rate success

[Christian Gagneraud]

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.
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: iio and jack - 1MHz sample rate success

[Matt Flax]

On 14/02/14 11:47, Christian Gagneraud wrote:
> 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.
>

Thank you,

The chips were AD7476A chips, so an SPI bus. There was hardware level 
and kernel level support from Lars-Peter Clausen and Alexandru Tofan.

Matt

> 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.
>>
>> -- 
>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
> -- 
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html