[hpsdr] Metis/Ozy Together on Atlas

[John Marvin]

Alberto,

Thanks for replying and also for writing Winrad. I do have a question 
about the implementation. Couldn't the extio api have been extended to 
add api's for writing the demodulated audio back to the device? That way 
all of the hardware dependencies could have been contained in the extio 
dll and the latency would not have been a problem. Since I have not 
looked at it closely I may have missed something.

As far as latency is concerned, as you said, VAC should be no worse than 
using an audio card. So yes, you lose the latency advantage but at least 
you would still be able to choose which audio output to use, which 
depending on your circumstance may be important. At this point a 
solution like this may be the only option for supporting Metis and/or 
Hermes users.  I may look into doing this sometime in the future.

John
AC0ZG

On 12/14/2012 3:22 AM, Alberto I2PHD wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
>
>
> On 12/13/2012 11:57 PM, John Marvin wrote:
>
>> /But I wonder if there isn't another way of doing this. Perhaps a new
>> extio that understands the metis/hermes UDP protocol combined with using
>> VAC would allow development of an extio that doesn't need support within
>> the program itself.  The VAC part wouldn't be necessary if you were
>> happy with using the computer sound for the audio output. But if you
>> wanted the sound to go back to the Mercury/Hermes you could set Winrad
>> to output to VAC and the extio would have an option to listen on the
>> other side of the VAC and send that audio back to Mercury/Hermes via the
>> network interface. Just a simple weekend project as Phil likes to say//:)//./
>
> John,
>
>     I thought at this possibility when developing the ExtIO DLL for
> HPSDR, but then I dismissed
> it because it negated the main advantage of using the on-board DAC of
> Mercury...  latency...
> If you pass through VAC you have about the same latency of a real sound
> card.
>
> The reduction in latency is directly perceivable if you enable both the
> sound card output and
> the DAC output in the DLL... a few tens of a second...  that's why I
> took the way to modify
> Winrad to send the demodulated audio through the reverse USB channel to
> Mercury for playback.
> I would have preferred to keep the main program hardware-agnostic,
> relegating all the HW
> specific functions to the ExtIO DLL, but in this case I had no choice.
>
> BTW, while we are talking of this, I switched on my HPSDR combo after
> more than year that
> it was on hold on a shelf (I needed the table space for other tasks),
> and noticed that the
> DLL has some problems with the latest firmware V3.3 for Mercury.  I am
> modifying it (almost done)
> and will upload it to the SVN when ready.
>
> --
> /*73 Alberto I2PHD*/
>
>
>
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