Re: [Discuss-gnuradio] question about overruns with simple flowgraph

[Marcus D. Leech]

On 08/05/2013 09:00 PM, Nick Foster wrote:
> A couple of seconds seems pretty fast, however. Make sure you're 
> resampling the audio to a rate which is actually supported by your 
> soundcard.
>
> --n
The two-clock problem tends to manifest as the occasional "click" or 
occasional 'O'.

But if the rates between USRP source, and audio sink are significantly 
mis-matched, you end up with overruns very quickly, since buffers will
  start to fill up to exhaustion, since the sink isn't taking samples 
as fast as they're being produced.

There's no "magic" rate-adaptation in Gnu Radio.  If you have a filter 
block that is decimating down to, let's say, 50kHz, and then feed it into
  an audio sink that's expecting data at 48kHz, things will get stuffed 
pretty quickly.  Just because a (hardware) sink is expect data at
  some rate, doesn't mean that Gnu Radio automatically "tweaks" the 
flow graph to deliver data at that rate.  Gnu Radio is a streaming
  architecture, it doesn't actually inherently "know" about sample 
rates, so you have to take care of decimating/interpolating data streams
  so that things "match".


--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org