Re: [Discuss-gnuradio] Stupid Soundcard Sample Tricks

[Eric Blossom]

On Sun, Jun 12, 2005 at 04:30:52PM -0400, John Ackermann N8UR wrote:
> Hi --
> 
> After successfully getting gnuradio and the USRP to run on my laptop
> (Thinkpad R40), I decided it was time to install it on my main hamshack
> computer.  Using the lessons I learned the first time, the code built
> just fine and I can talk to the USRP.
> 
> However, I'm having trouble getting audio out of the box.  The on-board
> AC97 soundcard seems frozen at 48ksamples/second, and the example
> programs I've tried print something like:
> 
> audio_alsa_sink[hw:0,0]: unable to support sampling rate 32000
>   card requested 48000 instead.
> 
> and I get extremely distorted audio and lots of underruns printing to
> the console.
> 
> Any suggestions how to resolve this problem?  I messed with the various
> decimation params in the example tvrx_wfm program, but managed only to
> prove how little I know what's going on inside the system.
> 
> Thanks,
> 
> John

Hi John,

Some sound cards will only run at 48,000 S/sec.

Try using plughw:0,0 as the pcm device (second arg to
audio.source/sink).  It will insert an automatic sample rate
converter.

Eric