On 3/20/2014 6:13 PM, Alexandru Csete wrote:
Few weeks ago I was trying "rtl_fm ... | aplay ..." on a raspberry pi,
but all I got was very choppy audio. There was no significant CPU load
and if I used rtl_fm and aplay separately they worked just fine.
Perhaps they changed something in the kernel configuration that lead
to this behaviour. Do you remember which OS configuration used to work
for you
Thanks Alexandru, good to know it's not just me. Actually, several
others have reported the same problem in the past few weeks, so
something has definitely changed. After looking through my dpkg
history, I can't see any updates to ALSA in that timeframe so I think it
may be some changes to the Rasbian OS. But I'm not sure where to look
specifically.
I can run the identical command line parameters on a low-powered Xubuntu
box with exactly the same verbose aplay display, yet audio plays
smoothly without any underuns. One difference is that box has
Pulseaudio installed, but since it sits on top of ALSA I don't see it
fixing a buffering problem between rtl_fm and aplay.
Here's an oddity: with the CPU maxxed-out by a rogue process, audio
played smoothly with no underruns. But as soon as I killed the rogue
process, choppy, interrupted audio resumed.
73, Bob W9RAN
