On 4/16/2014 12:02 PM, David Radakovits wrote:
Hi!
So i finally got the rtl-sdr "working" on my raspberry pi.
What i have now, are buffer underruns when i type
rtl_fm -f 87900000 -M wbfm -s 200000 -r 48000 - | aplay -r 48k -f S16_LE -t raw
-c 1
i had those underruns too on ubuntu which i ran in virtual box on my mac,
but i didn´t get them on a notebook running xubuntu, everything was working
fine there.
any ideas why i get them and how to fix it?
David,
I and others have been working this issue on the Raspberry Pi forum, as
the root cause has been identified as an unintended side-effect from a
recent kernel change. For details see:
http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=72545 and related
threads. The issue affects other ALSA applications and the issue has
been opened on github. At least one user has reverted to a previous
kernel version which does eliminate the problem, but creates new ones in
terms of keeping the Pi updated.
One experiment you might try is to run top in another console while
you're experiencing the buffer underruns - CPU utilization should be
running <20%. Then run top again using this command option: top -d .01
(causing top to update almost continuously). In my case, anything like
this that prevents the CPU from becoming idle allows the audio from
rtl_fm to stream without interruption.
Hopefully the linux kernel developers will be fixing this soon,
especially with the recent improvements that have been made to rtl_fm.
73, Bob W9RAN
