audio crackling when playing low frequencies

[Nicolas Dufresne]

Le vendredi 09 juin 2017 à 12:45 -0300, wellington wallace a écrit :
> Hi,
> 
> When running the command:
> 
> gst-launch-1.0 audiotestsrc freq=40 ! pulsesink

I also can't reproduce at 40. Cracking can be heard starting at freq=8
and lower for me.

> 
> I can hear the test signal but also lots of crackling. When using
> higher frequencies(above 100Hz or 200Hz) I do not hear any crackling.
> Replacing pulsesink with alsasink does not change the problem. Is
> there a test I can do to know if this problem is in Gstreamer or
> Pulseaudio?

Note that to really test against alsasink, you need to set the device
property to avoid the default, which is likely going through pulseaudio
on most system. On my Intel SoC, I use this to compare:

  alsasink device=sysdefault:CARD=PCH

Though, it makes no difference. I have done further test, I have
recorder the test stream into a wav and use aplay to play it back.
Result would show the same crackling. That least two option, the wave
generator might be broken, or it's driver/alsa issue. The fact it's
better for certain users might indicate that different version of the
driver are handling this better (the generator code in GStreamer
haven't changed for years).

  gst-launch-1.0 -e audiotestsrc freq=8 is-live=1 ! wavenc ! filesink location=test.wav
  aplay test.wav -D sysdefault:CARD=PCH

Maybe you should share the kernel verison your are running this on. I'm
running Fedora kernel 4.11.3 and AlsaLib version 1.1.1.

regards,
Nicolas
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: This is a digitally signed message part
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20170609/82c03075/attachment.sig>