[Pkg-alsa-devel] Bug#881715: alsa-utils: High CPU usage on the default device

[Elimar Riesebieter]

Control: tags -1 unreproducible


* Andoru <aekkusu at gmail.com> [2017-11-14 23:45 +0200]:

> >
> > Just run htop while an alsa-process needs high cpu load. Copy the
> > line which shows that from (h)top to this bug report. Or just file a
> > screenshot to a puplic server somewhere.
> >
> 
> Alright:
> VLC playing a FLAC file on the default device:
> 
> >  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
> COMMAND
> > 26183 andoru    20   0 1191000  66424  46296 S  13.6  0.8   0:09.43 vlc
> ___________________________________________________________________________________________________
> 
> VLC playing the same file with "Analog Front Speakers" subdevice selected
> under Audio -> Audio Device:
> 
> >  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
> COMMAND
> > 26183 andoru    20   0 1195412  69176  48644 S   1.3  0.9   0:11.35 vlc
> 
> ___________________________________________________________________________________________________
> 
> As you can see, the CPU decreased from 13.6% to 1.3% when switching the
> device.

I tried that on 3 different soundcards. I don't get vlc as a htop
COMMAND. It is always /usr/bin/vlc. Please tell me how you fired up
vlc. The %CPU usage isn't reproducible on none of the soundcards
handy for me. 

> ___________________________________________________________________________________________________
> To confirm that this is not an issue with the decoder in VLC here's VLC
> playing an OGG Vorbis file on the default device:
> 
> >  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
> COMMAND
> > 26183 andoru    20   0 1263372  76228  48368 S  18.3  1.0   0:15.95 vlc
> ___________________________________________________________________________________________________
> 
> Same test as above, this time with an MP3 file:
> 
> >  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
> COMMAND
> > 26183 andoru    20   0 1416816  91532  60188 S  17.0  1.2   0:19.64 vlc
> 
> ___________________________________________________________________________________________________
> 
> And foobar2000 playing FLAC OGG and MP3 files, respectively:

I don't know how you got foobar2000 into Debian but this isn't¬
maintained in the repos, so not relevant to this bug.

> Also, in the initial report, I forgot to mention that when I select "Analog
> Front Speakers" subdevice in VLC, with some decoders (particularly APE) and
> when the sample rate is below 44100Hz, I can hear some distortion
> (crackling on high pitched sounds), so I'm guessing the high CPU usage is
> maybe due to an inefficient resampler?

Try to cancel all pulseaudio stuff and test again. Let me know....

Elimar
-- 
  Never make anything simple and efficient when a way
  can be found to make it complex and wonderful ;-)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: not available
URL: <http://lists.alioth.debian.org/pipermail/pkg-alsa-devel/attachments/20171115/683b1ae3/attachment.sig>