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

[Andoru]

>
> 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.
___________________________________________________________________________________________________
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:


>  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
COMMAND
> 2375 andoru    20   0 1153140  62276  13140 S  21.3  0.8  29:36.91
foobar2000+

>  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
COMMAND
> 2375 andoru    20   0 1153140  62032  13140 S  24.6  0.8  29:16.33
foobar2000+

>  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
COMMAND
> 2375 andoru    20   0 1153140  72756  11808 S  22.6  0.9  29:03.99
foobar2000+


Let me know if you need any additional info.

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?
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