pulseaudio eats almost 100% of cpu resources during hdd i/o stress by other program (Re: audio skipping/pure sound quality)

[Michał Piotrowski]

Hi,

2011/1/18 Richard Ryniker <ryniker at alum.mit.edu>:
> I have experienced effects like those you described when Pulseaudio (or
> perhaps something else in the audio-processing chain) must do sample-rate
> conversion, such as from 44.1 KHz to 48KHz, to drive my USB speakers.
>
> Sox has been an effective solution for me.  Try "play" (a link to sox that
> denotes output to sound hardware instead of a file) to learn whether sox
> may offer superior sample-rate conversion that avoids the problems you
> hear.
>
> There are probably a handful of tools that will display information
> about sound devices.  Audacity has a convenient one:
>
>    Help -> Audio Device Info
>
> that displays supported sample rates.  For example, I see:
>
>    Default capture device number: 13
>    Default playback device number: 13
>    ==============================
>    Device ID: 0
>    Device name: ALSA: Bose USB Audio: USB Audio (hw:0,0)
>    Input channels: 0
>    Output channels: 6
>    Low Input Latency: -1.000000
>    Low Output Latency: 0.010667
>    High Input Latency: -1.000000
>    High Output Latency: 0.042667
>    Supported Rates:
>        48000
>    ==============================

Hmmm...
==============================
Device ID: 1
Device name: ALSA: SB Audigy 2 NX: USB Audio (hw:1,0)
Input channels: 2
Output channels: 0
Low Input Latency: 0,010667
Low Output Latency: -1,000000
High Input Latency: 0,042667
High Output Latency: -1,000000
Supported Rates:
==============================

What an interesting coincidence with high/low i/o latency numbers :)

Apparently my card doesn't support rates, but there is a

==============================
Device ID: 4
Device name: ALSA: surround51
Input channels: 0
Output channels: 2
Low Input Latency: -1,000000
Low Output Latency: 0,011610
High Input Latency: -1,000000
High Output Latency: 0,046440
Supported Rates:
    8000
    11025
    16000
    22050
    32000
    44100
    48000
==============================

I think that problem is somehow related to disk i/o in my case.

I'm doing yum upgrade on one console and on second console I did
dd if=/dev/zero of=plik.dat bs="128M" count=32
and pulse audio eats almost 100% of cpu resources
 1308 michal    20   0  669m  54m  36m S 99.9  2.7   5:36.03 pulseaudio

I use amarok for playing music - I'm not sure if it has any relevance.

Tomorrow I can take some time to try trace what is the source of this
behavior. All suggestions would be appreciated


>
> Output like this may display a needed sample rate for your USB sound
> device (48000 in my case).  If you use sox to convert a file to the
> target rate before you play it, and it then sounds good, this confirms
> the problem involves resampling.
> --
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-- 
Best regards,
Michal

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