Pulseaudio glitches and CPU usage (netbooks with hda-intel by realtek) 5 February, 2009
Here you can find an example of the “pulseaudio glitches” we (unlucky netbook’s owners) hear.
I decided to reinstall pulseaudio, because I share Lennart’s idea that it’s better to start fixing drivers and applications as soon as we can: it’s useless, imho, to stop freesoftware’s development just because vendors/drivers/applications are bugged.
Some things work better than in the past months, banshee seems to be almost glitch-free (it wasn’t when I tried it in december).
I’m going to share with you my glitch-free experience: 
just recordered, sorry for the white noise but the netbook’s speakers have a low power noise removed thanks to audacity.
pulseaudio-frozenbubble-no-noise (FLAC, 1.8 MB, I can hear more glitches here)
pulseaudio-frozenbubble-no-noise (WAV, 3.2 MB)
pulseaudio-frozenbubble (FLAC, 2.0 MB, I can hear more glitches here)
pulseaudio-frozenbubble (WAV, 3.5 MB)
Pulseaudio 0.9.14, snd-hda-intel (Realtek ALC 272), Fedora Core 10.
Also, CPU usage for pulseaudio is between 10% and 35% (and ~25% without the g-f feature). Not really fun for the laptop’s battery.
5 February, 2009 alle 12:25
So I guess you have one of those buggy drivers.
http://pulseaudio.org/wiki/BrokenSoundDrivers
Have you tried to disable the g-f feature?
Regards
Achim
5 February, 2009 alle 12:40
@1:
disabling g-f makes the music stuttering… every glitch I heard before becomes a pause, like GO-OD-MO-R-NI-N-G.
5 February, 2009 alle 13:16
@2: (Cimi)
Could it be that the problem you have is related to SDL somehow?
5 February, 2009 alle 13:20
@3:
but I’m having glitches with banshee, lastfm, totem… I can fix them by adding tsched=0, but the CPU usage is still high, and I can’t have 20-30% of CPU usage on a netbook (for both battery life and performance)!
5 February, 2009 alle 19:41
you have better sound results than me then, obviously. Congratulations. My work laptop crashes horribly after a few minutes of broken sound output.
yes, Realtec chipset, Pulseaudio, glitchfree disabled.
Pity the good idea doesn’t work.
5 February, 2009 alle 21:49
The high CPU usage with pulseaudio and Intel HDA is from pulse using a CPU-heavy audio resampling algorithm to upsample 44.1kHz audio to the sound chip’s native 48kHz.
If you want lower CPU use, install the OSS4 driver, yum erase pulseaudio, use ossxmix to set up the jack functions (and set input vols to 0 to get rid of the noise), do `vmixctl rate /dev/dsp 44100` and use gconf-editor to set the audiosinks in system/gstreamer/0.10/defaults to osssink.
You do _not_ want to use oss4sink, as it requires gstreamer to upsample, and gstreamer’s audioresample is/was 5 times slower than pulse’s speex. You could use `speexresample ! audio/x-float-raw,rate=48000 ! audioconvert ! oss4sink’ for gstreamer, but that’s just as CPU-heavy as pulse’s as it uses the very same libspeex, so no gain there.
5 February, 2009 alle 21:57
@6:
I don’t know why you would upsample, the quality is the same if not even worse… after upsampling you have duplicated samples, which is the point on having them? spread the cpu?
I can understand that it is required for syncing the audio requests, but after knowing that pulseaudio is a big-no. I don’t want upsampling in software.
5 February, 2009 alle 23:31
You need upsampling if your hardware is only capable of 48KHz input and your audio file produces 44,1KHz. There is really no other choice in this situation. Additionally, you have to remember that functions are being removed from hardware and put into software. First multichannel mixing, then flexible frequency input, lately even volume level got removed from HW.
6 February, 2009 alle 0:44
it’s not resampling, it’s just a high cpu usage.
Just checked out.
8 February, 2009 alle 2:46
There is a bug with SDL that causes it to behave badly with PulseAudio.
https://bugzilla.redhat.com/show_bug.cgi?id=474745
25 February, 2009 alle 10:01
I’m having good results with pulseaudio from git. On my Archlinux with cpu usage is between 7 and 10% (Playing an mp3 at 320KB with banshee compiled from svn)
25 February, 2009 alle 12:17
@lorenzo:
It is not a good result. Pulseaudio should be 1-2%, not 10%.
26 February, 2009 alle 20:43
Well, for me, disabling the glitch-free feature has probably solved it. I am an ArchLinux user. (Acer notebook, Realtek ALC268 audio codec)
26 March, 2010 alle 13:20
topic PulseAudio - Tune your setting and prevent glitching
http://forums.linuxmint.com/viewtopic.php?f=42&t=44862