sound volume changes randomly all the time

hybrid · 2011-09-10 11:50:42

For some time now I notice the volume on my machine is changing whenever it plays a sound. For example when I listen to music, out of the sudden the music is a lot more loud or a lot quieter. It will keep changing from louder to quieter pretty much permanently and seemingly randomly. The mixer controls do not change, just the sound coming off my speakers does. This is really annoying.
So far I noticed this in audacious, amarok, mplayer, or when I watch tv with kaffeine (dvb), or when I watch videos with mplayer, xine, or with flash in firefox and opera. Basically whenever any application plays a sound. However I did not notice skipping or an otherwise distorted sound. Only the volume changes randomly.
I use alsa, no soundservers are installed. Soundcard is a soundblaster live.

pacman -Qs alsa
local/alsa-firmware 1.0.24.1-1
    ALSA firmware package
local/alsa-lib 1.0.24.1-1
    An alternative implementation of Linux sound support
local/alsa-oss 1.0.17-2
    OSS compatibility library
local/alsaplayer 0.99.81-2
    A heavily multi-threaded PCM player that tries to excercise the ALSA library
    and driver quite a bit
local/alsa-plugins 1.0.24-2
    Extra alsa plugins
local/alsa-utils 1.0.24.2-3
    An alternative implementation of Linux sound support

lsmod | grep snd
snd_emu10k1           121609  2 
snd_rawmidi            15196  1 snd_emu10k1
snd_ac97_codec         90021  1 snd_emu10k1
ac97_bus                 810  1 snd_ac97_codec
snd_pcm                60015  3 snd_emu10k1,snd_ac97_codec
snd_seq_device          4252  2 snd_emu10k1,snd_rawmidi
snd_timer              15374  2 snd_emu10k1,snd_pcm
snd_page_alloc          5837  2 snd_emu10k1,snd_pcm
snd_util_mem            1804  1 snd_emu10k1
snd_hwdep               4942  1 snd_emu10k1
snd                    43561  10 snd_emu10k1,snd_rawmidi,snd_ac97_codec,snd_pcm,snd_seq_device,snd_timer,snd_hwdep
soundcore               4986  1 snd

let me know if you need more information.

I already tried setting the cpufreq governor to performance to see, if this issue is related to the cpufreq scaling (archlinux wiki -> alsa recommends that to get rid of sound skips) but the volume was still changing. I did not change my computer hardware, nor did I change my setup software wise (eg installed a soundserver or whatever, did not do that). Unfortunately I can't say exactly for how long I'm experiencing this sort of trouble, maybe a couple weeks (like 2 - 4 weeks). It could be that this issue occured with the change to kernel 3.0 but I can't say that for sure.

thisoldman · 2011-09-10 13:30:51

Your problem is not unusual. It's most probably because of the recorded sound levels, not your equipment or your ears.

Modern commercial recordings have the dynamics compressed and are mastered 'hot'. Non-commercial and amateur recordings are recorded at many different signal levels.

A possible solution is to add an effect plugin called a compressor or limiter into the audio chain.

You can read the article "Loudness war" on Wikipedia. My favorite illustration of the different dynamic levels used for commercial recordings is from http://johnvestman.com/disease.htm. The author credits Wikipedia for the image.
Increasing loudness waveform

Captioned: The trend of increasing loudness as shown by waveform images of "Something" by The Beatles mastered on CD four times since 1983.

Edit: I don't know why the perceived differences seem to only be recent for you. This has been a complaint of mine for the last ten years.

Did you change your listening environment?

Last edited by thisoldman (2011-09-10 13:53:12)

stqn · 2011-09-10 14:00:58

Have you tried other speakers or headphones?

hybrid · 2011-09-10 14:13:14

Well that's definately an interesting article, but I'm not sure, how this may be related to my issue.
I mean, from what I understand this loudness race you are referring to is a general development over the past decades. So why has my computer never ever shown this sort of issue with the playback. And out of the sudden my computer is thrown off by that?
My volume problem occurs regardless of wether I play old mp3 files, old family videos, old tv recordings, newer videos, newer tv recordings, files that were played fine up until only a couple weeks ago on the same computer. I just booted a linux live dvd (knoppix 6.7dvd) and it plays the very same files perfectly fine.
That makes me think, that aside from that general development you mentioned, there must be something acute.

Edit I havent tried different speakers/headphones yet, but I will get some tomorrow and try that. Though since everything works with a linux live dvd, I personally don't expect a difference. But you're right, I should try that too. Will do that tomorrow.

Last edited by hybrid (2011-09-10 14:17:28)

thisoldman · 2011-09-10 14:23:15

Some gstreamer plugin upgrades were made available August 10. Does that seem a likely cause?

hybrid · 2011-09-10 14:50:38

I do have gstreamer installed. I use fluxbox as my WM. 'mplayer -ao alsa' on a test video is suffering the volume changes.
I don't know, is gstreamer involved in this case? I wouldn't think so, but again, I don't know alsa that well and I know even less about these "modern" things like gstreamer. I can only make (more or less) educated guesses and supply you with information.
What can I do to test, if gstreamer or it's plugins are causing this?

thisoldman · 2011-09-10 15:24:46

I don't know how intimately ALSA and gstreamer are connected.

I'm pretty sure VLC doesn't use gstreamer but I'm not 100% certain. Do the sounds show similar level variations using VLC? I don't have time to remove gstreamer and test this.

An annoying aspect of your problem is that your audio reproduction is probably more accurate now than before. I'm much more familiar with audio hardware than software and I usually opt for hardware solutions.

hybrid · 2011-09-10 17:11:26

To my understanding the only connection between alsa and gstreamer is, that if an application uses gstreamer, gstreamer will pass it on to alsa. But there shouldn't be a deeper connection - if an application does not use the gstreamer framework but alsa directly then gstreamer shouldn't be able to interfere in any way. So wouldn't the question be wether or not an application utilizes gstreamer or not? That probably sounds pretty obvious but I'm trying to understand things.
Anyhow, yes, vlc is showing the same behaviour.
Back to describing the changing volume: It's not like the volume jumps up or down to set levels, it's more like a little kid is playing with the stereo and cranking the volume control up and down. Holding at some level for a second or sometimes holding a level for up to a minute before the volume starts to have a mind of it's own.
What did you mean when you said the "audio reproduction is probably more accurate now than before"?

thisoldman · 2011-09-10 17:24:37

My mistake. I thought the volume difference was between files, not within a single file or stream.

Can you boot with something like an Ubuntu Live CD and see if the sound does the same thing?

hybrid · 2011-09-10 20:46:17

As I mentioned in post #4: done that, linux live cd played everything perfectly.

thisoldman · 2011-09-12 02:29:02

I really am at a loss. The only thing I can think to suggest, is try a different kernel. The last kernel update was around August 7, the one before that was around August 9. I have no experience rolling back kernels.

Last edited by thisoldman (2011-09-12 02:30:23)

Arch Linux

#1 2011-09-10 11:50:42

sound volume changes randomly all the time

#2 2011-09-10 13:30:51

Re: sound volume changes randomly all the time

#3 2011-09-10 14:00:58

Re: sound volume changes randomly all the time

#4 2011-09-10 14:13:14

Re: sound volume changes randomly all the time

#5 2011-09-10 14:23:15

Re: sound volume changes randomly all the time

#6 2011-09-10 14:50:38

Re: sound volume changes randomly all the time

#7 2011-09-10 15:24:46

Re: sound volume changes randomly all the time

#8 2011-09-10 17:11:26

Re: sound volume changes randomly all the time

#9 2011-09-10 17:24:37

Re: sound volume changes randomly all the time

#10 2011-09-10 20:46:17

Re: sound volume changes randomly all the time

#11 2011-09-12 02:29:02

Re: sound volume changes randomly all the time

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