Sound Streaming Problem

Mark Eggers mdeggers at
Fri Jul 30 20:13:22 UTC 2010

On Fri, 30 Jul 2010 12:09:13 -0500, Rick Sewill wrote:

> Hash: SHA1
> On 07/30/2010 10:43 AM, Oliver Ruebenacker wrote:
>>      Hello,
>>   I have a recurring problem with sound streaming with Fedora 13 (and
>> earlier versions - I am having this problem for quite a while, across
>> different Fedora versions) on my Dell Latitude 820 laptop. This affects
>> equally the sound of YouTube videos and music CDs. Sometimes it works
>> flawlessly, sometimes there is no sound, and sometimes the sound cycles
>> through short intervals, like a stuck record, but with faster
>> repetitions.
> Someday, I will be proficient with Fedora Sound, but I'm not there yet.
> I think you looked for a pattern to get an idea what is happening. -
> From your message, I don't think you found any pattern. It can be quite
> frustrating.
> Could you be having multiple problems?
> When you said you had youtube videos stuttering, I thought of Internet
> latency, but you wouldn't have that issue with music CDs.
> When having a problem, I would focus on the simplest problem first. If
> possible, focus on the problem with music CDs to rule out networking.
> You might have music CD stuttering issues if a program were hogging the
> CPU.  Is there any program, in the background, that might hog the CPU?
>>   Occasionally, restarting the application (Firefox, Rhythmbox, etc)
>> helps, often it does not. Sometimes, logging out and back in helps,
>> sometimes it does not help. On rare occasions, changing the volume
>> control helps (when I'm not listening, I usually keep the volume at
>> zero, and it sometimes seems as if the system has not noticed that the
>> volume has been turned up, until I turn it up some more).
> Does the problem happen in the middle of playing something or always at
> the beginning?  Does the problem ever clear itself, in the middle of
> playing something, without you intervening?
> There are multiple sound drivers in Linux. There are multiple sound
> servers in Linux. When I say sound system below, I am referring
> collectively to what sound drivers and sound servers you are using.
> What sound systems being used may have a bearing on your problem.
> As far as your configuration, what sound system are you using? Are you
> using Pulse Audio -or- are you using Alsa directly? Are you using
> something else?
> I am using pulseaudio so I have /usr/bin/pulseaudio running. I can also
> see that pulseaudio is running by using the pacmd. pacmd is in "rpm -q
> -i pulseaudio-utils" I can do "pacmd stat" to get a quick status of
> pulseaudio.
>>   I tried different plugins/add-ons with Firefox, and different
>> application to play the music CD, but it does not seem to make a
>> difference.
> - From this, I will assume it is the sound system, or something
> happening in the background in your PC, not a specific program.
>>   What can I do? Thanks!
> I will assume you keep your RPMs up to date.
> I believe more information on your configuration is needed.
> Please check what programs are running in the background. Try to rule
> out programs hogging the CPU.
> Please provide more information on your sound system configuration.
> Knowing your configuration, I would start looking through bugzilla. I
> would start searching the internet for people having similar problems.
> Assuming you are using Pulse Audio, I would look at
> Your configuration might have sound going directly to Alsa. I'm not sure
> what to suggest in this case.  Perhaps looking at
> Perhaps,
> If you are using Pulse Audio, I believe the following: Currently, I
> believe Pulse Audio is an abstract layer acting like a generic interface
> for sound, providing certain higher level features.
> Pulse Audio talks to Alsa.  Also, in turn, talks to the Alsa sound
> device drivers that talk to the hardware.
> Pulse Audio provides APIs for programs that think they are talking to
> Alsa so those programs really talk to Pulse Audio, which in turn, talks
> to Alsa.
> If you are using Alsa directly, I believe the following: Alsa provides
> its own API for programs.  Alsa talks to the Alsa sound drivers which
> control the hardware.
> You might not be using Pulse Audio or Alsa at all. You might be using
> OSS.  I believe OSS is a competitor to Alsa.
> I believe OSS has its own
> sound drivers that talk to the hardware.
> I found a URL talking about Linux sound, which predates Pulse Audio.
> It is "old" webpage, but
> still interesting.
> I think Linux sound is still evolving. I know my understanding of Linux
> sound is still evolving. I expect and welcome others correcting me each
> time I comment on sound.
> There are many people who stay with one sound server or another, one set
> of sound drivers or another, who are far more knowledgeable. Hopefully,
> they will be stirred to comment once they know more about your sound
> system configuration.

I was also having a lot of problems with pulseaudio with a rather anemic 
2.66 GHz P4. Audio would quit working, skip, crackle, and otherwise be 

Alsa worked just fine on this card, but pulseaudio would give 
inconsistent results depending on CPU load and multimedia application.

I posted a request in IRC and was directed to the following page:

Following the instructions on this page resolved the majority of my sound 
issues. In particular editing /etc/pulse/daemon.conf with the following 
changes helped quite a bit:

Skip down to about line 34 where it reads:
; realtime-scheduling = no

Change this to:
realtime-scheduling = yes

Skip down to about line 76 where it reads
; default-fragments = 4
; default-fragment-size-msec = 25

Change this to:
default-fragments = 8
default-fragment-size-msec = 5

I think the default-fragments and default-fragment-size-msec are the 
parameters made the most difference.

I still occasionally have trouble with audio, mostly when I rapidly 
change volume. Flash gives me some trouble as well, but as long as I 
don't attempt to play Flash and another audio source at the same time 
things work.

. . . just my two cents


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