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I've recently freshly reinstalled Ubuntu, and Mythbuntu, on all my computers.

On one of my computers, Mythbuntu 11.10, when I play a video, when it starts, I get a burst of white noise (static) that stays on.

If I stop the video and restart it, the noise goes away.

Sometimes if I fast forward or manipulate the video, the noise will start. It seems to be initiated, and stopped, by starting or interacting with the video.

Any ideas as to why this is happening and how I can get rid of it?


Now that I have some free time on the holidays, I've made a video of the problem and uploaded it here.

As you can see in the video, it starts playing normally. I hit the skip forward button a few times, and it's fine. After a few presses, you can hear the white noise burst. After that, the noise comes or goes at each press of the button. Each button press will randomly initiate or kill the white noise.

Also note that in the video it started without white noise. Sometimes, however, the white noise begins immediately on video start. Lastly, in the video I just pressed the skip forward and backward buttons. However, pause and and most any other button will also sometimes trigger the white noise.

I hope that makes much more clear what the problem is.

Questioner
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2 Answers2

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To confirm if this is a pulseaudio issue, I would temporarily disable pulseaudio:

echo autospawn = no|tee -a ~/.pulse/client.conf && killall pulseaudio

Then in MythTv - Utilities/Setup - Setup - General change your Audio settings to ALSA:default

To revert to pulseaudio:

change the value of autospawn=no to autospawn=yes in ~/.pulse/client.conf

Then logout and login


Once confirmed as a PulseAudio issue, you perhaps have three choices:

  1. File a bug report with the MythTV developers and hope that they fix the issue. You'll need to be proactive with them to enable them to help you etc.
  2. Look at the existing 10.04 pulse-audio bug report and see if the same or similar patch can be done to the Oneiric MythTV sources - not for the faint-hearted!
  3. Look at just use ALSA:Default as the MythTV audio-setting. You shouldnt need to kill the host pulse-audio - thus multicasting etc should still work. You may need to enable the MythTV software controls to change sound settings. Alternatively/Additionally, install gnome-alsamixer or just alsamixer to control your audio settings such as volume, enabled speakers etc.
fossfreedom
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Some applications can directly access to your sound card or using PulseAudio, or they use different solutions such as ALSA, and this is the main reason why you are experiencing this kind of problem only with certain software.

The solution is really tricky, because different sound cards can have really different behaviour, and with that i mean "really really really really different", also different application can use different framework.

try to change the output with the gstreamer-properties dialog menu.

or you can try this https://bugs.launchpad.net/ubuntu/lucid/+source/mythtv/+bug/550100/comments/8 that is a post from this topic https://bugs.launchpad.net/ubuntu/lucid/+source/mythtv/+bug/550100

Micro
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