[mythtv-users] mythbackend random high cpu usage

Jeremy Green jrgreen at MIT.EDU
Sun Sep 18 22:14:58 UTC 2011

I am running MythTV 0.24.1 on Fedora 14, on a computer with a pcHDTV 5500 tuner, 
1.8GHz Core 2 Duo, and 2GB memory. For analog channels, the card is a 
framegrabber and my recording profiles are set to encode MPEG-4.

When recording of an analog channel starts, one of the following two things 
happens, seemingly at random:
1. mythbackend uses around 50% of one core, and the recording is fine.
2. mythbackend CPU usage is around 120% (and one of the threads is around 90%). 
Usually audio sync in the recording is bad, and becomes worse over time (toward 
the end of a 30 minute recording, audio sometimes lags a few seconds behind the 
video). Sometimes a recording will have a few instances where about a second of 
audio repeats itself.
If a recording starts with high CPU usage, and I stop and restart it a few 
times, I am able to cause it to switch to the low CPU usage behavior.

Any help would be appreciated, as this is obviously quite annoying.


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