[mythtv-users] Random lockups on Mythbackend

dwoody1 dwoody1 at charter.net
Mon Dec 20 19:16:01 UTC 2010

Brian Wood wrote:
> On Sunday, December 19, 2010 08:46:45 pm dwoody1 wrote:
>>> As always, it depends. Are we talking about SD or HD program
>>> material?
>> I record OTA and Mythtv shows 720, 1080, HD and sometimes blank. But,
>> we live in Texas, so I assume it is all digital if that makes a
>> difference.
> So we're talking about HD. I suspect your CPU is not capable of that 
> much activity with HD, especially since you are using software decoding.
> I guess everything's bigger in Texas, including file sizes :-)
>> I have been using the HDMI output. I thought that used less cpu than
>> using VGA output. But perhaps still too much.
> I wasn't aware that HDMI made any difference in CPU usage, first I had 
> heard of that.

I read some where that with the HDMI output the computer did not have to
convert to analog, which would take more processing. Do not really know
if this is true or not.
>> Could cpu usage between 88% - 95% be causing my problem?
> Yup. Remember that top shows only an average over time, and you probably 
> have peaks that are well over that.

I used gkrellm which presumably gives real time info. But there were
spikes to 99% and at one point 100%.
>> If so, from your comments above, a VDPAU-capable video card would be
>> called for. From your experience, are there cards that you would
>> recommend or avoid?
>>From comments here and other places I'd go with an nVidia GT220 or 240, 
> they are reasonably priced and seem to work well.

Any brand better than another? Also, how much on board memory should I get?

> First thing I'd try is turning off commflagging, that should reduce the 
> load considerably, and I'd guess you could play back a single program 
> OK.
> But an nvidia card should reduce your decoding load a lot, but I still 
> wouldn't try commflagging more than one program at a time.

Kevin Ross also responded with some info (thanks for the input). Of the
two lockups he had encountered, the mceusb remote control receiver
looked interesting. So I tested with a keyboard only. I recorded a 1080
show, commflaged a 1080 show and watched a 1080 show -- no lockup. I
then removed the keyboard and reinstalled the remote control and did the
same test -- LOCKUP. I then replaced the remote receiver with an
identical one from another computer. The test was the same except that
the show I recorded was an HD -- NO LOCKUP. The cpu usage was still high
and the temperature was also high, so I think a video card is still
called for.

Before I call this one solved I want to run for several weeks. If I have
no more lockups then I will reply adding SOLVED to the subject line.

Do I need to reply to Kevin's email with the info about the remote or is
it adequate with the info in this reply?

Thanks to Brian and Kevin for their help,


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