[mythtv-users] Backend drops frames at start of recording; add RAM?

Brian Wood beww at beww.org
Thu May 11 16:42:06 EDT 2006

On May 11, 2006, at 2:36 PM, kanetse at gmail.com wrote:

> I have noticed that when my master backend is starting to record 3
> programs simultaneously, it tends to drop frames at the beginning of
> the recordings.  By my estimate, it probably drop around 30s to 1min.
> I have confirmed that it's not a frontend issue, because the
> recordings always skip at the beginning, and regardless of which
> remote frontend I use to view the show, the exact same frames are
> skipped.
> I think it has something to do with the 3 tuners being set to record,
> and then stopping the recordings that were previously going, as well
> as starting up and queuing all the new and old transcoding/commercial
> flagging jobs.  I allow the machine to run 2 comm-flag/transcode jobs
> simultaneously.
> My machine only has 512MB RAM it (but it's a dedicated backend).
> Would topping this machine up to 1GB help this problem?
> My dedicated backend specs:
> MythTV-0.19-127
> 1xPVR-250
> 1xPVR-500
> 512 MB RAM
> Celeron D 2.93 GHz
> Fedora Core 4

You can check to see if it is having to hit swap by monitoring it  
when the problem seems to be happening.

Free, top, vmstat and a host of other programs can help to tell you  
what's happening.

I doubt that swapping to disk would cause delays on the order of what  
you mention though, I'd have a look at your disk subsystem, check  
that DMA is enabled, make sure you;re not trying to store on a USB  
1.1 drive etc., thugh to be honest even that sort of trouble  
shouldn't cause delays of a minute.

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