[mythtv-users] chunks missing from recordings?

Brian Wood beww at beww.org
Tue Jun 19 13:43:18 UTC 2007


Robert Longbottom wrote:
> On Tue, June 19, 2007 1:30 pm, Joe Borne wrote:
>> I recently upgraded to the atrpms bleeding version in order to eliminate
>> some problems I was having with dvd's, transcoding etc. It did fix the dvd
>> problems, but not my transcoding issues. (I'll save that for another post)
>>
>> The new behavior I am seeing now is that on occassion, a recording will
>> have
>> pieces missing from it. They appear to be about 2-3 minutes in length and
>> bunched together in a particular spot, usually 30 minutes into the
>> recording. The recording will just jump forward 2-3 minutes and there will
>> be the sort of mpeg compression blocks you would see in a digital
>> transmission that was having signal problems. (I used to see this effect
>> when I had digital satellite and was having reception problems.)
>>
>> It usually clears up and the rest of the recording is fine. I don't think
>> this is the transmission though because I am seeing it in recordings taken
>> from my STB with firewire and also in ones recorded analog by my PVR-150.
>>
>> Has anyone seen this before and is there a fix?
> 
> Have you checked that it isn't some sort of commercial flagging gone
> wrong?  Maybe have a look to see if any of the recording is marked for
> cutting - I think - when you are watching the recording, open the menu "M"
> and select edit recording.  See if any bits are cut out.
> 
> Thats a total guess, and probably way off the mark, but thought I might as
> well suggest it!

I thought of that as well, and I suppose it is possible, but commercial
skip doesn't usually cause macro-blocking after the skip, which  is what
it sounds like he is getting.

I'm wondering if it's some sort of resource limitation, perhaps the
system is not able to write to the drive(s) fast enough, or something is
sharing an interrupt with something else?

Perhaps look into PCI latency, check that DMA is enabled on the drives,
use hdparm to check the srive status, or even bonnie to check the
filesystem performance?

BEWW


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