[mythtv-users] Preview Errors caused by superfluous LiveTV zero length files?

Tom Dexter digitalaudiorock at gmail.com
Fri Apr 18 13:29:25 UTC 2008


On Fri, Apr 18, 2008 at 2:35 AM, Michael T. Dean
<mtdean at thirdcontact.com> wrote:
> On 04/15/2008 03:07 PM, Tom Dexter wrote:
>  > I frequently get these preview errors in my mythbackend.log.
>  >
>  > 2008-04-13 12:29:01.342 Preview Error: Previewer file
>  > '/video/recordings/1051_20080413122857.mpg' is not valid.
>  > 2008-04-13 12:29:01.343 Preview Error: Run() file not local:
>  > '/video/recordings/1051_20080413122857.mpg'
>  > 2008-04-13 12:29:01.349 Preview Error: Preview process not ok.
>  >
>  > fileinfo(/video/recordings/1051_20080413122857.mpg.png) exists: 0
>  > readable: 0 size: 0
>  >
>  > I've been able to determine that they're occurring because, every time
>  > I enter LiveTV or change channels in LiveTV, a zero length mpg file
>  > gets created in addition to the valid file that gets streamed to the
>  > frontend.
>
>  Dummy video.  It's required for some capture card types.
>

Aha...I didn't know there was actually a reason for those.  Like I
said, they never appeared to cause any harm anyway.

>
>  >   It gets auto expired and disappears shortly after.  I had
>  > this issue in 0.20.2.  It's never caused any problems, but I thought
>  > for sure this would be fixed in 0.21.
>
>  Patches welcome.  :)
>
>
>
>  >   In 0.21 I've also been
>  > occasionally getting these in the mythbackend.log:
>  >
>  > 2008-04-13 13:00:30.833 Preview Error: Encountered problems running
>  > '/usr/bin/mythbackend --generate-preview 0x0 --chanid 1071 --starttime
>  > 20080413124200 '
>  >
>  > I'm not sure what's trying to do that, but the '0x0' part certainly
>  > looks suspect...maybe those are related to the bogus zero length
>  > LiveTV files as well.
>  >
>  > Is anyone else seeing any of the above?  Like I said...the extra zero
>  > length LiveTV mpg files have been occurring ever since I first built
>  > the system and they happen every time I enter LiveTV or change
>  > channels without fail.  For example, I just went into LiveTV and
>  > surfed though a few channels and get this:
>  >
>  > /video/recordings $ find . -size 0
>  > ./nfslockfile.lock
>  > ./1021_20080415145909.mpg
>  > ./1041_20080415145916.mpg
>  > ./1051_20080415145926.mpg
>  >
>  > ...and here are some of the zero length files along with the valid
>  > ones that get streamed to the frontend:
>  >
>  > /video/recordings $ ls -alt *.mpg
>  > -rw-r--r--     1 mythtv video    12806560 Apr 15 14:59 1051_20080415145928.mpg
>  > -rw-r--r--     1 mythtv video    12549188 Apr 15 14:59 1041_20080415145918.mpg
>  > -rw-r--r--     1 mythtv video                  0 Apr 15 14:59
>  > 1051_20080415145926.mpg
>  > -rw-r--r--     1 mythtv video      8618484 Apr 15 14:59 1021_20080415145910.mpg
>  > -rw-r--r--     1 mythtv video                  0 Apr 15 14:59
>  > 1041_20080415145916.mpg
>  > -rw-r--r--     1 mythtv video                  0 Apr 15 14:59
>  > 1021_20080415145909.mpg
>  >
>  > Also, I have "Display thumbnail preview images of recordings" turned
>  > off for my frontend.  Does the backend try to generate them for all
>  > recordings anyway?
>
>  Yep.  The setting only affects whether they're displayed in the frontend.
>
>
>  >  I suppose in any case they'd be needed for mythweb
>  > even if no frontends used them.
>  >
>
>  Ahem.  (muttering)not really since mythweb uses custom-sized preview
>  images...  However, some other clients may use them.
>
>  And if they haven't been generated ahead of time, enabling their display
>  would make the Watch Recordings screen completely unusable.  Since
>  there's no harm in generating them, ...
>
>
>  > I use the "Display live preview of recordings option"...speaking of
>  > which (getting a little OT here)...where did the low cpu option for
>  > the live preview go in the setup menus?  I still have it set in the
>  > settings table (PlaybackPreviewLowCPU),
>
>  We don't remove old values from settings (as they don't hurt anything).
>  Doing so would be dangerous.
>
>
>  >  but I don't see it anywhere in
>  > the menus...it's definitely not on the same screen with the "Display
>  > live preview" option.
>
>  It was removed in development of the mythtv-vid branch (and was since
>  merged to trunk before the 0.21 release).  I'm not sure why Daniel took
>  it out, but I trust there was good reason.
>
>  Was it /really/ necessary for you?
>
>  Mike
>

Thanks much for all the answers Mike.

The low cpu preview thing certainly wasn't a must...without it the
watch recordings screen tends to use as much CPU as watching shows, so
I feel like I have to make sure (and remind my wife) to not leave myth
on that screen overnight.  The preview certainly look better at full
speed.   If I was concerned enough of course, I'd just switch to
thumbnails.

Thanks again.
Tom


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