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

[Michael T. Dean]

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.

>   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