[mythtv-users] Odd pauses when starting recorded shows...

[Lee]

Michael T. Dean wrote:

> mythtv at varga.co.uk wrote:
>
>> Now that my Myth box seems to be fairly stable, I'm slowly starting to
>> migrate recording shows off the Tivo and onto the Myth box. As I'm
>> actually using Myth a lot more, I've noticed a few problems...
>>
>> 1) When I select a recorded show to play from the menu, on about 20% of
>> them, the screen goes black and there is no sound, it sits there like 
>> this
>> for anything from 10-45 seconds and then the show starts and plays as
>> normal...
>> I've run the database check and it's all fine and playing the files 
>> over a
>> samba share is OK too. Playing videos in MythVideo has no problems...
>>  
>>
> This is most likely swapping all the "unnecessary" stuff out of 
> buffers/cache and swapping the playback code back into memory.  
> Basically, Myth is a long-running process and the most-used parts of 
> it are not the TV-watching parts, but the recording, commflagging, 
> transcoding, etc.  So, when you haven't watched TV for 20 hours, the 
> system has to make all that "infrequently-used" code available.  You 
> can affect the delay by setting kernel options for "swapiness," 
> buffering/caching, ...  (How to do so is left as an exercise to the 
> reader.  ;)  Do a Google search to see just how much discussion exists 
> on the right way to tune your system (and read them all since they all 
> tend to disagree).)  For example, I travel a lot for work, and when 
> returning from a one-week trip, it can take so long to load the code 
> for playing back a recording that Myth gives up and tells me I 
> finished watching the recording and asks if I'd like to delete it.  I 
> just say no and try playing a second time and it begins playing 
> instantly.  On a more typical once-a-day playback (i.e. haven't watch 
> TV for almost 24 hours), I'll get a more reasonable delay like the 
> ones you mentioned above.

That isn't it, I watched several shows, in a row and then it happened 
again.... :(
Should it be swapping stuff out? There are something like 480MB of free RAM?

>
> If this is happening multiple times in a single TV-watching session, 
> it may be caused by an I/O wait situation.  For example, if you delete 
> a recording, and then attempt to play back another recording, you 
> might get stuck waiting for the disk to finish the delete before it 
> provides any new data (i.e. the next recording) for playback.  This is 
> especially noticeable using a filesystem that is not known for fast 
> deletes of large files, i.e. ext3.  Even with other filesystems, it 
> may cause some delay.

No deleting going on, I hit the 'Back' button before the end of the 
shows...
Any more possible solutions?

>
>> 2) Scrolling up and down the recorded shows menu, occasionally pauses 
>> for
>> a few seconds, with what sounds like harddrive thrashing about, before
>> continuing as normal, this is a minor problem, but it's SOOOOOO
>> annoying... 
>
> The first time you scroll past a show, Myth creates a thumbnail image 
> of that show.  (And, I think with Risto Treksler's new "preview image 
> honors commflag/cutlist" stuff in recent versions, if you create a 
> thumbnail by scrolling over a show before commflagging finishes, it 
> will create a new thumbnail the first time you scroll over the show 
> after it has been flagged.)  This is causing the delay.

Now you've got something there... After I'd been slowly down the whole 
list, it didn't do it any more...
Is there any way to automatically create a thumbnail without comm 
flagging? It's just that a lot of my stuff is recorded from channels 
that don't have adverts, so no need for comm flagging...

>
>> 3) When using the 30 second skip, it skips and then kind of does slow
>> motion for about 1 sec or 2 and then plays properly. Is this normal? 
>> or is
>> there a problem? It's annoying after using the 30sec skip on the Tivo 
>> for
>> years...
>>  
>>
> Never seen this, so if it is normal, my system isn't.  :)  It sounds 
> like a problem with your sound settings.  For example, make sure you 
> don't enable, "Aggressive Sound card Buffering."

Aggressive sound card buffering was off already... Anything else to look at?

Thanks again,
Lee