[mythtv-users] Live TV Program Change Over

[Pieter De Wit]

Hi,

I "had" the same issue. I posted it to the group but was in a rush and 
didn't include all the details. Anyways, here goes:

My system had 1x IDE 250gig harddrive. I noticed that a few of the .24 
patches caused these type of freezes when flipping over. It would skip a 
few frames and resume playing. Not a big issue. In .25 this became much 
worst. I have never fallen back to the Main Menu, but the pauses was bad.

At this moment, using LVM, I have installed a 70gig SCSI harddrive and 
everything is served from there. I plan to move the "livetv" storage group 
to the IDE but havn't gotten to it yet.

This has reduced the pauses back to less than a second, much more 
acceptable. It would prove to me, that the IO requirement is heavier in 
.25 than it was in .24.

I have noticed a lot of queries in the mysql-slow log that doesn't use 
indexes. Although they are served quickly, they still generate IO.

Using "iostat -x 1" it will show the IO per disk, you might want to use 
"iostat -x 1 sda sdb sdc sdd" if you have LVM and a lot of Device mappers.

Have a look at the IO during a change over. Perhaps this is motivation for 
an upgrade :)

Cheers,

Pieter

On Mon, 26 Mar 2012, Scott & Nicole Harris wrote:

>>> I have had always had an issue during Live TV during the change over form
>>> program to another (not a channel change).  In < 0.25, there would be an 
>>> ~5
>>> second “freeze” at the change over point, but playback very reliably 
>>> always
>>> continued playing after the freeze.
>>> 
>>> With 0.25, the reliability of the continuation of playback has become 
>>> rather
>>> suspect with it frequently crashing back to the MythTV menu with the “live
>>> buffer failed too many times” (paraphrased).  The other night, my wife was
>>> up all night with a sick kid and told me that “the TV kept giving me this
>>> error message every 30 minutes”.  I didn’t put 2 and 2 together until
>>> tonight when it died on me during the local news –> nightly news and then
>>> nightly news –> what ever was next.  So I looked back at what she was
>>> watching that night and sure enough, it was all 30 minute sitcom reruns.
>>> 
>>> Anyone have any suggestions for addressing this?  I’m wondering if maybe
>>> giving Live TV a second storage group on a separate disk from the first 
>>> Live
>>> TV storage group might help?  It occurs on my MBE/FE locally as well as my
>>> remote FEs.
>
>> There is another recent thread about a similar problem on changes to
>> and from commercial breaks. It seemed to be traced to changes in the
>> audio stream going from program-->commercial (and maybe the other
>> direction too). Might this be the same problem?
>
>> I found it... 
>> http://www.gossamer-threads.com/lists/mythtv/users/509778#509778
>
>> You may have a similar problem?
>
> Though I don't know for sure, I don't think this is the same issue.  I've 
> seen this issue for quite some time (as in back to possibly even 0.23 days?), 
> it occurs when Live TV changes from one program to another on the same 
> channel.  There is a significant pause (a/v freeze is a more accurate 
> description) while Myth takes care of everything it needs to do to do this. 
> More like what Mark describes in #3 here 
> http://www.gossamer-threads.com/lists/mythtv/users/454127#454127.
>
> However, since my conversion to master, the "a/v freeze" quite often doesn't 
> recover and ultimately crashes to the Myth main menu and the "video buffering 
> failed too many times" (again paraphrased) error message pops up.
>
> The reason I am wondering about having multiple storage groups on separate 
> disks for Live TV is because possibly it could reduce some I/O load at these 
> changeovers?  I can't test right now, stuff recording, can't stop backend. 
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