[mythtv-users] Live TV Program Change Over

Scott & Nicole Harris snharris99 at live.com
Tue Mar 27 01:23:17 UTC 2012


>>>> 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.
>
>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

Thanks for the info.  I'm not using lvm, I just have 5 SATA drives operating 
independently, each with it's own recordings directory and the I/O scheduler 
set to "Combination.  One of the drives has the livetv group on it as well 
as a recordings directory.  A lot of the time when this happens, there is no 
other recording activity other than the Live TV session.

Though, this is a fresh installation and I haven't added any of the fstab 
optimizations for mysql / ext4.  Though the db is on an SSD. 



More information about the mythtv-users mailing list