[mythtv-users] Recordings start & end 10 seconds too soon, on all channels

[steve]

On Mar 21, 2016, at 10:33 PM, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> 
> (fixed top posting)
> 
> On 03/21/2016 07:31 PM, steve wrote:
>> On Mar 21, 2016, at 7:19 PM, Bill Meek wrote:
>> 
>>> On 03/21/2016 04:07 PM, steve wrote:
>>>> My system time is correct to the exact second, so I assume an os level ntp is enabled and working fine.
>>>> Ubuntu 14.04 LT
>>>> Myth 27.6
> 
> What makes you think recordings start and end 10 seconds too soon on all channels?
> 
>>> Have you changed anything like: Time to record before start of show (secs)
>>> in the frontend Setup->Video->General about 4 pages in?
>> Thanks, I thought for certain you nailed it...  but unfortunately, it wasn't that one
>>   Time to record before start of show (secs): 0
>> Time to record before past end of show (secs): 1 <-- Did I change this to 1?    I'll set it to 0 now.
>> 
>> Any other ideas?
> 
> Are you sure your broadcaster/rebroadcaster is airing shows "to the exact second"?  Especially if it's a rebroadcaster and/or if your video is going through some intermediate tuner/decoder/..., there may be some delay in the actual delivery of the video, which could appear as if MythTV were starting and ending shows too early.
> 
> Or are you saying that the mythbackend logs show mythbackend starting a recording at 10 seconds before the start time (where, there should be a slightly early start--though I'm thinking it's more like 2 seconds, IIRC) and ending the recording 10 seconds before the end time, based on the time stamps in the log?
> 
> In other words, you really need to show us some log files to get anything other than guesses (albeit, educated guesses). https://www.mythtv.org/wiki/Posting_Logs
> 
> Mike

Sorry, you were right. Just checked the logs and it shows Myth is performing accurately, ie a show set to record at 23:00:00 indeed starts its recording at exactly 23:00:00.

Yet my problem persists in that shows are still starting about 8-10s early and ending 8-10s early.   

This is with comcast cable cards and an HD Homerun Prime. 

And since it affects recordings on all channels equally, I guess you could think its the broadcaster... but what I don't understand is that I am coming from Windows Media Center with the same tuners, and I did not notice this problem there.

If I can't get to the root of it, then is there a way I can to just compensate for it in mythbackend? Tell mythbackend to start and end all recordings 10 seconds late to compensate?