Re: [mythtv-users] mythfilldatabase: Ignoring unknown timestamp format: 20161231235960

On 12/18/2016 1:55 PM, Robert Eden wrote:
> On 12/18/2016 3:30 AM, Ian Campbell wrote:
>>>        {
>>>          "videoProperties": [
>>>            "letterbox"
>>>          ],
>>>          "new": true,
>>>          "md5": "mOC4USUaW5ASAWno3ii81A",
>>>          "programID": "EP025790950001",
>>>          "liveTapeDelay": "Live",
>>>          "duration": 2100,
>>>          "airDateTime": "2016-12-31T23:25:00Z"
>>>        }
>> Is this correct? A program running from 23:25 until midnight is 35
>> minutes, which is 2100 seconds, but with the leap second should it not
>> be 2101?
>

I looked at the raw data received by SD for the SD-DD service. SD-JSON 
gets data from multiple Gracenote feeds, so that's a little more 
complicated.

SD-DD receives:   Start and Duration.

So, you could argue that Gracenote is sending the wrong duration. 2100 
seconds, not 2101.  Technically, that's true.

However,  not all systems recognize 2016-12-31T12:31:60.  Look at the 
RedHat article:  https://access.redhat.com/articles/15145

Most systems never display 12:31:60.  They either move back the kernel 
or ignore it entirely and NTP would slew it at the next time sync.

If Gracenote sent 2101 seconds and that was used to compute a stop 
times, all stop times post leap second would be off as the system clock 
was updated.  I think 2100 is the best answer as it only effects shows 
that stop at exactly midnight.

In our case, I think ignoring it in computations and letting a slew deal 
with it is the best approach.  I think that's better than RedHat's 
default of a kernel step, but it doesn't really matter to me much either 
way.

If you do really care about accurate time, there are time standards 
other than UTC (used for navigation for example), that don't have leap 
seconds.

I'll be meeting with Gracenote at CES... this will be an excellent 
discussion mixed with alcohol. :)

Robert


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