[mythtv] NTP config

Daniel Kristjansson danielk at cuymedia.net
Thu Oct 20 13:14:41 UTC 2005

On Thu, 2005-10-20 at 08:58 -0400, Steve Adeff wrote:
> On Thursday 20 October 2005 06:35, Andrew Wilson wrote:
> > On 19/10/05, Adrian Wilkins <adrian.wilkins at gmail.com> wrote:
> > > As an aside, the "dvbdate" utility makes a fabulous alternative to NTP
> > Yes, this is one of the nice spinoffs of using DVB. I have it sync the
> > clock on bootup and in a daily cron job. Works perfectly, You need to
> > tune first though. Do something like:
> unless your cable company doesn't send the signal for this! I just tried, but 
> either comcast doesn't support this or I have to tune to a specific channel?

I think dvbdate only works with DVB streams, ATSC uses a different
system time table. I've considered adding this capability to MythTV,
which can decode the ATSC STT, but the time isn't nearly as accurate
as ntpd and it would be somewhat complicated to adjust the clock as
nicely as a running ntpd daemon does it. If I did implement it, I
would probably just make MythTV a read-only ntpd server which your
ntpd could connect to if it doesn't have a better time source.

DVB/ATSC time can never be as accurate as ntpd time because the
transmission, buffering, and capture delays can not be measured.
But it should always be within a few seconds of the correct time,
so it is more than good enough for a MythTV backend.

-- Daniel

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