[mythtv-users] US MythTV users: will your recordings be 1 hour off on March 11th?

mythusers.jtuttle at xoxy.net mythusers.jtuttle at xoxy.net
Wed Jan 17 14:29:30 UTC 2007

Does anyone know how to perform a similar check on a Debian-based system?

Or more generally, how to check and see what the local timezone rules are,
and what's going to change on what particular dates? I had a devil of a time
getting my local timezone set initially when I set up my box (system clock
was set to the correct local time but with zone "UTC", apparently the result
of Windows that was running on the hardware before...took me longer than I'd
like to admit to notice what was wrong).

I'm running Knoppmyth R5D1 (Thanks, Chris!) so I suspect that it has all the
new TZ rules, but I'm curious how one would do the equivalent of "rpm -q
tzdata". I think the timezone files are all kept in */usr/local/etc/zoneinfo
*, but I'm not sure which package updates them (maybe tzselect?).

Any more experienced Debian users want to clarify?

Slightly OT, is it possible to have MythTV grab and update the time from
XDS? At least at one point, almost all PBS stations transmitted a digital
timestamp in the vertical blanking interval, which was used by self-setting
VCR clocks and such. I assume that it's local, rather than UTC, time that's
transmitted, so it would provide a nice reference as to which timezone the
user was in. Do most video-capture cards even preserve / pass on this
information to the system? (Based on some patches I'm seeing on mythtv.org,
it looks like the answer is yes, at least in some cases.)


(Direct replies please use jwtuttle at gmail dot com, to avoid

---------- Forwarded message ----------
> From: "Ross Campbell" <ross.campbell at gmail.com>
> To: "Discussion about mythtv" <mythtv-users at mythtv.org>
> Date: Tue, 16 Jan 2007 13:36:09 -0800
> Subject: [mythtv-users] US MythTV users: will your recordings be 1 hour
> off on March 11th?
> For those who don't know or forgot, daylight savings time rules change
> in most parts of the US this year... DST will start 3 weeks earlier
> and end 1 week later thanks to the brilliant minds behind the Energy
> Policy act of 2005 -
> http://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005
> So what?!
> Well, your NTP time sync keeps your system time correct, but your
> TIMEZONE is locally interpreted, so anyone with old/custom/unsupported
> Linux distros risks having their mythtv recordings off by ONE HOUR for
> the duration of the timezone change periods (4 weeks out of the year).
> That's probably not what you want... and the change starts March 11th
> this year - less than two months from now.
> If you run an OLD distro that doesn't have updated timezone rules, you
> may want to do some research about if there is an updated 'tzdata'
> source package you can install.
> For FC/redhat/EL distributions, 'rpm -q tzdata' will tell you the
> version installed.
> I believe anything newer than about tzdata-2005m will add the
> appropriate changes needed to ensure that your recordings don't miss a
> beat.
> You may have luck building a newer tzdata src rpm from here:
> http://rpmfind.net/linux/rpm2html/search.php?query=tzdata
> Or... you may be able to copy the tzdata binary files for US timezones
> from a newer Linux/UNIX distribution (?) - I don't know much about the
> tzdata binary format... is it compiled or endian or just a common
> binary blob?
> -Ross
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