[mythtv-users] Some questions about HDTV recording

Bruce Markey bjm at lvcm.com
Sat Dec 11 21:10:13 UTC 2004

Brad Templeton wrote:
> On Fri, Dec 10, 2004 at 07:09:54PM -0600, Nate Carlson wrote:
>>1) How does recording schedulding work for HDTV? My PVR-250's are hooked 
>>up to the local cable feed; the PCHDTV card will be set up for OTA. If a 
>>show is available via both HDTV and cable, how do I tell it I prefer the 
>>HDTV version?

Each channel is uniquely identified by a "chanid" in the database.
Normally, record types that require a channel (Single, Weekslot,
Timeslot or Channel) will only record for the exact channel of
the item selected to record. If two channels have the exact same
callsign (say, two different sources carry the same station) the
scheduler treats these as interchangeable and the lower input number
is preferred by default but it can fail over to the other channel
if the preferred input is busy with a higher priority recording.

However, in this case, this probably doesn't come into play because
the HD channels normally have different callsigns.

| chanid | channum | callsign |
|   1008 | 8       | KLAS     |
|   1010 | 10      | KLVX     |
|   2730 | 730     | KLASDT   |
|   2731 | 731     | KLVXDT   |

So, if you know that something is HD, select the HD channel or
choose the SD channel if the it isn't high def and you want to
save space. If you choose FindOne or All, it can record from
either channel and will again prefer the lower input by default
when the same show is listed at the same time for different

> The HDTV channels are different channels to the system.  You would
> select "record this show on this channel."  I believe there is also
> a priority system for channels and tuners so you can tell it to prefer
> the HD tuner.

In the setup program Input connections section there is an "Input
preference". If you set this to 1 it says that the priority is
one higher when an episode is on this input over the same episode
shown on another input. TV Settings->Recording Priorities->
Channel Priorities allows setting a specific channel to have a
higher or lower priority that other channels.

> However, that turns out to be a problem.  SD shows appear on the HD
> channels, but unfortunately, they appear in HD, and not at a very reduced
> bitrate.  So even if you record a half hour of SDTV on an HDTV channel
> it will take 3gb or so.
> You want a fancier system that knows when a program is truly HD, and
> records it HD if it is, but from either the twinned SD channel when it
> isn't or from the cable.

DataDirect includes a flag for HDTV but, of course, this can only
be as good as the accuracy of the information provided by the

mysql> select count(*) from program where chanid > 2700 and hdtv > 0;
| count(*) |
|      823 |
1 row in set (0.01 sec)

mysql> select count(*) from program where chanid > 2700 and hdtv = 0;
| count(*) |
|     2054 |
1 row in set (0.00 sec)

If this information seems reliable enough, it would be trivial
to modify the the scheduler to check this flag for showings on
the HDTV input and raise the priority if set or lower it if unset.
That's easy. It may take more thought to determine the best way
to present the user with this option if they want this behavior
and to identify the HDTV input(s) that should act this way.

--  bjm

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