[mythtv-users] Working around a lack of a IR Blaster

Nick Rout nick.rout at gmail.com
Wed Nov 25 01:08:14 UTC 2009

On Mon, Nov 23, 2009 at 11:55 AM,  <stefan_jones at comcast.net> wrote:
>> From: "Nick Morrott" <knowledgejunkie at gmail.com>
>> To: "Discussion about mythtv" <mythtv-users at mythtv.org>
>> Sent: Sunday, November 22, 2009 10:30:27 AM GMT -08:00 US/Canada Pacific
>> Subject: Re: [mythtv-users] Working around a lack of a IR Blaster
>> 2009/11/22  <stefan_jones at comcast.net>:
>> > I don't have a working IR Blaster but want to record a few select shows.
>> >
>> > Shouldn't this work?
>> >
>> > Set up Analog video tuner card.
>> >
>> > Configure Input Connection to set tuner to a given channel (3).
>> >
>> > Connect output of STB to tuner. Set the STB to the desired channel.
>> >
>> > Put some dummy command in the outside tuner command line.
>> Using /bin/true is the recommended way to 'fool' MythTV into thinking
>> channel changing was successful in this scenario.
>> > Record anything in the appropriate time slot to make the tuner record
>> > from
>> > the STB for the appropriate length of time.
>> >
>> > Now, I tried this out this afternoon. First I tried watching Live TV on
>> > the
>> > Analog tuner. I saw the appropriate channel . . . the one that the STB
>> > was
>> > tuned to.
>> Expected if you have one or more tuners in the machine and (if more
>> than 1 tuner) you configured the analog tuner's input connection
>> _last_ in mythtv-setup. This gives the tuner the lowest recording
>> priority (as long as you have not made any other tuner/channel/LiveTV
>> priority changes) and will be used first for LiveTV.
>> > Then I tried a test record. No dice. If I'm looking at the right
>> > messages,
>> > another (digital) channel tried to tune in.
>> This is again expected if the digital tuner(s) has a higher priority
>> for _scheduled_ recordings. If you want to test the analog tuner for
>> scheduled recordings, you need to tell the scheduler to prefer to use
>> the analog tuner over other possibly higher-preference inputs. You can
>> do this in the scheduling options for each recording rule where you
>> want this to be the case.
>> > Do I need  to "scrub" the channels for the video source so they have no
>> > tuning information? It seems to me that the Input Connection's channels
>> > just
>> > need to supply a channel number . . . no tuning information that might
>> > cause
>> > a digital tuner to try to take over.
>> If you are using a video source that relies on using an external
>> channel change script, you need to ensure that each channel configured
>> on that input has a valid frequency value. In the case of controlling
>> an STB, it is the digits you want passed to the changer script.
>> A lack of tuning information will cause the recording to fail -
>> another tuner will not try to take over.
> Thanks, I think I've got things working.
> For posterity:
> * The error messages from the digital recorder in the mythfrontend console
> output were a red herring. I have two "ghost tuners" from a previous
> install. They don't show up in mythtvsetup, but their being in the DB causes
> errors on exit from mythtvsetup ("Tuner 8 is pointed at channel 71 which
> doesn't exist") and when mythfrontend starts up. I guess I'll have to use
> SQL to remove them.
> * I changed priorities so that the analog tuner is 0, and the three digital
> tuners ranked 1,2 and 3.
> * I removed all of the channels from the analog card's lineup that overlap
> with the digital card's range. (The digitals listen to the clear QAM
> stations on the cable signal . . . essentially the broadcast HD lineup plus
> SD digital versions of the low-tier cable TV channels; I added a "D" to the
> channel number to differentiate them. The analog tuner has its own lineup,
> consisting of the upper-tier cable channels that are now only viewable via
> the STB.)
> * I wrote a little script called changechannel.sh to plug into the external
> tuner command line field. It writes the cable channel passed to it to a
> file. I'll eventually include the date as well. This will come in handy for
> debugging when the IR transmitter is functional.
> * I was able to record two shows in a row. They look fine. The STB has a
> nice strong analog signal for the PVR-150 to pick up.
> Thanks again.

The SKY TV STB in NZ used to have a "book a show" feature, where it
would change to a particular channel at the appropriate time.
Scheduling was a matter of scheduling on mythtv and the stb.

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