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Working around a lack of a IR Blaster

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stefan_jones at comcast

Nov 21, 2009, 10:43 PM

Post #1 of 4 (568 views)
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Working around a lack of a IR Blaster

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.

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.

Then I tried a test record. No dice. If I'm looking at the right messages, another (digital) channel tried to tune in.

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.

Any ideas welcome.

knowledgejunkie at gmail

Nov 22, 2009, 10:30 AM

Post #2 of 4 (499 views)
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Re: Working around a lack of a IR Blaster [In reply to]

2009/11/22 <stefan_jones [at] comcast>:
> 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.

Cheers,
Nick

--
Nick Morrott

MythTV Official wiki: http://mythtv.org/wiki/
MythTV users list archive: http://www.gossamer-threads.com/lists/mythtv/users

"An investment in knowledge always pays the best interest." - Benjamin Franklin
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stefan_jones at comcast

Nov 22, 2009, 2:55 PM

Post #3 of 4 (491 views)
Permalink

Re: Working around a lack of a IR Blaster [In reply to]

> From: "Nick Morrott" <knowledgejunkie [at] gmail>
> To: "Discussion about mythtv" <mythtv-users [at] mythtv>
> 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>:
> > 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.

Stefan

nick.rout at gmail

Nov 24, 2009, 5:08 PM

Post #4 of 4 (459 views)
Permalink

Re: Working around a lack of a IR Blaster [In reply to]

On Mon, Nov 23, 2009 at 11:55 AM, <stefan_jones [at] comcast> wrote:
>> From: "Nick Morrott" <knowledgejunkie [at] gmail>
>> To: "Discussion about mythtv" <mythtv-users [at] mythtv>
>> 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>:
>> > 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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