[mythtv-users] Issues with using an IR blaster
Michael T. Dean
mtdean at thirdcontact.com
Wed Aug 2 00:53:18 UTC 2006
On 08/01/2006 01:00 PM, Cool Frood wrote:
>I've run against a couple of issues using the IR blaster with a
>PVR-150 card. I'm running MythTV version 0.19.
>1. The external channel changer command gets the frequency id instead
>of the channel number when it is asked to change the channel. I
>looked into the sources and I could verify this and also rectify this.
> Perhaps this is fixed in one of the bugfix releases.
It definitely hasn't been fixed in any bugfixes (in 0.19-fixes or SVN
trunk) because that's the desired behavior. The freqid is the
identifier used for a channel's frequency (which could be either a
frequency in kHz /or/ a channel number); whereas, the channel number is
the /user-specified/ number the user enters to tell Myth to change to
another channel. In other words, users can (and do) change channel
numbers to anything they want instead of getting stuck with the cable
companies idiotic^H^H^H^H^H^H^H"good-for-us-but-not-for-users" numbering
scheme (i.e. putting Fox 35 on channel 3--users can, instead, change Fox
35 to be on channel 35).
When using an external channel change script that requires channel
number, you /must/ specify the channel number in the freqid field
instead of a frequency in kHz. (Note, also, that in the case I referred
to above, that would mean channel 3--the channel number used by the
external cable box--instead of channel 35.) You may edit the values in
the freqid field inside the mythtv-setup channel editor.
>2. There is a setting to tune the TV-capture tuner to a particular
>channel (in my case, channel 3) when using an external channel
>changer. The problem is that channel 3 is not in my database of
The video source should provide a list of all channels that are
available through that video source. If your cable box is set up to
output an RF-modulated signal on channel 3 (or channel 4), you specify a
Preset tuner to channel
Leave this blank unless you have an external tuner that is connected to
the tuner input of your card. If so, you will need to specify the preset
channel for the signal (normally 3 or 4).
If you're having issues with this option, see
> even though it is part of the data received from zap2it. My
>question is, how do I fix the channel data received from zap2it.
Huh? How can it be not be there, but be there? What do you need to fix?
>Secondly, why should MythTV go looking for channel 3 in the database
>anyway if you have an external channel changer?
It won't unless you tell MythTV to change to channel 3--at which point,
if it's not a valid channel, Myth tells you that it doesn't exist (how
could Myth change to a channel that doesn't exist).
Just in case this helps... If you're using an RF-modulated output from
your cable box on channel 3, you specify that in the "Preset tuner to
channel" setting, then you tell Myth to change to the channel you want
to watch (i.e. 217). Myth then sets the capture card to channel 3 and
sends the freqid (which should be 217) to the external channel change
script. The external channel change script then tells the
cable/satellite box to change to channel 217. And, it's quite possible
that the video source may not have a channel 3--if the cable company
doesn't use that channel number--which is fine because you're watching
channel 217, not channel 3 (only the capture card is tuned to channel 3
and only because you're using RF-modulated output on channel 3 from the
(However, as mentioned above, the "Preset tuner to channel" setting may
not work now, so you may want to add an appropriate line to your channel
change script to change the capture card to the appropriate channel.)
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