[mythtv] 4 digit channel support

Chris Weiland hobbiticus at gmail.com
Tue Nov 16 17:38:42 UTC 2010

Yes, sorry, I do mean Myth's internal firewire channel changer.  I'd
love to avoid a configuration option, but I don't see a way around it.
 I believe that the number of digits in the channel depends on your TV
provider company, which I doubt that Myth can detect.  For example,
the same cable box might be used for Comcast service that uses 3
digits, or it could be used for FiOS that uses 4 digits.  Also,
sending more digits than expected will cause errors.  For example,
sending "0620" will work just fine when the cable box is expecting 4
digits, but otherwise, the cable box will tune to channel 62 instead.

If you know of a way to detect the appropriate number of digits to
send, then that would be great.  I guess you COULD try sending 4
digits then query the cable box to see what channel it actually tuned
to, but that would assume that you're trying to tune to a valid
channel in the first place.  To do THAT right, you'd have to already
have the channel lineup.  Then there's the matter of do you store the
result of that experiment or redo the experiment (for example) every
time the backend starts up?  If you store the result in the database,
then you might as well have a configuration option anyway.  If you
repeat the experiment, there's always the chance that something could
go wrong and break the device.  It just seems like a "number of
digits" field is the best way to go, especially if 5 or more digits
might be required in the future.

Alternatively, if there's a way to send the "Enter" key over firewire,
then that can solve everything - just send the minimum number of
digits that represents the channel number then send Enter.  No options

On Tue, Nov 16, 2010 at 12:18 PM, Robert McNamara
<robert.mcnamara at gmail.com> wrote:
> On Tue, Nov 16, 2010 at 9:12 AM, Chris Weiland <hobbiticus at gmail.com> wrote:
>> Implementing the 4 digit channel change is almost trivial.  I can
>> easily submit a patch for that.  However, hardcoding 4 digits for the
>> channel changer will break everyone with only 3 digits, so it has to
>> be a configuration option (in the capture card screen of
>> mythtv-setup).  That's where my expertise runs out.  I could probably
>> figure it out myself, but it would be a lot less painful if one of the
>> existing devs could handle that part.
> I assume you mean Myth's internal firewire channel changer?  We don't
> distribute any of the contrib channel changers any more, they've all
> moved to the wiki.
> I'm also not sure why using four digit channels instead of three digit
> channels should require a config option at all?  This is exactly the
> kind of thing that has plagued the project in the past-- adding a
> teensy toggle switch to the field of thousands of toggle switches
> because it's easier than doing it right.  I'm wracking my brain and
> can't come up with any reason myth can't pass a four digit channel
> number when appropriate, and three, two, or one digits otherwise.
> Robert
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