[mythtv-users] External Channel Change Question? - WAS Re: CentOS and MythTV

[Kenneth Hadley]

Brian Wood wrote:
> On Feb 12, 2006, at 8:33 PM, Kenneth Hadley wrote:
>
>   
>> Len Reed wrote:
>>     
>>> Kenneth Hadley wrote:
>>>
>>>       
>>>> Brian Wood wrote:
>>>>
>>>>         
>>>>> On Feb 12, 2006, at 7:02 PM, Kenneth Hadley wrote:
>>>>>
>>>>>           
>>>>>> Appears I spoke too soon about have no further problems.
>>>>>>
>>>>>> I use a MyBlaster to control my external Samsung DirecTV  
>>>>>> receiver and
>>>>>> with my previous box this worked fine using the MyBlaster.pl  
>>>>>> script.
>>>>>>
>>>>>> This time...not working so well.
>>>>>>
>>>>>> I have the script located in /usr/local/bin/ and typed into the  
>>>>>> input
>>>>>> field of "mythtvsetup=>input connections=>/dev/video0/=>External
>>>>>> channel
>>>>>> change command" the script path/filename (/usr/local/bin/ 
>>>>>> MyBlaster.pl)
>>>>>> but when I record programs the channel never changes and when  
>>>>>> watching
>>>>>> the MyBlaster transmitter when the recording starts and it  
>>>>>> should be
>>>>>> blinking, it does not.
>>>>>>
>>>>>> Manually typing at the CLI
>>>>>> [mythtv at pvr01 ~]$ /usr/local/bin/MyBlaster.pl 298
>>>>>> Does change the channel.
>>>>>>
>>>>>> Anyone have any thoughts?
>>>>>>
>>>>>> Thanks!
>>>>>>
>>>>>>
>>>>>>             
>>>>> Probably the most common problem with scripts is that they have be
>>>>> both readable and executable in order to work. Just a simple  
>>>>> thing to
>>>>> check.
>>>>>
>>>>>
>>>>>           
>>>> chmod +0777 /usr/local/bin/MyBlaster.pl
>>>> chmod +x /usr/local/bin/MyBlaster.pl
>>>>
>>>>         
>>> They don't, however, have to be world writable and it's bad  
>>> practice --
>>> even on a dedicated system on a safe LAN -- to make things world
>>> writable.  0755 maybe, but not 0777.
>>>
>>> Are you running your command line test (which works) as the same user
>>> that mythbackend is running?  This script will have to access some
>>> device, which will also have permission issues if mythbackend isn't
>>> running as root.
>>>
>>> Beware also if you're running mythbackend as setid root: perl may see
>>> that real-user != effective user and try to run a taint-controlled
>>> version.  That can be tricky to get working.
>>>
>>> Len
>>>
>>>       
>> To be honest I have no idea what user the mythbackend is running as, I
>> followed Jarod's guide substituting FC4 with CentOS (RHEL4). Is  
>> there a
>> way to find this out?
>>
>>     
>
> Sure, just run ps -aux | grep backend. The first column will tell you  
> what user the process is running as.
root it would appear.

MythTV suffers one of the same problems most Linux based (including
Linux itself!) programs have; your forgot how to debug it cause once you
get it going it just keeps going and going and going ;-) Of course, that
isn't a "problem" until you have to relearn how to fix :D

A hunt in /var/log/mythtv/mythbackend.log showed me this error on
mythbackend startup
2006-02-12 20:03:27.573 Channel(/dev/video0)::Open(): Can't open video
device, error "No such file or directory"
2006-02-12 20:03:27.577 Channel(/dev/video0)::Open(): Can't open video
device, error "No such file or directory"
2006-02-12 20:03:27.579 ChannelBase: Could not find input: S-Video 0 on
card when setting channel 286

I went ahead and shutdown the backend, reloaded the ivtv driver,
restarted mythbackend and low and behold it works!
2006-02-12 20:09:02.400 Started recording "376 (NASA)" on channel: 1376
on cardid: 1, sourceid 1
2006-02-12 20:09:08.752 External Tuning program exited with no error
2006-02-12 20:09:09.294 Changing from None to RecordingOnly

So the actually problem I'm having is with ivtv not loading properly
BEFORE mythbackend starts. At least I know why, now to fix :D

Thanks much!

-Kenneth