[mythtv-users] Comcast OnDemand on Multiple STBs

Michael T. Dean mtdean at thirdcontact.com
Sun Nov 11 06:37:37 UTC 2007

On 11/10/2007 07:08 PM, Worldnet wrote:
>> Have the channel change script write some status information to a file 
>> and use it to determine which capture card is watching what?
>> Basically, the point is that the external channel change command knows 
>> which capture card/input is being used, so, don't throw that information 
>> away. Put it somewhere you can find it... Specific implementation 
>> instructions would require knowledge of exactly what your plan is for 
>> navigating the On Demand menus, but it shouldn't be too difficult to 
>> figure out (once you start going down the right path ;).
> I'm not following you. If the channel change script was to write to a
> status file it would reside on the backend. How would the frontend
> go about reading this file?

Oh, yeah.  I suppose you're right.  My logic is completely based on an
impossible scenario:  one computer being able to access a file on
another computer's filesystem.  Well, maybe some day someone will invent
a means of sharing files.  Until then, I guess you're out of luck.

>  Further more since all OnDemand programing
> is on Channel 1 if two frontends were to watch OnDemand at the same
> time the status file would show 2 STBs watching channel 1.

Another insurmountable problem.  :(  Sorry to have wasted your time
(which, BTW, could /not/ be used as a discriminating factor).

> The exact plan is to be able to send left, right, up, down and select
> to the correct STB. Since I am already controlling 4 STBs in exactly
> the way you suggest I don't see where I am not on the right path.
> I have 1 master backend server which has 5 tuners and 4 STBs. In the
> configuration of each tuner that is connected to a STB there is a
> place to enter a command to control an external tuner. I have added
> code to the DCT2000 channel_change executable to accept a command
> line argument for the port to send the information to and in each
> tuner configuration I have entered "/usr/local/channel_change x"
> where x is the serial port that the STB is connected to. This is
> EXACTLY how this is supposed to be done as well as how you recommend
> I do it, so up to this point we should be in FULL agreement. Now,
> I have 5 remote frontends, one in the living room, one in the kids
> playroom, one in my bedroom, one in the boys bedroom and one in the
> girls bedroom. If the kids are watching OnDemand in the playroom
> how should I go about sending the left, right, up, down, and select
> interactive codes to the STB that they are watching?
> I can only see 2 scenarios that would work.
> 1)	Modify Myth so that you can send things other than channel
> 	numbers out through the external tuner command.

That's probably what you'll have to do, because this magical "thing
other than channel numbers" is critical information that's not available
in any other way.  And, this way, the information won't be trapped on
the backend (where the external change channel command exists) and
inaccessible from the frontend due to the different filesystems.

> 2)	Somehow have the frontend that you are watching interogate
> 	the backend to see what STB it is connected to.
> 		As I undersand I can query the database to get this
> 		information. I do not yet know how to do this but
> 		it appears I will have to learn.

Direct access of the DB is always a good idea.

> 	Somehow send the codes to the STB which is connected to the
> 	backend.
> 		At this point the frontend knows which STB it needs
> 		to send the codes to but I am not sure how to go
> 		about calling a program on the backend. I would
> 		imagine that a daemon would have to be created
> 		to listen for requests from the frontends and
> 		forward the codes to the STBs		
> If you think I am on the wrong path then please tell me where I'm
> going wrong.

It seems that VOD just plain won't work with Myth.

(Perhaps I should get some sleep as I may be a little bit grumpy right now.)


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