[mythtv-users] Linux/MythTV HDTV options and questions

David George david at thegeorges.us
Wed Oct 20 14:47:18 UTC 2004

On 10/20/2004 9:25 AM, Shelby McGregor wrote:

> I have been watching the threads here for quite some time while I 
> contemplate building my MythTV box. One of the most import issues for 
> me is HDTV support, and preferably QAM support so that I can get my 
> HDTV signals from cable. Anyway from what I can see there doesn’t 
> appear to be a currently available HDTV turner for Linux that supports 
> QAM. I was interested in the Sasem OnAir USB tuner since it tunes ATSC 
> and QAM as well as provides a MPEG2 encoding chip for analog channels. 
> I contacted Sasem and they tell me that they currently have Linux 
> driver support on the roadmap but don’t expect beta level drivers 
> until at the earliest Q2 2005, so at the moment it looks like my only 
> choice is the HD-3000.
> Anyway sine the HD-3000 isn’t currently available I have some time 
> before I start to build my box. One question I have is about how 
> MythTV handles channels with similar content. I plan to put some sort 
> of HDTV tuner in my box as well as 2 PVR-250s that will be receiving 
> content via DirecTV, and basic analog cable respectively. Is it 
> possible to stack the channels on top of each other with preferred 
> tuning devices?

> For example I will have 3 input sources all of which will have the 
> local CBS channel 62 available. What I am curious about doing is 
> setting up the system so that there is only one Channel 62. If I tune 
> to the channel I would prefer to use the HDTV card first but if that 
> is busy recording a program fall over to one of the analog tuners, 
> preferring cable 1^st and then satellite. Likewise when scheduling 
> recordings, I would prefer to record from HDTV tuner first and then 
> fall over to analog tuners if I have no other choice.
Each card can have a priority. I have my HDTV input set to a higher 
priority than cable. If the HDTV card is busy Myth will schedule the 
show on my Directv input.

> Actually in a perfect world it would be great if MythTV knew that one 
> tuner was HDTV capable and then only used that tuner for content that 
> is flagged as being HDTV in the program guide,
Content is only marked HD on HD channels so this is supported by default.

> but I am guessing that sort of beyond the current functionality.
I always laugh when I see statements like this. You know what they say 
when you assume...

> In order to do this, I would need to map channels from the different 
> tuners to one unified “virtual” channel guide and again this is 
> something I don’t know is possible (I couldn’t find any similar setups 
> in Gossamer-threads or in Google, though maybe I don’t know what 
> keywords to search for). I would prefer to use the DirecTV guide as my 
> starting point but have a method of hiding the fact that Channel 62 
> one DirecTV is actually channel 15 on cable and channel 44 on HDTV. It 
> seems that it should be logically possible since my HDTV content is a 
> subset of my cable channels and my basic cable channels are a subset 
> of my DirecTV channels.
You will need to setup two lineups in DataDirect. One for HDTV and one 
for Directv. Where the callsigns are the same the channels will be 
grouped so you will no longer see a ton of duplicate channel entries in 
the program guide. Search the archives for "callsign".

> Any information on how to setup something like this would be very much 
> appreciated. I have played with MythTV briefly and if I can iron out 
> these sort of issues I think I am ready to build my dedicated box.
First suggestion is to go for it. It doesn't sound like you are doing 
anything that hasn't already been done (except for cable HD). If you run 
into any stumbling blocks there are people here that can help. I hope 
the pointers I gave above help.


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