The table is used to group capture card inputs, which can not be used at the same time. For example, if a card can record analog (cardinput=1) and digital (cardinput=2) channels, but the card has only one shared receiver, there will be two entries in this table with a common inputgroupid. That group is given the name inputgroupname (which must be repeated for all rows).
Even a card with only one input gets an entry with a unique inputgroupid (as this simplifies the implementation).
|cardinputid||int(10) unsigned||NO||NULL||REFERENCES cardinput(cardinputid)|
- Taken from MythTV HowTO: http://www.mythtv.org/docs/mythtv-HOWTO-12.html
Usually, inputs on different cards can record at the same time but two or more inputs on the same card cannot. However, there are cases where inputs on different cards should not be allowed to record at the same time, for example, a firewire card and s-video analog card connected to the same set top cable box.
| | coax +--------------+ firewire ------------------+ | .-=|Cable Provider|=------------=| Card 1 input 1 | HDTV | | |HD/Cable STB |=--. +-----|||||||||||| | | +--------------+ | s-video ------------------+ | | `---------=| input 2 | Digital |wall | coax | Card 2 | |=---=^=------------------------------=| input 3 | Cable | +-----||||||||||||
Input 1 and input 2 receive content from the same set top box and the channels can not be tuned independently. Therefore only one of these two inputs should be used at any given time. The solution is to create an "Input Group" with mythtv-setup in "Input connections". Including these two inputs in the same Input Group will tell the scheduler that these are mutually exclusive and may not record at the same time. Inputs 2 and 3 are automatically mutually exclusive because they are on the same card so there is no need to create an Input Group for these inputs.
Cards such as the Hauppauge PVR-500 are able to record as two cards simultaneously because it has two MPEG-2 encoders and each encoder appears as a separate device. DVB cards may be allowed to capture content from more than one channel at a time if the channels are in the same MUX.
The following is an entries for a DVB-T source:
These examples are for a machine which has two "Nova T" (not the 500 model) cards and each card is configured for two tuners. (even though it can only tune to two channels on the same transport).
cardinputid: 1 inputgroupid: 1 inputgroupname: HDHR_/dev/dvb/adapter0/frontend0
cardinputid: 2 inputgroupid: 1 inputgroupname: HDHR_/dev/dvb/adapter0/frontend0
cardinputid: 3 inputgroupid: 2 inputgroupname: HDHR_/dev/dvb/adapter1/frontend0
cardinputid: 4 inputgroupid: 2 inputgroupname: HDHR_/dev/dvb/adapter1/frontend0