[mythtv-users] Number of virtual tuners

Simon Hobson linux at thehobsons.co.uk
Mon Apr 30 07:08:44 UTC 2012


Pieter De Wit wrote:

>During the channel scanning phase a scan is done to see how many 
>channels a card can tune to. This can be done to /dev/null to drop 
>out disk/display and other bottle necks.
>
>Once this number is known, Virtual tuners can be used to record from 
>the real tuners. Virtual tuners is something that "we" control so we 
>can limit them based on other factors. I am sure we can safely say, 
>that you only need to display 2 channels at once (watch, someone 
>will give us a screenshot with 4 PnP's :) )

That won't help in the general case - there is more to recording 
multiple streams than just getting them from the tuners and stuffing 
them on disk, not to mention that if you have multiple tuners then 
the system may not be able to handle the max no of recordings the 
tuners are collectively capable of doing while it can handle the max 
for any one tuner on it's own. It's been suggested earlier in the 
thread that some other factors come into play - for example, what 
does it do to the system when several recordings start at once and 
the <something> kicks in to update the database ? Then you've got an 
arbitrary number and type of user jobs, and an arbitrary number of 
frontends - in theory there's no limit to the number of frontends/TVs 
someone could have hanging off the backend.

But the biggest problem with any automated system like you describe 
is that they always end up getting in the way sooner or later. It's 
like using MS Office - you know exactly how you want to format your 
document, but the darn software keeps getting in the way and doing 
different things "to be helpful" because the vendors have the same 
mindset of "making it easy".

Personally I'm inclined to say it's a documentation problem to be 
solved. You cannot set a limit that satisfies the requirement to be 
"safe" for all users (you've found that a limit of just 3 wouldn't be 
"safe" for your hardware) while not artificially restricting other 
users. The problem as I see it is that MythTV is a complex project 
for a new user (it's still complex for me and I've been using it for 
years !), and the documentation in some areas can be difficult to 
navigate.
So how can it be made easier for a novice to find the right bit of 
information when they arrive at each setting of the many they need to 
know about ? It's probably a whole wiki page to cover just how to 
setup multirec AND determine how many tuners is "safe" for your 
hardware.

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.


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