A question about multiple tuners

Christian Hansen

Hi,
I am wondering how tvheadend handles multiple tuners. In my setup I have a HDHomerun with dual tuner. My frontend is XBMC (actually there are multiple frontends) and connects fine to tvheadend. However when I setup tvheadend as endpoint in xbmc there is no option to which tuner it should use. So my guess is that tvheadend automatically chooses a free tuner. My original plan was to have dedicated tuners for my xbmc clients, is that possible at all?

This raises another question, assuming tvheadend 'auto selects' a free tuner, in the case I schedule a recordning at time and then 5 min before recording, two other clients begin watching TV and now no tuner is available for the recording. Or does tvheadend lock a tuner as soon as recording is scheduled?

Thanks in advance.

Peter Vágner

I am afraid this is a bit more complicated as it is possible to watch and record channels broadcasting on the same transponder / multiplex even with single tunner. There are small countries where there are only two multiplexes so for these regions two tunners are enough to be able to record and broadcast all DVB-T channels.

Adam Sutton

Christian,

As Peter pointed out there are several factors that come into play. Currently TVH does not allow you to either:

1) restrict certain users to a specific set of tuners
OR

2) restrict certain users to a maximum number of tuners

I know users that have achieved this by simply running multiple TVH instances, but that's far from ideal.

Personally I wouldn't suggest trying to tie people to a specific tuner, it could be quite limiting because as Peter pointed out 2 users may want to watch 2 programs that happen to be on the same transponder/multiplex and therefore doesn't require 2 tuners (but could if you were explicitly restricting users). Its much better to let TVH just do its best to figure out how to assign things. Though I can certainly see some room for improvement generally in user management (point 2 above would be such an idea).

With regard to recordings v live tv. In the simple case it depends on the priorities you've set, generally speaking though recordings (by default) have a higher priority than live viewing and would therefore kick out a live viewer. You can of course change this (for recordings).

There are some additional complexities involved when you have multiple tuners that do NOT provide the same set of services, but have an overlap. For example I have 2 DVB-S feeds and 2 DVB-T feeds. The T feeds can mostly be considered a sub-set of the S. Should I start recording something that's only on the S tuners such that it ties them both up, if I then want to watch something else only available on the S I can't. However one of those first 2 things might also be on T. Unfortunately TVH doesn't pre-calculate and try to optimally balance these things, everything is treated first come first serve. So that is definitely one area that could be improved in the future.

Anyway hopefully that helps clear things up (or confuses the heck out of you :) ).

Adam

Kev S

However one of those first 2 things might also be on T. Unfortunately TVH doesn't pre-calculate and try to optimally balance these things, everything is treated first come first serve. So that is definitely one area that could be improved in the future.

Although of course it is possible to prioritise the tuners so the DVB-T ones are used first.

Where I am there are just five services available on DVB-T which are not on DVB-S and I have three DVB-T and one DVB-S tuner.

My DVB-T tuners are top priority (the highest propriety being assigned to one which only has knowledge of the most used multiplex - i.e. the one carrying all the BBC services) meaning nothing uses the DVB-S tuner unless either all the -T tuners are tied up or another DVB-S tuner is being watched (and hopefully when we have to retune for the seventh time in under two years next month :( ). In reality this means I've not seen a DVB-T recording fail or been blocked from viewing a DVB-T service due to a lack of tuner. DVB-S on the other hand is a different kettle of fish (thanks to the 100 multiplexes and single tuner!), although it's surprisingly rare that is a problem (as the majority of decent channels are on DVB-T too).

Adam Sutton

Indeed, but everything else aside on my setup I'd always prefer the s
services as the input is more reliable (better tuner), better signal, and
often higher bit rate. So there is lots of factors to possible take into
account, it could be a scheduling nightmare which is why tvh currently

keeps things simple.

But I think we've strayed off topic :)

Adam

On Apr 5, 2013 7:05 PM, wrote:

> Tvheadend - General: RE: A question about multiple tuners
>Kev Swindells >
>However one of those first 2 things might also be on T. Unfortunately > TVH doesn't pre-calculate and try to optimally balance these things, > everything is treated first come first serve. So that is definitely one > area that could be improved in the future. >
> Although of course it is possible to prioritise the tuners so the DVB-T
> ones are used first.
>
> Where I am there are just five services available on DVB-T which are not
> on DVB-S and I have three DVB-T and one DVB-S tuner.
>
> My DVB-T tuners are top priority (the highest propriety being assigned to
> one which only has knowledge of the most used multiplex - i.e. the one
> carrying all the BBC services) meaning nothing uses the DVB-S tuner unless
> either all the -T tuners are tied up or another DVB-S tuner is being
> watched (and hopefully when we have to retune for the seventh time in under
> two years next month [image: :(] ). In reality this means I've not seen a
> DVB-T recording fail or been blocked from viewing a DVB-T service due to a
> lack of tuner. DVB-S on the other hand is a different kettle of fish
> (thanks to the 100 multiplexes and single tuner!), although it's
> surprisingly rare that is a problem (as the majority of decent channels are
> on DVB-T too).
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