[mythtv-users] 3 Mux but recording schedule indicating using 4 tuners?

tortise tortise at paradise.net.nz
Sun Sep 18 04:13:45 UTC 2011

On 18/09/2011 3:03 a.m., Ronald Frazier wrote:
> Well, it looks like you've got your tuners all configured correctly in
> the right order, so I don't see any problem there. Your schedule was a
> bit difficult to imagine in my head, so I diagrammed it out:
> http://ronfrazier.net/mythtv/schedule.png

Wow, that's very kind of you, thank you Ronald. I was going to do this 
myself on a spreadsheet, as you've gone to all this trouble I'll fill in 
some gaps. I was thinking its a good example of a real world complex 
case that may be helpful in various ways.

I've appended the Muliplex numbers added in as that would likely help, I 
printed off your pic and added the Mux numbers.  They can be summarised 
as all are M48, excepting D1 with Flintstones(Ch4) and Atonement(ch3) 
being on M50.  Ch 21 and 5 are M59, the two middle and parallel 
recordings on D2. Ch 5 on D4 is also on M59.  As below....

> OK, what I think happened is as follows:
> 1) even though ONE news at 6 starts first, myth determined that
> Flintstones was more important, and thus gave it a higher tuner (D1)

I think that must be the explanation as all tuners (from recordings 
page) were free for 56 minutes (allowing for padding) before 5.59pm.

> 2) ONE news at 6 then gets D2


> 3) the news ended, freeing up D2

M48 closed

> 4) Fuzion and Rugby came on and grabbed the first tuner available. D2

Yes, M50.

> 5) Bloodlines now comes on and grabs the first available tuner - D3

Yes, using Mux 48.

> 6) Fuzion and Rugby ended, freeing up D2

> 7)
> So now you have Goldfinger that needs to be scheduled. The scheduler
> can't use D1, because it's still on Atonement, so it grabs D2...the
> first available.

Yes, D2 resumes by Tuning Mux 48

> I think your complaint here is that it should grab
> D3, since it can reuse that multiplex.

Yes.  The picture suggests there remain 2 D3 virtual tuners available so 
it does not seem to be a padding problem.

FWIW I was more asking than complaining, I appreciate and respect the 
developer coding priority.  The first step is to understand. With an 
understanding there may be no second step. The explanations are no doubt 
helpful for more than me.  I thought it was a relatively complex real 
world example / exception to put up and consider, while noting we only 
have 3 multiplex's here, no doubt many users have to deal with more....

8) The consequence that interested me was that I was expecting RWC on D4 
to be on D2 however it used D4.  However the cause happened earlier as 
you have correctly illustrated without the benefit of the multiplex 

9) If Live TV was called from a Frontend during the D4 program that had 
locked that tuner to Mux 59 the available channels would be limited to 
those on Mux 59.  If it were me I could select the tuner I wanted via 
the menu and watch whatever live, however the rest of the family would 
voice their frustrations!!  I reiterate I am merely noting this to 
understand and nothing more, I think the developers do a fantastic job 
and I am in no position to suggest a change of priority here.

> Unfortunately, myth doesn't have the ability to prefer a tuner that's
> already tuned to the same multiplex.

That's a nice concise description of the issue, thank you.

> Multirec is a relatively new
> feature (only arrived in the last few years), and it's implementation
> was sort of wedged into a lot of existing code. As a result, some
> sacrifices were made just to get it working with what's already there.
> I'm pretty sure everyone would agree that favoring a recorder on the
> same multiplex (assuming equal priority) would be the preferable way
> to do it, and if the scheduler were to be redesigned from the ground
> up, I'm sure that would be taken into account. However, as was
> discussed in other recent threads, rewriting the scheduler is an
> enormously complex task, with so many variables to take into account,
> and a ton of optimization logic needing to take place to ensure that
> in doesn't perform extremely poorly under busy schedules. In short,
> it's a huge task, and I think a lot of people feel that, although not
> optimal, it works well enough in most cases that it doesn't justify
> the huge investment of effort that would be needed to significantly
> rewrite it. That effort could be better spent elsewhere.

I am not questioning this either.

It seems relevant to observe that lots of hardware tuners is a good idea 
if one wishes to concurrently use a good amount of myth capability!  My 
design expectation was that I only needed 3 tuners, however as the 500's 
came dual it seemed more sensible to match these, to reduce the 
potential for driver (etc) issues.  The 4th tuner D4 was prioritised for 
live TV and that seemed to justify its existence, however the above also 
unexpectedly justifies its expense!

Tuners probably cost a lot less (potential hardware limitations noted) 
than the developer and user time and angst revising these working things.

It is useful considering how I look to future backend configurations.

I used 4 virtual tuners (simplified from the real one + 3 virtual tuners 
as is sometimes described) initially by accident, I had intended 5 
however somehow I got 4 (I forget exactly how that came about now) so I 
kept it at 4 thinking that was 4 less (20-16) tuners to see in mythweb 
(and mythdroid) that would most of the time be redundant.

A first glance reaction to this example was I can fix this by simply 
changing to 5 channels per tuner, however working through the logic that 
would not have made any difference in this case, indeed the same would 
probably have happened with 3 virtual tuners.  For New Zealand it seems 
there is very unlikely to be benefit from setting up 5 virtual channels 
per tuner.

I am not sure what would have happened if I had 3 Tuners, the D4 
recording may have possibly failed?

Again, I record my gratitude here.

I've also sorted the recordings by Mux (M48, M50 and M59)

D2 M48 ONE News At 6 	1 - TV ONE 	Sat Sep 17, 2011 (05:59 PM) 	1 hr 32 mins
D3 M48 ¼Bloodlines 	1 - TV ONE 	Sat Sep 17, 2011 (08:30 PM) 	1 hr 45 mins
D3 M48 Rugby World Cup 2011 	1 - TV ONE 	Sat Sep 17, 2011 (10:14 PM) 	32 
D3 M48 ½Things We Lost In The Fire 	2 - TV2 	Sat Sep 17, 2011 (10:29 
PM) 	2 hrs 27 mins
D2 M48 ½Goldfinger 	1 - TV ONE 	Sat Sep 17, 2011 (10:44 PM) 	2 hrs 17 mins

D1 M50 Flintstones, The 	4 - Four 	Sat Sep 17, 2011 (06:29 PM) 	1 hr 57 mins
D1 M50 Atonement 	3 - TV3 	Sat Sep 17, 2011 (08:29 PM) 	2 hrs 27 mins

D2 M59 Fuzion Bollywood Film: Phir bhi Dil Hail Hindustani 	21 - Stratos 
Sat Sep 17, 2011 (07:59 PM) 	2 hrs 32 mins
D2 M59 Rugby World Cup 2011 	5 - Maori Television 	Sat Sep 17, 2011 
(07:59 PM) 	2 hrs 32 mins
D4 M59 Rugby World Cup 2011 	5 - Maori Television 	Sat Sep 17, 2011 
(10:29 PM) 	2 hrs 12 mins

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