[mythtv-users] DVB-S multirec: how many recordings per card?

Andre mythtv-list at dinkum.org.uk
Fri Nov 19 22:43:17 UTC 2010


On 19 Nov 2010, at 21:59, Stefan G. Weichinger wrote:

> Am 19.11.2010 19:32, schrieb Andre:
> 
>> To give you a datapoint I find that 4 virtual tuners works well with
>> a dual tuner slave backend that has a 1.8Ghz C2D cpu clocked at 1Ghz
>> for quiet running and 2GB ram. I can record 4 HD streams in the tests
>> I did and I find that 2 virtual tuners is used a lot of times for
>> overlaps, 3 is used sometimes, 4 I've never seen "in the wild" but I
>> know I can record two shows on two channels with overlaps.
>> 
>> I have 5 sata disks to spread the load but they are shared between a
>> master and nfs slave backend, The master has a Q6600 2.4Ghz C2Dquad
>> 4GB ram, grand total of 6 tuners, 24 virtual tuners.
> 
> For comparison:
> 
> BE has C2D E7400 (2.8 GHz), 4 GB RAM, 4x1T hdd (two of them for
> mythtv-storage). And "only" the 2 mentioned tuners.
> 
>> You need to set everything to max (5) get a channel plan (king of sat
>> maybe) and pile on the recordings until it breaks then back off a
>> little :-)
> 
> So I assume my box should do fine with 3 ;-)

Should be fine for 4 or maybe even 5, I find 4 is the ideal but 3 covers most things.

I remember reading some discussion about some hardware managing 15 simultaneous recordings in the early developments of multirec but I understand 5 was chosen as a limit that was enough to be useful and still attainable by most contemporary hardware.

> 
> king-of-sat looks somehow scary ;-)

Ah, sorry, I do this stuff for a living! Really the only thing you need to know is the position of the Satellite(s) you are picking up, 19.2E in your case, then you really only need this page:
http://en.kingofsat.net/pos-19.2E.php

Then anything that is DVBS (blue groups) can be received, if you don't have a cam and card then only the white channels will work.

I'd start a 5 minute manual recording on Eins Extra, then add more channels on the same transponder, txp 51 in this case so Eins Festival, then Eins Plus, checking each time (I use mythweb status) that the recordings are all going to one tuner.

Still feeling adventurous, pick another transponder say, txp 20 Montagne TV and keep adding channels from there... 

As there doesn't seem to be any HD you could receive on 19.2E then you should easily manage the max 5 simultaneous recordings, probably 10 SD simultaneous is possible if your motherboard's PCI allows.

Have a look at the recordings afterwards and see if they are clean or have glitches, if the first two or three things you recorded seem ok and the last are bad or the end of any of the recordings is bad or has finished early then you have overdone it.

> 
> Thanks so far, Stefan
> 



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