Recording 9 programs at once.. (1 Viewer)

[hotponyshoes]

Just tried out some recordings from DVB-T.
I have a pair of the black gold dualtuner cards (so 4 tuners) and I am able to start recording more than 4 programs at the same time.
I currently have 9 recording and I am watching one of those at the same time with no problem.

No,
As I only have 4 tuners fitted how is this possible???????

 

[craigparris1]

Hi hotponyshoes,

It's probably to do with the "muxes" (I think that's what they're called). I'm going to guess that while you may be recording 9 different shows (possibly across different channels) those shows are only coming from a total of 4 different broadcasters - does that sound correct?

For example, one broadcaster may have a range of frequencies that it can use, and it may broadcast different channels across these different frequencies - but because they're all coming from the same broadcaster (ie. the same "mux"), your tuner card can receive all the streams (channels) from that broadcaster at the same time.

So, with your 4 tuners, you could recieve channels from up to four different muxes, which could be any number of possible channels. However, once you recordings going across those four different muxes, you wouldn't be able to then watch or record a channel from a 5th broadcaster.

Well, that's my understanding, anyway - I'm sure someone who actually knows what they're talking about will be able to explain it better ....

Cheers,
Craig

 

[amphibem]

What Craig said is right, a digital 'mux' can carry multiple channels up to a throughput limit and one tuner can record all of those at once.

What country are you in, and what provider is it?

 

[hotponyshoes]

I'm in the U.K. and it's the FTV 'Freeview' broadcasts.
I presume there must only be a few "mux's" as I managed to get over 15 recordings going last night!

I could maybe get more but the live chanell picture started to get a bit choppy.
I presume this is either due to bandwith restrictions accross the pci-e buses or a lack of processing power on the pc?

I just presumed you would be limited to one stream from each tuner, thats why I bought 2 of the dual-tuner cards.

I will never need to record this many so I will put one of the cards up for sale and hope dropping down to one card helps with some of the system issues I keep getting.

Shame I can't get the thing to work properly as whenever I do something like record 15 programs at the same time (plus listen to a ripped cd while doing it) It makes you thing all the cash and effort to use only a pc was worthwhile!

As soon as the better half comes home, brings the thing out of standby, and gets the 'Can not start time-shifting - unable to create graph' message I will start thinking about going back to the sky box again..

 

[jonaskp]

Just an addition to what Craig said, because actually it was almost spot on:

A MUX is actually just one frequency. With old analog Broadcast, a Frequency contained only one Analog Channel. With the new DVB-T, the frequencies (or MUX'es) can contain a number of channels. I know that here in Denmark, when they get a new DVB-T provider in 2009, they will Broadcast 10 channels on each of their MUX'es. This would mean that you could, with just one Dual Tuner, record 20 Channels at the same time. Quite Amazing.

Of course, this show in the quality of the channels. To be able to put so many channels in a MUX, you have to Compress the video/audio quite a lot. I think, that in MPEG-4 compression, you could have 4-6 Digital SD channels on a MUX, without loosing quality over the original source. I think it is 1-2 HD channels on a MUX, with MPEG-4.

So, with only a Dual Tuner card, You can record alot of channels, but be aware of the facts that it has to be the "right" channels, which is not always easy to see. If you want to record 3 channels, there is no way of knowing if it is possible to do this, before you try to add the recordings - then MP will tell you if you cannot, which will be because the channels are on different MUX'es.
This may not be the easiest thing to explain to your significant other: "Yes honey, I can record Desperate Housewives, Melrose Place and 18 other Crap programs you don't want to see, but I cannot also record Friends".
Hopefully she'll understand though ;-)


[edit]On a sidenote, I have been running MP for quite some time now without dealing with the horrifying "Unable to create graph"-monster. Using just RC1 and an older SVN (which I haven't updated out of fear of the return of the monster).
Oh no, I may have just Jinxed it, please work when I get home, Please...

 

[Paranoid Delusion]

as soon as the better half comes home, brings the thing out of standby, and gets the 'Can not start time-shifting - unable to create graph' message I will start thinking about going back to the sky box again..

Theres a couple of settings that really help with standby all in TVServer config, first is under general, set a delay for detecting cards, mines set to 20 seconds to overcome my usb tuners, second is reinitiliase tuners in powerscheduler plugin, between the two they should get most cards working with standby.