[Fwd: Re: [mythtv-users] DVB-S support and mythtv]

[Edward Wildgoose]

Wander over to www.linuxtv.org for DVB support.

Many cards are supported.  The USB ones appear to be, but I don't understand how, the interface appears to be far too slow.  Stay away if you can is my recomendation on the USB stuff.

All the major DVB cards have support though.  VDR is the main myth type competitor and is very polished in many respects.  Personally I like the eye candy with myth and so I'm really looking forward to Ben's new code.  

The way DVB works is that several mpeg streams are all beamed together.  The full featured cards can demux this in hardware and give you a single mpeg stream.  The budget cards give you the whole mpeg stream and you need to demux to get any individual channel yourself (well the driver does it for you, but all the data has to cross the PCI bus).

If you get VDR and have a play first then you will see that this supports multiple channels from a single card, say recording two channels, and watching a third, all with a single card.  Very handy.

There are still a few bugs in Ben's code and since I'm leaving the country in a few days time we need someone else to help out with debugging the last few bits.  I don't think it is major stuff, it's just that Ben doesn't actually have a card of his own so he has written everything blind using my machine over ssh!

Anyway, if you get a DVB card today you can record a film as easily as:

tzap -r "BBC ONE" | ts2ps 0 0 > myfilm.mpg

Hit control C when it has finished recording.  Great huh.  Quality is top notch (on my channels at least)

-----Original Message-----
From: Barry Davis [mailto:bdavis at eurologic.com]
Sent: 06 May 2003 18:38
To: Discussion about mythtv
Subject: [Fwd: Re: [mythtv-users] DVB-S support and mythtv]




I'm thinking about making a machine up as well. I've got a lot of 
experience with Linux (its my job) so I don't mind getting my hands 
dirty with some experimental code.
What is support like for digital TV in Linux? Is it just the satalite 
cards that are supported (WinTV Nexus-s and Nova) or are the Terrestrial 
cards supported as well (WinTV Nova-t PCI)? Or even USB versions (WinTV 
Nova-t USB and DEC 2000-t).
I'm particularly interested in the DEC2000-t as it can be used without a 
computer.

Why does the video stream need prefiltering? What does this entail? 
Don't these cards feed out an MPEG2 stream?

Barry.


Ben Bucksch wrote:

> jbeuree at rogers.com wrote:
>
>> Would the issue around cards not being able to prefilter cause a 
>> significantly larger load on the PCI bus?
>>
> I don't think that PCI is an issue, I think we have a TS of maybe 
> 16Mbit/s or something in that area. I was more concerned about RAM 
> bandwidth. But I don't think that's going to be a problem either. It's 
> not *that* much of data to process.
>
> If anybody has more concrete data about the size of transport streams 
> and the load that PID filtering and TS->PS conversion brings per card, 
> I'd like to know it.
>
> In any case, I think the code should work with both types of card. But 
> I don't know, I'll need to test it.
>
>> I'd eventually like to have a machine with a couple of these cards 
>> (and maybe even keep a cable tuner in it also).
>>
> me too. Note that they are limited to 4 per machine, I think.
>
>> But if this would prevent this setup I may be better off getting a 
>> better card.
>>
> I will personally go with 2 Nova cards and maybe keeping the analog 
> card for backup.
>
> _______________________________________________
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> mythtv-users at snowman.net
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>



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