Multistandard PC/TV - System Requirements
 

Hi,

Prompted by tvden's post I thought I'd start a new thread about this.

Something I'll have to explain is that it's all very much "up in the air" at the moment, and exact system requirements will depend on what software is used and what features are required. Also it depends to some extent on me testing it all (and there's a lot to test) on different systems; and I've only got one system right now, and there's only one of me, too ;)

At the moment, my full-featured MythTV PVR setup is working reasonably well on an 800MHz AMD Duron system with 256M RAM, but bits of MythTV are sluggish and off-air digital TV can take a good few minutes to settle down and stop "stuttering" after a channel-change. The MythTV developers are addressing a bug which should, when dealt with, lower the CPU load a bit and mean it settles down more rapidly.

So, as a rough estimate, an 800MHz Duron with 256M RAM or similar-spec Intel system ought to be ok for a 'basic' MythTV system running one digital TV card. Anything less and you may struggle, but there's no harm in trying - DVD playback at least ought to work on lesser systems.

I first tried a 600MHz P3 system; this was ok playing back DVDs and was good enough to support direct unbuffered off-air TV from a basic analogue TV tuner/framegrabber card using a basic TV viewer application (not MythTV - analogue TV with a basic framegrabber on MythTV would probably take a 1.3GHz processor.) I was unable to test the 600MHz P3 system with a digital TV card as the card wouldn't work in the particular motherboard; partly why I swapped the board for the 800MHz Duron board from one of my servers.

For some reason I couldn't get streamed video off the 'net to work particularly reliably with the 600MHz P3; but this may be down to configuration. I've not had time to work on streamed video again with the current system.

For anyone wishing to experiment; I'd suggest reading the general information on MythTV system requirements; particularly this section http://www.mythtv.org/docs/mythtv-HOWTO-3.html#ss3.1

Any capture devices which already work with MythTV should work with MythTV on 405, 819, etc.

I'm using a Hauppauge Nova-T DVB-t internal PCI card (not the external USB version); this works fine although I've not got the bundled remote control working particularly well yet; so my system still has a wired PC keyboard on it.

Now - Graphics Cards. All I can say with any certainty is that the nVidia GeForce4 works, the nVidia GeForce2 doesn't support interlaced modes. There's some fun and games involved as nVidia have released some broken driver versions which refuse to produce proper syncs and interlace on the HD-15 RGB output; but I can confirm the latest driver does work - this is version 1.0-8756

Theoretically, any nVidia card from GeForce4 onwards should be ok, but I've not tested them personally - again, feel free to try yourself. Other cards may work; some cards might work fine with the 405-line modeline I calculated for the GeForce4, some might need a new modeline calculating, and some may be completely unable to produce correct 405-line timings at all. This needs further investigation; I may end up asking for graphics cards on loan, so I can try them out myself.

Before I release my KnoppMyth-based custom "obsolete standard" distribution (FotH Linux), if anyone feels like experimenting with 405-line (or 441, 819, etc., when I've worked those out) from a PC; first get MythTV working on a PC monitor; then get it working with the card's TV-out (S-Video or composite) with a PAL/625 (or NTSC/525 if appropriate) set.

The easiest way I've found to do this is to install KnoppMyth (which is a complete dedicated-purpose Linux distro) see http://knoppmythwiki.org/.

The latest KnoppMyth public pre-release (R5B7) currently contains an older (broken) nVidia driver though. At present it takes a bit of mucking around inside the system to install the version 1.0-8756 nVidia driver. The included nVidia driver does work on a progressive-scanned PC monitor though, and at least lets you play with MythTV a bit :)

Additional hardware required for obsolete standards: an RGB+sync combiner circuit. I'm currently working on a Mark II version which I'll release schematics for once it's tested. Hopefully it'll be the Mark II in use at NVCF :)

I hope this isn't too off-putting - basically it's all still very much in the "experimental" stage - one thing where commercial software and open-source software differ is that open-source software is developed in public - you can get your hands on development software long before it's stable, complete, reliable... :)

After NVCF I hope I'll be able to find somewhere to host a "FotH Linux Wiki" where I and others can post information which, in the interim, will help anyone modifying KnoppMyth for obsolete TV standards and eventually become a repository for information about the FotH Linux distro itself.

Regards, Kat

Re: Multistandard PC/TV - System Requirements
 

I've just installed Knoppmyth on a 1.4GHz P4, with 256MB of RAM and 120GB hard disk, and it seems to run OK (no tuner card yet - waiting for something to turn up on eBay), the video is an Nvidia but lower spec than the GeForce 4. I'll try and follow Kat's instructions for forcing 405 line out of it another day.

The installation was easy, even for a Linux virgin, with most of the stuff being self explanatory.

My only gripe so far is the broken DVD software - it will play region 0 disks, but not region 2, so it's off to read the manual!

Jim.

Re: Multistandard PC/TV - System Requirements
 

Hi Jim,
Ah, that's good to hear :)

Hmm... I've spent more time playing with off-air digital TV since I switched to KnoppMyth (the system is also used with our main 625-line set in the living room), and did note that the only DVD I tried (Region 2) didn't work... I'll look into this... The same DVD was working on the "MythTV-on-Gentoo" I was using previously; Mike Phelan can confirm ("The Day of the Triffids" BBC series :) )

After NVCF I'm going to run through installation and "405-ifying" KnoppMyth a few times, writing it up as I go along as a "step-by step" guide; then I'll turn my brain off and blindly follow my own instructions as a test... I'll publish this somewhere once I've written it :)

Right now I'm focussing more on having a reliable system with as much working as possible for NVCF; after then I'll work more on sorting out documentation enabling others to do it too.

Regards, Kat

Re: Multistandard PC/TV - System Requirements
 

Hi,

I got DVD playback in KnoppMyth working

This answer in the FAQ is the clue.

Decryption of encrypted discs is disabled by default; as the software to do this is illegal under the DMCA in the US.

So, they don't ship KnoppMyth with the decryption software installed.

But they do provide a script to install it.

We're in the UK and don't have the DMCA, so it's probably safe to say:

Get a root login by one of the following means:

• exit MythTV, right-click on the desktop, select XShells and start an xterm; then /bin/su - and give root password.
• Ctrl-Alt-F1 to switch to a console, log in as root.
• ssh root@hostname from another machine, replacing 'hostname' with whatever you called the machine.

Then (the # indicates the root prompt, don't type it):
If any moderator believes my publishing information on how to watch commercial DVDs you paid for on your own hardware to be illegal, please delete it and replace it with a "PM Kat for info" message.

Regard, Kat

Re: Multistandard PC/TV - System Requirements
 

There won't be any legal issues around watching region 2 DVDs in the UK. When it comes to other regions, the position is basically the same as publishing 'mulitiregion hacks' for DVD players.

I believe the entire DVD regionalisation system has collapsed (good thing too :D) I've never bought a DVD player in my life because I keep getting given them with trivial faults, but *all* the ones that I've encountered have been multiregion (really). This often isn't publicised though.

Best regards, Paul

Re: Multistandard PC/TV - System Requirements
 

That's fine with me.

Let's not get into a discussion about multi-region DVD players etc here though, as it's not relevant to this thread.

Re: Multistandard PC/TV - System Requirements
 

Kat many thanks info I had a read on the mythtv site, my 500 mhz p3 cpu wont be any good and the board is a microstar ms-6168 and wont take a very much bigger cpu, so I will now have to get another motherboard with at least a 1.5 gig cpu oh well off to flebay regards Den

Re: Multistandard PC/TV - System Requirements
 

Potential good news!

The box I've been playing with has an nVidia FX5200 card in it, which I was going to replace with a GeForce 4, however, after looking at the files suggested by Kat, and trawling the nVidia website, it appears that the FX series cards are capable of producing 405 output. They are listed as supporting interlace mode, and appear to offer the same basic options as the GeForce.

Now that I understand the basics of the mode line for X windows, I'll hook up a scope over the next couple of days, and see if it will produce the correct timings (at least I will if I can get Telnet access to the Myth box to work).

Jim.

Re: Multistandard PC/TV - System Requirements
 

Hi Jim,
I'm reasonably sure that anything from GeForce4 onwards should work; I just tend to be careful not to guarantee anything I've not tested myself ;)

A couple of things - the nVidia driver that comes with the current release of KnoppMyth is broken - it won't produce correct syncs or interlace on the VGA output. I've not worked out how to "properly" update the driver to the latest (working) 1.0-8756 version (I'm still finding my way around what is basically Debian underneath.) I've PM'ed you with info on how I did it - it's a bit messy but it worked for me.

Telnet's disabled by default - as it's a security risk (password is transmitted over the network unencrypted) - I ssh into remote systems, this is secure, encrypted and enabled by default.

Regards, Kat

Re: Multistandard PC/TV - System Requirements
 

OK, I can now confirm that the nVidia FX5200 will generate the 405 line timings:clap:

With a huge amount of help from Kat:thumbsup:, I've got a KnoppMyth system built and running, and have managed to load the correct modeline (thanks again Kat!), and as I type this, the 'scope is displaying correctly timed synch pulses.

All I have to do now is build the hardware, and finish repairing my 405 line sets;)

Jim.

Re: Multistandard PC/TV - System Requirements
 

Jim

Good news that your FX5200 card works, but can I suggest that you keep an eye on the displayed video quality when you get your 405 line sets going. FX5200 cards showed softer video than GeForce 4 cards on a PC based video product I worked on a couple of years ago. This appeared to be an issue with the GPU's scaling filters as the softness was apparent when using either the analogue RGBHV output or the digital DVI output.

John

Re: Multistandard PC/TV - System Requirements
 

Hmm, Well,

After seeing the demo at the NVCF today, I feel the need to source a suitable pc and vid card!

Amazing results, with very little hardware external to the box, and unlike the low cost Aurora it will not slip off the bench to be lost forever! (not that the Aurora is a bad thing, just very,very small.....)

I wonder if the slight vertical "jitter" on the picture is just a bug to iron out?

Cheers
Sean

Re: Multistandard PC/TV - System Requirements
 

If the jitter was on the Pye monitor and not on the Sony TV, that's because the Pye was only received by Kat today (as you know since you bought it in for her), and has tempremental hold. It also needed thumping to make it start working!

Also Kat only finished building the external circuit on Saturday evening, so it is not really a finalised design yet.

Despite that, the results were most impressive, especially on Jeffrey's professional monitor.

Re: Multistandard PC/TV - System Requirements
 

Hi Paul,

Well, I did see the effect on both the little Sony and the Pye monitor (points taken regarding its questionable reliability, however, a good thump usually fixes most things!)

Anyway, certainly enough of an incentive to get me going!

Cheers
Sean

Oh, sorry for not having a natter - Once I was clear of getting shot of the monitor I got dragged away by another matter!

Re: Multistandard PC/TV - System Requirements
 

Hi Sean,
Very probably - XORing the syncs seems enough to prove the concept actually works; but in the long term it's not ideal. There's half the correct number of pulses and those that are there have the negative-going transition delayed by the width of the line-sync pulse compared to where they should be.

Now I've got that Pye monitor (thanks again for bringing it, that was really appreciated) I have a much better display device (after I've refurbished it a bit) which will help with hardware improvements - the first is to devise means to generate syncs which bear some relationship to the standard. I think a PLL may be involved.

Still, I don't think it's too bad for an experimental system; it even worked from booting up right through the day with no problems :)

Regards, Kat

Re: Multistandard PC/TV - System Requirements
 

I was impressed ..... I know that you were up rather late Kat sorting out last minute things.

I thought that some of the jitter was certainly more of a monitor fault rather than your unit. I might be wrong though.

Re: Multistandard PC/TV - System Requirements
 

Trish, you are not wrong. The interlace on my Prowest was OK and everything was rock solid. The simplified field sync waveform will almost inevitably give poor interlace on some sets. Kat's Pye monitor required some percussive adjustment to make it work:) so it's hardly surprising that after years in storage it's less than perfect.

Not directly related to Kat's converter but one nice touch in the Aurora converters is that equalising pulses can be added to the waveform at the click of a switch. This gives best possible interlace on many sets but can be switched off for complete authenticity.

Re: Multistandard PC/TV - System Requirements
 

More compatability news.....

KnoppMyth is happy to work with the Hauppage WinTv 38105 card, which is a basic analogue Tv receiver card. The one I've tried is revision B435, which seems to refer to the PAL-I (UK type PAL) system.

Jim.

Re: Multistandard PC/TV - System Requirements
 

Gidday Jeffrey,
the equalising pulses are ony interesting for sets with an integrator V- sync separator. The british (vintage!) TV sets don't have one and so there is definately no need for equalising pulses. The dual standard sets have an integrator and they have trouble without these pulses. I am sure your monitor has an integrator too. Some sets with integrator have an "interlace adjust".
Look for examples in the BVWS trader sheets.

Kind regards,
Darius