405-line o/p from Linux

[davegsm82]

[Split from here - Kat]

Kat, if I make a break-off thread, would you be so kind as to elaborate on the process involved in getting a linux based system to output 405 lines?

I have a first class degree in computer and network technology, so don't worry, you shouldn't baffle me with tech-speak.

Dave.

[Kat Manton]

Okay...

• Use nVidia GeForce 4 or GeForce FX 5200 card.
• Use binary drivers from nVidia.
• If you already know how to configure your X server for old fixed-rate Unix workstation monitors, you'll know what to do with the following fragment from one of many "Monitor" sections in my X server configuration file. If you don't, all the information is on the 'net, in man pages and in the documentation for the nVidia driver.

    Option      "ConnectedMonitor" "CRT"
    HorizSync   9.0 - 11.0
    VertRefresh 45.0 - 55.0
    DisplaySize 128 96
    Modeline "405i50" 8.10  664 680 752 800  378 379 386 405 -hsync -vsync interlace

Disclaimer: Use at your own risk. No responsibility accepted if your computer monitor screams at 10.125 kHz then catches fire or you fry a 405-line TV by feeding it with 1600 x 1200 @ 85 Hz etc. (Hint: ssh/telnet; don't connect monitor; only connect RGB/sync combiner, modulator and TV when H/V sync measure 10.125 kHz and 50 Hz respectively.)

Kat

[julie_m]

Do you actually need the nVidia binary driver, or will it work with the open source one? After all, it's only a mode line .....

[Kat Manton]

I couldn't get smooth playback with the 'nv' driver (probably as it lacks XvMC.) The 'nouveau' driver also lacks XvMC, so I haven't tried it. What I've listed works. Anything else; I've tested it and it doesn't work, I know it won't work or I haven't tested it.

[neon indicator]

The newer Ubuntus use a different method than X server file...

I've not tried two graphics adaptors on Linux. Maybe you could use Motherboard video for the VGA and a PCI/AGP /PCIe card for the 405?

[Kat Manton]

Since I've split the thread...

Can I use this as a standards converter?

If you mean converting an analogue 625-line input to an analogue 405-line output; probably, but you really don't want to.

MythTV is massively over-complicated for this and really won't work all that well. It's not what it does. You'd require a fairly powerful PC or a capture card with hardware encoding. MythTV buffers live TV (which is what an analogue input is treated as) to hard disk, then plays it back. This is so you can pause and rewind live TV, or decide you want to keep a programme you've watched from the start. An analogue input would normally be used with a cable box and an IR sender, controlled from MythTV (to allow channel changing and timed recordings.)

Obviously, this will delay the video signal considerably; you have to feed your audio source into the system as well so that it can be recorded along with the video signal, then played back in sync.

It's all rather clumsy and I haven't bothered attempting to use it like this.

What does work is producing 405-line (or other standards) from digital sources internal to the PC; a DVD drive or one/more DVB-T/DVB-S cards or off-air recordings previously stored to hard disk.

If all you want to do is convert analogue 625-line video to analogue 405-line, get an Aurora. It works.

Why MythTV? Isn't there something simpler?

There's tvtime. This is fairly basic, it'll work with (supported) analogue and digital TV cards and can use the composite video input of cards which have one. It just displays whatever channel is selected or displays whatever is being fed into the analogue input.

When I last tried it, it appeared to assume that the display had a 1:1 pixel aspect ratio; so when used with my modelines for 405/819/etc. it produced a squashed/stretched display.

MythTV OTOH knows that whatever resolution it's outputting to has a display aspect ratio of 4:3 (or 16:9, selectable in a menu) and so will scale DVD/Freeview to fit it even if the pixel aspect ratio differs wildly from 1:1 (which it does with my modelines.)

It may be that 'tvtime' will work now. I haven't tried it as I'm happy with a MythTV system (which is our normal means of watching/recording TV etc. and is usually hooked to a DLP projector and the main hi-fi system.) It may be possible to modify 'tvtime'; but I have no particular incentive to do so.

Can't you make modelines with 1:1 PAR?

No. The pixel clock is derived from a crystal oscillator on the graphics card and the PLL on the card can not be programmed to produce any arbitrary pixel clock frequency. You can specify any frequency you like in the modeline; but the driver will (silently) select the closest frequency which can be generated.

Thus a modeline calculated using a nice 1:1 PAR and 4:3 DAR is likely to require a pixel clock frequency which can't be generated. It'll "work" (as the driver will select a frequency that's close), but H and V timings will be incorrect.

My modelines have been calculated to produce correct H and V timings for the TV standard in question, within the constraints imposed by the hardware (and the pixel clock frequency isn't the only one), hence the anything-but-1:1 PAR (as it doesn't matter with MythTV anyway.)

Which Linux distro should I use?

Whichever distro you're most familiar with. Setting up MythTV is non-trivial, so it helps if you know your way around.

I use Gentoo. It lets me install only the bits I need for a MythTV system and compile those bits only with features/support needed for MythTV. So I don't have anything like Gnome or KDE or a web-browser or office software etc. installed; it's a dedicated MythTV system hooked to a TV/projector and hi-fi, controlled from an IR remote; no keyboard, mouse or monitor.

I like Gentoo. That doesn't necessarily mean you'll like it. Lots of people seem to like Ubuntu; I tried it for a couple of weeks on one system and really didn't get on with it.

I hope that pre-empts a few questions (which I've answered previously but the answers are scattered throughout threads over the last five years.)

Kat

[Kat Manton]

Originally Posted by neon indicator

The newer Ubuntus use a different method than X server file...

But you'll find you can still use the file. Newer X (regardless of distro) attempts to auto-detect and auto-configure hardware and doesn't need a configuration file but still works with one if you write one. Gentoo updates haven't stopped my MythTV system working and my X server configuration file is long, complicated and very necessary!

Originally Posted by neon indicator

I've not tried two graphics adaptors on Linux. Maybe you could use Motherboard video for the VGA and a PCI/AGP /PCIe card for the 405?

It could probably be made to work (I've run two graphics adapters, one PCI and one AGP) but that was on a general-purpose desktop system, not my HTPC setup. Personally, I don't want the clutter of a monitor, keyboard and mouse in my living room. It's not like you need anything more than a console for configuration/admin etc.; you can do that from another box easily enough. So IMO it's somewhat pointless trying to get a dual-head setup working (on top of everything else.) I might run two cards to get 405 and 819 out of the same PC, running two instances of the MythTV frontend...

Kat

[neon indicator]

Have you tried MeTV? I use it to test new Linux boxes + USB or PCI digital tuners as it's fast to install.

Do you need a Media TV application at all, simply to use media players or photo viewers if graphics is set to 504 x 378i etc?

Presumably if the 405 works doing 625 i25 or 525 i30 on regular VGA is ensured?

I presume one could create a boot menu that waited for 0, 1, 2, 3 etc and if nothing typed used last mode
0 = last VGA mode
1 = 405
2 = 440
3 = 525
4 = 625
5 = 819
Or something?

Clark connect boots to a menu by default.

[Kat Manton]

Originally Posted by neon indicator

Have you tried MeTV? I use it to test new Linux boxes + USB or PCI digital tuners as it's fast to install.

I've been using MythTV as our main HTPC system for 5+ years and know it inside-out, I'm not really interested in trying anything else. I installed it once and have just updated it (and the rest of the system) ever since; so ease/speed of installation/configuration is a non-issue for me.

Originally Posted by neon indicator

Do you need a Media TV application at all, simply to use media players or photo viewers if graphics is set to 504 x 378i etc?

See above. 504 x 378 won't give correct timings; my modeline does but you get 664 x 378. If the s/w copes with non 1:1 PAR then it'll work. MythTV works (and I've hacked an image viewer which works into MythTV so I can display test cards, though I forget which.)

Originally Posted by neon indicator

Presumably if the 405 works doing 625 i25 or 525 i30 on regular VGA is ensured?

I'm not sure what you mean.

Originally Posted by neon indicator

I presume one could create a boot menu that waited for 0, 1, 2, 3 etc and if nothing typed used last mode
0 = last VGA mode
1 = 405
2 = 440
3 = 525
4 = 625
5 = 819
Or something?

When I've got more sets working and set up somewhere, I'll just set up a MythTV frontend (probably diskless) for each standard, since a frontend box connects to the master backend box (which doubles as our HTPC frontend) so has access to the tuner cards, stored recordings, EPG data etc.

The MythTV system boots straight to the MythTV main menu. If I wanted to select multiple standards on one box, I'd knock up a means to select them via the IR remote. It only needs to restart X so it'd take less than a second to change standards.

Kat

[davegsm82]

Cheers Kat, Very informative and does indeed spark some idea's.

Me and a friend who both have embedded programming experience are going to attempt to build a converter of our own in the near future, however with no (currently) working 405 set available, its all going to be academic in the short term.

When I get time I will set up a Linux system, I have a Micro ATX P4 based motherboard and assosciated gubbins which will make the basis of the setup. Eventually it will hopefully become a 'dedicated' unit.

I'm not against buying an aurora, I just prefer the challenge of building something myself

Dave.

[julie_m]

Quite true. But some would see "Just buy an Aurora" through the same sort of perception filters that make a "Danger, Keep Out" sign on a barbed wire fence appear more like "Interesting Stuff Inside, Climb Me" .....

[Karen O]

Presumably Kat, if you just want to watch DVDs on 405 lines then you just need a Linux machine, one of the video cards you mentioned plus driver, the external VGA-405 hardware and the right modeline?

[Kat Manton]

MythTV includes a DVD player...

But if you don't want to go to the trouble of setting up a dedicated MythTV system, you're likely stuck with players intended for use on general-purpose desktop systems, controlled from keyboard/mouse.

KDE/Gnome/etc. are unusable when the only "monitor" attached is a 405-line TV. So what you'd probably want to do is set up a dual-head system; you can then direct the video output of DVD/media players to the 405-line head while having the desktop environment and player controls on a regular monitor.

Or run the software (maybe a full KDE/etc. session) remotely from another machine. (I have a PowerBook G4 perched on the arm of the sofa and often run applications or full desktop sessions on other machines around the house while I'm watching TV.) Or set up the machine next to the sofa with a long video cable trailing round the room to the TV.

I just find these sort of approaches rather clumsy; hence my preference for MythTV - it's designed for the ten foot user interface - you end up turning a PC into a dedicated DVD player, Freeview box, hard disk recorder etc. all rolled into one, controlled via a remote and on-screen menus on the TV.

Once it's all set up it's great to be able to sit back on the sofa with the remote and drive the whole thing just like any modern system. Except that, instead of a big LCD hung on the wall, the set you're aiming the remote at could be a fifties console set with doors (and I think that's cool!)

But if you don't mind the clutter and the inconvenience of having a general-purpose computer system with keyboard/mouse/monitor with a second card providing 405-line (etc.) output for DVD/etc. playback, I see no major reason why it couldn't be set up this way (barring problems with software expecting a 1:1 PAR producing a squashed/stretched display on the TV.)

What it boils down to is - I use MythTV on a dedicated single-head setup without a keyboard/mouse/monitor via the IR remote which came with one of the DVB-T cards. I'm happy with this system, I haven't tried alternative approaches, nor have I much incentive to try them. I've worked out a bunch of modelines which produce various TV standards using two types of nVidia card I own and nVidia's binary drivers. They've been posted on this forum several times in the last five years. What you do with them is up to you.

If you fancy turning a PC into a set-top box on steroids which will do obsolete standards and which has been confirmed to work fairly reliably over the last five years, use MythTV.

If you want to try something else... I have no idea whether it'll work or not if I haven't tried it myself, so you're on your own...

Kat

[Karen O]

It sounds like MythTV is too good not to use!

And a desktop on a TV is barely useable. I have to squint enough as it is to see things

[neon indicator]

Need bigger screen Karen O


Actually I use DVBviewer on XP, full media solution inc Onscreen Display + Remote, Dual Satellite & Terrestrial Digital Tuners and full MHEG5 (no MHEG5 on any Linux other than commercial set-box). It's full 1920x1080@50p only output to the HDTV. Lives in a different room with HDMI & IR Remote via Cat5e cable and a USB extension for a compact USB DVD player under TV.

But not free and no use for 405 line. However BBC and RTE interactive text work and full EPG of both.

If you're able to configure Linux, then MythTV is the most supported and full feature solution on Linux, but MeTv is only a couple of minutes to setup to check your tuner card/USB stick works (MythTV uses all the same stuff, so if MeTv doesn't work with the cards/USB stick, Myth TV won't).


Even on a 42" HDTV a regular desktop is no use as the viewing distance for TV is 1.2m to 3m (4' to 10') rather than 30cm to 40cm for working at a screen (reading distance).

[Kat Manton]

Originally Posted by neon indicator

[...] and full MHEG5 (no MHEG5 on any Linux other than commercial set-box)

Pardon? Interactive's worked on MythTV for ages! (If you don't use MythTV, bear in mind it's under constant development; what didn't work last time you looked might work now.)

Originally Posted by neon indicator

MeTv is only a couple of minutes to setup to check your tuner card/USB stick works (MythTV uses all the same stuff, so if MeTv doesn't work with the cards/USB stick, Myth TV won't).

Ah, found it. Similar standalone application to tvtime; but it doesn't seem to be in portage and it requires GTK. So it involves extra hassle to install and would pull in libraries I don't need. I'll stick with tvtime for quickly checking hardware; it's smaller/lighter than Me TV.

And can we stay at least vaguely on-topic, please? Commercial software which runs on Windows and won't do obsolete standards anyway isn't exactly relevant...

Kat

[Kat Manton]

Originally Posted by Karen O

It sounds like MythTV is too good not to use!

I'll freely admit that it does take quite a bit of setting up. But once it is set up, it's amusing to see the look on a visiting non-enthusiast's face when you fire up a fifties 405-line set or an 819-line set which never would have worked in the UK, sit back with the remote, scroll through 14 days of EPG, bring up the local weather, flick through a few Freeview channels, watch an episode of Doctor Who stored on the fileserver upstairs[1], then bung a DVD in...

It's why I'd recommend it over 'clunky' dual-head setups needing a monitor/keyboard/mouse; you end up with a vintage set doing everything a modern set plus PVR does (okay, apart from colour.) This is, IMHO, extremely cool.

From 3rd March 2006, here's the thread which started this off; I was playing around with MythTV with a view to setting it up as our living room system. I was tweaking a modeline for RGB 625-line (to feed the SCART on our main set at the time) and thought, "hang on... I bet I could get 405 out of this" and the rest is, I guess, history

(I'm amused to be reminded that I didn't own a vintage telly at the time and got a 405-line signal out of the thing without being able to watch it!)

Kat

[1] "The Idiot's Lantern" is highly recommended for demonstrating this set-up to visitors.

[davegsm82]

Kat, i've been thinking, some laptops (I have some at my disposal) have a TV-out decoder built in, albeit at S-Vhs. Do you think this could be implemented? I'm not sure what chipset is used, some OLD laptops have a separate philips QFP chip on board which handled it, newer ones I *think* have mainly ATI based chipsets, which handle the video directly.

Dave.

[neon indicator]

S-video, not S-VHS. Just ignore the C channel and only use the Y connection for Mono.

Going from VGA to composite isn't hard. I made an RGB VGA - SCART adaptor with one transistor and 2 resistors in mid 1990s and programmed the Trident ISA card in DOS to do 625 lines.

Even on windows some of the Nvidia drivers will let you create custom timing that can include 405, 625 etc..

All the free linux video tools and more are also on Windows. If you are using a dedicated PC/Laptop it's worth getting to grip with Linux. If you want to quickly experiment there are plenty of the same stuff on Windows too, but XP better than Vista or Win7 due to driver lock down issues.

[Kat Manton]

Originally Posted by davegsm82

Kat, i've been thinking, some laptops (I have some at my disposal) have a TV-out decoder built in[...]

I looked into this (not too extensively; enough to determine it was impractical.)

Cards (and presumably laptops) which have a TV output have a scaler/encoder. This accepts the output from the graphics chip at 800 x 600, 1024 x 768, progressive; whatever the LCD or VGA output is set to produce; scale it to PAL/NTSC resolution then encode to PAL/NTSC to produce composite video. (I may not be entirely correct, but that's the rough impression I got of how it works.)

Reprogramming the scaler would involve:

• Obtain documentation for all chips involved
• Determine if the scaler can be reprogrammed for 405-line timings
• Obtain open-source driver for chipset which supports TV out
• Modify driver

IMHO this is non-trivial; I am not going to investigate any further, but don't let me stop you!

Reprogramming the VGA output is relatively trivial once one knows how the pixel clock is derived from the crystal on the card. The X configuration file already provides a means by which non-standard timings can be generated. So there's no coding involved.

(I also happen to prefer reprogramming the VGA timing; the PC is then only scaling DVD/Freeview/etc. once to the desired standard. If the TV output were usable, the software would scale to, say, 800 x 600 progressive then the hardware scaler would scale again to the desired TV resolution.)

Kat