Slashdot Mirror
Linux and SVHS Outputs
Gerr
asks: "I'm looking into building a project that
uses S-Video output to display a simple menu system
onto a television/monitor (or going through a
stereo to display output to a device). Are there
any Linux projects currently working on S-Video or
anyone in the world of Linux hacking who has some
technical information about displaying information
via this protocol? "
WHen programming for these, you dont need to be concerned about what the pin out and synch rates are, just the cards that have the S-Video output. I have a Canipus Pure3D (voodoo1) card that has an RCA and S-Vid out on it, and works fine for outputting to the TV, as long as the display is initialized for a resolution it can use (512x384(?), 640x480, and 800x600) otherwise is flickers wretchedly because it cant synch the information right. I have seen cards that adjust for this, and automatically adjust the synch for various resolutions; it is all dependant on the card itself and the graphics chipset controlling it.
FInd a card that automatically sends data to both the TV and monitor (or has a jumper to tell it always to the TV) and just program your software using X or SVGALib, using a resolution the card will correctly interpret. If the motherboard your intending to use has S video out on it, get more information on the graphics chipset controlling it.
Toodles D Clown
You can probably use a 2d card with svideo out. I don't know if it's "always on", but ask around. Otherwise, someone has developed a capture card with linux drivers. Sorry, I don't have the URL off-hand, but then again, that was almost a year ago. I wish I could find them again because I would really like to get one since I can't seem to find info on neomagic. I'm trying to do something similar...
I've emailed everyone possible - Redhat, Precision Insight, the XFree86 team, newsgroups, etc. No luck. Not even a response.
I want to write a driver to enable the capture device in the neomagic chipset. So, if anyone out there is reading this, feel free to email me with info. Thanks.
Robert Dale
rdale@digital-mission.com
PAL
Does anyone know how to use RivaTNT's SVHS video
inputs and outputs under Linux ?
I haven't found anything on the Web for that.
Based on what consoles and arcades display the following can be said about optimal television resolutions. Keep in mind that televisions display images in lines, not in pixels.
PAL @ 50 Hz. Interlaced 512 lines
PAL @ 50 Hz. Non-Interlaced 256 lines
NTSC @ 60 Hz. Interlaced 448 lines
NTSC @ 60 Hz. Non-Interlaced 224 lines
That's what almost every arcade and console displays when using a standard TV monitor
Theoratically there are more lines but a lot of them are reserved for the so called V-blank period and other things like teletext. There are no real standards on how long the V-blank period is, this is differen for every manufacturer. But above setting are safe. Also you have to keep in mind that, because of the differances per manufacturer you have to take into account that you can't be certain about thing near the edge are being displayed; vital information needs to be in the so-called safe area. If you want square pixels 4/3 times the number of lines for the width; this gives the following resolutions;
PAL Int. 768x512 (Official PAL)
PAL Non Int. 384x256
NTSC Int. 640x448
NTSC Non Int. 320x224 (Used by most consoles)
(Note the NTSC resolutions aren't really square pixels but the easiest for computer graphics...)
All of this requires carefull tuning of the video-timings...
Does anybody know if X allows for these carefull tunings and non-standard resolutions?
Jeroen van Oorschot
Semi-Anonymous Coward Too Lazy To Create An Account
Forgive me if the English is weird, it's not my native language...
Well I noticed on my Canopus Spectra that it mentions NTSC in the bios message, so I figured that if I unplugged the monitor while booting up that it would use the composite and s-video outputs. Well, it did. So, since I couldn't get any sleep I decided to get it to work under X. Anyway, I did get it to work, but only at 640x460 (I used that res. to get everything to fit on the TV). If anybody want's the modeline, you can email me. Also if anyone has gotten it to work at 640x480 or 640x485 please email me.
That's what I said when I posted my message -- I asked about SVideo, not SVHS. Apparently, Malda thinks he knows more than we do about this subject and had some sort of calling that the true subject line should read SVHS and not SVideo.
S-VHS is a format for recording high resolution video on a VHS tape. S-Video is a method of transmitting video that seperates chroma and luma for a clearer picture. S-VHS decks have S-video outputs on them, but there are many other things out there with S-video outputs, so calling them "S-VHS" is misleading.
Remember:
S-VHS == video recording format on a tape
S-Video == video transmission method.
Sorry to nitpick, but this confusion drives me nuts!
- =^o.o^=
I imagine someone has pointed this out already, but the new voodoo3 3000s have an svhs out that people are working on drivers for. At the moment, there is the 3dfx.glide.linux and 3dfx.linux.apps.games newsgroups for relevant
articles, as well as
http://www.netroedge.com/~lm78/
with the lm sensors project, including a driver for the bt869 chip that {will, may} run the v3's svhs out.
good luck
jeff
Death and danger are my various breads and various butters.
I've got phono and SVHS on my ATI Xpert@Play card. When I used Windows I just had to tick a box, can it be turned on under Linux?