RGB or S-Video output?
Kloss
Posts: 43
Hi.
Did someone ever write a module that generates RGB or chroma/luma instead of
composite video?
Kloss
Did someone ever write a module that generates RGB or chroma/luma instead of
composite video?
Kloss
Comments
mahjongg
The tv.spin object can be configured to output chroma on the 4th pin. You must kill the chroma mix into the baseband by setting bit 2 of 'tv_mode'. Then, set 'tv_pins' to %xxx_0111 or %xxx_0010 to select baseband+chroma. The lower 3 pins·must be hooked up to resistors, as usual, to form the baseband·signal, and the 4th pin can be coupled·via a .1uf cap·to form the chroma signal for the S-Video connector. It's all documented in tv.spin. S-Video looks way better than composite. You get much sharper luminance control, allowing higher horizontal resolution.
I'd like to make an HDTV (RGB) object sometime, but haven't gotten into it yet.
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Chip Gracey
Parallax, Inc.
I've read through the tv code, but it was some times ago.
Maybe that I didn't notice it.
Kloss
Another great example of the versatility of the Propeller. I cannot congratulate you enough for this remarkable realization.
dro.
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in medio virtus
portable DVD players to do this.
I have one.
I've built a couple of small boards for composite and S-Video. The composit board works just fine, but when I try the S-Video board after making the changes indicated to TV_Terminal.spin, no output.
Earlier in this thread, Chip G. wrote:
"The tv.spin object can be configured to output chroma on the 4th pin. You must kill the chroma mix into the baseband by setting bit 2 of 'tv_mode'. Then, set 'tv_pins' to %xxx_0111 or %xxx_0010 to select baseband+chroma. The lower 3 pins must be hooked up to resistors, as usual, to form the baseband signal, and the 4th pin can be coupled via a .1uf cap to form the chroma signal for the S-Video connector. It's all documented in tv.spin. S-Video looks way better than composite. You get much sharper luminance control, allowing higher horizontal resolution."
That seemed fairly straight forward, so I looked in TV_Terminal and found in the DAT section:
DAT......
tvparams··············· long··· 0···················· 'status
··························· long··· 1···················· 'enable
tvparams_pins········ long··· %001_0101······ 'pins·········
··························· long··· %0000············ 'mode
I changed "pins" to %001_0111 and "mode" to %0100.
My S-Video board is wired nearly the same as the composite board. The resistor array on pins 12,13 & 14 is tied to pin 4 of the S-Video connector (female), pin 15 has a series .1uf cap (see above) to pin 3 of the S-Video connector. Pins 1, 2 and the shield are connected to ground.· This setup doesn't work. I also tried "pins" set to %001_0010. No difference.
After reading more of the documentation contained in TV.spin, I found the following:
''····· the baseband signal nibble is arranged as:
''······· bit 3: chroma signal for s-video (attach via 560-ohm resistor)
''······· bits 2..0: baseband video (sum 270/560/1100-ohm resistors to form 75-ohm 1V signal)
No mention of a cap, but a resistor instead. I tried that instead of the cap and got the same results, nothing (however, with the code changes described above, using the little composit board produced the proper output, but in B&W as you would expect)
I must be missing something simple here and would appreciate a shove in the right direction.
I'm using a ViewSonic video switch that can switch RGB, VGA, composite video or S-video to the the analog port of my LCD monitor. My computer is attached to the digital port on the monitor. Other S-video sources (a DVD player) work fine with this setup.
Thanks in advance,·· Steve