Anybody use the 4th bit(p15) on Composite Video

hinv

In the Demo Board schematic, it has 4 wires connected to a resister based DAC for a composite video output.
The fourth is labeled "This resister is only required for aural subcarrier in broadcast mode".
I don't even know what that means, but I need to free up some pins, and I want to keep my board compatible with much of the software out there.

Thanks,
Doug

Post Edited (hinv) : 5/27/2009 4:30:34 AM GMT

Bill Henning

That resistor is in case you want to broadcast RF NTSC with an audio channel.

hinv said...
In the Demo Board schematic, it has 4 wires connected to a resister based DAC for a composite video output.
The fourth is labeled "This resister is only required for aural subcarrier in broadcast mode".
I don't even know what that means, but I need to free up some pins, but I want to keep my board compatible with much of the software out there.

Thanks,
Doug

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Phil Pilgrim (PhiPi)

If you want to send video over the air to, say, channel 3, and include sound with it, you need that fourth pin. Otherwise, no: it's superfluous and can be used for other purposes.

-Phil

Rayman

I've read that you can also use it for SVideo output. But, it seems that that is rarely used too...

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

ericball

My NTSC240H sprite driver uses all 4 pins to get brighter colors. However, the palette could be customized to only use 3 pins (or use 8 pins for 4+4 SVideo).

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Composite NTSC sprite driver: http://forums.parallax.com/showthread.php?p=800114
NTSC color bars (template): http://forums.parallax.com/showthread.php?p=803904