Quote:
Originally Posted by Penthode
I suppose I can visualize an algorithm to rescale and interpolate at baseband spatially or temporally for example the CBS field sequential system, it blows my mind to think you would be able to accurately realize in firmware the correct relationship between the the baseband luma and properly interleaved chroma!
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Modern video encoders use purely digital techniques to generate the composite signal. Writing the algorithms for my converters to do both quadrature modulation for NTSC/PAL and FM modulation for SECAM was relatively trivial. You can also add FIR/IIR filters for limiting the subcarrier bandwidth to the correct spec.
Implementing a discreet analog approach is certainly possible, but unless the source for the component video is coming from a very old piece of equipment, it's being sourced as digital data anyway, so it's just easier and cleaner to do all the work in the digital domain.
The great thing with fpga's is they can be thought of as equivalent to a software based solution but for hardware. You are still physically wiring low level hardware blocks together, but using firmware to do so, so you can change and add to the design ad infinitum without having to actually change physical parts or wiring. They are also extremely cheap for applications like this, so not only are they very flexible, it would be difficult to do a discrete design for a lower size or cost.
Darryl