[ppppenguin]

This suggestion of using a PC to do conversion has been made many times before. There has not been any noticeable success using this approach. Until recently there was not even a hope of doing it this way.

The conversion algorithms are trivial in software. But try actually doing them, taking in the video data at full speed, doing the conversion algorithms, and outputting the 405 data, also at full speed.

One approach that could be workable is programming a special mode on a graphics card. A colleague once did a 405 output mode for a BBC " B " . He has also implemented non-standard graphics modes on standard PC graphics cards.

Using a modern graphics card with video replay facilities and custom output modes could be feasible. The PC would actually be doing relatively little, most of the work would be on the graphics card.

When you start adding hardware things start to get tricky. I have customised graphics cards for some specialist applications and can assure you that they are not the easiest things to work on. A custom PCI card will suffer from all the same low voume/high cost troubles as a complete converter. Having designed PCI cards myself I am well aware of what's involved. I'm sure that Darryl (tubesrule), who has much more experience than me on PCI cards will confirm this. The only way to make PCI cards cheaply is to make lots of them.

And remember that even a modest PC will cost as much as a Domino. Do you really want to fire up a PC every time you want to use a 405 TV?