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Line Quadruple on the VP50 Pro

If you’ve been using a DVDO iScan VP50 or VP50 Pro with your OSSC, you’ve probably noticed that, while line double and triple modes work fine, line quadruple simply refuses to work. Thanks to the help of the community, most specifically this thread on our forums, it is possible to get line quadruple working on a VP50 Pro (and most likely a VP50 too). There are some caveats, but it can be done.

To get started, attach your OSSC to your VP50/VP50 Pro as normal and your 240p games console to AV1 or AV2 via your cable of choice. Make sure you’re getting a picture using the standard settings.

Now, press the menu button on the OSSC remote, navigate to “Output Opt”. Press OK and then navigate to “240p/288p Proc” and change it to “Line 4x”. At this point the picture should disappear on your VP50.

Exit the Output Opt menu and navigate to “Sampling opt”. Hit “OK” on the remote and then choose “Adv. Timing”.

Find the “V. active” setting and increase it from the default of 240 to 256.

Find the “V. backporch” setting and decrease it to 3.

At this point you should get a picture on your VP50. You will probably find that the image isn’t centred and that part of it is missing, so adjust the H. backporch value to around 160 to compensate. Our old friend the 240p test suite is invaluable here of course as it lets you check that the image is centred and that no parts are lost or overscanned.

After these tweaks you will end up with an image that’s smaller than in line 3x mode and a little squashed horizontally, but only by a couple centimetres. To compensate for this we can use the excellent zoom feature on the VP50. Zoom the picture to around 1.063 horizontally and 1.125 vertically. Adjust by small increments if the scaling looks off. The nice thing about the zoom control on the DVDO processors is that it produces good results and keeps generally nice even scaling even if you really abuse the image.

With all these settings in place the image should look very good. Under really close scrutiny you may be able to pick out a scanline that’s taller than another one, but you’d be hard pressed to do so at normal viewing distance.

Line4x mode on our VP50 Pro. Sadly, our capture card couldn’t handle this mode so this is a digicam shot.

To quad or not to quad?

Would we recommend using your OSSC and VP50 Pro in Line 4x mode? Honestly, we were pretty impressed by the picture, though admittedly having to put so much zoom onto the image is off putting. Given that the VP50 and VP50 Pro all sample an image in 4:2:2 colour space, it makes sense in principle to feed in the highest resolution possible from the OSSC, so that the least amount of colour information is lost in upscaling. In practise however a 720p image is hardly affected by the 4:2:2 conversion. This is one of those situations where it is really too close to call, give it a try yourself and see which mode you prefer. Remember to actually play some games too after all that tweaking settings!

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