Bumping this one
Thanks to the findings in this thread and the help of forum members here, I've been trying to get 480p and 480i down to 240p via creating custom res on a few select scalers. I've had very good results going 480p to 240p with a Corio2 scaler (
picture here), but 480i downscaling is a no-go on my unit (misaligned scanlines, horrible flicker), even when fed the OSSC single-field deinterlaced 480p output (a few TvOne machines have selectable bob deinterlacing, but not the one I've got).
I have recently acquired an iScan HD+, which, beside having very low latency, handles 480i deinterlacing much better, and only exhibits a slight, bearable amount of flicker when dealing with the OSSC bob deinterlaced 480p output. I found that 4:2:2 subsampling is a non-issue
for downscaling. The only issue I have with the iScan is that I can't quite get a perfect picture on the vertical axis. There would be an ever so slight scanline misalignament in the game I use
for testing, both when outputting in 480p and 480i (the game has selectable resolution). It is
very subtle, but still falls short of the picture linked above obtained with the other scaler (with 480p input only). Fiddling with the vertical size/positioning can provide a perfect result in the offended area, but break another area above and/or below. Here's a few images with explanatory labels:
http://image.ibb.co/dcCfUc/480i_to_240p.jpg
http://image.ibb.co/iibkvH/480p_to_240p.jpg
http://image.ibb.co/gdgJFH/480p_to_240p_Size_Tweak.jpg
http://image.ibb.co/dOCsaH/480p_to_240p_DT_V.jpg (untweaked 240p on another monitor - DT-V17 - same problem)
( I am 99% I have labelled the pictures correctly, but I've been at it
for a couple of hours now, testing out the two scalers with the two original resolutions on two monitors with and without the OSSC in between, tweaking left and right, taking dozens of pictures, dealing with sync loss and monitors screaming pain, and I'm starting to do the same
)
Here's a short video with me tweaking (480p original res, direct input into the iScan no OSSC in-between), which shows that I can get one thing right, only to break another:
https://vimeo.com/260257300
Now I might well live with this, it's not too much trouble, but was curious if anyone here was still using an iScan
for downscaling and run into this little alignement issue?