OSSC Pro feature request

[Zacabeb]

Here is a handful of features I would love to see in the OSSC Pro. I figured I’d just throw them into a short list.

16:9 stretch for widescreen games
Vertical stretch for PAL aspect ratio correction (squashed proportions in PAL has frustrated me for ages)
Widescreen Signaling (WSS) decoding
SCART pin 8 widescreen detection
Gamma compensated non-integer scaling (this would also allow for non-integer scaling with good looking scanlines)
Oversampling to improve pixel recovery on games that switch between multiple horizontal resolutions
Dither reduction and pseudo-transparency blending
Artifact color recovery
Ability to export profiles from OSSC to SD card
Audio polarity inversion on one channel – this one would come in handy specifically for one game on the PS2, Jak II. This game has Dolby Pro Logic II encoded surround, but with the front-to-back axis reversed. Inverting the polarity on one channel would be a workaround, and the OSSC/OSSC Pro could help do just that.

[nmalinoski]

Slight detour: I’d like to see Widescreen Signaling in the regular OSSC.

After looking it up on Wikipedia (I knew it existed, but I couldn’t remember what it was called), there’s a note regarding NTSC systems that no video player generates those signals and no TV understands them, but I know for a fact that my Sony KV-27FV310 automatically responds to changes in aspect ratio settings on my Xbox (connected via YPbPr component); so that’s not entirely true?

[Harrumph]

Two of those points are already possible on the regular OSSC

Vertical stretch for PAL aspect ratio correction (squashed proportions in PAL has frustrated me for ages)

Reduce V.Active (e.g to 256 or 240), has the effect of stretching the image vertically.

Oversampling to improve pixel recovery on games that switch between multiple horizontal resolutions

OSSC is oversampling by default compared to 240p/288p source material (in generic modes: 858 samples in 2x mode, and even more in higher line modes (multiples of 390 in Lx3-4, 341 in Lx5).
For 480i/480p, oversampling can be enabled by “allow upsample 2x”.

[Zacabeb]

What I was thinking with respect to oversampling is that the OSSC Pro could oversample at a rate matching the console’s subpixel clock and then scale it down horizontally with a box filter to say, 1440 pixels. For instance, the PlayStation2 has a 67.5 MHz subpixel clock (135 MHz in progressive mode). Sampling at that rate would catch all its output resolutions pixel perfect with one setting. It might be madness to do that compared to say, 27 or 54 MHz and let the input low-pass filter do blending of pixel boundaries (at 67.5 MHz the active area would be 3,200 pixels wide). But it would be fun to see it tried out.

Regarding the vertical stretch for PAL, this is where I hit a snag with the OSSC and my TV. The TV has limited compatibility with non-standard resolutions, especiall at 50 Hz. There I’m limited to Line2x mode, and the TV assumes the start and end of active video to comply with standard 576p timings. Trying to adjust the active area or backporch doesn’t affect how the TV handles the picture (increasing the backporch simply blanks part of the picture). Having a pixel aspect ratio control in the OSSC Pro with provision for PAL correction would solve this type of problem. I imagine compatibility is much worse with 50 Hz than 60 Hz even on newer TVs.

[Author]

Posts