[Zacabeb]

To me it looks like aggressive sharpening/edge smoothing being done in the display as part of rescaling the input, possibly because the TV assumes a 50 Hz signal to be a video source rather than graphics irrespective of resolution (many TVs don’t even accept non-standard resolutions at 50 Hz.)

Make sure that the TV picture profile is in Custom mode or similar and all picture enhancements are disabled.

[Zacabeb]

The adaptive de-interlacing is quite basic in its interpretation of the picture, so it does make mistakes. Altera has a more sophisticated version than is used in the OSSC Pro, but it consumes substantially more resources.

The de-interlacing logic measures the difference in contrast across fields between the same and neighboring pixels to determine if there is motion. The resulting value controls whether the pixel is left as-is (weaving) or is given a weighted mean of the value across fields (effectively bobbing or blending.) The Motion Shift adjustment controls the threshold between those modes by dividing the motion value by a power of 2 (shifting the bits in the variable right to decrease the value, hence the somewhat unintuitive name Motion Shift.) At 0 it basically forces bobbing and at 7 it forces weaving.

Dropping Motion Shift to 1 or 2 may reduce the artifacts, but at the cost of increased bobbing in static parts of the image.

The more sophisticated version Altera has uses Sobel edge detection to derive motion vectors and more intelligently determine what to do, but I don’t know if it’s realistic to implement in the OSSC Pro given the additional performance overhead. Sharp pixel graphics are also more unforgiving since they more easily confuse the de-interlacer and reveal artifacts more clearly.

[Zacabeb]

@marqs Thank you so much for adding the aspect ratio adjustment to scaler mode! It’s great being able to adjust it on the fly. 🙂

[Zacabeb]

Those giant Gateway Destination monitors were sold as part of their short-lived attempt at making a PC the center of the living room. They reportedly have CRTs with coils for the 30-40 kHz range, so from what I understand they display 800×600@60 natively.

The little information available on them however suggests that they should handle most standard resolutions in that range, such as 640×480@60, but the model in question may be intentionally picky.

[Zacabeb]

What refresh rate is reported by the OSSC? If the PC outputs at 70 Hz, the TV as well as capture devices may not like the resulting signal.

They may also not like the output from an OSSC Classic or an OSSC Pro in pure line multiplier mode if the resulting output resolution is too far away from a standard TV or computer resolution.

If you have an OSSC Pro, using scaler mode and setting frame lock to 60 Hz should resolve the issue, at the cost of judder if the input has a different refresh rate.

[Zacabeb]

I remember experiencing an issue with the OSSC Classic on my Sony TV (an old 2007 model) where the Cr and Cb samples got mixed up in its internal processing under some circumstances, which was fixable by offsetting H.backporch by 1. It was some time ago though, so I no longer remember the exact details.

It could be a similar issue, the display getting confused and swizzling the components around because of the input signal being non-standard.

[Zacabeb]

That sounds awesome!

Could the six unlabelled buttons be included for custom configuration as well? They’d need some form of naming scheme to hint at which one is which and be marked in the picture of the remote on the wiki.

[Zacabeb]

Check the file for the Legacy AV In adapter case, the lid is probably the same.

[Zacabeb]

Yeah, it’s probably a very rare issue.

[Zacabeb]

I think the P and color buttons should be user configurable. Possible even the unlabeled buttons could be. So, for each of those buttons you’d be able assign a command from a list.

That way, any of the P or color buttons could be used for either a profile shortcut or another command such as power.

[Zacabeb]

The D1 diode looks to be the right way around in the picture.

I noticed though that pin 8 (CVBS signal status) in the SCART socket is unconnected in the adapter, which might cause issues with some TVs as they only switch to the input if it has voltage (+5V to +12V) and otherwise ignore it, even if pin 16 (RGB signal status/fast blanking) is active. I don’t know if the Grundig and Sony TVs in question are affected by that quirk though.

Edit: Marqs’ suggested causes in the post above are probably the more likely ones.

[Zacabeb]

Looking at the schematics, it seems that the two LSBs of each component from the TVP7002 are just floating.

https://raw.githubusercontent.com/marqs85/ossc_pcb/v1.8/doc/ossc_board.pdf

From what I gather, 30-bit color would require more bandwidth and GPIO pins than the FPGA has available.

[Zacabeb]

By-the-book decoding of Dolby Surround and Dolby Pro Logic II is a bit complicated as it relies on active steering logic. The existing Quad mode in the OSSC Pro just replicates the fronts in the surrounds from what I can tell.

Passive decoding (L-R) is probably simple to implement but produces a lot of “magic surround”, i.e. unintentional surround content.

On playback devices, Dolby Pro Logic II and Dolby Surround Upmixer decode Dolby Surround correctly and remain part of the Dolby Audio licenses as far as I know. Dolby has done a terrible job promoting Dolby Surround Upmixer and not explaining how it works, making it seem arbitrary even though it follows the same set of rules as its predecessors.

Edit: Even though passive decoding has its disadvantages, it could still be useful as a compromise.

Mono surround can be extracted by Ls = Rs = 0.707L – 0.707R and stereo surround by Ls = 0.866L – 0.500R and Rs = 0.500L – 0.866R. In my experience it’s best for encoded content if the two surrounds are extracted in phase with each other. Preferably the surrounds should be bandpass filtered to about 100 Hz – 7 kHz and delayed by 10-20 ms to reduce some of the audible leakage from the front channels.

• This reply was modified 7 months, 1 week ago by Zacabeb. Reason: Added thought

[Zacabeb]

So would I. It would also increase the lifespan of the OLED display and reduce uneven burn-in.

[Zacabeb]

The one to ask is @marqs who developed the OSSC Pro. It seems there aren’t that many other contributors yet for the OSSC Pro firmware.

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