InfoFrame content

[Harrumph]

Due to my recent interest in video timings (damn you Lx4 & Lx5 🙂 ), I’ve been eyeing through the CEA 861 E spec sheet (HDMI 1.4).

As an aside, I looked a bit in the InfoFrame section and noticed the Source Product Description, there is a byte that can be set to determine source type, such as PC or Game Console. It got me thinking if this could help those TVs (4k Samsung model) that has been reported to not be able to recognize OSSC as a PC source?

Then perhaps there could be three TX modes: HDMI, HDMI-PC, DVI. What do you think?

There’s also the AVI InfoFrame where things such as content type (eg Graphics or Game, which then indicates to TV to do minimal scaling/enhancement) or aspect ratio can be specified.

[virsago]

As the owner of one of “those TVs” (the Samsung 4K to be specific), I would love this. All of my other consoles can use my TV’s PC Mode, but for some reason the OSSC just can’t access it. I’m not sure if it would even help, but it’s the only thing I can think of that would allow my TV to accept something other than 240p passthrough. Nothing else seems to work.

[marqs]

At least in the past displays typically ignored most non-essential Infoframe parameters. Maybe they more “smart” these days, though. I’d guess setting “IT content” flag, and possibly Source Product Description could help if some TVs limit their processing options based on Infoframe data.

[virsago]

If it’s something you want to test out before going ahead and fully implementing it into an official FW update, I’d be glad to help.

[marqs]

Yeah, that should be tested with a couple sets. Regarding “IT content”, I’ve seen some contradictory information. According to CEA specs, setting the bit should tell displays not to apply excessive video processing to the signal. However, reading some comments comments from Intel HD graphics users, it may have negative/opposite effects on some sets. Either the driver has the option wrong way around, or it gets misinterpreted by certain displays.

[Harrumph]

Hmm, well could depend on what type of IT content is set maybe? It seemed unclear to me if this problem was due to the video driver itself, like you also pointed out.
Either way, this obviously needs to be tested by a couple users (we seem to have some volunteers here). 🙂

Thanks for your reply!

[marqs]

IT content flag is now configurable in the latest build. Didn’t make any difference with my own displays, though.

[virsago]

@marqs That’s disappointing. I’ll give it a shot on my own display once the newest build is released and see if it makes a difference for me. Thanks for adding it though. Crossing my fingers.

[virsago]

So I don’t know why, but everything works on my TV now. Thank you so much @marqs!

[Harrumph]

I have seen a number of people having issues with their display forcing 16:9 mode when in Game Mode. Or TVs/monitors just lacking an aspect ratio selection in general. This becomes problematic for people who can only use 2x mode, or for any scenario involving 480i/576i. I thought perhaps utilizing the “force aspect” bit in AV InfoFrame could be useful for this scenario?

It’s described in pages 42-45 in CTA-861-F (https://glenwing.github.io/docs/CTA-861-F.pdf) (Byte 1, A01 bit together with Byte2 R3-R0 bits).

Then perhaps a “force 4:3” can be added to compatibility or advanced timing menu?

An alternate way seems to be to send VIC (byte 4).

We saw before that activation of InfoFrame in regards to IT content did not seem to have an effect on most displays, but one can still hope maybe in the case of AR it could be of use…

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