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marcan_42 | 3 years ago

No, really, it can't. Feed it a checkerboard input and you'll get gray on the way out. It's horizontally processed at a lower resolution internally. Might be 960x1080 at 30FPS, and it can't do it at 60FPS at all. Yes, you're going to get 1920x1080 JPEG bitstreams out the USB end, but it's not actually 1920x1080.

I suspect this happens because it doesn't actually have enough internal RAM to buffer a full 1080p frame (this chip uses on-die RAM, so probably SRAM since they wouldn't go for a fancy EDRAM process, and SRAM is expensive by capacity).

discuss

rubatuga|3 years ago

Agreed, likely an internal resolution of 1280x1080. You can check out the checkerboards on my blog post here, which also analyzes the chroma sub sampling and post sharpening.

https://www.naut.ca/blog/2020/07/09/cheap-hdmi-capture-card-...

kingcharles|3 years ago

Nice review, thank you!

daneel_w|3 years ago

Yes, really, it can, because a checkerboard test along with other fine detail tests and frame rate tests was what I put the device through to make sure I really received what I needed. It correctly manages exactly what I stated: 1080p at 30 fps, 720p at 60 fps. It's a let-down since the specs claimed otherwise, but that's what it can do.

ThePowerOfFuet|3 years ago

Then the two of you are clearly not discussing the same hardware.

gsich|3 years ago

I have 2 devices, one has 1280x1080, the other 1920x1080. Can't really be differentiated from the outside. The one has a silver casing, the other a black one.

zo1|3 years ago

Has someone done this sort of analysis" on YouTube? Anecdotal: Even though it claims it's giving me the 1080p resolution, everything still seems blurry. The only time I get actual crisp visuals is when I watch a 4k stream and "down scale" it to 1080p. I feel like they're pulling a fast one on us.

nolok|3 years ago

You're talking about a different thing, compression bitrate and artifact.

Take a 4k video, encode it into 320p, then encode that into 1080p. For the matter of what they are discussing, your video file will be true 1080p. For the matter of what you are discussing, that video will be horribly blurry and full of artifacts.

russdill|3 years ago

A nice side effect is you can feed to 1920x1200 and it will do the same downscaling.