Roku Developer Program

[EnTerr]

"TheEndless" wrote:
Those are compression artifacts.  Assuming you took that from a screenshot captured via the box, that's not an accurate representation of what's being displayed.  Screenshots are captured as JPEGs by default.

Ringing artifacts for the @squirreltown indeed. Fourier transform (which is foundation in JPEG/MPEG/MP3/etc) "really doesn't like" sharp transitions. A signal is represented as a sum of harmonic functions and to represent a perfectly sharp edge, an infinite number of harmonics would have to be used. And since nobody likes infinitely big in size JPEG/MP3s, from some point on the higher frequencies would be dropped. 

Which in practice is fine, since neither the human eye nor ear have infinite resolution. The mere fact that image/audio/video has been digitized testifies to that. Nature abhors sharp edges, one may say.

[EnTerr]

"Komag" wrote:
In this situation this is the Roku Home screen, not my program, so it's not 720p to 1080p conversion. The overscan, if happening, wouldn't smudge the graphics nearly that much. Just resizing the image 2% in any image editor on quick/dirty settings looks much better than the Roku result.

That is true, here is windows paint resizing by 5 pixels in each direction (from 290x218 to 295x223):

Looks better indeed. But we don't know what algorithm your TV or capture card uses for overscan, most likely is quick&dirty linear (vs Paint... bicubic?).

Have you tried this on different Roku models btw? There might be surprises (OpenGL v DirectFB)

I believe it's image compression, pure and simple.

But whose image compression? Elgato, HDMI, Roku?

[Komag]

My in-game graphics are perfectly crisp and sharp and perfect, no problem with overscan scaling or HDMI or elgato compression. I can take PNG screenshots (after changing the setting on that one hidden screen) and fine details come through completely sharp.

In general I have tried to avoid single-pixel-thin drawing simply to make the game playable for people with SD screens (I even do some testing on a old 13 inch CRT), but in some cases I use fine details where it doesn't impact playability, and everything shows up pixel perfect on three different HD displays.

I've tried on:
- A computer monitor with HDMI input running Roku 2 XS and original Roku 3
- A computer monitor with HDMI input running the older streaming stick
- my Roku TV
- and of course, the 13" old CRT tv (with Roku 1 2710)
(I haven't tried hooking up the 2710 to the other monitors recently)
All of them have (except old tv) have sharp clear pixel-accurate lines in-game. It's ONLY the Roku Home screen icon that looks like mud, and it looks that way on all of them. That has led me to believe there is some under-the-hood shenanigans going on, such as Roku heavily compressing all the home screen icons for a performance boost, or a strange combination of resizing back and forth, or something.

[EnTerr]

"Komag" wrote:
All of them have (except old tv) have sharp clear pixel-accurate lines in-game. It's ONLY the Roku Home screen icon that looks like mud, and it looks that way on all of them. That has led me to believe there is some under-the-hood shenanigans going on, such as Roku heavily compressing all the home screen icons for a performance boost, or a strange combination of resizing back and forth, or something.

Hmm, i am at a loss - although as always excited to troubleshoot a problem 🙂
Here are couple of ideas to try -
(1) "burn-in" the exact size info into each of the images (i.e. 540x405 image should have the text "540x405" somewhere in it and so forth) - just like Netflix has test clips with stamped dimensions/bandwidth per each HLS stream chunk. This is to help figuring out if 295x223 image you see actually came from resizing 290x218 or from 540x405 or something else. Because notice that 540x405 was supposed to be the FHD image but in reality you see 295x223.
(2) Try both in 720 and 1080 video HDMI output and compare which images are used and if there is difference in blurring.

[Komag]

I already had unique images for each one. 1080p and 720p both display the hd image 290x218, both seemed to appear about the same quality. Only SD Roku displayed the 214x144. The different looking fhd 540x405 image was never shown. This is a side-loaded app, so maybe it works different with a private channel or a published channel.

I did another test, which was to make a big shape in-game, exactly 800x320 (based on a pic I already had). When Roku is 720p, the in-game shape (red block) is EXACTLY 800x320, no scaling for overscan or anything. When Roku is 1080p, the shape is exactly 1200x480 (50% larger each way), which is roScreen scaling the 720p game up to 1080p perfectly. So in-game there is no issue with HD overscan from either the HDMI or the elgato device. I also double confirmed this result with direct Roku screenshots in png mode.

(Interestingly, on this computer monitor, I found a setting for the HDMI input to act either as "Video" or "PC" - when I put it on "Video" it slightly zooms in the screen, cutting off the edges a little bit, creating overscan! Of course I set that junk back to "PC" where it will remain forever - where it was before.)

Back on subject...
So in-game there is no overscan happening at all. Is it possible there is some overscan happening only on the Roku home page? Maybe now you want to spill the beans how you measured 290x218? 😄

Anybody else have a way to capture a screenshot of the home page in 1080p and measure some pixels as they appear on-screen? See if the channel pictures are 290x218 as they are supposed to be, or something more like 295x223 as I'm measuring.

Maybe there is some crapification of side-loaded icon image files that doesn't happen the same way with private/public channels. Maybe they get squished, prodded, translated to jpg, enlarged, pushed into a box and shrunk down again, and compressed to boot.

[Komag]

I made a new icon with thicker lines
Here is my new mm_icon_focus_hd.png



And here is the slightly better than last time but still crappy home screen result



Here is the original full screen cap that came from:
https://www.dropbox.com/s/5vmjsddj7074z ... l.png?dl=0

Still getting blurred out for whatever reason.

I really would prefer the thinner lines, looks so much more retro/80's that way, which is the flavor of the game.

[EnTerr]

"Komag" wrote:
(Interestingly, on this computer monitor, I found a setting for the HDMI input to act either as "Video" or "PC" - when I put it on "Video" it slightly zooms in the screen, cutting off the edges a little bit, creating overscan! Of course I set that junk back to "PC" where it will remain forever - where it was before.)

Yes, you got it - that's exactly what such settings do, switch overscan mode on/off.

Back on subject...
So in-game there is no overscan happening at all. Is it possible there is some overscan happening only on the Roku home page? Maybe now you want to spill the beans how you measured 290x218? 😄

I don't want to - but fine, let me be laughing stock: i just measured the posters as well as the dimensions and calculated roughly the dimensions. No, there is no way i got anywhere near exact results... wait, this bizarre - i found in my desk pile the envelope i scribbled on and i actually had got numbers close to yours! With a friggin' tape measure!!

13.6cm/88.4cm*1920 = ~295
10.3cm/49.6cm*1080 = ~224

So anyway, i looked at these numbers and said to myself "well duh, obviously that's 290x218 - there is no way they will deviate by only a few pixels, that is a no-no" - and so i rounded to the "right" values, proud that my jury-rigged methodology gave results so close (2-3%) to reality...

Maybe there is some crapification of side-loaded icon image files that doesn't happen the same way with private/public channels.

That's actually easy to test - why don't you? Create a private channel for your app, upload, "publish" and install, observe.

Maybe they get squished, prodded, translated to jpg, enlarged, pushed into a box and shrunk down again, and compressed to boot.

Bad JPEG compression would have had ringing, just like the other example.
Hmmm. Here is an insane theory... what if the home menu UI is actually rendered in 720p, even on 1080p screens? That means the poster first gets shrunk by ~1.5 (incl. some interpolation smearing) - and then blown up by ~1.5 (some extra smearing).