Cloning the GameCube component cable

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 8:01 am

Also, one thing I have noticed that isn't unique to the HDMI output, it's present on standard component although not as obvious, is if a game doesn't use the standard 640x480p resolution, and many of them don't, they use something like 660x448p, you can see the GameCube's dithering effect very clearly without the blurriness of composite to hide it. It's not present in any games that output in 640x480, but with any games that use a non standard resolution you can see it. With component, it looks more like scan lines, but with HDMI, you can see individual dithered pixels. Very odd.

megalomaniac · Post by **megalomaniac** » Wed Oct 21, 2015 8:31 am

ive never seen any wobble, what title did you see this on?
...and the artifacts you describe, are you sure its not a result of using the Framemeister also...

everything seems to look sharp and clear on my end in both analog and digital versions...

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 9:14 am

No specific title causes it to wobble, it jitters regardless with enhanced DVI switched on and connected to my monitor directly. With regards to the artifacts, I don't think I'm alone in experiencing them, if you look at those close up screenshots of the comparison between the Wii and GameCube component output, you can see them, and I've watched captured footage from a GameCube with component output and progressive scan, and they are present. Some games display them more obviously than others, and only in certain areas. For example, Sonic Heroes and Shadow the Hedgehog do not exhibit them as they output in 640x480. Mario Kart Double Dash does show them, but very faintly, you have to look very hard to see them. They are present in Wind Waker, but only really noticeable in darker areas, like Forsaken Fortress, they are very obvious. Prince of Persia the Sands of Time they are always visible, same in Time Splitters 2. Like I said, I don't think it's anything wrong with the cube or the Framemeister, it's just something that the cube does.

Edit: Here is a link to show you what I mean, it's direct capture footage of Wind Waker using an HD PVR with progressive scan on component cables, and you can clearly see lines across the screen. As it's not being displayed on a CRT, you can rule out scan lines: https://youtu.be/rZWIKsyej9Q?t=4m13s

Unseen · Post by **Unseen** » Wed Oct 21, 2015 9:19 am

Xaranar wrote:No specific title causes it to wobble, it jitters regardless with enhanced DVI switched on and connected to my monitor directly.

Does your monitor claim to be HDMI-compatible?

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 9:25 am

Unseen wrote:
Xaranar wrote:No specific title causes it to wobble, it jitters regardless with enhanced DVI switched on and connected to my monitor directly.
Does your monitor claim to be HDMI-compatible?

Yes, yes it does.

Unseen · Post by **Unseen** » Wed Oct 21, 2015 9:32 am

Xaranar wrote:Yes, yes it does.

In that case it should work in theory, but since it doesn't in practice I guess that there is some minor "bug" in the output of GCVideo that your monitor doesn't like. Unfortunately I have no idea how to figure out where the problem is (HDMI protocol analyzers are ridiculously expensive), so I'm sorry to say that I can't solve your problem.

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 9:37 am

Unseen wrote:
Xaranar wrote:Yes, yes it does.
In that case it should work in theory, but since it doesn't in practice I guess that there is some minor "bug" in the output of GCVideo that your monitor doesn't like. Unfortunately I have no idea how to figure out where the problem is (HDMI protocol analyzers are ridiculously expensive), so I'm sorry to say that I can't solve your problem.

That's quite alright, running it as a direct passthrough through my Framemeister fixes the problem, it also suits me fine as my Framemeister can operate as an HDMI splitter so I don't have to keep swapping cables out.

Any word on the scanline/dithering effect I described? Like I said, I'm fairly confident that it's something the GameCube just does, as if you look at the youtube link I posted of the direct capture footage from Wind Waker, you can see artifacts resembling scan lines running across the screen.

Unseen · Post by **Unseen** » Wed Oct 21, 2015 9:47 am

Xaranar wrote:Any word on the scanline/dithering effect I described? Like I said, I'm fairly confident that it's something the GameCube just does, as if you look at the youtube link I posted of the direct capture footage from Wind Waker, you can see artifacts resembling scan lines running across the screen.

I don't see anything in that video that I would describe as "scan lines". Could you take a screenshot and maybe annotate it with Paint or similar to make sure we're talking about the same effect?

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 9:59 am

If you zoom the picture to full size, you can see the striped effect I'm talking about. I put it as a URL so you can see the full size image.

You can see them here, too, albeit very faintly.

tesla246 · Post by **tesla246** » Wed Oct 21, 2015 10:06 am

I couldn't help you earlier, but I remember reading this somewhere in this thread, so maybe I can point you in the right direction

. The lines are supposedly a side effect from the Gamecube's internal scaler and have nothing to do with the HDMI output, aside from making it more visible. Tuedj explained it earlier in this thread:

tueidj wrote:The vertical stripes are from the GC's horizontal scaler, they appear on a lot of games.

For the jumpy image problem with the linedoubling I believe what meneerbeer is suggesting is to add one extra blank line to the top of the bottom field image to properly align the original scanlines with their intended display position, rather than implement some sort of deinterlacing algorithm.

tueidj wrote:
bobrocks95 wrote:Is there any more info I can find out there on this? Is it used to upscale a lower res back buffer to the standard output resolution or for some other reason?
Basically yes, the unscaled YUV data is resampled before being fed to the D/A converter.
http://hitmen.c02.at/files/yagcd/yagcd/ ... tml#sec5.3
HSR controls the stepping size, where each "step" is one tick of the 13.5MHz clock used to drive the output signal. The FCT registers may hold the weights used for the resampling (they are NOT used for anti-aliasing), in any case the values used are hardcoded in the SDK and not configurable by games.

A similar artifact in gamecube/wii games is visible dithering when the internal framebuffer has the alpha buffer enabled or anti-aliasing is active, due to reduced color depth (6 bits per channel when alpha is used, 5-6-5 when SSAA is used). This is normally very visible in Super Mario Sunshine due to lots of flat colored surfaces being used.

I remember seeing it in other games as well and being particularly visible during smoke effects. The quotes are from page 25 of this thread, you may read up on it a few pages before that.

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 10:14 am

tesla246 wrote:I couldn't help you earlier, but I remember reading this somewhere in this thread, so maybe I can point you in the right direction . The lines are supposedly a side effect from the Gamecube's internal scaler and have nothing to do with the HDMI output, aside from making it more visible. Tuedj explained it earlier in this thread:

tueidj wrote:The vertical stripes are from the GC's horizontal scaler, they appear on a lot of games.

For the jumpy image problem with the linedoubling I believe what meneerbeer is suggesting is to add one extra blank line to the top of the bottom field image to properly align the original scanlines with their intended display position, rather than implement some sort of deinterlacing algorithm.

tueidj wrote:
bobrocks95 wrote:Is there any more info I can find out there on this? Is it used to upscale a lower res back buffer to the standard output resolution or for some other reason?
Basically yes, the unscaled YUV data is resampled before being fed to the D/A converter.
http://hitmen.c02.at/files/yagcd/yagcd/ ... tml#sec5.3
HSR controls the stepping size, where each "step" is one tick of the 13.5MHz clock used to drive the output signal. The FCT registers may hold the weights used for the resampling (they are NOT used for anti-aliasing), in any case the values used are hardcoded in the SDK and not configurable by games.

A similar artifact in gamecube/wii games is visible dithering when the internal framebuffer has the alpha buffer enabled or anti-aliasing is active, due to reduced color depth (6 bits per channel when alpha is used, 5-6-5 when SSAA is used). This is normally very visible in Super Mario Sunshine due to lots of flat colored surfaces being used.
I remember seeing it in other games as well and being particularly visible during smoke effects. The quotes are from page 24 of this thread, you may read up on it a few pages before that.

This is acually pretty useful information, thanks, though the stripes are horizontal, not vertical, and in fact, they aren't stripes at all, but interweaved pixels as made visible by the HDMI output.

Unseen · Post by **Unseen** » Wed Oct 21, 2015 10:15 am

Xaranar wrote:If you zoom the picture to full size, you can see the striped effect I'm talking about. I put it as a URL so you can see the full size image.

Oh, interesting - the horizontal scan lines didn't show up for me when playing the video in Firefox, but it's visible in Chrome. It does look as if someone had turned on a scanline generator and since the effect disappears during motion I would guess that it is present in the file that was uploaded to Youtube.

I don't remember seeing something like this on my Cube, but I'm not sure if I have tested an NTSC version of Wind Waker in 480p mode. Unless you explicitly turn on scanlines in GCVideo it shouldn't produce an effect like this, so my initial assumption is that the lines are generated by the Gamecube.

(and the scaling artifacts at the edge of the cap have been explained by someone else already)

Xaranar · Post by **Xaranar** » Wed Oct 21, 2015 10:24 am

Unseen wrote:
Xaranar wrote:If you zoom the picture to full size, you can see the striped effect I'm talking about. I put it as a URL so you can see the full size image.
Oh, interesting - the horizontal scan lines didn't show up for me when playing the video in Firefox, but it's visible in Chrome. It does look as if someone had turned on a scanline generator and since the effect disappears during motion I would guess that it is present in the file that was uploaded to Youtube.

I don't remember seeing something like this on my Cube, but I'm not sure if I have tested an NTSC version of Wind Waker in 480p mode. Unless you explicitly turn on scanlines in GCVideo it shouldn't produce an effect like this, so my initial assumption is that the lines are generated by the Gamecube.

(and the scaling artifacts at the edge of the cap have been explained by someone else already)

That's what I thought, as those lines are present when using the component cable on my setup, too. If I use the direct HDMI output, then you can see that those lines are not lines at all, but rather are dots arranged in a grid pattern but display as lines, likely due to the scaling of the display. As the poster before me quoted, if you look at where the original quotes come from earlier in this thread, he has included a picture gallery and his does in fact display vertical lines, and I would wager that because these artifacts are individual dots rather than lines, that this is due to display scaling as well.

tueidj · Post by **tueidj** » Wed Oct 21, 2015 10:05 pm

The annoying thing about the dithering (which is performed by repeating an 8x8 bayer matrix over the internal framebuffer when converting to YUV) is that in theory it's not meant to be observable when viewing live frames, IF the game devs have followed the recommendation of adjusting the framebuffer's vertical offset for each frame (which in turn causes the bayer matrix to be applied with a different offset on each frame). Unfortunately not many devs followed these directions.

megalomaniac · Post by **megalomaniac** » Wed Oct 21, 2015 11:17 pm

Unseen wrote:
Xaranar wrote:If you zoom the picture to full size, you can see the striped effect I'm talking about. I put it as a URL so you can see the full size image.
Oh, interesting - the horizontal scan lines didn't show up for me when playing the video in Firefox, but it's visible in Chrome.

HA,
i dont see it in chrome
here is my best attempt to capture the exact same frame in the youtube link posted before

windwalker.JPG: (109.12 KiB) Not downloaded yet

i dont see scanlines on my end

marcus9199 · Post by **marcus9199** » Thu Oct 22, 2015 3:28 am

Finally got around to building my own. Excited about installing in the rest of my cubes.

andre104623 · Post by **andre104623** » Fri Oct 23, 2015 11:54 pm

marcus9199 wrote:Finally got around to building my own. Excited about installing in the rest of my cubes.

Very nice I just built one lite version last night and it was hard soldering this thing. After comparing both DVI and analog version I can firmly say that picture quality is much better with the DVI/HDMI. I'm still waiting for the Shuriken video V2 PCBs to come back from the fab. I'll see how it performs compared to the pluto 2x since I'm using the 200a FPGA instead of the 50a.

This new job I got on monday is taking all my free time away but at least I'm making more money.

megalomaniac · Post by **megalomaniac** » Sat Oct 24, 2015 2:17 am

I prefer analog picture quality...but either way, the pic quality is great on both analog or digital

some TVs do better with analog signals than others
some TVs dont display digital signals as well as others
some people cant see as well....some people cant hear as well....
so everything is mostly matter of opinion / preference

bobrocks95 · Post by **bobrocks95** » Sat Oct 24, 2015 3:03 am

megalomaniac wrote:I prefer analog picture quality...but either way, the pic quality is great on both analog or digital

some TVs do better with analog signals than others
some TVs dont display digital signals as well as others
some people cant see as well....some people cant hear as well....
so everything is mostly matter of opinion / preference

I remember reading Sony TV gaming reviews on shmups forum and it was noted that the sets processed 480p better through the component input than the HDMI input. So that's definitely a very valid point. Nice to have options either way though!

megalomaniac · Post by **megalomaniac** » Sat Oct 24, 2015 3:30 am

....exactly
this is something to always keep in mind with testing.

its hard to prove how GCVideo analog or digital can look better than the other even while comparing the quality using the same TV since feeding the signal thru different input connections can impact the video quality. TVs have both an analog tuner and a digital tuner. So comparing Component to HDMI on the same TV leads to invalid results because the picture quality is dependent on the TVs separate analog and digital processing of the signal.

If anything, comparing the two would only allow the tester to determine if their own TV is better at accurately displaying from an analog or digital input source. But even this would not be a true test since GCVideo analog and GCVideo digital use two different hardware solutions to create the signal.

Try connecting your BluRay player to your TV and compare Component vs HDMI, and guess what? even this is not an accurate test because within the BluRay player the signal gets converted from digital to analog. So component video quality will depend on the quality of BluRays own video conversion hardware.

I could go on and on....
but the simple truth is: there is no real way to compare analog to digital since there are many factors that affect how either signal would be reproduced on your TVs screen....and in the end: it still comes down to opinion / preference based on the TV/hardware you are using....

meneerbeer · Post by **meneerbeer** » Sat Oct 24, 2015 7:55 am

For old systems analog + crt is best imo. Thanks to analog low res images + dithering are blurred to a degree.

I would still like to try GameCube on an old CRT monitor with analog inputs some day, but I do not have one anymore.

Unseen · Post by **Unseen** » Sat Oct 24, 2015 8:16 am

megalomaniac wrote:But even this would not be a true test since GCVideo analog and GCVideo digital use two different hardware solutions to create the signal.

A combined version with both analog and digital outputs could be created, although I doubt there would be much demand.

meneerbeer · Post by **meneerbeer** » Sat Oct 24, 2015 8:47 am

By the way, I think last time when I checked the video timings for 480p, I believe the hsync was 64 cycles long. According to CEA-861 it is 62 cycles. I don't think it matters that much, but it might be good to have knowledge of it.

I believe the Dreamcast has a hsync of 64 cycles as well. So maybe it is not just a coincidence.

megalomaniac · Post by **megalomaniac** » Sat Oct 24, 2015 9:40 am

Unseen wrote:
megalomaniac wrote:But even this would not be a true test since GCVideo analog and GCVideo digital use two different hardware solutions to create the signal.
A combined version with both analog and digital outputs could be created, although I doubt there would be much demand.

i had thought about this a few months back too and wondered....
then i remembered people for the most part are pretty much set in their decision to use either analog or digital.
A combined version could most likely only result in unused features and extra parts costs for the majority of people....

when i worked on the MX chip project i included the ability to have VGA or YPBPR with the flip of a switch....
if i recall properly, i think everyone only used one of the video outputs with no real need for the other...
im pretty sure the same would apply here....

bobrocks95 · Post by **bobrocks95** » Sat Oct 24, 2015 5:03 pm

megalomaniac wrote:i had thought about this a few months back too and wondered....
then i remembered people for the most part are pretty much set in their decision to use either analog or digital.
A combined version could most likely only result in unused features and extra parts costs for the majority of people....

when i worked on the MX chip project i included the ability to have VGA or YPBPR with the flip of a switch....
if i recall properly, i think everyone only used one of the video outputs with no real need for the other...
im pretty sure the same would apply here....

In the Gamecube's case I would switch between a CRT for Gameboy Player and an EDTV for everything else. What it really comes down to is the additional cost/manufacturing effort (if you're hand-soldering components) of including both. If I have to buy a second Gamecube and another board it's not the end of the world.

If you use the same board design for the analog and digital versions, and just add the components you need to for either version, would it be possible to make a dual-output version for people who want it? Not knowing anything about the design I could be talking out of my ass here of course.

meneerbeer wrote:For old systems analog + crt is best imo. Thanks to analog low res images + dithering are blurred to a degree.

I would still like to try GameCube on an old CRT monitor with analog inputs some day, but I do not have one anymore.

Low-res digital panels hide a lot as well.
For 480p stuff I'd say a PC CRT would look the best, and if you don't have one it's a toss-up between a 15KHz SD CRT or a modern LCD depending on how well it handles 480p content. The extra sharpness of 480p makes a big difference imo compared to flickery 480i on a CRT.

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