+stephena Posted July 25, 2017 Author Share Posted July 25, 2017 It has to do with the fact that the display is shifted somewhat. It seems to be inherent in how an NTSC signal is encoded, so I'm not sure it would even make sense to disable them, even if we could. Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted July 25, 2017 Share Posted July 25, 2017 It has to do with the fact that the display is shifted somewhat. It seems to be inherent in how an NTSC signal is encoded, so I'm not sure it would even make sense to disable them, even if we could. I didn't want to criticize the lines at all, only wanted to state that they are not depending any of the parameters. BTW: PAL shows them too. Quote Link to comment Share on other sites More sharing options...
+stephena Posted July 25, 2017 Author Share Posted July 25, 2017 Yes, this is an idiosyncrasy of the TV effects. Technically they're only defined for NTSC modes, but we apply them for PAL too. This is mostly because I've never seen a PAL TV before, and I don't know what the output should look like. Quote Link to comment Share on other sites More sharing options...
DirtyHairy Posted July 25, 2017 Share Posted July 25, 2017 (edited) I am curious about the actual origin of those lines, too. My theory is that this is an artifact caused by the shadowing that occurs at vertical high-contrast edges, both with Blargg and with actual TV signals. The Draconian logo uses flickerblinds, so each single frame shows a pattern of eight colored pixels alternating with eight blank pixels. This produces edges, and my suspicion is that the shadowing caused by these edges creates the dark lines that can be observed The same effect can be seen with other ROMs that use flickerblinds. Edited July 25, 2017 by DirtyHairy Quote Link to comment Share on other sites More sharing options...
RevEng Posted July 25, 2017 Share Posted July 25, 2017 The Draconian logo uses flickerblinds, so each single frame shows a pattern of eight colored pixels alternating with eight blank pixels. This produces edges, and my suspicion is that the shadowing caused by these edges creates the dark lines that can be observed In terms of the non-emulated effect, the edges are just real-world square waves (luma) taking a slower aount of time to rise vs fall. Flickerblinds relies on signal edges to line up... ______ ______| |______ odd frame ______ ______ |______| even frame But in the real world, we get something like... _____ _______/ |______ odd frame _______ ______ |_____/ even frame When I created my first flickerblinds display I was a bit bummed over the black gaps. But I suspect most people don't get as distracted by them as programmers do. 3 Quote Link to comment Share on other sites More sharing options...
DirtyHairy Posted July 26, 2017 Share Posted July 26, 2017 Interesting, thanks alot. So is the effect that I described as "shadowing" around edges actually the finite raise time of the luma edges? Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted July 26, 2017 Share Posted July 26, 2017 (edited) In terms of the non-emulated effect, the edges are just real-world square waves (luma) taking a slower amount of time to rise vs fall. Vice versa, isn't it? Both are not immediate, but because the lines are dark, the fall must be faster than the raise. And depending on the difference, the lines are more or less visible. BTW: I wonder if phosphor plays a role here too. Edited July 26, 2017 by Thomas Jentzsch Quote Link to comment Share on other sites More sharing options...
RevEng Posted July 26, 2017 Share Posted July 26, 2017 I believe I have it the right way around. If the fall were slower than rise, we'd have brighter overlap between the lined up regions. If it's easier, consider which scenario has more average high, or more average low. I was originally going to comment on phosphor - I'm not sure how much it contributes, because I haven't checked to see if the effect is present on LCD. Whenever we talk about CRT phosphor, it also involves persistence of vision too. So square waves here has to mean everything from electrons in TIA to nerve impulses. Confirmation of the effect on LCD would put the reason for the effect back to signal, since LCD doesn't strongly trigger persistence of vision like CRT does, and has no phosphor. Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted July 26, 2017 Share Posted July 26, 2017 If the fall were slower than rise, we'd have brighter overlap between the lined up regions. If it's easier, consider which scenario has more average high, or more average low.Agreed. I got you the wrong way, probably just my non-perfect English. Quote Link to comment Share on other sites More sharing options...
RevEng Posted July 26, 2017 Share Posted July 26, 2017 Agreed. I got you the wrong way, probably just my non-perfect English. Looking at my original non-perfectly worded English, I see where the confusion occurred. The blame is all mine. 1 Quote Link to comment Share on other sites More sharing options...
devwebcl Posted November 25, 2017 Share Posted November 25, 2017 is there a way to run faster Stella emulator ? (1000% etc, depending on the host machine's speed) I found that feature in other emu's but I can't find that option in Stella Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted November 25, 2017 Share Posted November 25, 2017 In Video Settings you can set the Framerate to 300 and disable VSYNC. Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted June 1, 2022 Share Posted June 1, 2022 On 2/24/2017 at 7:19 PM, SpiceWare said: In regards to TV jitter Issue #11, I have a sticky note on my dashboard about a bug that was introduced into the jitter logic. That link is to this: I don't know if this is common knowledge, but you can use the curved arrow at the top-right of the quoted text to jump to the original reply in order to see it in context. @SpiceWare Did you ever get back to this? It looks like the 2 lines threshold is still in Stella. It even got increased to 3 meanwhile. Quote Link to comment Share on other sites More sharing options...
+SpiceWare Posted June 1, 2022 Share Posted June 1, 2022 51 minutes ago, Thomas Jentzsch said: @SpiceWare Did you ever get back to this? It looks like the 2 lines threshold is still in Stella. It even got increased to 3 meanwhile. No, one of the Mac updates removed Dashboard so I've not seen that sticky note in years. 1 Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted June 1, 2022 Share Posted June 1, 2022 OK, thanks! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.