Timeline for How to create a composite video signal from Hsync, Vsync and Video?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 18, 2024 at 10:35 | vote | accept | Bart Friederichs | ||
| Nov 18, 2024 at 10:35 | comment | added | Bart Friederichs | Wow, thanks a lot for this very extensive explanation. Looks like it is never simple when dealing with old electronics. And yes, calling it trivial would be an understatement if not plainly wrong. Looks like I have quite some studying to do. | |
| Nov 11, 2024 at 19:51 | history | edited | Ste Kulov | CC BY-SA 4.0 | Per request, I clarified the terminology between PAL and 625-line scanning. Clarified that AND logic is a poor approximation. |
| Nov 11, 2024 at 19:29 | comment | added | Ste Kulov | @Justme Yes, I know. I linked my blog post that explains all this in great detail. You must've overlooked it. The whole point is YMMV. | |
| Nov 11, 2024 at 19:26 | comment | added | Justme | XNOR has another issue - TVs are sensitive to falling sync edge, so XNORing HS and VS will invert the HS edge. HS should be a short falling edge pulse, while VS should be a long falling edge pulse. So YMMV, it's not trivial. | |
| Nov 11, 2024 at 19:08 | comment | added | Ste Kulov | @Justme It’s hit or miss, but in my experience with the Sega Master System it’s way more hit than miss. I’ve only come across one set that rejects it. Anyway, I wasn’t proposing a great solution (don’t have time to design a robust system for a random person on the web). I just wanted to propose something minimal that might work. The questioner can take this as a starting point and choose to implement an XNOR solution or even implement the true serrated pulses. I agree with the terminology problems. I was using the terms loosely for simplicity, but I’ll try to fix that. | |
| Nov 11, 2024 at 17:30 | comment | added | Justme | I think modern TVs with composite input would have issues with the missing Hsync during Vsync. They don't like C64 signal either, which is also 288p but the chip sends out a bit skewed syncs during Vsync. And minor technicality; PAL is a colour encoding standard, not a scanning system - so a monochrome signal cannot technically be PAL even if it has 625i50 or 288p50 scanning system. | |
| Nov 11, 2024 at 15:45 | history | answered | Ste Kulov | CC BY-SA 4.0 |