Fisher wrote:
- I need to take a picture of a SNES that got a transcodification problem and try to understand it. It consists of two resistors and a capacitor on the video encoder. I need to write down the values.
I used to use 3K3 and 104 (100nf) capacitors. What that circuit does is inject the CSYNC on the PAL/NTSC selection pin of the video encoder so it switches the mode during the blanking phase. That hack makes it generate PAL video signal while using NTSC timing. Same trick Tec Toy used with the MC1377 on the first Master System console.
Fisher wrote:
- On the MegaDrive's case I think that it's the alternating phase that's the problem. It gets black and white and with alternating colors. But it only happens in some games, that's weird!!
Again, timing problems with the color burst. They put two 100nf capacitors at strategic spots to reduce that a bit.
Fisher wrote:
- I need to take a look at the PS1's transcodification circuit. If I remember correctly it was a transistor, a crystal and two resistors.
Maybe that was a little oscilator that generated the color subcarrier frequency.
PS1 has some special optimizations to make the CXA145 image better:
The "GPU" (frame buffer is a better denomination here) outputs a triangular wave for color carrier which helps reducing edges. It also generate that in phase with the HSYNC which helps with dot crawl. Gives out a crisp image on NTSC. Transcodification on that system throw the optimizations out of whack and you get worse picture quality as result. It also has optimizations for PAL video but those are active if the vertical frequency is 50Hz.
Fisher wrote:
- How's the N64 transcodification done? I think it's similar to SNES.
Replied already on another post.
Fisher wrote:
- And at last but not least, is the color subcarrier what carries the colorburst? I'm a bit confused about these two names...
Colorburst is encoded on the sync signal during the blanking phase.
Basically... PAL-M is a hack and you're better avoiding it like the plague.