Yes I do realize that my caps lock key was pressed, I PRESSED IT, sometimes I LIKE to scREAM people.
Put very simply the synch information is sent or generated on EVERY LINE of video information, there are 525 of them for a single frame of video and there are 60 frames per second. What the OP wanted to do was regenerate the "Lost" video when there is no line or frame synch. The real problem is that when synch is lost so is the video because the video is sent between the synch information. There is a great deal more lost than that as well Studio or originating COLOR synch is lost as well because it is a part of the frame synch period. 8 cycles of 3.58 MHz color "Burst" information is there on the "Back Porch" of the synch pulse... so is the "BLACK LEVEL" or the absolute reference for the LUMINANCE level of the video signal and there are no readily possible solutions to that process that an Arduino is capable of. For those with an "Inquiring Mind" I took the liberty of attaching a data sheet for the aforementioned "LM1881" in of itself it Should be enough... Material..
This is the short answer:
Without the synch information everything else is lost because the synch information is the "Wrapper" for all the rest of the "composite" video signal information. The issue is, that the OP was told several times that what he wanted to do was not readily possible with an Arduino and unfortunately the reasons for the NO answer are beyond the education level of the OP. MY son once said to me... "Daddy Why can't I Fly to the Moon"" and I said "it's too far away" He then said "New York is far away and I can Fly there...". Had the OP the simple theoretical knowledge of NTSC television, He wouldn't have asked the question because the answer is inherent in the knowledge of the medium used to transport the information...
Docedison
This was one of several "answers" that the OP chose to ignore:
There are those that don't know enough to be able to hear "NO" as a reasonable answer... and the OP wanted PAL too. I think did he truly understand why the "Pixelation" happens he might realize that the GENLOCK information isn't there and without it is vaguely like reading semaphores in a tornado.
Doc
LM1881.pdf (178 KB)