I am overlaying video on top of video in Premiere 6 via transparency. When I do this, render, and play back, a very slight grid effect appears on the picture. This problem is only slight, but is noticable. What I mean by a grid effect is small cubes covering the entire picture. The picture itself is not pixelated. Hard to explain, but I am hoping someone knows what the cause of this problem is and how to solve it!

Many thanks in advance.
mrobbo

Hi, Ive just come on this forum to ask the same question.

Ive been reviewing old videos on a television and on several overlayed shots a horrible grid is just noticable under the image, I accept that its too late to get rid of this now, but i wonder if anyone knows if it is Premier causing it? Is it a program glitch? I have vrs 6.5

I use Premiere 6.0, I've seen this before and I believe it's due to the footage being re-encoded repeatedly from DV AVI to DV AVI, I've noticed it on overlayed tracks as you have,

I think a solution could be to export the movie from Premiere with a lossless codec, then encode to the final source (MPEG2 for DVD etc.)

as I haven't experienced the problem that badly I haven't experimented yet, but I will do now and get back to let you know if that plan solves the problem.

EDIT:
Had a go at trying to solve it, not as easy as I'd hoped. There's some JPEGS in a zip file you can DL and look at: here

I did a simple bluescreen to overlay two layers (P6_bluescreen.jpg), then overlayed another layer on top with the screen transparency setting, this seemed to create bad blockyness (P6_3layers.jpg),

It helped quite a lot if I rendered the blue-screened layers and then imported this so I was using 2 layers, although there was still bad blockiness in areas of high contrast between the layers (P6_2layers.jpg).

but exporting in lossless formats didn't make any noticeable difference, maybe due to not changing the project settings, more messing about could provide an answer.

I then re-created the 2 layered version from Premiere 6.0 in Premiere Elements 2.0, I used the chroma keying effect rather than the unavailable screen, and I got even worse blockiness, especially in contrasty areas (PE_2layers.jpg).

So it seems like the problem isn't easy to solve, it would be interesting to see if it happens in Premiere Pro to the same extent...

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