Composite output

[lask1]

Hello everyone!

I have been programming a cool application in C++ with OpenGL ES 2. Everything was going great 1080p hdmi and then I wanted to try using my application the composite output on the pi and WOW I got some weird results. Everything scales great and my application looks good at 720x480 on a non interlaced signal however whenever I go to an interlaced signal it looks like I am staring into a fish tank and everything is being distorted vertically. I have very little experience with drawing in an interlaced environment and was hoping somebody could help me figure out what is going on or at least help point me in the right direction.

Thank you in advance for your feedback!

lask.

[dom]

Can you post a link to a photo?
It's hard to imagine what you are describing.

[lask1]

Hi,

Thanks for the reply. I am not sure how a screenshot or photo will help as this problem occurs over multiple frames. I am running my program through the composite output to an old tv. I believe that my game updates and the monitor scans the even lines and then my game updates before the monitor has scanned the odd lines. This results in a funny effect on any vertical scrolling lines or text.

I hope that helps to understanding my problem.

Thanks again,

lask

Oh and I just tried lowering the program to 30 fps and it seems to be better. I am wondering if there are more ways to decrease this effect caused by interlacing hmmmmm

[lask1]

Please does anyone know? When you draw a progressive image to an interlaced screen you get some weird results. This is what I am doing and I am wondering how I should draw when I am working with an interlaced display. Do I use a stencil and only draw to the odd or even lines and alternate?

I would really appreciate any help I can get! Sorry I can not share any screenshots and with my problem I do not see how they would help.