Problem with Sky texture when rendering animation


I have a problem when I render an animation with sky using ‘Cloud’ texture.

The sky seems to be blurred and looks like “scatter pixel” while the other parts are all fine. Each frame caption from the file looks fine and there is no problem when render each frame as an image. The problem seems to be when an animation runs (when starting VDO file, it the sky looks okay, but when start to play, the problem can be seen.)

I set rendering resolution to 100% but it does not help.

The attachment shows the capture where the VDO had already been played to the last frame. The sky was scatter and rough.

Please advise.

Thanks and best regards,

Edit: It’s okay now. I change the format to AVI and it works fine.