Samsung 8000 Series User Manual page 539

No caption on digital channels.
Check the
Caption Mode Service1
Some channels may not have caption data.
The picture is distorted: macro block error, small
block, dots, pixelization.
The compression of video contents may
cause picture distortion, especially with fast
moving pictures such as sports and action
movies.
A weak signal can cause picture distortion.
This is not a TV problem.
Caption Setup menu. Try changing
to CC1.