Here is an old thread over at AVS about the issue...
http://www.avsforum.com/forum/26-home-t ... creen.html SD has also acknowledged the issue in the past but unfortunately those threads are long gone on their forums. Somewhere in that thread I have a link to a video I made demonstrating the problem (though in that case it actually said display driver error rather than a blank screen that it would if I just used the integrated graphics)
Unfortunately the channels you provided are the same for "every" cox market in OK (based on your location shown, when I did a search for cox OK showtime 832... often cox i OKC and Tulsa use different lineups/equipment) so I only checked OKC for contour channels... the following would be considered contour channels and will probably have the issue. To confirm it is the h.264 issue, press 411 info (411 ctrl+d if using keyboard)... make sure to press info or ctrl+d prior to it trying to tune channel 411... then hit the right arrow 8 times to go to the last page and it should state what the video is encoded as... I believe in the blank screen issue it will say unspecified)
699 FOX College Sports HD◊
708 ESPN Goal Line/Buzzer Beater HDנ
710 Outdoor Channel HD◊
772 Hub HD◊
777 DIY Network HD◊
778 Cooking Channel HD◊
803 RetroPlex HD◊
804 IndiePlex HD◊
812 HBO Signature HD◊
813 HBO Family HD◊
815 HBO Zone HD◊
816 HBO West HD◊
817 HBO2 West HD◊
821 MoreMAX HD◊
823 ThrillerMax HD◊
824 Cinemax West HD◊
825 ActionMAX East HD◊
826 5 StarMAX HD◊
832 SHOWTIME West HD◊
834 Showtime Extreme HD◊
839 TMC West HD◊
843 STARZ In Black HD◊
844 STARZ Kids & Family HD◊
846 STARZ Comedy HD◊
850 MC PLAY HD◊
1321 MLB Network Strike Zone HD◊
1324 Big Ten Network 2 HD◊
1325 Big Ten Network HD◊
1327 Pac-12 Network HD◊
1336 Universal Sports Network HD◊
1354 World Fishing Network HD◊
1355 Outside Television HD◊