I understand you are needing information on aspect ratios. Here are two articles that may give you all the information you need:
Hope this helps!
Sling Media Moderation Team
Karl thank you for your reply.
Although the info you provided is helpful, I want to make sure that if I purchase another sling product I am not going to have the same issues that I have with my ProHD.
Which is to say, with my ProHD I get black bars when I HDMI or Composite out of my ipad air 2, ipad 3 and my ipad 2 (using the most recent sling app and most recent iOS version). I know airplay is a known issue - it wasnt until something was changed or upgraded on your end but nevertheless its a problem I am aware of.
My STB is verizon fios quantum IPC1100 and I have tested it with both 1080p and 1080i. The TV I am trying to display it on has been tested on all of its picture size settings and no matter what I still find myself watching a stretched screen. The picture looks great but once I zoom it looks horrible. I have also followed the instructions on HQ and Auto via the app and all of the other advice offered on the forum.
As far as apple tv airplay goes - its a nice feature to use but it is far from a priority since I have the cables (both composite and hdmi) to connect to the ipad.
I have tried to cable out of the ipad on other tv's and have the same issue so that is ruled out.
Bottom-line is I understand I have an older model slingbox. If I need to upgrade I will however I want to be sure a newer model is going to be the solution to the screen issue.