This app was mentioned in 2 comments, with an average of 3.50 upvotes
Yup. My understanding is that you have to have your DVR connected to the internet. Hit the dash button on your remote (Lower left) and it should tell you on your TV if it's connected or not.
Then, you can login to the app store and download the DirecTV app by DirecTV. You'll need to enter your username and password. If you don't have one, you'll need to go on the Directv website and set one up.
I use it all the time. If you are in the house, it will let you control your box. If you are out of the house, you can setup recordings and stream DirecTV channels. (You can't stream recordings from your DVR.)
Android:
https://play.google.com/store/apps/details?id=com.directv.dvrscheduler&hl=en
Ipod:
you might have better luck in the directv (sat) forum:
https://www.reddit.com/r/DirecTV/
but... I did a search of the roku store and it doesn't look like there is a normal old directv app for roku (just the OTT now app which is not the same right now)
There is a direct tv app for android devices: https://play.google.com/store/apps/details?id=com.directv.dvrscheduler&hl=en
and for ios devices:
https://itunes.apple.com/us/app/directv/id307386350?mt=8
so in theory if you have an ios or android phone you might be able to cast it over to the roku (some apps let roku support the google casting standard)... or a chromecast or apple tv, but as far as a native roku app for the directv sat service... there isn't one.