This app was mentioned in 6 comments, with an average of 34.00 upvotes
As the developer of an early IR blaster application, The Off Button, I can tell you that HTC and Samsung had to use their own standards, because Android didn't have an IR API at the time.
In fact, I think they added an IR API in response to the success achieved by these companies.
HTC and Samsung both moved to the Android standard soon after it was announced, but LG still remains on its proprietary standard.
Mine is "The Off Button" - https://play.google.com/store/apps/details?id=com.codisms.offButton
It only turns TVs on or off, but I find people appreciate the simplicity and it's easier to be covert since it can continue to send codes in the background.
This one called The Off Button does just that - it cycles through over 300 codes to turn most TV's off.
You can also use Anymote Smart IR Remote which after you set it all up for your devices, will let you program a Macro to do different things. One of them is a mass command to power your devices down with one push. You can then link that macro to a Widget on your screen. If I am not mistaken, you can also give it a voice command so it will execute the macro at your whim.
The Off Button is what you are looking for:
https://play.google.com/store/apps/details?id=com.codisms.offButton
Goto Walmart and have fun with demo tvs App https://play.google.com/store/apps/details?id=com.codisms.offButton