Controlling volume (television / sound system)
Hi,

As you know, Broadlink's eControl app allows IR control for televisions / sound systems (i.e. receivers).
One of the best features is controlling the volume through the app (attached screenshots).
![img_0182](https://user-images.githubusercontent.com/7550012/27510959-38823f5e-5924-11e7-98fe-f6f9f5bc5575.PNG)
![img_0183](https://user-images.githubusercontent.com/7550012/27510960-388a88a8-5924-11e7-992a-b21b01f40997.PNG)

What is the best option to achieve such control?