This app is in legacy mode, as it is no longer being updated/supported (as of December 2017).
Only these devices are supported:

Samsung Galaxy S4
Samsung Galaxy S5 (And *some, not all* newer Samsung phones)
LG G3

If you have a different device, feel free to try it. But if it doesn't work, you have been warned that these are the only ones that are confirmed working (it definitely does not work on tablets). I have spent many frustrating hours trying to make this app compatible with the LG G4 with their proprietary SDK, only to have an internal SDK error that wouldn't go away no matter what I tried. Please do not ask me to support your device, as I have already tried to expand the device support, without success.
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This app is for controlling the Chinese LED RGB Light Bulb or 24-Key 5M Strip Lights MagicLighting brand. As of v1.0.7, it will also work with the generic (Chinese) 24-Key LED RGB Strip light! The 48-Key version is not supported! (See the Settings page for switching)

It does not, and will never work with Sylvania or other name brands.

Others may possibly work, but nothing else is guaranteed! (You must have a phone with an IR blaster, with open-source drivers. Any HTC device will not work, unfortunately)
The only device I owned and tested it on is the Galaxy S4, users have reported it working in GS5 and LG G3. (G4 not supported, use the LG app for importing the code)

If your device DOES work and is not listed, feel free to tell me so I can add it to the list!
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Background: I had tried all the free RGB LED Remote IR apps, and none of them worked for my specific LED bulb, and noticed in the reviews that it didn't work for a lot of other people either. So I ripped the codes from my own IR remote control ("Magic Lighting Remote Controller"), and started learning how to create my first app.

This application is ad-supported, and there is a link to donate in the settings, if you wish to do that.

if my remote controller does not work for your LED light bulb, I am sorry. There are probably 10 or 20 different codesets for different (but similar looking) LED strip hardware, my app has 2 of them (switch in the settings).

Permissions explained:

Full network access, view network connections - Used only to retrieve ads via Google Admob
Control vibration - to allow haptic feedback (enabled/disabled in settings)
Transmit infared - to allow access to the IR blaster