My 1’st thought was to make the IR you use to control your box very different from the existing remote so if the soundbar sees it, it won’t react and get out of sync. So your box is both an IR repeater and translator. Perhaps there’s a remote you like that can be the new remote ?
Alternately (if possible ?) block the soundbars IR sensor and have your box be just a repeater/“blaster”. Use the existing remote at the risk of getting de-sync’ed due to an accidental reception.
I think all the IR remotes use light in the 920-950 nm waveband and any IR LED in that range can be made to work. As you should now know that LED is turned on/off (100 % AM) with a duty cycle btw 33 % and 50%. The DC isn’t all that critical but the mod frequency (32 - 40+ kHz) can be. If you can’t Google to find it, you should measure it for both remotes. While an O-scope would be nice, I’d think a simple logic analyzer would also work. If you can’t steal either, that’s OK 'cuz what I think you’ll need to do the job can also be used as test equipment.
So how’s this all going to work ? A concept is you use a different remote or somehow block reception by the soundbar. You send commands to the box, it receives and decodes the IR stream and then does at least 2 things. It recodes (if needed) the command and modulates it’s IR LED to send a stream to the soundbar in it’s protocol. It also keeps track of the command, updates some memory component, and displays (perhaps only for a moment) the new parameter setting. Perhaps the box does other things, like dim the display vs the sensed ambient light level or some other useful feature.
While there may be other ways to do all these functions, using a microcontroller (MCU) will be the simplest IMO. Time to learn some programming ! The tasks are well within the capabilities of low level MCUs like an 8 bit PIC or ATMega. Your system could be as simple as the right IR receiver (as I linked too), the MCU (and it’s support stuff, caps, xtal, etc) and the IR LED … and power supply of some sort, perhaps some buttons for non-IR interfacing, sensor for ambient light, etc, etc.
The MCU can be used w/the simple IR sensor you linked to, to measure the mod freq and DC. Then you can pick the correct receiver and use that to decode the protocols used. Or just record the bits and timing for the commands used.
Again Google is your friend.
http://learn.adafruit.com/ir-sensor
http://www.brainlinksystem.com/how-deco … red-remote
http://www.adafruit.com/blog/2013/07/29 … l-decoder/
http://tech.cyborg5.com/irlib/
http://www.remotecentral.com/features/irtips.htm (GOOD PLACE TO FIND PROTOCOLS)
The choice of MCU is up to you, both PICs and (these-days) Arduino’s have been used and there’s all manner of info on the WWW. One thing to consider before an MCU is the display as that may drive your MCU choice (# of I/O pins needed, communication protocol to display, etc). You may find it easier and worth the $30 to get a “dev” (development) MCU board, use that and a breadboard to get everything working … and then either repackage the same or buy smaller, more purpose built and packaged components or even make your own PCB to put in the final box.
http://en.wikipedia.org/wiki/Universal_ … ng_remotes
http://en.wikipedia.org/wiki/Infrared_blaster