Thank you for the app, it works great!
Just a heads-up for people who use a cheap IR sensor (TSOP4838) on the Raspberry Pi with lirc_rpi: the sensor is so sensitive that it gets confused by the IR noise that is emitted from the proximity/gesture sensor on the S4. If I cover the hole right of the speaker, the cheap RPi sensor has no trouble to receive the codes from this app (there's a pronto2lirc script that can convert Pronto codes to a lircd.conf file), but if I don't cover that "hole", the cheap RPi sensor apparently can't distinguish the noise from the signal. I wrote about it here
S4 i9505, stock (Adam kernel)
Nexus 7 16GB, Rootbox
HTC Desire HD, PACman