Anyway I bought my first and actually still my only smartphone, a Samsung Galaxy SII, in late 2012.
I am still very happy with it, but recently I had the need to take pictures silently : I wanted to shoot a newborn who was falling asleep. I was almost sure that the camera shutter sound would have awaken him, and incidentally make his mother to go crazy on me.
At this exact moment I discovered that there was no option to make it silent; no matter I muted the phone, taking a picture would whir loudly its awful mimic of a mechanical camera.
I then started to trim the internet, assuming it was already handled by some google play app... I tried several, without much luck. After a couple of evenings trying this and that, I dropped it.
Until recently, when I had another need, leading me to root my device (very easily with KingoRoot).
It came to my mind this annoying shutter sound and I fiddled a bit around this solutions :
[...] <multimedia> <camera> <shuttersound>on</shuttersound> </camera> </multimedia> [...]I changed "on" to "off", saved it with TotalCommander, rebooted my device and Tadaaaam ! The camera is now totally silent :)
Hope it helps !