Is there any way to disable the camera beep when I start recording video? I have an Xperia Ray mobile phone and I wanted to get one of those spy camera applications so as to film undetected.

I tried a couple and the best so far were Ninja Cam and Hidden Mobile Camera. However, all of them have one problem: when I turn out the camera there is a beep (regardless if the sound is off or on).

Is there any app that doesn't have this problem? Alternatively, is there any other way I can delete that sound? I don't really need it anyway.
There are several "silent cameras" available on google play, as e.g. Silent Camera and Silent Camera (and many more) for photos. I remember there was some settings app to completely silence the camera (regardless of the camera app used), but I currently cannot find it.