LM3916 is a dedicated IC for VU LED meter. Unlike LM3915 which have 3dB step between voltage levels, the LM3916 have nonlinear steps: -20, -10, -7, -5, -3, -1, 0, +1, +2, +3db, just like old school analog VU meters. I saw in YouTube an interesting commercial LED VU meter, which imitates the needle movement in analog VU meters and I thought I can make a similar one. All I needed I found in the datasheet of LM3916.
The LM3916 can be feed with AC signal without any rectification, but I wanted to implement a precision full wave rectification. I chose the schematic on page 13, fig.21 of the datasheet: "Precision Full-Wave Peak Detector".