Function sample::slice::add_in_place_with_amp_per_channel

pub fn add_in_place_with_amp_per_channel<FA, FB, A>(
    a: &mut [FA], 
    b: &[FB], 
    amp_per_channel: A
) where
    FA: Frame,
    FB: Frame<Sample = <FA::Sample as Sample>::Signed, NumChannels = FA::NumChannels>,
    A: Frame<Sample = <FB::Sample as Sample>::Float, NumChannels = FB::NumChannels>, 

Scale the amplitude of each frame in b by amp_per_channel before summing it onto a.