The VMA (Variable Moving Average) is also known as VIDYA or Variable Index Dynamic Average. It's an exponential moving average that auto adjusts the smoothing weight based on the volatility of the data.
In times of low volatility, such as when the price is trending, the period should be shorter for the inevetiable break in trend. However, in times of more volatile non-trending bars, the period should be longer to filter out chop.
VMA uses the CMO indicator for internal volatility calculations. You can adjust the length of both periods.