How to get the FFT of the audio sample from videoFileReader object

I am a beginner in Matlab and I wanted to get the power spectrum values from the audio sample of a given frame in a video. I tried doing this.

[I,AUDIO] = step(videoFReader)
y = fft(AUDIO)

but it is giving me an error undefined function 'fft' for input agruments of type 'int16'

Answer 1

[Honglei Chen]

you can do

y = fft(double(AUDIO))