function[] = function5(x, fs, nfft, unit)
frame_length = nfft;
frame_number = floor(length(x)/frame_length);
y = [];

for i = 1:frame_number
    sub_y = x((i-1)*frame_length + 1 : i*frame_length);
    sub_y_FFT = abs(fft(sub_y, nfft));
    sub_y_FFT_log = 20*log(sub_y_FFT);
    y = [y; sub_y_FFT_log];
end

%imagesc(y);
frame = 1:frame_number;
frequency = fs*(1:frame_length)/nfft;
mesh(frequency, frame, y);
xlabel('frequency');
ylabel('frame');
zlabel('log magnitude');
end