# Convert 96 Khz to 48 Khz audio: is this simple downsampling method ok?

I have an audio signal x sampled at 96 Khz. I have already lowpassed it with a cutoff somewhere between 20 Khz and 22 Khz, so there should be nothing left of frequency > 22 Khz.

I need to resample it to 48 Khz. Since we are in the specific case 96000=2*48000, is it ok to do it this way:

y[n] = x[2*n]


by just forgetting every two elements?

What are the drawbacks of this method, in comparison to more complex downsampling algorithms? (Since 96 Khz is an integer multiple of 48 Khz, I thought that there would be no risk of aliasing here).

Also, what would happen with a downsampling y[n] = x[n * 2] if I had not low pass filtered at 20 Khz? What could be the potential problems?

• Thank you! Just to be sure: what would happen with a downsampling y[n] = x[n * 2] but if I had not low pass filtered at 20 Khz? What could be the potential problems? – g6kxjv1ozn Sep 8 '18 at 8:34