How to make feature vectors size equal for training neural networks?

I am training a neural network, but the feature vectors do not have the same size.

This problem may be fixed by adding some zeros or removing some values, but the greater problem would be data loss or generating meaningless data.

So, is there any approach to make them equal size, without mentioned weaknesses? Maybe transformation to other dimensions? I do not want to use random values or "NA".

Solution

Adding zeros or zero padding is the most common method of making very short audio signals longer as well as it can be used to match the lengths of audio data before feature extraction.

In my understanding, this does not affect the outcome of the analysis, specially as you are using a neural network.