Several first digital streams of first digital samples at a first sampling frequency are processed to issue corresponding stream that are converted into second digital streams sampled at a second sampling frequency lower than said first sampling frequency. At least one delay to be applied to at least one first digital stream to satisfy a condition on the second digital streams is determined and applied to at least one first digital stream before converting. The converting operation performed is decimation filtering of the first digital streams. The application of the at least one delay to at least one first steam involves skipping a number of first digital samples in the at least one first digital stream. The number skipped depends on the value of the at least one delay. Samples that are skipped are not delivered for decimation filtering.