Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Identify the control being changed
An audio diagnostic page may offer an FFT size selector next to a spectrum display. MDN defines fftSize as the sample window used for the frequency transform. Increasing it changes the analysis tradeoff; it does not reencode the programme or restore missing frequencies. The documented values are powers of two within a defined range. Treat an invalid value error as a configuration issue rather than a defect in the audio being examined.
Calculate the window duration
Using an explicitly illustrative sample rate of 48,000 samples per second, a 2,048 sample window covers about 42.7 milliseconds. A 4,096 sample window covers about 85.3 milliseconds. These durations come from dividing the window length by the sample rate. The larger selection examines a longer span of sound at once. This calculation explains why a graph can look different even when the underlying recording has not changed at all.
Keep comparisons reproducible
When comparing two spectrum screenshots, retain the sample rate, window size and the same source passage. If the measurement settings changed, do not attribute every newly visible narrow peak to an improvement in the programme. Use the analyser as an observation tool alongside listening and a source inventory. This article does not prescribe a universal FFT value for all diagnostics or claim that a prettier graph establishes higher streaming quality. Choose the window to answer the actual frequency or timing question.