Potential bug with audio normalize [SOLVED]

[Paul2]

Hi all,

I know that there have been other posts about this but didn’t want to revive old threads.

Yesterday was messing about with the audio levels of a few short clips.
I’m no audio guy but I see a discrepancy in the 1 pass normalize filter in SC.

In the final export, the audio is always 3 LU higher than the wanted.
(In all cases I exported to XDCAM which uses stereo PCM audio).

Case 1:

Set to -23 LUFS, got around -20 (Integrated)

Case 2:

Set to -26 LUFS, got close to wanted -23 (Integrated)

In both cases, results were confirmed with the RTW TM3.
https://www.rtw.com/en/support/product-archive/touchmonitor-tm3.html

The setup feeding the RTW as follows:

(The whole analogue audio chain was set for unity gain).

Like I said, I’m not an audio guy so maybe doing something wrong?

[brian]

I believe the filter is working as intended. Since it is a 1-pass filter, it can only respond changes in loudness slowly on a delay. So the final result will never perfectly match the target loudness. I predict that you will find that it works better for some clips and worse for others. It depends on the dynamics of the clip.

If you need the final result to be exactly -23LUFS, I recommend the 2-pass filter.

If you want to test further, it might be interesting to try your test with a fixed tone (where the loudness is constant for the duration of the clip).

[Paul2]

Hi @brian

You are correct about the single tone:

The 2 pass filter is much better for other audio.
Thank you very much.