Introducing the One Pass Normalize Filter and Audio Loudness Scope


The previous audio normalize filter has been renamed to “Normalize: 2 Pass”. Its functionality has not changed. You can select a clip, analyze loudness of the clip and then the filter will apply a fixed gain “shift” to achieve the target loudness across the clip. The target loudness is configurable. This type of normalization is most appropriate for pre-mixed clips like music or clips where the volume is constant for the duration of the clip.

A new audio normalize filter has been added named “Normalize 1 Pass”. This filter works differently than it’s two pass brother. Rather than analyzing the entire clip at once, it analyzes the audio in real time as the clip is played and adjusts the gain on the clip in real time in order to achieve the target loudness. The filter can accept configuration parameters to define the target loudness and constraints on how much and how quickly it can change the gain. The “Analysis Window” parameter specifies how much history should be used to determine the input loudness. The UI for the “Normalize 1 Pass” also provides status indicators which show the Input Loudness (as measured during the Analysis Window) and the Output Gain that is being applied to the clip.

The filter will reset its own analysis if it notices the clip change or if seeking is performed (as the history is no longer valid). This reset is also shown in the UI status area. Unlike the 2 pass filter, the “Normalize 1 Pass” filter can be applied to an entire track as well as a clip. This filter is most useful for clips where the audio has not been mixed, or it changes very dynamically. Also, because the filter is being applied dynamically, and it is reacting to historical loudness, it may not actually achieve the target loudness with high accuracy.

To compliment the audio loudness normalization filters, a new Audio Loudness scope has been added. This scope shows the Momentary, Shortterm, Integrated loudness as well as the Loudness Range. The Integrated and Loudness Range status accumulate over time. So, a reset button is provided to allow the user to reset the measurement in case they have been seeking or have changed some filter parameters. A time indicator next to the reset button shows how long the meter has been running.

Audio normalisation in LUFS

If I understand right, you have to play the whole clip in real time in order to get the Normalize 1 Pass filter to actually work? If I apply that filter but don’t play the whole clip in real time then it won’t take effect?

Also, in regards to Normalize 2 Pass, if I do the analysis but then I decide to change the target loudness do I have to hit the Analysis button again?

I see that the Compress filter doesn’t have an analysis button like the Normalize 2 Pass does. Does that mean that the Compress filter works like the Normalize 1 Pass feature in that it analyzes the audio in real time?


The filter will always be applied. It works on an averaging window. So if you seek to the middle of a clip, the filter will have to clear and then refill the averaging window. There is an “indicator light” on the filter panel that signals when the window has been reset.


Yes. The compress filter works on a much shorter time window and will only reduce the gain - it will not increase the gain.

I typically use the “Normalize: 1 pass” and “Compress” filters together to achieve simple normalization. The normalize filter handles average loudness and the compress filter handles peak loudness (spikes).