Does Alex make Toni unemployed?

Alex Audio Butler (AAB for short) is a small series of VST plug-ins that plug into popular video programmes and promise to handle sound mixing independently. Currently these are DaVinci Resolve, Premiere Pro and Adobe Audition. Others are in the works. AAB runs under Windows 10 and Mac OS 10.13 or higher, and even natively with M1 on the Mac, but it does not work with the AppStore version of Resolve. (But who wants that?)

My expert colleague Björn Eichelbaum gives you a general overview of AI in the audio sector in this issue from page 72 onwards. I, on the other hand, am a tester without any audio expertise; at best, in my younger years I was able to use the equaliser on my stereo system to crank up my music to disco levels. In demanding film projects, I have always respected the important role of sound and left this work to the professionals.

Final mix from the robot

But what about a small, underfunded project with no budget at all? We carried out a practical test on a video portrait with which a university from an emerging country wanted to introduce itself. Alex Audio Butler from the Dutch company Unimule was asked to control the volume, use a compressor if necessary and take care of the audio ducking (i.e. reducing the background music or effects when speech starts).

We worked with Resolve, where AAB can be found after installation under the filters for Fairlight in Uncategorised > VST. When editing, we naturally made sure to assign the sounds to individual tracks according to their function. AAB differentiates between Voice, Music and Sound FX (although the latter were not used in our project). However, you should not only place the little helpers on the individual tracks, but also on the master.

After selecting the function for the respective track, you don’t have to deal with hertz, decibel or attack and decay times in the settings. Instead, the respective task is selected from a few generally understandable terms, which are also provided with explanatory texts. Even a video enthusiast should have no problem understanding them – if necessary, it helps to try them out. The PDF manual is limited to installation and licensing. In itself, this is sufficient, but you can also find additional videos under “Alex Audio Butler” on YouTube.

Push

If you try to output the complete work straight away, you often get an error message saying that Alex hasn’t finished analysing it yet. There’s no point in waiting, instead you have to give the little guy a little help. You should either listen to the entire film once or simply output the sound alone two or three times, which is usually quicker than calculating all the images.

You will then receive a message that the analysis was successful and you can now render the entire film with video. However, the screen messages should be a little larger – we could hardly recognise them on a 27-inch monitor with 2,560 x 1,440 pixels, although the fonts in Resolve were still clearly legible.

Result

The result is certainly worth listening to – a complete audio amateur could hardly do better. In our case, there was essentially the usual problem with inexperienced speakers, who often start loudly and then get quieter and quieter or slowly increase in volume. AAB manages this quite well with internal keyframes, without raising the background noise during pauses, because it recognises the human voice. A compressor can also be used in several stages. Background music from two completely different sources on one track was well regulated to the same subjective volume. However, you can also use several tracks with different settings for the music. You only specify the volume for music in the foreground and the auto ducking ratio. When assessing compression and audio ducking, it also depends on the monitoring system. We were quite satisfied with the result via loudspeakers on the computer and also via high-quality headphones. However, we were criticised after the demonstration on a sound system. No problem: we quickly changed the compression and ducking, gave it a new push and the university was also satisfied.

Comment

What AAB cannot do at all is repair errors and faults in the recording. This has to be done by specialists with trained ears through precise adjustment of appropriate filters (which nowadays can also be based on AI). Alex will also not deliver a perfect feature film mix, where the emotional impact depends on very subtle factors. But the Butler can handle simple projects with interviews, voice-over and background music with technically clean recordings – currently for the introductory price of 79 euros.