What is 32-bit floating audio and should you record it?

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For a little more scale, someone whispering can be around 20-30 dB, while a typical conversation is around 60 dB. A motorbike driving by would be around 90 dB, and a very loud concert might be around 110 dB. Much higher than that and you enter a range where the sound becomes physically painful. If so, why should recording equipment go beyond the 144.5 dB dynamic range of 24-bit audio?

Adjustment of levels (or not)

The insane dynamic range of 32-bit floating audio is behind the claim that you never need to adjust levels, although even that is a bit trickier than it sounds. The highest level at which a device can record is called 0 dBFS (the FS stands for “full scale” here). Anything higher than that will be cut off, which is why it looks distorted when YouTubers shout like that.

Now, you typically set audio levels when setting up your gear to avoid hitting this limit. Adjusting these levels involves applying gain to the mic signal, which is an irreversible step that crushes the dynamic range of even a 24-bit recording.

“When you’re recording sound on set, you’re usually going to apply gain. And some recorders will apply between 30 and 90 decibels of gain,” says Pereira. “It’s good when you have a quiet scene where two people are whispering. So you can crank up the recorder dial for, say, plus 60 [decibels]. So now when someone decides to scream, between 60 and 145 is not a lot of dynamic range.

With 32-bit floating point recording, on the other hand, there is no need to apply gain before recording. “When you’re recording in a 32-bit format, there’s no volume knob, it basically creates a mathematical array of data that it can then interpolate in post,” Pereira says.

Adjusting levels on 24-bit systems can be tricky due to background noise. To oversimplify, no matter how quiet you make your recording space, there is always some amount of noise coming from background objects, or even the electronics you are recording on. Adding gain to the signal while recording amplifies that noise, along with your audio source, and once it’s in the recording, it’s there for good.

32-bit float recordings have more flexibility to make adjustments after the fact (and in some cases can even help with low level noise issues). That said, it’s important not to let this give filmmakers and sound producers a false sense of security. “It’s not going to solve the problems inherent in your filming location. For example, if there is a noisy air conditioner or fan nearby, recording in 32-bit won’t make that noise go away,” says Pereira.

Managing on-set noise and ensuring microphones are picking up the signal correctly will always be important, but once your gear is set up correctly, having the ability to capture audio even beyond the peak point is a tool. useful in the belt. But don’t expect to leave 24-bit audio behind forever.

Chain links

So if 32-bit is so great, why isn’t it the default? For starters, many stages of production, including editing, mixing, and especially distribution, will use a 24-bit workflow, which means additional data will be lost at some point. And a sound engineer will at some point need to make adjustments to ensure that the audio signal doesn’t clip when downsampling to 24-bit, as it would if the levels weren’t set correctly when downsampling. initial registration.

Essentially, this means that the work that would have been done initially on set is transferred to post-production. So you have a choice: either set the levels correctly on set and record directly in 24-bit, or record in 32-bit and add the extra step later. Either way, it’s a step you’ll have to do, and some would say you might as well do it when you’re on set.

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