Safety track vs 32 bit float recording?

Fixed point and floating point are different ways of representing numbers.

Fixed point numbers have discrete values, eg 1,2,3... up to the maximum value allowed. The maximum value allowed depends on the number of bits. Specifically, the number of values you can represent with a fixed point number is 2 to the power of the number of bits. 24 bits gives you values 0-16777215, 32 bits gives you 0-4294967295. Note that you can't represent eg. 1234.5 in this system - you'd have to choose between 1234 and 1235. This is how the A/D converters on an audio recorder convert the input from the mic to a value that can be processed digitally.

With floating point numbers, you represent the "significant digits" separately from the exponent. Eg. the number 1234.5 could be represented as the significant digits 1.2345, with an exponent of 3 (ie. move the decimal point three places to the left). That's not really how actual electronics do it, but hopefully you get the idea. 32 bit floating point allows you to represent numbers outside the range offered by 32 bit fixed point, and also to represent fractional values within that range. However the trade-off is that representations are inexact.

This is useful for some kinds of digital audio processing because you may end up outside the available range provided by fixed point, and floating point will save you from clipping in such circumstances. It doesn't as far as I can see stop you from clipping your A/D converters, which is the what people are normally talking about when they refer to recorders clipping.

However dual-level recording might, and thanks (I think) to some weird marketing by Zoom it seems like a lot of people mean that when they say "32 bit float". If enough people have this confusion, 32 bit float will come to mean dual-level recording in the audio recording world. Dual level recording means you send your mic signal to two separate A/Ds at different levels, and the recorder picks the one where the level is set most optimally. At least that is my understanding, I've never used such a recorder.

/r/LocationSound Thread Parent