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Q. Should I bounce to 32-bit floating point or 24-bit fixed point audio files?

Published December 2016
By Hugh Robjohns

Floating-point audio has its advantages, but 24-bit fixed-point files are generally more compatible.Floating-point audio has its advantages, but 24-bit fixed-point files are generally more compatible.

I’m using Ableton Live and bounced my last few finished tracks in the 32-bit float format because I’ve read something along the lines of keeping the word length as high as possible for the mastering process. However, I like to send these tracks to my friends to play on their Serato-type DJ setups, so when we get together they can play my tracks amongst other records to see how they stand up. Unfortunately, though, these last few 32-bit float tracks have failed to load into one of my friend’s Serato. I previously dithered all my tracks to (fixed-point) 24-bit files and they worked just fine with my friends’ Serato systems. So, my question is: as I’d rather not have too many different versions of the same tracks floating around, is there a preferred word length for when I bounce files out for mastering?

SOS Forum post

SOS Technical Editor Hugh Robjohns replies: I’m not surprised you’ve had a problem with getting 32-bit floating-point files to play in Serato, or any other conventional playout system, and in fact the Serato web site lists only the familiar standard file formats as being compatible — ie. WAV and AIF for conventional fixed-point formats (up to 24 bits), ALAC and FLAC as lossless data-reduced formats, and MP3, OGG, and AAC for lossy data-reduced files. So yes, Serato would have been fine with fixed-point 24-bit WAV files, but wouldn’t know what to do with 32-bit floating-point files at all.

32-bit floating-point (and other similar large word-length) formats are intended purely for the internal signal processing of a DAW during mixing, and are designed essentially to maintain the quality of individual sound elements at wildly varying levels while performing complex signal processing. Floating-point formats aren't intended, appropriate or efficient for use as a delivery medium for consumer applications.

So, by all means, work on and store ongoing mix projects in a 32-bit floating-point (or higher) format — most DAWs do that anyway by default. But for taking finished mixes to a mastering house (or for sending out as auditioning files) a fixed 24-bit word-length WAV file is the most universally acceptable format. Ideally, you should retain a few decibels of headroom, too (ideally 3-6dB) — don’t normalise it to 0dBFS because that will make life harder for your mastering engineer!

As always, there are caveats, and one is that if you’re expecting your mastering house to re-balance individual stems as part of the mastering process, it might be more practical to send the whole DAW project still in its native 32-bit floating-point file format. However, there might still be a potential problem of incompatibility because there are many different and incompatible 32-bit floating-point formats employed by different DAWs, so check that the mastering house can deal with your specific DAW project format first!

In general, though, if you’re sending straightforward stereo mixes to the mastering house they will be expecting standard 24-bit WAV files. So, I’d recommend keeping your work-in-progress projects in the DAW’s native 32-bit floating-point format, but bounce mixes out for auditioning or for sending to a mastering house as fixed-point 24-bit WAV files — simply because you can guarantee they will always work with all standard external audio-file players, DAWs, and mastering systems.

Published December 2016