Serato Mode

Serato mode creates .serato-stems files for Serato DJ and places them right next to the original file.

Example:

• track.mp3 -> track.1.2.serato-stems

Alpha feature

Serato integration is currently an alpha feature released in 4.1.0-alpha.1 and subsequent releases.

The most important thing to test is:

1. Create .serato-stems using NUO-STEMS 4.1. It places the .serato-stems file right next to the original file. This is Serato's expected location and cannot be customized.
2. Open Serato DJ.
3. Confirm that the original track now has a stems icon next to it.
4. Confirm that the track loads correctly into the deck and that toggling stems does not make Serato move the .serato-stems file to system Trash or remove the stems icon from the track.

Technical explanation: Serato expects the .serato-stems file to have the exact same decoded sample length as the original file that Serato loads into memory on that machine. I tested around 5000 tracks to make sure these lengths match across different audio types in normal same-platform workflows, and everything I had matched perfectly. But it is still possible that some weird originals may produce a mismatch. If lengths do not match, Serato rejects the .serato-stems file and moves it to Trash.

Overview

When using Serato mode:

• NUO-STEMS 4 generates .serato-stems files for the original track.
• .serato-stems files are always written next to the original file.
• Serato scans for .serato-stems files when opening a Crate.
• If the Crate is large, for example around 1000 tracks, Serato may need a bit of time to update the stems icon for each track.
• Stems generated by NUO-STEMS 4 are marked with the same stems icon in Serato as stems generated by Serato itself.
  • 
• You can load the track with stems icon into the deck and toggle stems on/off just like Serato's own stems.

How to tell whether stems came from NUO-STEMS 4 or Serato

Once Serato accepts the file, both look the same in the library. Two practical ways to tell them apart:

• Listen to them and hear that the stems are super clean 😅😅😅 (because NS4 generates really clean stems).
• Use Extract individual stems from .serato-stems in NUO-STEMS 4 and inspect the metadata of the file.

Recommended setting: Sum of stems = original mix

tip

It is recommended to keep Sum of Stems = Original Mix disabled in Serato mode.

Serato plays the original track when all 4 stems are enabled.

If at least 1 stem is disabled, Serato plays the remaining enabled stems simultaneously as a sum. This also means you get slightly cleaner stems and faster processing time when "sum of stems = original" is disabled.

Restart Serato after changing existing stems

Serato caching behavior

Serato never fully unloads tracks from RAM.

For example, I played around 2000 tracks in Serato without closing it and memory usage was around 11 GB. Fresh restart was around 2 GB.

Stems also seem to be cached. If you already loaded existing Serato stems into the deck, unloaded the deck, generated stems using NUO-STEMS 4, and then loaded the deck again, you may still get the old Serato version even if the .serato-stems file is now different. Restarting Serato resolves this and loads the updated .serato-stems file.

Platform compatibility for AAC / ALAC originals

AAC / ALAC limitation

.serato-stems created for AAC / ALAC originals on macOS are not compatible with Windows, and vice versa.

This is the same class of issue already documented for TP4 .stem.m4a migration, where AAC / ALAC originals may decode to different sample lengths on different platforms.

Technical explanation: Serato expects the .serato-stems file to have the exact sample length of the original file that Serato loads into memory. If lengths do not match, Serato rejects the .serato-stems file and moves it to Trash.

In my experiments for 5000 tracks, macOS and Windows decoded frame counts matched for every covered type except .m4a:

Type	Shared tracks	Exact same frames	% exact	Min delta (win - mac)	Max delta (win - mac)
.aiff	8	8	100.00%	0	0
.flac	22	22	100.00%	0	0
.m4a	416	71	17.07%	-4097	914
.mp3	4379	4379	100.00%	0	0
.mp4	1	1	100.00%	0	0
.ogg	103	103	100.00%	0	0
.wav	66	66	100.00%	0	0
Overall	4995	4650	93.09%	-4097	914

Short version:

• .mp3, .aiff, .flac, .mp4, .ogg, and .wav all match perfectly across macOS and Windows.
• .m4a is the only covered type that differs across platforms.

Serato and Traktor cannot be generated in one pass

You cannot generate stems for Serato and Traktor at the same time.

If you need both, convert them separately in each mode.

Technical explanation: originals are decoded differently, resulting in different sample lengths and offsets.