On-Air Detection
The Problem On-Air Detection Solves
Section titled “The Problem On-Air Detection Solves”DJ software considers a track “active” as soon as it’s loaded into a deck, but loading a track is not the same as your audience hearing it. A DJ might spend several minutes previewing tracks in headphones, scrolling through candidates, or queuing something up while a completely different record is fading out on the main output. Without on-air detection, Now Playing would update your stream overlay the moment a track lands in a deck, displaying a song your viewers may never actually hear.
This creates a frustrating experience: the overlay shows one track while the speakers are playing something else, then updates again when the next one loads, and so on through an entire browsing session before the DJ has actually made a selection.
On-air detection solves this by continuously monitoring your mixer’s signals. The overlay only updates when Now Playing has determined that a deck is actually contributing to the main output, that is, when your audience can realistically hear it.
How On-Air Detection Works
Section titled “How On-Air Detection Works”Now Playing watches a combination of mixer signals in real time to evaluate each deck’s audibility. Each signal is assigned a weight that reflects how strongly it indicates a deck is on-air. The deck with the highest weighted score becomes the active track.
Channel fader. The volume fader for each channel controls how much of that deck’s signal reaches the main mix. A fader at 0 means silence; a fader at full means the channel is contributing completely. If the channel fader is fully closed, the deck’s score is immediately set to zero regardless of other signals.
Fader values range from 0 (fully closed) to 1 (fully open).
Crossfader. A two-channel crossfader determines the balance between the left
and right decks. Crossfader values range from -1 (fully left) to 0 (center,
equal mix) to 1 (fully right). A small dead zone around center (±0.15) is
ignored. Outside that zone, the crossfader contributes positively to the deck it
favors and negatively to the other.
EQ and filter state. Some mixing styles rely heavily on the low EQ to swap bass between decks, or use filter sweeps to transition. Now Playing monitors these values where available and accounts for them in the overall score.
Play state. A deck that is paused or stopped cannot be on-air. If play state is available from your hardware, a non-playing deck is scored at zero regardless of fader or EQ position.
On-air flag. Some Pioneer DJM mixers expose a direct on-air indicator over the network. When available, this flag carries significant weight in the score.
When a deck’s combined signal score exceeds all other decks, Now Playing marks it as on-air and triggers an overlay update.
DJ Style Presets
Section titled “DJ Style Presets”The easiest way to configure on-air detection is to select a DJ Style preset that matches how you mix. Each preset adjusts the signal weights to fit typical patterns for that genre.
Go to Settings > On-Air Detection and choose the style that best describes your mixing approach:
| Preset | Best for |
|---|---|
| Default | Balanced settings that work for most mixing styles |
| Bass / Dub | Heavy bass drops and filter sweeps with quick cuts |
| Drum & Bass | Quick doubles with bass swaps |
| Hardstyle | Hard drops and quick cuts with minimal blending |
| Hip-Hop / R&B | Crossfader cuts and scratch routines |
| House / Techno | Long blends with bass swaps and extended fader transitions |
| Trance | Extended layered transitions where multiple tracks blend for 32+ bars |
Each preset also sets a debounce time (how long a deck must hold the top score before the overlay updates), tuned to the transition speed typical for that genre.
Custom Mode
Section titled “Custom Mode”If none of the presets match your setup, select Custom to configure each signal’s weight individually. You can also start from a preset by clicking Copy to Custom and then adjusting from there.
In Custom mode you control the weight assigned to each signal. A higher weight means that signal has more influence on the on-air decision. Setting a signal’s weight to zero disables it entirely.
Available signals include:
- Channel Fader and Crossfader (mixer position)
- EQ Bass, EQ Mid, EQ High (equalization state)
- Filter (filter sweep position)
- Trim/Gain (channel gain level)
- Play State (whether the deck is playing or paused)
- On-Air Flag (direct indicator from supported DJM mixers)
- Master Deck (which deck holds the sync master)
- Jog Touch (whether the jog wheel is being touched)
- Loop Active, Loop Length, Track Position, Track Remaining, Beat Counter, Beat in Measure (playback position signals)
You can also set a debounce time in Custom mode. This controls how long the detection engine waits after a deck takes the top score before updating the overlay, which prevents rapid flicker during transitions.
Signal Value Reference
Section titled “Signal Value Reference”| Signal | Range | Meaning |
|---|---|---|
| Channel fader | 0 to 1 | 0 = fully closed, 1 = fully open |
| Crossfader | -1 to 1 | -1 = fully left, 0 = center, 1 = fully right |
| EQ (low/mid/high) | -1 to 1 | -1 = fully cut, 0 = unity/flat, 1 = fully boosted |
| Filter | -1 to 1 | -1 = full low-pass, 0 = off, 1 = full high-pass |
| Trim/Gain | 0 to 1 | 0 = minimum gain, 1 = maximum gain |
These ranges are standardized internally by Now Playing regardless of the physical hardware’s native MIDI range. You don’t need to think in terms of MIDI CC values (0–127). The weights you configure in Custom mode apply to these normalized values.
Supported Hardware
Section titled “Supported Hardware”On-air detection requires your mixer or controller to expose channel state over MIDI or a supported network protocol such as PRO DJ LINK or StagelinQ. Hardware with good signal coverage includes:
- Pioneer DJM series mixers: Fader and crossfader values exposed via PRO DJ LINK when connected to Rekordbox, or via MIDI. Supported models also expose the on-air flag directly.
- Allen & Heath Xone series: MIDI output for fader positions on supported models
- Native Instruments controllers: MIDI fader and crossfader data via USB
- Software mixers (Rekordbox, Serato, Traktor): On-air state relayed directly over the network connection when running in performance mode
Check the Track Sources section of the documentation for your specific hardware. Each supported source lists which signals are available and what connection type is required.
Choosing a Preset
Section titled “Choosing a Preset”| Situation | Recommended preset |
|---|---|
| Pioneer DJM mixer with PRO DJ LINK | Default or genre match |
| DJ software with network export enabled | Default or genre match |
| Rekordbox or Serato with MIDI mixer | Default or genre match |
| Hip-hop or turntablist style | Hip-Hop / R&B |
| Long progressive blends | House / Techno |
| Extended trance transitions | Trance |
| Unusual setup or fine-tuning needed | Custom |
Tuning Detection
Section titled “Tuning Detection”If the overlay is updating at unexpected times, try a different preset first. If no preset fits your style, switch to Custom and adjust the weights for the signals that matter most in your transitions.
Common issues:
- Overlay updates too early during a fade-out. Lower the weight for Channel Fader, or increase the debounce time so the deck must hold the top score longer before the overlay switches.
- Overlay updates too late. The debounce time may be set too high. Lower it toward the default (300 ms) or try a preset with a faster timing like Hip-Hop / R&B.
- Overlay flickers between decks during a blend. Increase the debounce time. House / Techno and Trance presets have longer debounce values designed for this situation.