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Sound Sync

If you have more than one device or wish to use Line Input but your audio source is not right next where your LEDs are, then Audio Sync is the feature you need, no need for multiple mics or long cables. Sound Sync is different from direct LEDs control using protocols like E1.31, DMX, DDP or AdaLight.

For the WLED instance that you wish to be the source, simply set the Sync mode in the Audio Reactive module to Send and then use Recieve on all the WLED instances you wish to use the data

You might have a setup something like this or just a simple wired line-in rather than Bluetooth or Chromecast

UDP Sound Sync is a feature to synchronize (share) the sound input of a 'master' device with one or more 'slave' devices.

UDP Sound Sync does not sync the actual animations, but rather transmits summary audio sampling information to several devices that still run their own animations locally. In a nutshell, it means that several devices can share a single audio source.


Before configuring UDP Sound Sync, make sure you have gone into the WiFi Preferences and clicked on 'Disable WiFi sleep' at the bottom of the page. It has caused us innumerable problems in the past.

In order to configure UDP sound sync, the ‘master’ needs to be an ESP32 configured as normal, but with Sync Mode set to Send

For devices without an audio input, Audio Reactive must be enabled but with the Sync Mode set to Receive. Make sure the UDP port is the same on all devices.

In order to change the UDP Sync Mode (Disabled/Transmit/Receive), you need to power-cycle the ESP32.


When an ESP32 is configured for audio transmission, it will connect to a UDP Multicast address, and begin sending a single UDP Multicast packet containing the data used to generate sound-reactive animations out to any other devices that are configured to receive on the same network. The following information is transmitted:

V1 format, used in SR WLED up to 0.13.x

#define UDP_SYNC_HEADER "00001"
struct audioSyncPacket {
  char header[6] = UDP_SYNC_HEADER;
  uint8_t myVals[32];     //  32 Bytes
  int sampleAgc;          //  04 Bytes
  int sampleRaw;          //  04 Bytes
  float sampleAvg;        //  04 Bytes
  bool samplePeak;        //  01 Bytes
  uint8_t fftResult[16];  //  16 Bytes - FFT results, one byte per GEQ channel
  double FFT_Magnitude;   //  08 Bytes
  double FFT_MajorPeak;   //  08 Bytes

UDP_SYNC_HEADER is a versioning number that's defined in audio_reactive.h

V2 Format - WLED version >= 0.14.0 (including MoonModules fork)

#define UDP_SYNC_HEADER_V2 "00002"
// new "V2" AC 0.14.0 audiosync struct - 40 Bytes
struct audioSyncPacket_v2 {
      char    header[6] = UDP_SYNC_HEADER_V2; // 06 bytes, last byte is '\0' as string terminator.
      float   sampleRaw;      //  04 Bytes  - either "sampleRaw" or "rawSampleAgc" depending on soundAgc setting
      float   sampleSmth;     //  04 Bytes  - either "sampleAvg" or "sampleAgc" depending on soundAgc setting
      uint8_t samplePeak;     //  01 Bytes  - 0 no peak; >=1 peak detected. In future, this will also provide peak Magnitude
      uint8_t reserved1;      //  01 Bytes  - reserved for future extensions like loudness
      uint8_t fftResult[16];  //  16 Bytes  - FFT results, one byte per GEQ channel
      float  FFT_Magnitude;   //  04 Bytes  - magnitude of strongest peak in FFT
      float  FFT_MajorPeak;   //  04 Bytes  - frequency of strongest peak in FFT

The V2 format expects that AGC is performed by the sender, so there is no need to transmit "AGC" and "non-AGC" samples separately. To save bandwidth, the myvals[] array was removed, and all numbers are either float or uint8_t.

SR-WLED 0.13.3 still sends out V1 format, however it is able to receive and decode V2 format, too.

What else ?

You might want to take a look at this library, which allows to send and receive WLED Audio Sync data independent from WLED.

When configured to receive audio data from another device, the receiver will disable any onboard microphone sampling and FFT processing, in favor of audio data received from the network. Any time a UDP Multicast packet is received from a transmitter, it will be treated as a discrete microphone sample and stored in memory the same way it would be if it were a local microphone.

  • The UDP  Multicast  IP is, and the default UDP port is 11988.
  • UDP port can be changed in WLED config pages, for example to have several groups of devices by assigning different UDP ports to each group.
  • UDP multicast can sometimes have issues with some Wifi routers, if you have issues, please try with a different Wifi

Using a PC as source (PC audio to WLED)

For windows, there is WledSRServer ( which is a small application that is doing the audio capturing, FFT computation and packet sending on the system. It sends out V2 packets.

UDP Sound sync brought to you by @spedione on Discord.