# Sidechain Compressor Pro

Render true sidechain compression with FFmpeg’s two-input sidechaincompress: filter the trigger, shape the envelope (attack/release/knee/link/mix), and get the output file plus measured gain reduction.

> Canonical page: https://elysiatools.com/en/tools/sidechain-compressor-pro

- **Category:** Media

- **Keywords:** sidechain compression, ducking, sidechaincompress, ffmpeg audio, kick bass ducking, voice over music, edm pumping, compressor attack release, parallel compression, trigger filter, audio mixing

## Overview

This is the real two-input ducking chain, not a volume automation guess. Your music track and a separate trigger track (a kick, a vocal, a snare) feed FFmpeg’s sidechaincompress, which compresses the music only when the trigger exceeds threshold. The trigger path runs through an optional high-pass/low-pass pair first — high-pass the trigger to stop sub-bass rumble from mowing down your mix, low-pass it so cymbal wash cannot trigger the compressor; 0 disables either. Full envelope control: threshold in dBFS (converted to the filter’s linear scale), ratio 1:1-20:1, attack 0.01-2000 ms, release 0.01-9000 ms, makeup 0-24 dB, knee 1-8, sidechain gain ±36 dB, RMS or peak detection, average or maximum channel link, and a dry/wet mix for parallel ducking. Presets carry working numbers, not folklore: kick-duck bass 5:1 with 4 ms attack (fast enough to clear the kick, slow enough to avoid clicks on a bass) and 60 ms release; voice-over bed 2:1 at 30/250 ms with ~2-3 dB of dip; EDM pump with a deep threshold and 1 ms attack. After rendering, the tool decodes input, trigger and output and measures what actually happened: per-frame gain reduction while the trigger is active (12 dB above its floor), the baseline drift, active-frame share and a 24-point ducking curve. Note the envelope terms follow the compressor convention — attack is how fast gain reduction engages, release how fast it lets go.

## Inputs

- **Music track (ducked)** (file)
- **Trigger track (sidechain)** (file)
- **Preset** (select)
- **Threshold (dBFS)** (number)
- **Ratio (n:1)** (number)
- **Attack (ms)** (number)
- **Release (ms)** (number)
- **Makeup gain (dB)** (number)
- **Knee (1-8)** (number)
- **Sidechain gain (dB)** (number)
- **Detection** (select)
- **Link** (select)
- **Mix (duck %)** (number)
- **Sidechain high-pass (Hz, 0 = off)** (number)
- **Sidechain low-pass (Hz, 0 = off)** (number)
- **Output Format** (select)

## When to use

- Ducking background music beds automatically whenever a voice-over, podcast dialogue, or dialogue stem is present.
- Carving low-end dynamic headroom in basslines and synth pads triggered by transient kick drums.
- Creating exaggerated rhythmic pumping effects across mix stems or instrument groups for electronic music tracks.

## How it works

- Upload your primary audio file to be ducked alongside a secondary trigger audio track.
- Select an optimized preset or adjust envelope parameters, including threshold in dBFS, ratio, attack, release, knee, and dry/wet mix.
- Optionally engage high-pass or low-pass cutoff filters to restrict the trigger frequency range that engages the compressor.
- Render the processed output to WAV, FLAC, or MP3 with computed gain reduction metrics and ducking profile data.

## Use cases

- Ducking a musical underscore beneath spoken narration in podcast production and broadcast video.
- De-conflicting low-frequency energy between kick drums and sub-bass lines in electronic mixdowns.
- Pumping ambient pads and synth textures in sync with rhythmic percussion or snare hits.

## Frequently asked questions

### What is the difference between peak and RMS detection?

Peak detection responds instantaneously to transient spikes, while RMS calculates average energy over time for a smoother dynamic response.

### How do the sidechain high-pass and low-pass filters work?

They isolate specific frequencies in the trigger track so unwanted low rumbles or high cymbal splashes do not activate ducking.

### Does attack refer to ducking onset or release recovery?

Attack controls how quickly gain reduction engages when the trigger exceeds threshold, while release determines the recovery time back to uncompressed levels.

### Can I perform parallel ducking with this tool?

Yes, adjusting the Mix slider below 100% blends the uncompressed original audio with the ducked signal.

### Which output audio formats are supported?

You can export the rendered ducked audio file in WAV, FLAC, or MP3 format.

## Related tools

- [Audio Compressor](https://elysiatools.com/en/tools/audio-compressor): Apply dynamic range compression with configurable threshold, ratio, attack/release, and makeup gain
- [Audio Deverb Lite](https://elysiatools.com/en/tools/audio-deverb-lite): Light de-reverb using EQ, compression, and denoise
- [Harshness Tamer](https://elysiatools.com/en/tools/audio-harshness-tamer): Detect and dynamically attenuate harshness in the 2–5 kHz presence band — a dynamic-EQ-style cut that only bites when the band actually plays loud.
- [Audio Parallel Compression (New York Style)](https://elysiatools.com/en/tools/audio-parallel-compression): Blend the dry signal with a heavily compressed, makeup-gained copy — upward compression that lifts quiet detail while the dry path keeps its punch, built from FFmpeg.
- [Audio Podcast Intro/Outro Ducker](https://elysiatools.com/en/tools/audio-podcast-intro-outro-ducker): Automatically duck a music bed under voice/dialogue using sidechain compression, with fade-in/out templates for intros and outros.
- [Audio Podcast Mastering Chain](https://elysiatools.com/en/tools/audio-podcast-mastering-chain): Apply a configurable podcast mastering chain: high-pass, denoise, de-ess, compression, EQ tilt, LUFS normalization, and true-peak limiting.
- [Audio Sidechain Compress](https://elysiatools.com/en/tools/audio-sidechain-compress): Mix two tracks using sidechain compression (e.g., voice or ads audio when overlaying sidechain audio)
- [Audio Telephone Effect](https://elysiatools.com/en/tools/audio-telephone-effect): Simulate the sound of a telephone call

## Samples

- [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
- [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio
- [Copyright-Free WAV Audio Samples](https://elysiatools.com/en/samples/wav-samples): Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
- [Copyright-Free Raw PCM Audio Samples](https://elysiatools.com/en/samples/pcm-samples): Raw PCM s16le audio samples featuring nature ambience and relaxing music for waveform, playback, and conversion workflows