Audio Reverser

How to Use

1. Click the area above to select a file, or drag and drop a file onto the page
2. Adjust parameters in the settings area
3. Click the process button and download the result when ready

Frequently Asked Questions

How It Works

The Audio Reverser uses FFmpeg WebAssembly with the areverse audio filter to play audio samples in reverse order. The filter reads the entire audio buffer and outputs PCM samples from last to first.

The process: (1) The input audio is fully decoded to PCM samples in memory. (2) The sample array is reversed — sample[N-1] becomes sample[0], sample[N-2] becomes sample[1], and so on. (3) The reversed samples are re-encoded to the target format. The entire operation is memory-bound — the full audio must fit in browser memory.

For PCM/WAV formats, reversal is nearly instantaneous since no encoding is involved. For compressed formats (MP3, AAC), the full decode-reverse-encode cycle is required. The areverse filter handles multi-channel audio correctly by reversing each channel independently while maintaining synchronization.

Tips & Best Practices

• Short clips work best: Reverse processing is memory-intensive. Keep clips under 60 seconds for reliable performance.
• Create backmasking effects: Reversed speech creates the eerie backmasking effect used in music and film soundtracks.
• Combine with speed: Reverse at 0.5x or 2x for dramatic time-reversed effects popular in electronic music production.
• Trim first: If you only need to reverse a section, trim it out first to reduce processing time and memory usage.
• Preserve format: Reverse in the same format to avoid unnecessary double-encoding quality loss.
• Use for sound design: Reversed cymbals, impacts, and ambient sounds create unique transitional effects in audio production.

Use Cases

Music producers creating reversed cymbal and riser effects for builds and transitions in electronic music.

Film sound designers reversing impact sounds and ambient textures for surreal and otherworldly audio effects. Horror content creators producing reversed speech and whispers for atmospheric dread. Podcast producers creating creative intro/outro effects using reversed speech segments. Sound effect libraries generating reversed versions of common sounds (doors, footsteps, nature) for creative projects. Educators demonstrating phonetics and speech patterns by playing recordings backwards for linguistic analysis.

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