FileMorf
Local slowed and reverb maker

Slowed and Reverb Maker

Create a slowed and reverberant edit with a visible starting preset: 0.8× tape-style speed and FFmpeg hall echo. The preset lowers pitch with speed, adds delayed reflections, and remains adjustable before export. Preview, trim, and render locally as MP3, WAV, FLAC, M4A, or OGG. Optional AI and transcription actions are separate, labeled server jobs.

Core edit stays local

AI and transcript are opt-in server steps

Drop an audio file here

or click to browse

MP3WAVFLACM4AOGG
Core edit stays local. File intake, timeline editing, preview, and export run in this browser. AI Enhance and Transcript upload only after you choose those panels and confirm their separate processing boundary.

Use this when

  • You want an adjustable tape-style slowdown with a hall echo starting point.
  • You can compare the result by listening before export.

Choose another approach when

  • You need a measured convolution of a specific physical room.
  • You do not own or have permission to transform and publish the source.

Reproducible example

Listen to the CLI reference fixture and output

These deterministic files are FFmpeg CLI references, not measurements of the shipped browser renderer or microphone capture. Automated checks are shown below; independent human review remains pending.

Automated checks passed

Synthetic input

SHA-256 a600e57ae8d593bbc95b9e36335dd1ac89174abc1442df0ae3e1b5c345af6850

Download input
  • Duration: 2 s
  • Size: 352.8 kB
  • Sample rate: 44,100 Hz
  • Channels: 2

Rendered output

SHA-256 dd94cf1832250f07cf8e3a526f543b48252c74a49928276e88ed3c72b5089fb5

Download output
  • Duration: 3.063 s
  • Size: 540.3 kB
  • Sample rate: 44,100 Hz
  • Channels: 2

Automated fixture check

  • Tape-style output frequency Pass.
    Observed: 264 Hz. Expected: 264 ± 1 Hz.
  • Echo-tail signal level Pass.
    Observed: 0.031474 FS. Expected: ≥ 0.01 FS.

Environment

audio-v1 · Sep 3, 2026, 2:44 AM UTC

FFmpeg CLI · darwin arm64 · v23.7.0

ffmpeg version 8.1.2 Copyright (c) 2000-2026 the FFmpeg developers

ffprobe version 8.1.2 Copyright (c) 2007-2026 the FFmpeg developers

@ffmpeg/ffmpeg 0.12.15 with @ffmpeg/core 0.12.10

Public evidence manifest
evidence.json
Fixture license
CC0 1.0
Generator source
generate-audio-flagship-evidence.mjs.txtSHA-256 228ca719f843debbddd1e1b3482f2b6d406b3d89afab34ef7797eacf01c998c7
Source base commit
e11eef48f52df732e0ef32d69f7ea10635b150bc
Browser renderer source
src/lib/audio/editor.tsSHA-256 159c26bb4f175dc8c823d2c70178f631d0125cf8059b3f8ea1494a3f3fba6479

The repository is private. The exact generator snapshot is public; the browser renderer and commit are retained privately and pinned here by full hash.

Fixture rights: CC0 synthetic audio generated in the repository. No customer or third-party recording is used.

Reference commandffmpeg -y -hide_banner -loglevel error -i public/fixtures/audio/v1/slowed-impulse-330hz.wav -filter:a 'aecho=0.8:0.9:300|450:0.4|0.25,aresample=44100,asetrate=35280,aresample=44100' -vn -c:a pcm_s16le -map_metadata -1 -bitexact public/fixtures/audio/v1/slowed-080-hall-reference.wav

Limitations and failure modes

  • The hall control is FFmpeg aecho, not a measured room impulse response.
  • Tape-style speed changes pitch and duration. Extreme settings can expose resampling or echo artifacts.

Methodology

The public corpus is deterministic. Full hashes, commands, engine version, and semantic signal checks are recorded in the manifest. These files exercise the native FFmpeg reference graph; browser workflow behavior is a separate release gate and device speed is not inferred.

Technical sources

How it works

Step 1

Load your audio

Choose a supported audio file. The 0.8× tape-style speed and hall preset are selected when it loads.

Step 2

Adjust the effect

Change speed, room style, fades, and other effects while you compare the local preview.

Step 3

Render your edit

Export the full timeline or a selection in the format you need. Check your rights before publishing music.

Questions from current search and product use

What does the preset do?

It starts at 0.8× tape-style speed, so pitch falls with tempo, and applies FFmpeg's hall-style aecho filter. It is an adjustable echo preset, not a measured simulation of a particular room.

Can I keep the original pitch?

Yes. Enable Keep pitch in the speed controls. Export then uses FFmpeg atempo rather than the tape-style resampling path.

Can I publish the result?

The tool can create a compatible audio file, but it does not grant rights to the source recording or composition. Obtain the permissions required by the destination platform and rights holders.

Is my source uploaded?

Core editing, preview, reverb, and export stay in the browser. Optional AI Enhance and Transcript actions are separate server jobs that start only after your explicit choice.

Continue the workflow

Open Audio StudioRead the related guide
audio speed changernightcore makerbass booster

Accountability

Author
Jesse Delia
Technical review
Pending independent review
Report a correction
support@filemorf.com

Change history

2026-07-30: Tool-first page, precise processing boundary, synthetic fixture evidence, limitations, and accountability record added.