Analyze first, then apply the gain once
The local analysis pass measures decoded sample peak and unweighted full-scale RMS, then applies the calculated gain during encoding. The result reports the applied gain and any linked-limiter reduction.
Local audio normalization
Set a consistent listening level with a measured target.
Choose a speech, general-listening, or peak preset. The worker measures decoded PCM, calculates the required gain toward a peak or unweighted RMS target, and protects the encoded result with a linked limiter.
Your selected file stays on this device. No upload, account, or server-side media job.
Browser-local workspace
Choose a local source to begin.
Choose one local audio file—or a local video on the conversion route—then create a separate, verified MP3 or WAV result. The source is not sent to Aftermath, modified, or handed to a fallback service.
No upload, account, or server-side media job.
The local workspace loads after you choose a source.
RMS is useful, but it is not LUFS
The speech and general presets use unweighted RMS, not broadcast-weighted LUFS or an equal-loudness model. Peak normalization uses a different target, and neither method makes every recording sound perceptually identical.
Private browser handling
Your source remains under your control.
Aftermath reads, decodes, processes, encodes, and verifies the selected file in this browser. It preserves the source and offers a separate MP3 or WAV result; unsupported inputs are never sent to an upload fallback.
How to use this tool
Use this route when gain should be calculated from the audio itself. The local worker measures decoded sample peak or unweighted full-scale RMS, computes bounded gain toward the selected speech, general, or peak target, applies linked peak protection, and reports the applied gain and limiter reduction in a separate MP3 or 16-bit PCM WAV result. Its RMS measurement is explicitly not LUFS or a guarantee of equal perceived loudness.
What to choose and what you get
What to choose
- one selected local audio file
Result
- a separately downloaded MP3 or 16-bit PCM WAV result
Supported use
- One decodable local audio file with a speech, general-listening, or peak normalization preset.
- Decoded-sample analysis followed by bounded gain and stereo-linked peak protection.
- A separate MP3 or 16-bit PCM WAV reporting applied gain, measured levels, and limiter reduction.
Before you start
- Broadcast LUFS compliance, equal-loudness modeling, calibrated SPL, or guaranteed perceptual matching between different recordings.
- Noise cleanup, dynamic mastering, time editing, or video-file input.
Supported formats
- Accepted formats: MP3, WAV, M4A, AAC, Ogg, Opus, FLAC.
- Output formats: MP3, WAV.
Browser support and permissions
- Modern browser with JavaScript and support for the selected audio container and codec; memory and performance vary by device.
- No camera, microphone, or screen permission is needed.
Choose the right settings
- Use this route when decoded peak or unweighted RMS should determine the applied gain.
- Use /increase-audio-volume when a specific manual gain is already known.
- Do not use these presets as LUFS compliance evidence; use /audio-tools when the desired operation is still unclear.
- Listen to the reopened result because measured normalization does not erase differences in dynamics or tone.
Worked example
Two voice clips need more comparable levels, so one source is normalized toward an explicitly selected RMS target.
Starting facts
- The route measures decoded peak or unweighted RMS.
- Perceived loudness depends on more than one scalar measurement.
Observed operation: Measure the source, choose peak or RMS normalization and encode a separate local MP3 or WAV result.
Review the result: Listen at a fixed playback volume and inspect clipping, noise and the reported measurement before using the output.
Boundary: This is not standards-based LUFS mastering and cannot guarantee equal perceived loudness across content or playback systems.
What you can do
Measure decoded peak or unweighted RMS and normalize one local audio file toward the selected target
Choose another tool when
- Applying a user-chosen gain without target analysis belongs to /increase-audio-volume.
- The RMS presets are unweighted full-scale measurements, not LUFS or perceptual loudness certification.
- Normalization does not make recordings with different dynamics and frequency balance sound identical.
If it does not work
- A track that cannot be decoded and measured provides no valid peak or RMS basis for normalization.
- A decoded track containing no PCM samples is rejected because it provides no measurement basis.
- The result is withheld when local encoding or reopened-output measurement cannot complete.
Things to know
- Codec support, performance, and memory use vary by browser, device, source, and operation.
Privacy boundary
The selected audio stays in the current browser session and is not sent to an Aftermath processing service. How local processing is verified.
What this tool verifies
Checks the displayed limits and reports or creates a separately downloaded MP3 or 16-bit PCM WAV result from one selected local audio file.
Check before sharing
Applying a user-chosen gain without target analysis belongs to /increase-audio-volume.