Local audio compressor
Start with a Smaller, Balanced, or Higher quality preset, or choose an approximate size budget. The local encoder selects a supported MP3 bitrate, creates the result once, and reports its actual byte size.
Your selected file stays on this device. No upload, account, or server-side media job.
Browser-local workspace
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 presets map a simple quality choice to a supported MP3 bitrate. An optional size budget derives a one-pass bitrate from duration, while explicit mono and sample-rate controls can reduce size further for suitable voice material.
The worker verifies the encoded MP3 container and reports actual bytes, duration, sample rate, and channels. A size budget influences the chosen bitrate, but container overhead and encoder behavior mean it is approximate rather than an exact-size promise.
Private browser handling
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.
Try a measured example
We used Balanced quality to compress the 1.5-second WAV. The output was reopened to check its audio track and size.
| Before compression · WAV | Bytes: 132,344 Seconds: 1.5 |
|---|---|
| After compression · MP3 | Bytes: 30,981 Seconds: 1.541 |
MP3 removes audio information to save space. This test tone proves the file workflow, not speech or music quality. Its measured duration includes encoding padding.
Tested: · Chromium 149.0.7827.55
These files passed through the actual tool controls. Downloads were reopened to check sizes, duration, dimensions, or page structure. Capture used synthetic streams; hardware permissions were not tested.
These synthetic samples are free to reuse under CC0. No personal files or recordings were used. Your results may differ.
Use this route when smaller output bytes are the primary goal for one local audio file. Choose an MP3 quality preset or approximate size budget, with optional explicit mono conversion; the worker selects one supported bitrate, encodes once, reopens the result, and compares measured bytes with any requested budget. WAV remains available as uncompressed PCM, but its size cannot be targeted and it is not a compressed output.
A spoken recording needs a smaller MP3 for delivery using a quality preset rather than an exact final byte promise.
Observed operation: Choose the MP3 quality or approximate one-pass byte budget, encode locally and reopen the completed output.
Review the result: Listen for speech clarity, artifacts and silence, then compare actual bytes and duration with the delivery need.
Boundary: The one-pass budget is approximate and cannot guarantee exact bytes, transparency or support in every player.
Reduce one local audio file’s size with MP3 quality presets or an approximate one-pass byte budget
The selected audio stays in the current browser session and is not sent to an Aftermath processing service. How local processing is verified.
Checks the displayed limits and reports or creates a separately downloaded MP3 or 16-bit PCM WAV result from one selected local audio file.
Preservation-oriented full-track MP3 or WAV conversion belongs to /convert-audio.
