About

This is not a toy recorder. It is a strictly engineered, local-first audio capture tool designed for critical tasks: long-form lectures, legal dictations, and musical sketching. Unlike cloud-based tools that risk data loss during internet outages, this application operates entirely within your browser's secure sandbox using the WebAudio API and IndexedDB.

We address the primary failure mode of web recorders: The Browser Crash. By streaming audio chunks to persistent local storage every 1000ms, we ensure that even if your battery dies or the tab closes unexpectedly, your audio is recoverable upon next launch. Precision controls allow for bookmarking key moments in real-time, and our post-processing engine offers studio-grade silence trimming and WAV conversion.

Formulas

Understanding digital audio requires grasping the relationship between sampling rates and file size. The fundamental limit of digital audio capture is defined by the Nyquist-Shannon Sampling Theorem.

{

f_s ≥ 2 ⋅ f_maxTo reconstruct signal without aliasing

Where f_s is the sampling rate and f_max is the highest frequency component. For CD quality audio:

44,100 Hz × 16 bits × 2 channels8 bits/byte

This results in the standard data rate of 176.4 KB/s or roughly 10 MB/min for uncompressed audio.

Reference Data

Format / Standard	MIME Type	Compression	Use Case	Bitrate (Typ)
WebM (Opus)	audio/webm	Lossy (High Efficiency)	Lectures, Meetings, Long Audio	64-128 kbps
WAV (PCM)	audio/wav	Lossless (Uncompressed)	Music Production, Mastering	1411 kbps
Ogg Vorbis	audio/ogg	Lossy (Open Source)	Streaming, Gaming	96-160 kbps
MP3	audio/mpeg	Lossy (Legacy)	General Listening (Not Native Rec)	128-320 kbps
Sampling Rate	N/A	N/A	Human Hearing Limit (20kHz)	44.1 kHz / 48 kHz
Bit Depth	N/A	N/A	Dynamic Range	16-bit / 24-bit

Frequently Asked Questions

Most web recorders keep audio in RAM. If the page closes, RAM is cleared, and data is lost. We utilize IndexedDB, a browser-based database, to write "chunks" of audio to your hard drive every second. When you reload the page, the tool scans the database for "orphaned" chunks and reconstructs the audio file automatically.

Browsers natively support the MediaStream Recording API, which typically outputs WebM or Ogg containers using the highly efficient Opus codec. MP3 encoding is patent-encumbered and computationally expensive in JavaScript. WebM offers superior quality-to-size ratios.

Yes. Once a recording is finished, our post-processing engine analyzes the waveform amplitude. It detects segments below the noise threshold (-40dB to -60dB) and mathematically removes them before regenerating the Blob for download.

Absolutely not. This tool is a "Client-Side SPA". All audio processing, storage, and conversion happen locally on your device's CPU and memory. No data ever leaves your browser.