Audio Info Checker
Read everything about an audio file: container, codec, sample rate, bitrate, channels, duration and measured levels.
Convert with this tool
or choose a file from your device — it is processed in this tab and never uploaded
Accepted: MP3, WAV, FLAC, M4A/AAC, OGG, Opus, WebM, MP4, MOV, MKV and more
Files stay on your device. There is no upload, no queue and no watermark, so a conversion works even with the network switched off after the page has loaded.
Supported formats & processing
| Accepted input | MP3, WAV, FLAC, M4A/AAC, OGG, Opus, WebM, MP4, MOV, MKV and more |
|---|---|
| Produced output | An inspection report with a downloadable JSON file |
| Processing | Web Audio API + canvas + native JavaScript encoders |
| Upload required | No — the file is read locally and never transmitted |
How to use this tool
- Add the audio fileThe header is parsed immediately and the report appears.
- Read the container and codec rowsThey tell you the actual format, not just the extension.
- Check the declared sample rate and bitrateThese come from the codec header.
- Check the measured duration and levelsThese come from decoding the audio itself.
- Download the JSON reportUseful for comparing two files or keeping an archive record.
About this tool
Knowing what is actually inside an audio file is the first step in almost every audio decision. A file with a .mp3 extension might be a 96 kbps mono encode from a phone call, or a 320 kbps stereo master. The difference matters when you are deciding whether to re-encode, archive or discard.
This checker works on two levels. It parses the container header directly — reading RIFF chunks, MPEG frame headers, FLAC streaminfo, MP4 sample tables and Matroska EBML elements — and it also decodes the audio to measure the real duration, peak and RMS levels. Those measured values are what tell you whether the file matches its own claims.
Features
- Real container parsing for WAV, MP3, FLAC, MP4 and Matroska
- Measured duration, peak and RMS levels from decoded audio
- Declared values from the codec header shown alongside measured ones
- Channel layout, bit depth and lossless status reported
- MIME type reported by the browser for comparison with the real format
- Downloadable JSON report
Frequently asked questions
Why do the declared and measured bitrates differ?
The declared bitrate comes from the codec header, which for variable-bitrate files is only a nominal average. The measured bitrate is calculated from the real file size divided by the decoded duration. Both are shown so you can judge which is meaningful.
What does the peak level tell me?
The loudest sample in the file, expressed in dBFS where 0 dBFS is full scale. A peak at exactly 0 dBFS suggests the recording clipped; a peak at −20 dBFS suggests it has plenty of headroom or was recorded too quietly.
Can the checker tell me whether a file is genuinely high quality?
It reports the bitrate, sample rate and whether the format is lossless, which is most of the answer. To see whether a lossy encode discarded the high frequencies, generate a spectrogram with the spectrum visualiser.
Is my file uploaded to check it?
No. The header is read with the File API and the audio is decoded in the browser's own audio engine. Nothing leaves your device.