How to gdpr-compliant audio redaction — no upload, free
- Step 1Open the redactor and drop your recording — Open the redactor and drop the recording held under your control. Audio input is accepted (MP3, WAV, FLAC, M4A, OGG, Opus); choose a tier that covers the file's size and duration (Pro = 200 MB / 120 min).
- Step 2Let the file decode in your browser — The tool decodes the audio locally to read its duration. Nothing is uploaded — FFmpeg 8.1 runs as WebAssembly inside the page, so the recording never leaves your device. The decoded duration becomes the upper bound for every range you add.
- Step 3Add a redaction range — Click Add range. A row appears with Start and End number inputs (in seconds). A new range defaults to 0 s to 1 s; type the real start and end of the segment you want silenced.
- Step 4Mark every segment that needs silencing — From your review (and any transcript), add a range for each piece of personal data to remove — names, numbers, contact details, special-category data. Manual marking gives you a documented, human decision per range.
- Step 5Process the file — Run the tool. For each range it applies
volume=0gated tobetween(t, start, end), so the audio inside every marked range becomes pure silence. The rest of the timeline is untouched and the file is re-encoded to the output format. - Step 6Download and verify — Verify the
-redactedoutput, keep the original under access control, and record what was redacted. Confirm no personal data remains in tags or filename. Treat redaction as one step in your documented process — consult your DPO for the full obligations.
What the redactor actually does
Every row verified against the browser processor and the range UI. The tool mutes — it does not bleep, beep, or insert noise.
| Behaviour | Implementation | What it means for you |
|---|---|---|
| Redaction method | Volume set to 0 (full silence) inside each marked range via the FFmpeg volume filter with an enable='between(t,start,end)' gate | No tone, beep, or noise is inserted — the range goes silent |
| Marking | Manual only — you add ranges with Add range and type Start and End in seconds | There is no auto-detection, transcription, or phone-number finder in the tool |
| Time granularity | Start/End inputs step in 0.1 s (100 ms) increments | Type a finer value directly if your browser allows; the filter uses your exact number |
| Range bounds | Each input is clamped to min 0 and max = the file's decoded duration | You cannot mark a range past the end of the file |
| Output format | Defaults to the input file's extension and is re-encoded through FFmpeg | Lossy inputs (MP3/M4A/OGG/Opus) are re-compressed; WAV/FLAC stay lossless |
| Filename | Original name with a -redacted suffix | e.g. interview.mp3 becomes interview-redacted.mp3 |
| Empty input guard | Throws Add at least one redaction range if no range is set | At least one Start/End pair is required before processing |
Input and output formats
Output is re-encoded through FFmpeg 8.1 (WebAssembly). The output extension follows the input by default; the encoder is chosen from that extension.
| Format | Output encoder used | Lossy on re-encode? |
|---|---|---|
| MP3 | libmp3lame | Yes — re-compressed (one extra lossy generation) |
| WAV | pcm_s16le | No — lossless PCM |
| FLAC | flac | No — lossless |
| M4A / AAC | aac | Yes — re-compressed |
| OGG (Vorbis) | libvorbis | Yes — re-compressed |
| Opus | libopus | Yes — re-compressed |
Audio tier limits that apply to redaction jobs
PII redaction runs inside the audio tool family, so the audio family limits apply. Numbers are per the live tier table; durationMin is a per-file duration cap that is separate from the file-size cap.
| Tier | Max file size | Max duration / file | Files per job |
|---|---|---|---|
| Free | 50 MB | 30 min | 1 |
| Pro | 200 MB | 120 min | 10 |
| Pro-media | 100 GB | Unlimited | 100 |
| Developer | 100 GB | Unlimited | Unlimited |
Cookbook
Common GDPR-style redaction cases. Times are seconds; type them into Start/End. None of this is legal advice — it is how to drive the tool.
Redact a caller's personal details from a support call
A support recording captures the caller's name, address, and phone number in the opening minute. Mute each as a separate range.
Add range 1 -> Start: 12.0 End: 13.6 (name) Add range 2 -> Start: 21.4 End: 26.0 (address) Add range 3 -> Start: 31.0 End: 34.2 (phone number) Output: support-call-redacted.wav (same length, aligned to log)
Subject access request: redact third-party personal data
Before releasing a recording to a data subject, you must remove other people's personal data. Mark every third-party utterance.
For each third-party detail in the transcript, add a range: [03:11] other caller's name -> Start: 191.0 End: 192.4 [07:55] other caller's ref -> Start: 475.2 End: 478.0 Release only the redacted copy; retain the original securely.
Special-category data spoken in an interview
A health detail (special-category data) is mentioned at 14:20. Mute it and document the redaction.
Range: Start: 860.0 End: 863.5 Note in your redaction log: 'special-category data muted 14:20-14:23 per minimisation; original retained, access-limited.'
Keep the timeline aligned with the transcript
Because muting preserves length, the redacted audio still maps 1:1 to the transcript line numbers and timecodes you hold.
Transcript timecode 09:42 -> still 09:42 in redacted file. Only the audio there is silent; everything else is in place.
Clear residual personal data outside the audio
After muting, check the file's metadata and name — GDPR personal data can hide there too.
1. Redact audio ranges here -> call-redacted.m4a 2. Open id3-editor -> clear name/number from title/comment 3. Rename file to remove any identifying string e.g. john-smith-call.m4a -> case-014-redacted.m4a
Edge cases and what actually happens
No range added
RejectedThe tool throws Add at least one redaction range if processed empty. Enter Start/End for each item of personal data first.
Personal data in ID3 tags / filename
Not handled hereAudio redaction does not alter metadata or filenames — both can contain personal data. Use id3-editor and rename the file as part of your process.
Treating the mute as full compliance
IncompleteMuting spoken personal data is a technical measure, not the whole obligation. You still need lawful-basis, retention, documentation, and original-copy controls. Consult your DPO.
Redacted span boundary clips part of a name
ExpectedIf a boundary is too tight, part of the personal data can survive. Pad ranges and verify by listening; widen and reprocess from the original where needed.
Original recording still retained
By designRedaction produces a new -redacted file and never alters the source. Keep the original under access control and apply your retention schedule to it separately.
Recovering the original from the redacted file
Not possibleSilenced samples are encoded out of the output; there is no way to reconstruct the personal data from the redacted copy. This is the intended irreversibility.
Overlapping ranges across several data items
SupportedOverlapping or adjacent ranges are fine — the union is silenced, so closely spaced personal-data utterances are fully covered.
Long call exceeds tier duration
RejectedPer-file duration is capped by tier independently of size (Free 30 min, Pro 120 min, Pro-media/Developer unlimited). Choose a tier that covers the call length.
Auto-detecting personal data
Not supportedThere is no automatic PII detection — every range is a human decision, which is useful for an auditable record but means a reviewer must identify each item.
Frequently asked questions
Is muting the audio enough for a compliance obligation?
Muting the spoken PII is a meaningful data-minimisation step, but it is one part of a process, not a full compliance programme. You still need to control the original recording, document what was redacted and why, and confirm no PII survives elsewhere (file metadata, filename, accompanying transcript). Scrub embedded tags with id3-editor and rename the file. Consult your Data Protection Officer for your specific obligations.
Can the silenced audio be recovered from the output file?
No. The samples inside each range are replaced with silence before encoding, so the original audio in those spans is not present in the output file — there is nothing to un-mute. Keep your original recording in a secure location if you ever need the un-redacted version; the redacted file cannot be reversed back to it.
Is my recording uploaded to a server?
No. All processing is 100% in your browser using FFmpeg 8.1 compiled to WebAssembly. The audio is decoded and redacted locally and never transmitted, which is what makes the tool suitable for sensitive recordings. You can disconnect from the network after the page loads and redaction still works.
Does the tool insert a beep, tone, or white noise over the redacted part?
No. The redactor sets the volume to 0 inside each range, so the segment becomes full silence. There is no beep tone, 1 kHz tone, or white-noise option in the tool — it is a mute, not a bleep. If you specifically need an audible censor beep for broadcast style, you would have to add it in a separate audio editor; this tool's output is silent across the marked ranges.
Can it automatically find names, numbers, or card details?
No. Marking is manual only — you add ranges and type the Start and End seconds yourself. There is no speech-to-text, entity recognition, or phone-number detector built in. Play the recording, note the timestamps where sensitive content is spoken, and enter those ranges. This keeps everything in the browser with zero upload, but it does mean you (or a reviewer) decide what gets silenced.
Does redacting also remove names or numbers stored in the file's metadata?
No. This tool silences audio samples within the ranges you mark; it does not touch ID3 tags, comments, or cover art embedded in the file. If a phone number or name is sitting in the title/artist/comment fields, edit those separately with id3-editor, and consider whether the filename itself leaks anything.
Will the redacted file be the same length as the original?
Yes. Muting a range does not remove time — the silenced spans stay in place, so the total duration is unchanged. This is intentional: it keeps every later timestamp aligned with your notes, transcript, or video. If you actually want the file shorter, trim or strip silence instead.
How many separate sections can I redact in one pass?
As many as you need — click Add range for each section. Every range is applied in the same processing pass as its own volume=0 gate, so a call with ten scattered account numbers is one job, not ten. There is no fixed cap on range count; the practical limits are the file-size and duration caps for your tier.
How precise can the redaction boundaries be?
The Start and End inputs step in 0.1 s (100 ms) increments, and the underlying between(t, start, end) filter uses the exact number you type. For most speech that 100 ms granularity is enough to catch a spoken digit or word; pad each range by a few hundred milliseconds on both sides so the leading consonant or trailing syllable is fully covered.
Which plan do I need to use the redactor?
The redactor is a Pro-tier tool. The audio family limits then apply by tier: Pro is 200 MB and 120 minutes per file with up to 10 files; Pro-media and Developer raise that to 100 GB and unlimited duration. Choose the tier that covers both your file size and its duration, since those are checked separately.
Can I redact the audio inside a video file?
This tool's accepted input is audio. To redact a video's soundtrack, first extract the audio (for example with the video-to-mp3 or video-to-wav tools), redact the ranges here, then mux the cleaned audio back over the video in a video editor. The redactor itself outputs audio, not video.
I marked the wrong segment — how do I fix it?
Each range row has a trash/remove control. Delete the wrong range, add a corrected one, and reprocess. Because the tool is non-destructive to your source file (it produces a new -redacted output), you can re-run as many times as you like from the same original until the boundaries are right.
Privacy first
Every JAD Audio tool runs entirely in your browser via FFmpeg (WebAssembly) and RNNoise. Your audio files never leave your device — verified by zero outbound network requests during processing.