How to archive wav as flac — lossless, verifiable, no upload
- Step 1Drop one WAV master onto the tool — The converter takes a single file per run (
acceptsMultipleis false), which suits a deliberate, file-by-file ingest. The master is written to FFmpeg's in-memory filesystem in your tab and never uploaded — important for embargoed or confidential collections. - Step 2Choose a compression level for the archive — Default is 8, the standard archival setting. For a deep cold-storage tier where every byte counts and ingest time is not a concern, 12 · smallest, slowest squeezes another ~1-3%. The level changes nothing about the stored audio — only encode time and size.
- Step 3Keep bit depth and sample rate native — Do not down-convert for archival. FLAC stores 24-bit/96 kHz (or higher) natively, so the FLAC is a faithful surrogate of the master at full resolution. Preserving the original resolution is a core preservation principle.
- Step 4Run the conversion — FFmpeg re-encodes the PCM with the
flacencoder and-compression_level <n>, writing an MD5 of the decoded audio into the header. No bitrate is applied — FLAC is lossless. Encode time scales with level, file size, and CPU. - Step 5Download and ingest the .flac — Save the
.flacinto your preservation store. Record its checksum in your collection manifest the same way you would for any preservation master. - Step 6Verify integrity now and on a schedule — Run
flac --test file.flacto confirm the internal MD5 matches the decoded PCM — your fixity check. Repeat periodically against your stored FLACs to catch bit-rot in cold storage; the embedded MD5 means the file self-describes its own correctness.
Why FLAC for audio preservation
How FLAC's properties map to common digital-preservation requirements. This is why memory institutions and labels standardise on it for surrogate masters.
| Preservation need | How FLAC (via this tool) meets it |
|---|---|
| Lossless / no generation loss | Decodes to bit-identical PCM; re-encoding never degrades |
| Self-verifying fixity | MD5 of decoded audio embedded in STREAMINFO; flac --test validates without the source |
| Open, documented format | Free, royalty-free, fully specified codec — no vendor lock-in |
| Hi-res support | Native 8/16/24-bit at any sample rate; no down-conversion |
| Storage efficiency | ~40-60% smaller than WAV at the same fidelity |
| Confidentiality / chain of custody | Browser-only conversion; masters never uploaded |
WAV master storage vs. FLAC surrogate (illustrative)
Approximate per-file sizes for common master formats and the typical FLAC surrogate. WAV size is exact PCM math; FLAC is a typical range and varies with content.
| Master format | WAV per minute (stereo) | 1 hour as WAV | Typical FLAC surrogate |
|---|---|---|---|
| 16-bit / 44.1 kHz | ~10.1 MB | ~605 MB | ~300-420 MB |
| 16-bit / 48 kHz | ~11.0 MB | ~660 MB | ~330-460 MB |
| 24-bit / 48 kHz | ~16.5 MB | ~990 MB | ~490-690 MB |
| 24-bit / 96 kHz | ~33.0 MB | ~1.94 GB | ~970 MB-1.4 GB |
Cookbook
Archival ingest patterns: each preserves the master losslessly and produces a verifiable FLAC surrogate. Sizes are illustrative.
Ingest a 24-bit master and record its fixity
The core archival loop: convert, then capture the checksum into your manifest so future audits have a baseline.
Master: reel01_master.wav 24-bit / 96 kHz / stereo / 18:00 Level: 8 Output: reel01_master.flac ~510 MB (was ~594 MB WAV) # Fixity baseline for the manifest: flac --test reel01_master.flac -> ok (internal MD5 valid) sha256sum reel01_master.flac -> record in manifest.csv
Prove a clean round-trip before deleting the WAV
If policy lets you retire the WAV after creating the FLAC surrogate, verify the round-trip first. Never delete the master on faith.
flac -d reel01_master.flac -o check.wav fc /b reel01_master.wav check.wav -> no differences found # Only after a clean compare: # FLAC surrogate is bit-identical -> safe to retire WAV per policy
Cold-storage tier at level 12
For an offline, write-once cold tier where ingest time is irrelevant, squeeze the last few percent. Audio is identical to level 8.
Master: field_session.wav 24-bit / 48 kHz / 42:00 Level 8: ~640 MB Level 12: ~625 MB (~2% smaller, slower encode) Decoded PCM identical either way.
Periodic fixity audit catches bit-rot
The embedded MD5 turns each FLAC into a self-checking object. Re-run --test on the whole store on a schedule.
# Annual audit script logic:
for each *.flac in archive/:
flac --test file
if not ok: flag for restore from backup copy
# A flagged file means storage bit-rot, not a FLAC defect.Hi-res orchestral master shrinks dramatically
Sparse, dynamic classical material is FLAC's best case — large savings with full 24-bit/96k preservation.
Master: symphony_mvt1.wav 24-bit / 96 kHz / stereo / 12:30 WAV: ~412 MB FLAC l8: ~245 MB (~40% smaller) Stored at full resolution, no down-conversion.
Edge cases and what actually happens
BWF bext timecode / production metadata
Not preservedBroadcast WAV stores origination date, timecode, and coding history in a bext chunk. Standard FLAC has no equivalent container slot, so this production metadata is not carried across. For broadcast and film preservation where bext is part of the record, keep the BWF master as the preservation original and treat FLAC as an access/space-saving surrogate.
32-bit float WAV master
Converted to integerFLAC's standard format is integer PCM. A 32-bit float master is converted to integer samples — lossless relative to that integer form but not a bit-for-bit float container. For float-native preservation, retain the WAV; archive a 24-bit FLAC only as a surrogate, and document the conversion in your metadata.
Master exceeds the per-file size cap
413 blockedFree caps a single file at 50 MB — far below most masters. Pro allows 200 MB; Pro-media and Developer allow up to 100 GB, which covers even long hi-res reels. The limit applies to the input WAV; pick a tier sized to your collection's largest master.
Master longer than the duration cap
RejectedA separate per-file duration limit applies: 30 min Free, 120 min Pro, unlimited on Pro-media and Developer. Long-form masters (concerts, lectures, oral histories) commonly exceed 30 or 120 minutes, so archival workflows usually need Pro-media or Developer.
Embedded cue points / region markers in the WAV
Not guaranteedWAV cue and LIST region chunks used for markers are container-specific and have no standard FLAC mapping. They may not survive the transcode. If markers are significant to the record, export them separately (e.g. a sidecar file) or keep the WAV.
Single-file workflow for a large collection
By designThis tool converts one file per run. That is deliberate for careful, verifiable ingest, but a bulk collection means repeating the loop per file. Capture each FLAC's checksum as you go so the manifest stays complete.
FLAC surrogate is only ~15-20% smaller
ExpectedHeavily limited, loud, full-spectrum material has little redundancy, so FLAC's gains are modest. This is normal and still fully lossless — the surrogate is faithful regardless of how much it compressed.
Relying on FLAC to 'restore' an old lossy transfer
No quality gainIf the WAV was decoded from a lossy source, the artifacts are in the PCM permanently. FLAC preserves them losslessly but recovers nothing. Document the provenance — a FLAC made from a lossy intermediate is not equivalent to one from an analog/PCM master.
Corrupt or truncated WAV master
Decode errorFFmpeg validates the stream as it decodes; a truncated or damaged WAV fails with an error rather than silently producing a bad FLAC. Treat such a failure as a flag to recover the master from backup before archiving.
Expecting the FLAC to embed your full catalogue record
Use Vorbis commentsThis converter carries source tags via -map_metadata 0 but does not author rich catalogue metadata. To add structured preservation metadata (rights, identifiers, provenance) edit the FLAC's Vorbis comments afterwards, or manage that record in your collection-management system rather than the file alone.
Frequently asked questions
Why is FLAC the standard for audio archiving?
It is open, royalty-free, fully documented, and losslessly reversible — and it self-verifies via an embedded MD5 of the decoded audio. That combination means an archive can prove, years later and without the original, that a FLAC is bit-identical to the WAV master, while spending ~40-60% less storage.
How do I verify the archive is truly lossless?
Run flac --test file.flac. FFmpeg's encoder stored an MD5 of the decoded PCM in the header, so the test re-decodes and compares against it — no original WAV required. For belt-and-braces, decode to WAV and byte-compare against the source before retiring the master.
Should I keep the WAV after making a FLAC?
That depends on your preservation policy. Since FLAC is bit-identical, many workflows retire the WAV after a verified round-trip. The exceptions: BWF bext timecode, 32-bit float, and embedded cue markers do not carry into standard FLAC, so keep the WAV if any of those are part of the record.
Does archiving at level 12 hurt anything?
No — level 12 is lossless, just slower to encode and ~1-3% smaller than 8. For cold storage where ingest time is irrelevant it is a reasonable choice. The decoded audio is identical to every other level, so you are only trading CPU time for a little space.
Will my 24-bit / 96 kHz masters stay hi-res?
Yes. FLAC natively stores 24-bit at any sample rate, so the surrogate keeps full resolution with no down-conversion. The only caveat is 32-bit float WAV, which FLAC stores as integer PCM — keep the float WAV if exact float preservation is required.
Are my unreleased masters uploaded anywhere?
No. Conversion runs entirely in your browser via FFmpeg 8.1 WASM. The master is written to an in-memory filesystem, encoded locally, and downloaded — nothing is transmitted. That keeps embargoed, rights-restricted, or confidential material under your control.
Does FLAC carry my catalogue metadata and album art?
Source tags carry via -map_metadata 0 and embedded cover art is re-attached as a FLAC picture block. For rich preservation metadata (rights, identifiers, provenance) you will typically author Vorbis comments after conversion or manage it in your collection system.
What about Broadcast WAV timecode?
The BWF bext chunk has no standard FLAC equivalent and is not preserved. For film and broadcast preservation where timecode is load-bearing, keep the BWF as the preservation master and use FLAC only as a size-reduced access surrogate.
How large and how long can a master be?
Per-file caps are 50 MB / 30 min on Free, 200 MB / 120 min on Pro, and 100 GB / unlimited duration on Pro-media and Developer. Both size and duration are checked. Long-form or hi-res masters typically need Pro-media or Developer.
Can I batch-convert an entire collection at once?
Not in this single-file tool — it converts one WAV per run by design. For a collection, repeat the loop per file and record each checksum as you go. If you need higher-volume throughput, a Pro plan's larger limits and the wider JAD audio toolset will help.
Does conversion ever degrade the audio over time?
No. FLAC has no generation loss — you can decode and re-encode it indefinitely and the PCM never changes. The only risk to an archive is storage bit-rot, which the embedded MD5 plus periodic flac --test audits are designed to catch.
What if I later need a portable copy of the archive?
Decode FLAC to WAV with any player or flac -d, or make a lossy share copy with the sibling FLAC to MP3 tool. The FLAC stays your verifiable lossless surrogate; the MP3 is a convenience copy you can regenerate any time.
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.