FLAC reverser

Reverse FLAC locally in your browser. Large files need RAM. Use FLAC versus WAV when you want lossless without huge PCM.

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Up to 60 seconds

FLAC exists so you can keep CD- or studio-quality audio without storing full-size PCM. This page reverses that audio in the browser. You upload a FLAC (or MP3, WAV, OGG, M4A, AAC), the decoder expands it to samples, the samples are played last-to-first, you download WAV. The FLAC file is not sent to a server. There is no FLAC encoder on the way out.

People pick FLAC for the same reason they pick WAV: they do not want another MP3 generation. The difference is on disk and on the wire, not in the reversed sound, once both have been decoded to PCM.

Lossless on disk versus lossless in RAM

FLAC is a lossless compressor. Decode should match the PCM that went into the encoder, bit for bit, for the audio samples. Reverse then changes time order. That time order change is the whole product. You are not “compressing backwards.”

After decode, a 20-minute stereo 96 kHz FLAC occupies the same RAM as the equivalent WAV. The small .flac on disk is not a small AudioBuffer. That is why a phone that opened the FLAC in a player can still die when this tab tries to hold the whole buffer and reverse it.

Reverse WAV online is the PCM-native twin. Use WAV if that is the bounce you have. Use FLAC if that is the archive you have. Use reverse audio high quality when the question is quality policy rather than container. Do not upload FLAC hoping it will sound better than the MP3 you already destroyed; if the FLAC was made from that MP3, you still have MP3 damage. Real lossless starts from a lossless bounce. See MP3 reverser when lossy is all you own.

When FLAC is the right upload

  • A CD rip you made yourself.
  • A Bandcamp or Qobuz lossless download you are allowed to edit.
  • A DAW export you chose FLAC for to save disk.
  • A foley library distributed as FLAC (common for reverse sound work).

When FLAC is the wrong upload:

  • A voice note (probably M4A or OGG).
  • A file named .flac that is actually a renamed MP3.
  • A 2-hour 24/96 mix on a low-memory phone.

FLAC versus WAV for this tool

| Concern | FLAC upload | WAV upload | | Same decoded audio | Yes, if both came from the same PCM | Yes | | Upload size | Smaller | Larger | | RAM after decode | Same order of magnitude | Same | | Tags | Ignored | Ignored (BWF chunks ignored too) | | Download | WAV | WAV |

Choose FLAC when you are tired of waiting on a 500 MB WAV to copy into the input. Do not choose FLAC to beat browser memory. Memory follows duration, sample rate, and channels.

OGG Vorbis is lossy; do not treat it as a FLAC alternative. OGG reverser is for those files.

Steps

  1. Keep the original FLAC. You will want it after the WAV reverse.
  2. Upload. Mic recording is still max 60 seconds and is not FLAC.
  3. Allow time for decode. Slow CPUs spend seconds on high-rate files.
  4. Play. Switch between Play reversed and Use original to compare directions.
  5. 0.5x–2x preview is for listening. It is not rendered into the WAV.
  6. Download WAV. Optional: encode that WAV to FLAC in an external encoder if you want a small reversed archive. That is off-site by design.

No YouTube paste. No polarity invert. No fingerprint lookup.

Bit depth, rate, and multi-channel

FLAC can be 16, 24, or (rarely) 32-bit, at many rates. The browser converts to its float AudioBuffer. The WAV you download is a view of that buffer. Do not file a bug that the WAV is not a bit-identical 24-bit FLAC clone. For delivery that must stay 24-bit integer, reverse in a DAW.

5.1 FLAC may or may not decode depending on the browser. If it fails, extract a stereo downmix or individual stems, then reverse the stems you need.

Tags, cues, and pictures

FLAC Vorbis comments can hold ISRC, ReplayGain, and a full booklet image. Cue sheets can mark CD indexes. None of that rides into the reversed WAV. If you reverse a whole album file, you also lose track boundaries unless you split first. Split in a FLAC tool, reverse track by track, and you will stay sane.

ReplayGain values would be wrong after reverse anyway; loudness of a reversed file is a different measurement.

Failures

Decode error: the file is not FLAC, or it is a hybrid/broken stream. Test in VLC.

Crash: RAM. Crop.

Silent output: you may have reversed a file that begins with a long digital zero (CD pause). The zero is now at the end. Skip forward in the player.

Quality stance

FLAC-in, reverse, WAV-out is as good as this browser path gets for a lossless source. It still is not a substitute for a DAW when you need exact word length, BWF timestamps, or a 4 GB stem. It is the right path when you have a lossless file and you want to hear it backwards without installing software and without handing the album to a server.

Store the reversed WAV next to the FLAC. Name both so you never overwrite the archive with the gag.

Frequently asked questions

Is reversing FLAC lossless end to end?

Decode is lossless: you get the original PCM in the browser buffer. Reverse then reorders those samples. The download is WAV from that buffer, not a new FLAC. Treat it as a working reverse, not a tagged FLAC archive.

When should I upload FLAC instead of WAV?

When the FLAC is what you have, or when you need to move a lossless file that is smaller than PCM. After decode, memory use is similar to WAV of the same duration and channel count.

Why did a 500 MB FLAC freeze Safari?

The decoder expands FLAC to PCM in RAM, then reverses it. Compression on disk does not shrink the working set. Crop the file or use a desktop with more memory.

Are FLAC tags copied to the download?

No. Vorbis comments and pictures stay in the original. The WAV is unnamed PCM.

Can I download FLAC instead of WAV?

Not on this site. Encoding FLAC in the tab is out of scope. Keep your original FLAC and store the reversed WAV beside it.

Does this identify the album from the FLAC fingerprint?

No. There is no AcoustID or song database. Reverse only.

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