Format guide

Slow Down FLAC Online

Slow down a FLAC file in your browser with speed, reverb and bass controls. Lossless decode in Chrome and Firefox, Safari caveats, memory use and MP3 export.

Open the free editor: upload MP3, WAV, AAC, OGG or FLAC, adjust speed, reverb, bass, tone, width and space, then export MP3 or a ZIP of many tracks. Everything runs in your browser.

FLAC gives you the quality of WAV at roughly half the file size, and for a slowed edit that is the sweet spot: a lossless source that does not fill your disk. The editor above decodes FLAC directly in the browser where the browser supports it, slows the track anywhere between 0.50x and 1.50x, and lets you add reverb, bass, tone and stereo width before encoding an MP3 locally. Nothing is uploaded.

This page covers what is specific to FLAC: which browsers decode it, how it compares to WAV as a source for slowing, what happens to the lossless quality on export, and a short note on high-resolution FLAC files. If you have a WAV instead, the WAV page covers memory and bit depth. If your source is lossy, the MP3 page explains why bitrate becomes the limiting factor. The slowed reverb maker page explains every control in depth.

FLAC as a source for slowing

FLAC is lossless compression. The decoded audio is bit for bit identical to the WAV it was made from. For the editor, that means a FLAC file and its WAV equivalent produce exactly the same slowed output. All the advantages of WAV apply: no compression artifacts to be stretched into audibility, clean cymbals at deep speeds, reverb tails that blend naturally with the room already in the recording.

The practical advantage over WAV is size. A FLAC of a four minute song is typically 20 to 30 MB where the WAV would be around 40 MB. That matters for storing a library and for moving files to a phone. Once loaded into the editor, though, both decode to the same uncompressed audio in memory, so the memory footprint during processing is the same. The savings are on disk, not in the tab.

Bandcamp purchases, CD rips made with a lossless setting, and most archive and audiophile downloads come as FLAC. If you buy music to slow it, FLAC is usually the format to pick.

Browser support

FLAC decoding in the browser depends on the browser's own media stack. Here is the state as it is generally understood; check in your browser by loading a file, because versions change.

The way to find out is to load the file. If the browser cannot decode it, the editor reports the failure rather than silently producing silence. If that happens on Safari, the fastest fix is to convert the FLAC to WAV on a computer, which is a lossless step, and load the WAV. Converting to a high-bitrate AAC also works as a source, with a small quality cost. Converting to MP3 defeats the purpose of having a lossless source. The AAC page covers what Safari handles most reliably.

Chrome and Firefox also decode FLAC inside an Ogg container (an .oga or .ogg file carrying FLAC), though most FLAC files are in the native .flac container and that is the simplest to work with.

What happens to the lossless quality

Here is the honest chain. Your FLAC is lossless. The browser decodes it losslessly. The speed change, reverb, bass, tone and width are all applied to that uncompressed audio with no loss. Then the export encodes to MP3 at 96 kbps, 32 kHz. That final step is the only lossy step, and it is a real one.

So a FLAC source does not give you a lossless slowed version. What it gives you is the cleanest possible input to the one lossy stage. The difference is audible: a 96 kbps MP3 encoded from a slowed FLAC sounds noticeably better than a 96 kbps MP3 encoded from a slowed 128 kbps MP3, because the encoder is not compounding artifacts that were already there.

For YouTube, TikTok, Reels and Shorts, this is the right trade. Those services re-encode your upload, and the export bitrate guide explains why a clean 96 kbps input to their pipeline is not what limits the final sound. For a file you intend to sell or distribute losslessly, this editor is not the last step; find your settings here, then reproduce them in a DAW that exports FLAC or WAV. The online versus DAW page covers that decision.

High-resolution FLAC

Many FLAC downloads are 24 bit at 88.2, 96 or 192 kHz. They decode fine in Chrome and Firefox. They also use two to four times the memory of a CD-quality file once decoded, and none of that extra resolution reaches the export, because the browser processes in 32-bit float and the MP3 is written at 32 kHz. There is no audible gain over a 16 bit, 44.1 kHz FLAC of the same master.

If you have both, load the CD-quality version. If you only have the hi-res version, it works, just expect it to take longer to load and to use more memory. On a phone, treat a 96 kHz FLAC as you would two or three normal tracks when deciding how many to load at once.

Settings for lossless sources

Lossless sources tolerate deeper slowing and less tonal masking than lossy ones. These starting points assume a clean FLAC.

On an MP3 source you would pull Tone further down to hide artifacts. With FLAC you can leave more of the top end in and let the recording speak.

Metadata and album art

FLAC files commonly carry Vorbis comment tags and embedded cover art. The decoder reads the audio and ignores the rest. The exported file, yourfile-remix.mp3, contains audio only. If you are building a release or a set of files for sale, add tags and artwork afterwards with a tag editor. The naming and packaging guide covers a consistent scheme.

Cue sheets and single-file album rips with an accompanying .cue are decoded as one long track. The editor does not split on cue points, and there is no trimming, so split the rip into tracks first if you want one output per song.

Batch processing FLAC albums

An album of FLACs loads comfortably on a laptop. Add all tracks, Select All Tracks, pick settings once, and Download All for a ZIP of MP3s named after the sources. On a phone, a full album of FLAC decodes into a lot of memory; load a handful at a time, export, Delete Selected, and continue. The bulk converter page has the group workflow and the naming of the ZIP files.