X FLAC Encoder

It ships from the X Codec Pack team as part of a wider audio toolkit and is distributed at no cost with no telemetry, no ads, and no premium tier.

Why this tool exists

For more than a decade, the standard free FLAC GUI on Windows has been FLAC Frontend - a thin .NET wrapper around flac.exe that hasn't seen a meaningful update since around 2013.

It still works, but it accepts WAV input only, runs files sequentially, has no album-mode ReplayGain, no cover-art embedding, and no dark mode.

For users moving to lossless in 2026, those gaps matter: most music libraries today are a mix of MP3, AAC, ALAC, OPUS, and FLAC, not pristine WAV masters, and most modern players expect ReplayGain album-mode tags so a full album shares a single gain value.

X FLAC Encoder is a direct response to that staleness.

It is a modern 64-bit Windows app built on the same proven core - the official FLAC reference encoder and FFmpeg - but with a queue-based UI, parallel workers, and the metadata controls that actually matter for serious music libraries.

Three operations in one tool

The interface is built around three modes that share the same queue, output template, and worker pool:

Encode to FLAC is the headline operation. Drop in any supported audio source and X FLAC Encoder transparently decodes it through FFmpeg to PCM at the correct bit depth, then hands the stream to flac.exe for lossless compression. WAV and FLAC inputs skip the decode step entirely.

Compression levels run from 0 (fastest, files about 5-7% larger) through 8 (slower, slightly smaller archive size) - the audio is bit-identical at every level since FLAC is mathematically lossless.

Decode to WAV runs the reverse direction. FLAC and OGG-FLAC files are extracted back to bit-perfect WAV with original sample rate and bit depth preserved, plus optional recovery of foreign metadata chunks (RIFF, AIFF) embedded during the original encode.

Test integrity is the operation most users overlook and most libraries need.

It validates each FLAC file against the MD5 fingerprint stored in its frame header, catching bit rot, transfer errors, and silent storage corruption across an entire library at once.

No output is written - it is a read-only check that runs in parallel across the queue.

20+ input formats, one lossless output

The format list covers essentially every audio container in active use: WAV, MP3, AAC, M4A, OGG Vorbis, OPUS, FLAC itself (for re-encoding at a different compression level), ALAC (Apple Lossless), APE from Monkey's Audio, WavPack, AIFF, WMA, MKA, plus DSD (DSF and DFF) which is converted to PCM during decode.

Video files are also accepted - MP4, MKV, and MOV inputs have their audio track extracted automatically before encoding.

The output is always FLAC (.flac) or OGG-FLAC (.oga). There is no transcoding to MP3 or Opus here - X FLAC Encoder is dedicated to lossless.

For lossy targets, the X Opus Encoder and X Audio Converter cover Opus and MP3 output respectively, both built around the same FFmpeg-driven workflow.

Hi-res audio handled correctly

This is the feature that separates X FLAC Encoder from older tools. The decoder pipeline probes each source's bit depth via ffprobe and selects the matching PCM sample format - pcm_s16le, pcm_s24le, or pcm_s32le - for the intermediate stream.

A 24-bit master that you re-encode at compression level 8 stays 24-bit through the entire round-trip with no silent truncation to CD-quality 16-bit.

FLAC supports up to 32-bit at 655 kHz, and X FLAC Encoder honours the full range, which matters for anyone working with studio masters, high-resolution downloads from Qobuz or Bandcamp, or DSD-to-PCM conversions where bit depth precision is non-negotiable.

Parallel workers, ReplayGain, and tag handling

flac.exe is single-threaded per file, which means that on a multi-core CPU the bottleneck is concurrency, not raw encode speed. X FLAC Encoder addresses this with a configurable worker pool that runs multiple files in parallel - typically a near-linear speedup ripping a full album.

The taskbar progress integration shows aggregate progress across the whole queue without needing the window in focus.

ReplayGain support covers both modes. Track mode computes a per-file gain value so a media player can level individual songs against each other.

Album mode computes a single album_gain shared by every track in a folder, which preserves the relative dynamics between songs on a record - the loud chorus stays louder than the quiet intro the way the artist intended.

Most modern players (foobar2000, mpv, Roon, MPD) respect these tags out of the box.

Metadata controls include a full Vorbis comment editor, copy-from-source mode that pulls existing tags via mutagen, JPEG/PNG cover-art embedding, and .cue sheet support for image-style album encodes.

A live flac.exe command preview updates as you change settings, so power users can see exactly what will run before committing - and save the configuration as a JSON preset for later.

Where it fits in the audio toolkit

X FLAC Encoder is dedicated to FLAC output. Different jobs call for different tools, and the Audio Encoders category on this site covers the full landscape:

For multi-format batch conversion with MP3, FLAC, Opus, and Ogg Vorbis output in one drag-and-drop interface, LameXP bundles every common encoder into a single window.

For converting a music library inside a player you already use, the foobar2000 Free Encoder Pack adds LAME, FLAC, qaac, Vorbis, and Opus encoding directly into the foobar2000 Converter dialog.

For AAC output specifically - useful for Apple devices and modern streaming - the dedicated X AAC Encoder companion covers FAAC-based encoding without re-engaging the full codec pack.

If you are downloading lossless audio from streaming services and want to verify the resulting files, pair X FLAC Encoder with SpotiFLAC and run a batch integrity test on the output folder before adding the tracks to your library.

For background reading on why lossless matters in the first place, the guides on FLAC and lossless audio and the FLAC vs MP3 comparison cover the format trade-offs in plain English.

System requirements and download

X FLAC Encoder 1.0 runs on 64-bit Windows 10 and Windows 11.

The installer is around 23 MB and bundles flac.exe, metaflac.exe, the FFmpeg binaries, and the GUI itself. Older Windows versions (7, 8) are not officially supported - the executable may run if all dependencies are present, but no builds are tested for those platforms.

macOS and Linux users can drive the underlying flac and ffmpeg command-line tools directly.

The application is fully offline. No internet connection is required, no audio is uploaded, and no telemetry is collected. The encoder is BSD-licensed (FLAC reference) and LGPL/GPL (FFmpeg), both free for personal and commercial use.