Remixer

Turn an authorized track into usable musical material without sending it to a hosted service. Remixer is a free, local Windows and macOS producer workstation for waveform selection, BPM/key/chord analysis, machine-learning stem separation, and DAW-ready WAV export.

Screenshot by Given Peace. Read the product story in Love of House or visit the Remixer product page.

One local workflow

• Find or import audio you are authorized to use.
• Draw and audition a sample-accurate waveform selection.
• Inspect BPM, key, and a beat-synchronized chord timeline.
• Separate six stems or run a focused high-quality vocal model on local hardware.
• Copy a full stem or exact selection directly into Finder, Explorer, or a compatible DAW.

Download

• Download Remixer 0.1.3 for Apple Silicon (.dmg)
• Download the portable Mac build (.zip)
• Download Remixer 0.1.3 for Windows (.exe)
• View all releases

Release assets include SHA-256 checksums. Supported targets are Windows 10/11 x64 with an NVIDIA CUDA GPU and Apple Silicon on macOS 12 or newer.

Architecture

The Electron renderer stays context-isolated from Node.js. A typed IPC boundary coordinates the persistent local worker, byte-range audio streaming, progress events, project storage, and a small native file-clipboard helper. Platform packaging builds the UI and private runtime separately so model and Python dependencies do not make every interface update enormous.

Validation snapshot

• npm ci, TypeScript checks, 9 renderer/unit tests, and the production build pass from a clean clone.
• Three versioned releases provide Windows and Apple Silicon assets with checksum files.
• Runtime downloads and the reviewed BS-RoFormer source are pinned and checksum verified during packaging.
• The current installers are unsigned; the exact trust and notarization limitations are documented below.

Product details

The entire interface follows the stark editorial visual system of givenpeace.com: black and white surfaces, condensed display type, sharp borders, and minimal decoration. The built-in YouTube browser opens on Given Peace's Down So Bad official video, lets listeners search YouTube without leaving Remixer, and can send the selected video directly into the existing audio-import workflow. Down So Bad is also the permanent pinned default track: the app installs its bundled base audio on a clean launch, opens it at startup, and never lets ordinary recent-history ordering displace it.

Release packages include the losslessly compressed Down So Bad base track and thumbnail, not hundreds of megabytes of pre-rendered stems. The first-run five-step walkthrough uses this track exclusively and guides the user through playback, detection, chord navigation, and their first real six-stem separation. The Help button remains available afterward.

Settings includes a project-audio budget with a 5 GB default and a 500 MB minimum. When usage exceeds the limit, Remixer offloads the oldest inactive project audio while retaining its lightweight history, source reference, thumbnail, BPM, key, selections, and chord map. Opening an offloaded project restores its source; stems can then be regenerated as needed. The active project and bundled tutorial are protected from automatic offloading.

Desktop releases

The supported targets are Windows 10/11 on x64 with an NVIDIA CUDA GPU and Apple Silicon (arm64) on macOS 12 or newer. Build artifacts are written to release/:

release/Remixer-Setup-0.1.3-x64.exe
release/Remixer-0.1.3-arm64.dmg
release/Remixer-0.1.3-arm64.zip

Current signing status

The current Mac build is ad-hoc signed for bundle integrity but is not Developer ID signed or notarized. After the first launch attempt, macOS may require System Settings → Privacy & Security → Open Anyway. A normal trusted Developer ID signature and notarization requires Apple Developer Program membership.

The current Windows installer is unsigned because no Authenticode certificate was provided. Microsoft Defender SmartScreen may show an unrecognized-app warning; a publicly trusted Windows release requires an appropriate code-signing certificate.

The completed Windows release checklist and measured results are recorded in WINDOWS_VALIDATION.md.

The UI and audio engine are installed separately so model and Python dependencies do not make every UI update enormous:

Windows app:    %LOCALAPPDATA%\Programs\Remixer
Windows engine: %LOCALAPPDATA%\Remixer\engine
Windows models: %LOCALAPPDATA%\Remixer\models
Windows tracks: %LOCALAPPDATA%\Remixer\data\tracks

Mac app data:   ~/Library/Application Support/Remixer
Mac engine:     ~/Library/Application Support/Remixer/engine
Mac models:     ~/Library/Application Support/Remixer/models
Mac tracks:     ~/Library/Application Support/Remixer/data/tracks

The local development build is unsigned. A distributable release still needs the owner's Developer ID signing identity, hardened-runtime entitlements, notarization, and stapling.

There is no legitimate no-fee Developer ID/notarization route for unrestricted public Mac distribution. Apple allows free development and personal testing, but Developer ID and notarization are part of the $99/year Apple Developer Program. Eligible nonprofits, accredited educational institutions, and government entities can request Apple's fee waiver. Until enrollment, releases remain unsigned and users must explicitly approve them in macOS Privacy & Security.

Installed size

Approximate Apple Silicon footprint after first setup:

• Download package with the bundled tutorial and private setup/audio tools: about 208 MB compressed; the installed .app is about 433 MB.
• Private Python/ML audio engine plus the copied FFmpeg/FFprobe tools: about 1.0 GB.
• Core six-stem model installed during setup: about 667 MB on disk (~699 MB advertised download).
• Optional HQ-vocal model: about 255 MB on disk (~268 MB advertised download).
• Expanded Down So Bad base track: about 61 MB.

With both models and the expanded base tutorial installed, the fixed baseline is roughly 2.4 GB before user projects. The 5 GB storage preference applies only to growing project audio, not the shared engine or model cache.

The Windows installer is about 214 MB and includes its own checksum-verified setup/audio tools. Allow about 5.5 GB for private Python, the CUDA engine, private FFmpeg/FFprobe, the core six-stem model, and the expanded tutorial. The optional HQ-vocal model adds roughly 255 MB. The same 5 GB preference applies only to project audio.

First launch

On Windows, install and open Remixer, then select Set up Remixer. The app includes its own verified x64 uv, LGPL FFmpeg/FFprobe tools, and reviewed BS-RoFormer source. It privately installs Python 3.11, CUDA-enabled PyTorch, the analysis stack, and the core six-stem checkpoint. No package manager, developer tools, Git installation, administrator password, commands, or PATH changes are required. Setup requires an internet connection; the optional HQ-vocal model is downloaded on first use.

On macOS, drag Remixer to Applications, open it, and select Set up Remixer. The app includes its own verified Apple Silicon uv, FFmpeg, FFprobe, and macOS 12 compatibility helper. It privately installs Python 3.11, verifies MLX and Torch MPS, and downloads/verifies the core six-stem checkpoint. No Homebrew, Terminal commands, administrator password, or PATH changes are required. The setup explains the roughly 1.6 GB download before it starts; the optional HQ-vocal model remains an on-demand first-use download.

Workflow

1. Play or search YouTube in the built-in browser, choose Remix this song, paste another authorized YouTube video URL, or choose Import audio. The featured example is Given Peace — Down So Bad.
2. Choose New selection, then drag across the waveform. Use Adjust to move the highlighted region or resize its bright edge handles. Press play with Loop enabled to confirm it.
3. Select Detect key, BPM & chords. Key and BPM describe the track; chords describe the selected region. The chord playing at the current transport time is highlighted in both the waveform and progression, and every chord can be clicked to seek directly to its start. Alternate tempo and key choices remain available for musical ambiguity.
4. Choose Six stems or HQ vocals.
5. Preview the resulting stems.
6. Use Full, Selection, Copy all full, or Copy all selection.
7. Paste one or more file items into Explorer or Finder, then drag or import them into Ableton Live as needed. Files remains the reliable fallback for Live views that do not accept a direct paste.

Selections are rendered sample-accurately as 32-bit float WAV files. Stems are never normalized independently, so their relative balance and alignment are preserved.

Separation models

• Six stems: roformer-model-bs-roformer-sw-by-jarredou / BS-RoFormer SW Fixed
• HQ vocals: roformer-model-bs-roformer-leap-xe-vocals-by-pcunwa / Leap XE
• Engine: bs-roformer-infer pinned to commit b0f1386fcced25f559f3e61c9f08a73cd9bddf80
• Windows compute order: Torch CUDA, then Torch CPU
• Mac compute order: native MLX, Torch MPS, then Torch CPU

The Apple Silicon engine pins Torch 2.11.0, MLX 0.31.0, and mlx-spectro 0.7.0. Both named models have been exercised through MLX with exact input/output frame-count validation. Leap XE keeps the STFT-hop chunk alignment fix (881559 -> 881152).

Audio analysis

The local worker uses librosa for beat tracking, selectable half/double-time BPM candidates, passage-voted key profiles with Camelot codes, and beat-synchronized chord matching. These estimates are probabilistic, so the UI exposes alternatives instead of hiding ambiguity.

Waveforms use compact peaks computed by the persistent worker. Playback uses byte-range streaming from the lossless working WAV, so long files remain seekable without sending full decoded audio arrays over IPC.

YouTube discovery

The official youtube-nocookie.com embed is used for playback, while search metadata is obtained locally through the installed yt-dlp engine. The packaged desktop player identifies itself with the first-party givenpeace.com HTTP referrer, as required by YouTube's embedded-player policy; no YouTube API key or hosted Remixer service is required. Electron context isolation remains enabled and the remote player is not granted Node.js access. Processing remains subject to the responsible-use requirements below.

Development

Windows:

npm ci
npm run build:windows-runtime
$runtime = (Resolve-Path .\build-tools\windows-runtime).Path
powershell -ExecutionPolicy Bypass -File .\scripts\setup-engine.ps1 -BundledToolsRoot $runtime
npm run build:tutorial
npm run typecheck
npm test
$env:PYTHONPATH = (Resolve-Path .\worker).Path
& "$env:LOCALAPPDATA\Remixer\engine\.venv\Scripts\python.exe" -m pytest .\worker\tests -q
npm run dev

macOS:

npm ci
npm run build:mac-helper
npm run build:mac-runtime
npm run build:tutorial
REMIXER_BUNDLED_TOOLS_DIR="$PWD/build-tools/mac-runtime" ./scripts/setup-engine.sh "$HOME/Library/Application Support/Remixer/engine"
npm run typecheck
npm test
PYTHONPATH="$PWD/worker" "$HOME/Library/Application Support/Remixer/engine/.venv/bin/python" -m pytest worker/tests -q
npm run dev

Build and package the native release for the current host (NSIS on Windows, unsigned DMG/ZIP on macOS):

npm run package

build:tutorial uses the owner-authorized base track at the normal Remixer app-data path. A release builder can override it with REMIXER_TUTORIAL_SOURCE. When no local source/archive exists, the script downloads the pinned v0.1.1 release asset and verifies its SHA-256 before packaging. The generated archive stays in build-tools/ and is intentionally not committed as source.

scripts/package.mjs prepares and verifies the platform's pinned private setup tools before selecting DMG/ZIP on macOS or NSIS on Windows. Windows CUDA setup and CF_HDROP clipboard support remain behind platform dispatch. The Windows runtime carries archive-level and per-file SHA-256 manifests and installs the reviewed BS-RoFormer source locally, so setup never depends on Git.

Responsible use

Download only audio you own, material in the public domain or under an appropriate license, or content you otherwise have permission to download. Remixer does not bypass DRM, authentication, geographic restrictions, or access controls. Model licenses and provenance should be reviewed before redistribution or commercial use.

License

Remixer's original source code is licensed under the MIT License. Third-party components, model weights, and audio assets retain their respective licenses; the MIT grant does not relicense them. See Third-party notices for component licenses and provenance.