Open source in Neverlag

Last updated: 26 September 2026

Neverlag plays video with the mpv stack: mpv, FFmpeg, libplacebo and the subtitle libraries around them. Most of it is licensed under the GNU Lesser General Public License (LGPL) 2.1 or later. This page is the notice the LGPL asks for: which components are in the app, in which exact versions, where their source code is, what we changed, how we build them, how you can replace the library, and our written offer to provide the source.

Neverlag itself — the app, its user interface and everything outside the media framework — is not open source. The libraries listed here are, and they stay under their own licences. The licence texts are in the app under Settings → About Neverlag → Legal → Open-source licences, unchanged from the source packages.

Components

Versions as pinned in the build (Vendor/build-scripts/versions.env in the Neverlag repository). Each source link points to exactly that version; the checksum is the SHA-256 of the release archive we build from, or the commit of the tag.

How the libraries are linked — and how to replace them

The libraries (mpv, FFmpeg, libplacebo, FriBidi and the others in the table) are built into one media framework that ships as a separate file inside the app bundle (folder Frameworks) and is loaded when the app starts. The app talks to it through the public libmpv API (client.h, render.h, stream_cb.h and the render_cb.h added by our patch) and through the FFmpeg headers listed below.

Because the framework is a separate, dynamically loaded file, you can replace it with your own build — a different mpv version, your own FFmpeg configuration, a patched libplacebo — as long as it keeps the same interface (LGPL 2.1 §6 b). Build it from the sources and flags on this page, sign it with your own certificate, and put it in place of the shipped framework (Libmpv.framework — on the Mac it is embedded twice: in the app, which uses libavformat for recordings, and in the playback service PlaybackService.xpc, which runs mpv; replace both). On a Mac that is all; on iPhone, iPad and Apple TV the platform additionally requires the whole app bundle to be re-signed with your own developer certificate — a rule of Apple's platform, not of this licence.

Neverlag does not contain the mpv player, only libmpv: no command line, no Lua or JavaScript scripting, no GPL parts. FFmpeg is configured strictly LGPL (--disable-gpl --disable-nonfree --disable-version3), mpv with -Dgpl=false.

What Neverlag changed

FFmpeg, libplacebo, libass, FreeType, FriBidi and HarfBuzz are built from the unmodified release archives. mpv is built with the following changes, published as one patch against the release tarball:

1. meson.build: compile osdep/utils-mac.c on Apple platforms even without Cocoa, because the CoreAudio and AudioUnit outputs reference its string helpers. All platforms.
2. meson.build: allow the VideoToolbox-GL hardware decoding path to build against plain OpenGL instead of requiring the Cocoa or iOS GL back ends. Mac only.
3. A new libmpv render back end "cb" (include/mpv/render_cb.h, video/out/libmpv_cb.c, option -Dlibmpv-cb): it hands the decoded frame to the app without copying it instead of rendering it. Enabled on Apple TV and on iPhone / iPad.

neverlag-mpv-changes.patch — Download: neverlag-mpv-changes.patch (mpv 0.41.0, unified diff, applies with patch -p1). The changes are licensed under the LGPL 2.1 or later like the files they touch.

How we build

All libraries are compiled with Apple clang from Xcode for arm64 (Mac additionally x86_64), deployment targets macOS 14.0, iOS 17.0, tvOS 17.0. TLS goes through the system (SecureTransport); no OpenSSL, GnuTLS or Mbed TLS is linked. The flags below are the ones in the build scripts; lines marked with a platform apply to that platform only.

./configure --enable-static --disable-shared --enable-pic --pkg-config-flags=--static
  --disable-autodetect --disable-gpl --disable-nonfree --disable-version3
  --enable-videotoolbox --enable-audiotoolbox
  --disable-doc --disable-programs --disable-avdevice
  --enable-protocol=file,http,https,tcp,tls,crypto,hls
  --enable-demuxer=mpegts,hls,mov,matroska,mpegps,flv
  --enable-decoder=h264,hevc,mpeg2video,mpeg4,vp9,av1
  --enable-decoder=aac,ac3,eac3,mp2,mp3,opus,flac
  --enable-zlib --enable-securetransport

# iPhone / iPad
  --enable-cross-compile --target-os=darwin --arch=arm64 --sysroot=<iPhoneOS SDK>

# Apple TV
  --enable-cross-compile --target-os=darwin --arch=arm64 --sysroot=<AppleTVOS SDK>

# Mac
  (x86_64 slice: --enable-cross-compile --target-os=darwin --arch=x86_64)

meson setup --default-library static --buildtype release
  -Dlibmpv=true -Dcplayer=false -Dgpl=false -Dtests=false
  -Dcocoa=disabled -Dswift-build=disabled -Dmacos-cocoa-cb=disabled
  -Dmacos-media-player=disabled -Dmacos-touchbar=disabled -Davfoundation=disabled
  -Dlua=disabled -Djavascript=disabled -Duchardet=disabled -Dzimg=disabled -Djpeg=disabled
  -Dlibarchive=disabled -Dlibbluray=disabled -Drubberband=disabled -Dvapoursynth=disabled
  -Dmanpage-build=disabled -Dhtml-build=disabled

# Mac
  -Dplain-gl=enabled -Dvideotoolbox-gl=enabled

# iPhone / iPad
  -Dlibmpv-cb=enabled -Dplain-gl=enabled -Dios-gl=enabled
  -Dvideotoolbox-gl=disabled -Dvideotoolbox-pl=disabled
  -Daudiounit=enabled -Dcoreaudio=disabled

# Apple TV
  -Dlibmpv-cb=enabled -Dgl=disabled -Dplain-gl=disabled -Dios-gl=disabled
  -Dvideotoolbox-gl=disabled -Dvideotoolbox-pl=disabled
  -Daudiounit=enabled -Dcoreaudio=disabled

meson setup --default-library static --buildtype release
  -Dvulkan=disabled -Dd3d11=disabled -Dshaderc=disabled -Dglslang=disabled
  -Dlcms=disabled -Dlibdovi=disabled -Ddemos=false -Dtests=false

# Mac
  -Dopengl=enabled

# iPhone / iPad
  -Dopengl=enabled

# Apple TV
  -Dopengl=disabled

./configure --disable-shared --enable-static --disable-fontconfig

meson setup --default-library static --buildtype release
  -Dharfbuzz=disabled -Dbrotli=disabled -Dbzip2=disabled -Dpng=disabled -Dzlib=system -Dtests=disabled

meson setup --default-library static --buildtype release -Ddocs=false -Dtests=false -Dbin=false

meson setup --default-library static --buildtype release
  -Dfreetype=enabled -Dglib=disabled -Dgobject=disabled -Dcairo=disabled -Dicu=disabled
  -Dtests=disabled -Ddocs=disabled -Dintrospection=disabled -Dutilities=disabled

# Mac
  -Dcoretext=enabled

# iPhone / iPad
  -Dcoretext=enabled

# Apple TV
  -Dcoretext=disabled

libtool -static -o libmpv-full.a libmpv.a libplacebo.a libass.a libharfbuzz.a libfribidi.a libfreetype.a
  libavformat.a libavcodec.a libavfilter.a libswscale.a libswresample.a libavutil.a
clang -dynamiclib -Wl,-all_load libmpv-full.a -install_name @rpath/Libmpv.framework/Libmpv
  -compatibility_version 1 -current_version 1 -Wl,-dead_strip
  -Wl,-exported_symbols_list Libmpv.exports   # _mpv_* _av* _sws_* _swr_* _swscale_* _swresample_*
  -lz -liconv -lc++ -framework VideoToolbox -framework AudioToolbox -framework CoreAudio
  -framework CoreMedia -framework CoreVideo -framework CoreText -framework CoreGraphics
  -framework Security -framework IOSurface -framework CoreFoundation

# Mac
  -arch arm64 -arch x86_64 -mmacosx-version-min=<macOS target> -framework OpenGL
  install_name @rpath/Libmpv.framework/Versions/A/Libmpv (versioned bundle)

# iPhone / iPad
  -target arm64-apple-ios<iOS target> -framework OpenGLES -framework AVFoundation -framework UIKit

# Apple TV
  -target arm64-apple-tvos<tvOS target> -framework AVFoundation -framework UIKit

Written offer (source code)

For at least three years from the date you received your copy of Neverlag, axiena AG will give any third party who asks the complete corresponding machine-readable source code of the LGPL-licensed libraries in exactly the versions the app contains — including all Neverlag modifications (the patch above) and the scripts and configuration used to build them — for a charge no more than our cost of performing this distribution. This offer is made under section 4 and section 6 c of the GNU Lesser General Public License 2.1.

Write to support@neverlag.app or info@axiena.ch and name the app version and platform (Settings → About Neverlag). You will get download links to the archives; if you prefer a physical medium, we will send one at cost.

axiena AG
Einsiedlerstrasse 535
8810 Horgen, Switzerland
support@neverlag.app · info@axiena.ch

Other third-party material

libass (ISC), FreeType (FreeType License), HarfBuzz (MIT), glad (MIT), fast_float (MIT) and GRDB.swift (MIT) require their licence and copyright notices to be reproduced; they are in the app under Open-source licences.

The demo channels play excerpts and trailers of the Blender Open Movies, © Blender Foundation, licensed under Creative Commons Attribution (CC BY 2.5 and 3.0), re-encoded and partly shortened for demo mode.

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