iptvnator/tools/embedded-mpv/README.md

Embedded MPV Runtime

This directory owns the source builders, staging, manifests, and archive helpers for IPTVnator's experimental Embedded MPV runtime.

The Linux architecture has a strict process boundary:

• Electron, embedded_mpv.node, and embedded_mpv_frame_reader.node must not load or link libmpv.
• Native-view starts a separate system mpv --wid process.
• Frame-copy starts iptvnator_mpv_helper; only that helper may link libmpv.

Do not weaken this boundary to simplify packaging. A missing helper/runtime must make frame-copy unavailable and leave native-view as the safe x64 fallback.

Runtime Policy

Release builds use an LGPL-compatible, dynamically linked runtime:

• FFmpeg is built without --enable-gpl and --enable-nonfree.
• mpv is built with -Dlibmpv=true and -Dgpl=false.
• Bundled libraries remain individually replaceable under native/lib.
• Exact source URLs, versions, checksums or git commits, submodules, licenses, build flags, local patches, and build scripts are published with the release.

Homebrew mpv is local-development-only. It requires IPTVNATOR_EMBEDDED_MPV_ALLOW_HOMEBREW=1, and release validation rejects it.

Generated Layout

vendor/embedded-mpv/
  darwin-arm64/
    include/mpv/client.h
    lib/*.dylib
    runtime-manifest.json
  darwin-x64/
    include/mpv/client.h
    lib/*.dylib
    runtime-manifest.json
  win32-x64/
    include/mpv/client.h
    lib/libmpv-2.dll        # accepted basename variants are preserved
    lib/libmpv.dll.a        # or an MSVC import library
    runtime-manifest.json
  linux-x64/
    include/mpv/client.h
    lib/libmpv.so
    lib/libmpv.so.2
    lib/<declared closure>
    notices/embedded-mpv-notices.json
    notices/THIRD_PARTY_NOTICES.txt
    notices/licenses/<package>/<upstream path>
    runtime-manifest.json

These directories are generated release inputs and are ignored by git. runtime-manifest.json is the profile-neutral source/build manifest. Packaging writes a normalized embedded-mpv-runtime.json beside the native artifacts. Bundled Linux profiles flatten the three notice entries from notices/ into that same native directory; system and marker-only profiles remove them.

Building And Staging

Stage an existing compatible prefix with:

pnpm embedded-mpv:stage-runtime -- darwin arm64 /path/to/prefix
pnpm embedded-mpv:stage-runtime -- darwin x64 /path/to/prefix
pnpm embedded-mpv:stage-runtime -- win32 x64 /path/to/prefix
pnpm embedded-mpv:stage-runtime -- linux x64 /path/to/prefix

Build the pinned macOS or Linux source runtime first when no prefix exists:

pnpm embedded-mpv:build-runtime -- arm64 /tmp/macos-prefix
pnpm embedded-mpv:stage-runtime -- darwin arm64 /tmp/macos-prefix

pnpm embedded-mpv:build-runtime:linux -- /tmp/linux-prefix
pnpm embedded-mpv:stage-runtime -- linux x64 /tmp/linux-prefix

The Linux builder runs only on Linux x64. It requires the tool versions and system development interfaces declared in build-linux-runtime.cjs, including Meson 1.6 or newer, gperf 3.1 or newer, Ninja, CMake, NASM, pkg-config, patchelf, and readelf. It builds into an owned staging directory and publishes atomically, so it will not delete or overwrite an arbitrary destination.

The pinned Linux source stack currently includes FFmpeg 8.1, mpv 0.41.0, libplacebo 7.360.1, libass 0.17.3, FreeType 2.13.3, FriBidi 1.0.16, HarfBuzz 8.5.0, Expat 2.8.2, Fontconfig 2.16.0, OpenSSL 3.5.7, hwdata 0.409, and libdisplay-info 0.1.1. The builder stages a private pinned pnp.ids/hwdata.pc; libdisplay-info is not allowed to consume the build host's /usr/share/hwdata.

Before publication, the Linux builder verifies:

• every archive digest and git/submodule commit;
• the exact FFmpeg/mpv flags and LGPL policy;
• an exact libmpv.so.2 SONAME and complete reachable shared-library closure;
• $ORIGIN RUNPATHs with no build-prefix paths or undeclared host fallback;
• the external system-library allowlist;
• GLIBC_2.35 and GLIBCXX_3.4.30 ABI ceilings;
• file hashes, byte sizes, build inputs, licenses, and source obligations.

Linux Package Profiles

Set one exact IPTVNATOR_LINUX_FRAME_COPY_PROFILE per packaging pass:

Profile	Formats	Runtime handling
system	DEB, RPM, Pacman	Remove native/lib; require the format-specific system runtime listed below
portable	AppImage, Snap	Retain the pinned LGPL closure under native/lib
flatpak	Flatpak	Retain the same pinned LGPL closure under native/lib

The system helper directly links libmpv, EGL, GL, and GBM. Package metadata therefore declares the full interface set:

• DEB: libmpv2, libegl1, libgl1, libgbm1
• RPM: mpv-libs, libglvnd-egl, libglvnd-glx, mesa-libgbm
• Pacman: mpv, libglvnd, mesa

The helper links libGL.so.1 (-lGL) rather than libOpenGL.so.0; the former is the direct GL interface supplied by all three system contracts and Snap's mesa-core22.

The DEB metadata is release-tested on Ubuntu 24.04 (Noble). Ubuntu 22.04 (Jammy) only provides libmpv1; use the x64 AppImage on that distribution rather than relaxing the runtime contract. CI explicitly installs the distro Mesa software renderer for headless smoke. IPTVnator does not add DRI-driver packages as direct dependencies; any transitive graphics-driver stack remains under the distro's dependency policy.

The Snap is base: core22 with strict confinement. It retains Electron Builder's default plugs and adds an auto-connected private shared-memory plug plus graphics-core22, targeting a real empty mode-0755 $SNAP/graphics with external mesa-core22 as default provider. The graphics provider supplies EGL/GL/GLX/GBM/DRM/VA, while Electron Builder's exact GNOME content runtime supplies ALSA/PulseAudio. Neither provider is bundled into IPTVnator's Snap, source archive, notices, or package-size accounting. The package hook creates the empty content target because core22 does not synthesize one; the extracted artifact verifier rejects a missing, redirected, non-empty, or wrongly permissioned target. Snap metadata must also contain exactly the canonical graphics-provider layouts: bind /usr/share/libdrm from $SNAP/graphics/libdrm, and symlink /usr/share/drirc.d to $SNAP/graphics/drirc.d.

The bounded probe and every playback helper share one sanitized loader environment derived from the validated, cached runtime mode. Ambient ELF audit/preload/origin/library overrides, direct EGL/GBM/GL/VA/Vulkan paths, shell startup/options, tracing hooks, exported Bash functions, and caller-provided architecture triplets are removed or replaced. The extracted-artifact verifier uses the same deny-set for its direct helper smoke and preserves feature/debug selectors such as LIBGL_ALWAYS_SOFTWARE. System packages then use the default loader; bundled packages put their validated native/lib first. Packaged addon/helper lookup is package-owned app.asar.unpacked only; cwd/dist candidates are development-only. AppImage and Flatpak use normal host/sandbox lookup for the declared external interfaces. Inside the exact packaged Flatpak /app context, the helper reconstructs only Freedesktop Platform 24.08's immutable __EGL_EXTERNAL_PLATFORM_CONFIG_DIRS value; the GL extension's add-ld-path remains available through the sandbox loader cache. Flatpak CI therefore invokes flatpak run com.fourgray.iptvnator --embedded-mpv-runtime-probe instead of executing the helper around the application gate. In a genuine Snap mount, filtered SNAP_LIBRARY_PATH GL roots under /var/lib/snapd/lib/gl come next, then the fixed x64 $SNAP/graphics roots, then exact $SNAP/gnome-platform graphics/audio roots, and finally generic $SNAP library roots. The helper rebuilds GBM, GL/VA driver, EGL vendor/platform, and Vulkan layer variables from those trusted locations. A Linux session without the validated cached mode is rejected before spawn. Both the bounded probe and playback execute through $SNAP/graphics/bin/graphics-core22-provider-wrapper. The graphics mount must be a real directory and the wrapper a regular, non-symlinked, readable executable. Otherwise the gate returns the stable snap-graphics-provider-unavailable reason before spawning the helper. The wrapper child also drops shell startup/options, tracing hooks, and exported BASH_FUNC_* functions, and uses a fixed core22 system PATH; ambient Bash configuration therefore cannot replace the probe before helper execution.

Installed-Snap CI disconnects graphics-core22, requires the application-level diagnostic to emit snap-graphics-provider-unavailable and exit with the controlled status 1, then reconnects the provider and requires a successful diagnostic. This keeps the canonical layouts and missing-provider fallback in the same regression contract.

Profiles cannot share one Electron Builder pass because its targets reuse the same unpacked application directory. A missing or unsupported profile, or a target from another profile, fails packaging.

Linux frame-copy release artifacts are x64-only. Non-x64 packages are always marker-only even if environment variables point at the x64 staged runtime.

Build Integration

apps/electron-backend/build-embedded-mpv.js builds the addon, frame reader, and helper against the staged inputs. On Linux it links the helper to the verified staged libmpv path rather than a generic host -lmpv, then checks with readelf that:

• the helper has exactly the declared libmpv DT_NEEDED;
• the helper RUNPATH is $ORIGIN/lib;
• the addon and frame reader have no libmpv dependency;
• no runtime dependency contains an absolute/build-prefix loader path.

The package hook copies native artifacts into app.asar.unpacked/electron-backend/native/, selects the system or bundled layout, restores exact file modes, writes the packaged manifest, and validates the bundled legal payload. AppImage, Snap, and Flatpak receive embedded-mpv-notices.json, THIRD_PARTY_NOTICES.txt, and licenses/<package>/**; DEB, RPM, Pacman, and marker-only packages must not retain them. Package validation also scans the Electron executable and all shipped Electron libraries for a direct libmpv dependency. Before target packaging, that scan is recursive over the pristine Electron tree. After Snap has merged its template runtime into the payload root, the post-target scan excludes exactly its package-manager lib/** and usr/lib/** trees while remaining recursive everywhere else.

At startup, Linux x64 frame-copy is advertised only after the main process validates that manifest/files and successfully executes:

iptvnator_mpv_helper --runtime-probe

The bounded probe initializes idle libmpv plus EGL/OpenGL and mpv render contexts, then creates, maps, validates, and destroys a minimal 16x16 shared-memory ring named /impv-fc-runtime-probe-<pid>. It does not open media or enter media/command loops. A timeout, loader failure, malformed protocol, missing file, hash mismatch, unusable graphics path, or shm lifecycle failure returns a stable reason and keeps the BrowserWindow sandbox enabled. The application diagnostic retains helper-probe-failed as the top-level reason for nonzero helper exits and adds helperReason only when the helper emitted one exact protocol-v1 line with a fixed allowlisted reason. The installed-Snap probe therefore tests the private shared-memory confinement needed by playback rather than only loader and graphics startup. Packaging CI invokes the same gate through snap run iptvnator --embedded-mpv-runtime-probe. This packaging-only application switch runs before BrowserWindow startup, emits one availability JSON line, and returns zero only for a usable runtime; it never directly loads libmpv in Electron.

Electron Builder excludes electron-backend/native{,/**/*} from app.asar. Only afterPack writes the profile-normalized app.asar.unpacked/electron-backend/native tree. Layout and final-artifact verification enumerate app.asar and reject any stale native entry, preventing hidden x64 helpers, bundled libraries, or notices in system and marker-only packages.

CI And Source Distribution

Linux CI builds or restores the pinned source runtime once, then packages and verifies system, portable, and flatpak independently. Every artifact is extracted for manifest, mode, package-metadata, ELF-isolation, and helper-probe checks. System formats are probed after their declared dependency is installed; Snap and Flatpak also require a sandboxed probe where the runner supports it. For a locally installed --dangerous Snap, CI explicitly installs and connects mesa-core22 and gnome-3-28-1804, verifies both connections, and then runs the application-level diagnostic under Xvfb. The Linux packaging matrix alone depends on the runtime-builder job. macOS and Windows use an independent matrix, while both matrices share the same anchored step list; draft release assembly remains atomic and requires both matrices.

The Linux runtime cache contains only staged headers/libraries/manifest plus immutable source inputs: exact downloaded archives (including hwdata), a clean recursive libplacebo checkout, and collected license files. It never caches finished notices or the compliance tarball. After either a build or cache hit, CI revalidates those inputs, regenerates vendor/embedded-mpv/linux-x64/notices for the current runtime manifest, and creates linux-frame-copy-runtime-sources.tar.xz for the current repository revision/diff. Before archiving, the clean cached libplacebo checkout is converted into a non-dereferenced working-tree snapshot with every .git entry removed; the validated main/submodule commits remain in the source index.

That source-compliance archive uses normalized tar metadata and contains the exact unique archive hash set, VCS-free libplacebo sources and recursive submodules, license inputs, generated notices, runtime/source index metadata, and the builder, stager, manifest, notice-generator, and source-snapshot code. The notice generator rejects missing, undeclared, symlinked, size-mismatched, or hash-mismatched license files.

Snap publication is a separate release.published workflow for public v* GitHub releases. It verifies that the public release already contains at least one Snap and exactly one non-empty linux-frame-copy-runtime-sources.tar.xz before uploading anything. The workflow uploads only to the Store's edge channel. Candidate/stable promotion is manual after installed-Snap frame-copy and missing-runtime fallback smoke; GitHub Actions never promotes automatically.

Windows CI stages a checksum-pinned x64 LGPL archive. The DLL basename encoded in its import library is preserved and must be present beside iptvnator_mpv_helper.exe. Tagged releases require explicit repository configuration; the public fallback is for non-tag artifacts only. The upstream keeps only its latest 30 daily builds, so the fallback URL and checksum plus any matching repository variables must be refreshed as one pair before they age out. A permanent mirror must publish the corresponding source/build records and license notices with the binary.

Local Development

Linux can use distribution development packages for an unshipped local build (libmpv-dev, EGL/GL/GBM development files, and X11 headers). Overrides: LIBMPV_INCLUDE_DIR selects the header root. LINUX_NATIVE_LIBRARY_DIR selects a link-time library directory that must already be visible to the system dynamic loader; it is not inherited as a helper LD_LIBRARY_PATH. Required/release package builds must use the pinned staged runtime and manifest.

On macOS:

pnpm run serve:backend:embedded-mpv

This explicitly permits Homebrew for the local native build and enables the experiment. It is not a release path.

See docs/architecture/embedded-mpv-native.md for the runtime capability, fallback, controls, and packaged-release contracts.