feat(moq-video): opt-out nvenc/vaapi features (default-on) + correct libva docs#1860
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The VAAPI backend comments (vaapi.rs, Cargo.toml) and DESIGN-native-codecs.md
claimed moq-vaapi dlopens libva, so a VAAPI-enabled Linux binary "builds
without system libva-dev" and "loads on machines without libva, falling back
to software." That is false for the published moq-vaapi 0.0.2 we depend on.
Verified in a Linux (rust:latest) container:
- Building a crate that depends on moq-vaapi 0.0.2 WITHOUT libva-dev fails at
`pkg-config ... libva` ("system library `libva` required by crate `moq-vaapi`
was not found"). So it does NOT build without libva-dev.
- With libva-dev, the linked binary carries `NEEDED libva.so.2` and
`NEEDED libva-drm.so.2` (readelf -d). So a libva-less host fails to load the
binary, before `backend::open` can fall back to openh264.
moq-vaapi 0.0.2's build.rs uses `pkg_config::probe("libva")` /
`probe("libva-drm")` (a hard link), and there is no dlopen anywhere in its
source. The dlopen design documented for the old cros-codecs `vaapi_dlopen`
git dep was lost when moq-vaapi was extracted to a published crate.
Correct the three spots to describe the current behavior and flag the dlopen
restoration as tracked in #1837. The no-GPU case (libva present, no usable VA
driver) still falls back cleanly: `Encoder::new` returns an error that
`backend::open` skips past. No code behavior change.
This reframes the "VAAPI driver-probe" box on #1837: the NVENC-style probe
does not apply (moq-vaapi links rather than dlopens, and its init returns a
`Result` rather than panicking), so the real fix is making moq-vaapi dlopen
libva.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
24 tasks
#1819 made the NVENC/VAAPI hardware encoders always-on for Linux, which also made libva a hard runtime dependency of every Linux moq-video binary (moq-vaapi 0.0.2 links libva: NEEDED libva.so.2 / libva-drm.so.2). Give self-compilers a way to drop the CUDA / libva deps without changing the default. moq-video: reintroduce `nvenc` and `vaapi` features (the Linux deps become optional), both in `default`, gating the backend modules + candidates with `#[cfg(all(target_os = "linux", feature = ...))]`. Default builds are unchanged; `--no-default-features` (or dropping one feature) builds without the corresponding dep. openh264 stays the always-compiled software fallback and V4L2 capture is unaffected. Consumers: the workspace moq-video dep is now `default-features = false` (mirroring moq-native), so each binary opts in. libmoq and moq-boy enable both encoders; moq-cli exposes default-on `nvenc`/`vaapi` passthroughs so a `capture` build can drop them: cargo build -p moq-cli --no-default-features --features "iroh quinn websocket capture" Verified: macOS builds all affected crates (features are no-ops off Linux); a Linux container compiles `moq-video --no-default-features` WITHOUT libva-dev and the default (nvenc+vaapi) WITH it; `cargo tree` confirms the feature resolution for every consumer scenario. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
kixelated
changed the title
…UDA/libva) Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Summary
Two related changes around how the Linux hardware encoders (NVENC / VAAPI) pull in system deps. Came out of the #1837 "VAAPI driver-probe" box.
1. Default-on
nvenc/vaapifeatures (the opt-out)#1819 made NVENC/VAAPI always-on for Linux, which also made libva a hard runtime dependency of every Linux
moq-videobinary —moq-vaapi 0.0.2links libva (NEEDED libva.so.2/libva-drm.so.2), so a libva-less host can't even load the binary. We're keeping that default (libva is near-universal on Linux GPU boxes), but giving self-compilers a way to drop the CUDA / libva deps.nvencandvaapifeatures (the Linux deps becomeoptional), both indefault. Backend modules + candidates gated with#[cfg(all(target_os = "linux", feature = ...))]. openh264 stays the always-compiled software fallback; V4L2 capture is unaffected. Features are no-ops off Linux.moq-videodep is nowdefault-features = false(mirroring the existingmoq-nativepattern), so each binary opts in.libmoq/moq-boyenable both;moq-cliexposes default-onnvenc/vaapipassthroughs so acapturebuild can drop them:Default builds everywhere are byte-for-byte the same as before — this is purely additive (a new way to turn things off).
2. Correct the libva docs (no code change)
The
vaapi.rs+Cargo.tomlcomments andDESIGN-native-codecs.mdclaimed moq-vaapi dlopens libva ("builds without system libva-dev", "loads on machines without libva"). That's false formoq-vaapi 0.0.2, which links it. Corrected to describe the real behavior + the now-default-on feature.Evidence (podman,
rust:latest)moq-vaapi 0.0.2without libva-dev → build fails atpkg-config ... libva; with it, the binary carriesNEEDED libva.so.2+libva-drm.so.2(readelf -d). So it links, not dlopens.cargo check -p moq-video --no-default-features→ succeeds without libva-dev (the opt-out works); the default (nvenc+vaapi) compiles with libva-dev.Why this isn't the NVENC-style "driver-probe" from #1837
moq-vaapi links libva and its
Encoder::newreturns aResult(no panic), so — unlike NVENC (which dlopens +panic!s, hence the #1844 probe) — a libva-less box fails at process load, before any probe could run, and the no-GPU case already falls back cleanly. The real "dlopen libva" fix lives in themoq-dev/vaapicrate; this PR makes the dep optional in the meantime. Issue #1837 reframed accordingly.Test plan
cargo checkfor moq-video / moq-cli (default +--features capture) / libmoq / moq-boy all pass;cargo test -p moq-videogreen.moq-video --no-default-featuresbuilds with no libva-dev; default builds with it.cargo treeconfirms feature resolution:moq-cli --features capture→ moq-videonvenc,vaapi;--no-default-features ... capture→ none;... capture nvenc→nvenconly; libmoq/moq-boy →nvenc,vaapi.cargo fmt+taplo format --checkclean (via nix).Cross-package sync
No JS mirror (native-only). Docs touched:
DESIGN-native-codecs.md. Themoq-cliflags doc may want a note about the new--no-default-featuresopt-out, but no example invocation changed.(Written by Claude)