Libva Rust Wrapper

This crate provides lightweight and (hopefully) safe libva abstractions for use within Rust code with minimal dependencies. It is developed for use in ChromeOS, but has no ChromeOS specifics or dependencies and should thus be usable anywhere.

Dependencies

By default (dlopen feature, enabled via default), libva is runtime-loaded via libloading (libva.so.2 / libva-drm.so.2), hence runs on systems without libva installed (e.g. generic distros, CI). Display::open() will simply return None/Err if the libraries cannot be loaded.

For compile-time linking, disable default features:

libva = { version = "0.1", default-features = false }
# or old alias:
# cros-libva = { package = "libva", version = "0.1", default-features = false }

This restores the old pkg-config --libs libva libva-drm link (-lva -lva-drm). You can also explicitly enable linked (alias, currently no-op) to document intent.

Headers are still needed at build time unless vendored is enabled (bundles libva/va/va.h from the submodule). The libva version needs to be 1.20.0 or newer. The VA-API driver corresponding to your hardware is also required: for Intel hardware it will be intel-media-driver, whereas AMD hardware relies on Mesa.

An easy way to see whether everything is in order is to run the vainfo utility packaged with libva-utils or as a standalone package in some distributions. vainfo will print the VA-API version, driver string, and a list of supported profiles and endpoints, i.e.:

vainfo: VA-API version: 1.13 (libva 2.13.0)
vainfo: Driver version: Intel iHD driver for Intel(R) Gen Graphics - 22.2.2 ()
vainfo: Supported profile and entrypoints
      VAProfileNone                   : VAEntrypointVideoProc
      VAProfileNone                   : VAEntrypointStats
      VAProfileMPEG2Simple            : VAEntrypointVLD
      VAProfileMPEG2Simple            : VAEntrypointEncSlice
      VAProfileMPEG2Main              : VAEntrypointVLD
      VAProfileMPEG2Main              : VAEntrypointEncSlice
      VAProfileH264Main               : VAEntrypointVLD
      etc

For decoding, the desired profile must be supported under VAEntrypointVLD. For example, in order to decode VP8 media, this line must be present in the output of vainfo:

      VAProfileVP8Version0_3          : VAEntrypointVLD

Whereas to decode H264 Main profile media, this line must be present:

      VAProfileH264Main               : VAEntrypointVLD

For more information on VA-API and its usage within ChromeOS, see this guide.

cros-libva can also be built in Android. Android.bp files are provided that should work on AOSP >= 15. Just check this repository into external/rust/crates/cros-libva and the libcros_libva library target will be available.

Using

Published as libva (fork of cros-libva to support generic distros + dlopen default). Use directly:

libva = "0.1"
# compat alias for old code:
# cros-libva = { package = "libva", version = "0.1" }

Testing

For a brief introduction on how to use this crate, see the libva_utils_mpeg2vldemo test under src/lib.rs. You can also quickly test MPEG2 decoding by running it:

cargo test -- --ignored libva_utils_mpeg2vldemo

Credits

The first/original version of this crate was written by Daniel Almeida and hosted in the crosvm repository before being split.