# 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
The native [libva](https://github.com/intel/libva) library is required at link
time, so make sure to have the `libva-dev` or equivalent package for your
distribution installed. The VA-API driver corresponding to your hardware is
also required: for Intel hardware it will be
[intel-media-driver](https://github.com/intel/media-driver), whereas AMD
hardware relies on [Mesa](https://gitlab.freedesktop.org/mesa/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](https://chromium.googlesource.com/chromium/src/+/master/docs/gpu/vaapi.md).
## Using
The name of this crate is `cros-libva` to highlight the fact that it originates
from ChromeOS and it not an official bindings. For ease of use, it is
recommended to rename it to just `libva` in your project by using the following
line in your `Cargo.toml`:
```
libva = { package = "cros-libva", version = "0.0.1" }
```
## 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 version of this crate was written by Daniel Almeida and hosted in the
[crosvm repository](https://chromium.googlesource.com/crosvm/crosvm/) before
being split.