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# dav1d
**dav1d** is a new **AV1** cross-platform **d**ecoder, open-source, and focused on speed and correctness.
The canonical repository URL for this repo is https://code.videolan.org/videolan/dav1d
This project is partially funded by the *Alliance for Open Media*/**AOM**.
## Goal and Features
The goal of this project is to provide a decoder for **most platforms**, and achieve the **highest speed** possible to overcome the temporary lack of AV1 hardware decoder.
It supports all features from AV1, including all subsampling and bit-depth parameters.
In the future, this project will host simple tools or simple wrappings *(like, for example, an MFT transform)*.
## License
**dav1d** is released under a very liberal license, a contrario from the other VideoLAN projects, so that it can be embedded anywhere, including non-open-source software; or even drivers, to allow the creation of hybrid decoders.
The reasoning behind this decision is the same as for libvorbis, see [RMS on vorbis](https://lwn.net/2001/0301/a/rms-ov-license.php3).
# Roadmap
The plan is the folllowing:
### Reached
1. Complete C implementation of the decoder,
2. Provide a usable API,
3. Port to most platforms,
4. Make it fast on desktop, by writing asm for AVX-2 chips.
5. Make it fast on mobile, by writing asm for ARMv8 chips,
6. Make it fast on older desktop, by writing asm for SSSE3+ chips.
### On-going
7. Make it fast on older mobiles, by writing asm for ARMv7 chips,
8. Improve C code base with [various tweaks](https://code.videolan.org/videolan/dav1d/wikis/task-list),
9. Accelerate for less common architectures, like PPC, SSE2 or AVX-512.
### After
10. Use more GPU, when possible.
# Contribute
Currently, we are looking for help from:
- C developers,
- asm developers,
- platform-specific developers,
- GPGPU developers,
- testers.
Our contributions guidelines are quite strict. We want to build a coherent codebase to simplify maintenance and achieve the highest possible speed.
Notably, the codebase is in pure C and asm.
We are on IRC, on the **#dav1d** channel on *Freenode*.
See the [contributions document](CONTRIBUTING.md).
## CLA
There is no CLA.
People will keep their copyright and their authorship rights, while adhering to the BSD 2-clause license.
VideoLAN will only have the collective work rights.
## CoC
The [VideoLAN Code of Conduct](https://wiki.videolan.org/CoC) applies to this project.
# Compile
1. Install [Meson](https://mesonbuild.com/) (0.47 or higher), [Ninja](https://ninja-build.org/), and, for x86\* targets, [nasm](https://nasm.us/) (2.14 or higher)
2. Run `mkdir build && cd build` to create a build directory and enter it
3. Run `meson ..` to configure meson, add `--default-library=static` if static linking is desired
4. Run `ninja` to compile
# Run tests
1. In the root directory, run `git clone https://code.videolan.org/videolan/dav1d-test-data.git tests/dav1d-test-data` to fetch the test data repository
2. During meson configuration, specify `-Dtestdata_tests=true`
3. Run `meson test -v` after compiling
# Support
This project is partially funded by the *Alliance for Open Media*/**AOM** and is supported by TwoOrioles and VideoLabs.
These companies can provide support and integration help, should you need it.
# FAQ
## Why do you not improve libaom rather than starting a new project?
- We believe that libaom is a very good library. It was however developed for research purposes during AV1 design.
We think that an implementation written from scratch can achieve faster decoding, in the same way that *ffvp9* was faster than *libvpx*.
## Is dav1d a recursive acronym?
- Yes.
## Can I help?
- Yes. See the [contributions document](CONTRIBUTING.md).
## I am not a developer. Can I help?
- Yes. We need testers, bug reporters, and documentation writers.
## What about the AV1 patent license?
- This project is an implementation of a decoder. It gives you no special rights on the AV1 patents.
Please read the [AV1 patent license](doc/PATENTS) that applies to the AV1 specification and codec.
## Will you care about <my_arch>? <my_os>?
- We do, but we don't have either the time or the knowledge. Therefore, patches and contributions welcome.
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