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diff --git a/README.md b/README.md new file mode 100644 index 0000000..813e6df --- /dev/null +++ b/README.md @@ -0,0 +1,347 @@ +# libplacebo + +[](https://code.videolan.org/videolan/libplacebo/pipelines) +[](https://code.videolan.org/videolan/libplacebo/-/jobs/artifacts/master/file/coverage/index.html?job=test-gpu) +[](https://github.com/sponsors/haasn) +[](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=SFJUTMPSZEAHC) +[](https://www.patreon.com/haasn) + +**libplacebo** is, in a nutshell, the core rendering algorithms and ideas of +[mpv](https://mpv.io) rewritten as an independent library. As of today, +libplacebo contains a large assortment of video processing shaders, focusing +on both quality and performance. These include features such as the following: + +- High-quality, optimized **upscaling and downscaling** including support for + polar filters ("Jinc"), anti-aliasing, anti-ringing and gamma correct + scaling. +- Dynamic **HDR tone mapping**, including real-time measurement of scene + histogram, scene change detection, dynamic exposure control, perceptual gamut + stretching, contrast recovery and more. +- Native support for **Dolby Vision HDR**, including Profile 5 conversion to + HDR/PQ or SDR, reading DV side data, and reshaping. (BL only, currently) +- A colorimetrically accurate **color management** engine with support for + soft gamut mapping, ICC profiles, accurate ITU-R BT.1886 emulation, black + point compensation, and custom 3DLUTs (.cube). +- A pluggable, extensible [**custom shader + system**](http://libplacebo.org/custom-shaders/). This can be used to + arbitrarily extend the range of custom shaders to include popular user + shaders like RAVU, FSRCNNX, or Anime4K. See the [mpv wiki on user + scripts](https://github.com/mpv-player/mpv/wiki/User-Scripts#user-shaders) + for more information. +- High performance **film grain synthesis** for AV1 and H.274, allowing media + players to offload this part of decoding from the CPU to the GPU. +- Tunable, fast **debanding** and **deinterlacing** shaders. +- High quality gamma-correct **dithering**, including error diffusion modes. + +Every attempt was made to provide these features at a **high level of +abstraction**, taking away all the messy details of GPU programming, color +spaces, obscure subsampling modes, image metadata manipulation, and so on. +Expert-level functionality is packed into easy-to-use functions like +`pl_frame_from_avframe` and `pl_render_image`. + +### Hardware requirements + +libplacebo currently supports Vulkan (including MoltenVK), OpenGL, and +Direct3D 11. It currently has the following minimum hardware requirements: + +- **Vulkan**: Core version 1.2 +- **OpenGL**: GLSL version >= 130 (GL >= 3.0, GL ES >= 3.0) +- **Direct3D**: Feature level >= 9_1 + +For more documentation, including an introduction to the API, see [the project +website](https://libplacebo.org). + +### Examples + +This screenshot from the included [plplay demo program](./demos/plplay.c) +highlights just some of the features supported by the libplacebo rendering +code, all of which are adjustable dynamically during video playback. + +[<img src="./demos/screenshots/plplay1.png" width="200" alt="plplay settings 1" />](./demos/screenshots/plplay1.png) +[<img src="./demos/screenshots/plplay2.png" width="200" alt="plplay settings 2" />](./demos/screenshots/plplay2.png) +[<img src="./demos/screenshots/plplay3.png" width="200" alt="plplay settings 3" />](./demos/screenshots/plplay3.png) + +[<img src="./demos/screenshots/plplay4.png" width="200" alt="plplay settings 4" />](./demos/screenshots/plplay4.png) +[<img src="./demos/screenshots/plplay5.png" width="200" alt="plplay settings 5" />](./demos/screenshots/plplay5.png) +[<img src="./demos/screenshots/plplay6.png" width="200" alt="plplay settings 6" />](./demos/screenshots/plplay6.png) + +### History + +This project grew out of an interest to accomplish the following goals: + +- Clean up mpv's internal [RA](#tier-1-rendering-abstraction) API and make it + reusable for other projects, as a general high-level backend-agnostic + graphics API wrapper. +- Provide a standard library of useful GPU-accelerated image processing + primitives based on GLSL, so projects like media players or browsers can use + them without incurring a heavy dependency on `libmpv`. +- Rewrite core parts of mpv's GPU-accelerated video renderer on top of + redesigned abstractions, in order to modernize it and allow supporting more + features. + +It has since been adopted by [VLC](https://www.videolan.org/vlc/) as their +optional Vulkan-based video output path, and is provided as a Vulkan-based +video filter in the FFmpeg project. + +## API Overview + +The public API of libplacebo is currently split up into the following +components, the header files (and documentation) for which are available +inside the [`src/include/libplacebo`](src/include/libplacebo) directory. The +API is available in different "tiers", representing levels of abstraction +inside libplacebo. The APIs in higher tiers depend on those in lower tiers. +Which tier is used by a user depends on how much power/control they want over +the actual rendering. The low-level tiers are more suitable for big projects +that need strong control over the entire rendering pipeline; whereas the +high-level tiers are more suitable for smaller or simpler projects that want +libplacebo to take care of everything. + +### Tier 0 (logging, raw math primitives) + +- `cache.h`: Caching subsystem. Used to cache large or computationally heavy + binary blobs, such as compiled shaders, 3DLUTs, and so on. +- `colorspace.h`: A collection of enums and structs for describing color + spaces, as well as a collection of helper functions for computing various + color space transformation matrices. +- `common.h`: A collection of miscellaneous utility types and macros that are + shared among multiple subsystems. Usually does not need to be included + directly. +- `log.h`: Logging subsystem. +- `config.h`: Macros defining information about the way libplacebo was built, + including the version strings and compiled-in features/dependencies. Usually + does not need to be included directly. May be useful for feature tests. +- `dither.h`: Some helper functions for generating various noise and dithering + matrices. Might be useful for somebody else. +- `filters.h`: A collection of reusable reconstruction filter kernels, which + can be used for scaling. The generated weights arrays are semi-tailored to + the needs of libplacebo, but may be useful to somebody else regardless. Also + contains the structs needed to define a filter kernel for the purposes of + libplacebo's upscaling routines. +- `tone_mapping.h`: A collection of tone mapping functions, used for + conversions between HDR and SDR content. +- `gamut_mapping.h`: A collection of gamut mapping functions, used for + conversions between wide gamut and standard gamut content, as well as + for gamut recompression after tone-mapping. + +The API functions in this tier are either used throughout the program +(context, common etc.) or are low-level implementations of filter kernels, +color space conversion logic etc.; which are entirely independent of GLSL +and even the GPU in general. + +### Tier 1 (rendering abstraction) + +- `gpu.h`: Exports the GPU abstraction API used by libplacebo internally. +- `swapchain.h`: Exports an API for wrapping platform-specific swapchains and + other display APIs. This is the API used to actually queue up rendered + frames for presentation (e.g. to a window or display device). +- `vulkan.h`: GPU API implementation based on Vulkan. +- `opengl.h`: GPU API implementation based on OpenGL. +- `d3d11.h`: GPU API implementation based on Direct3D 11. +- `dummy.h`: Dummy GPI API (interfaces with CPU only, no shader support) + +As part of the public API, libplacebo exports a middle-level abstraction for +dealing with GPU objects and state. Basically, this is the API libplacebo uses +internally to wrap OpenGL, Vulkan, Direct3D etc. into a single unifying API +subset that abstracts away state, messy details, synchronization etc. into a +fairly high-level API suitable for libplacebo's image processing tasks. + +It's made public both because it constitutes part of the public API of various +image processing functions, but also in the hopes that it will be useful for +other developers of GPU-accelerated image processing software. + +### Tier 2 (GLSL generating primitives) + +- `shaders.h`: The low-level interface to shader generation. This can be used + to generate GLSL stubs suitable for inclusion in other programs, as part of + larger shaders. For example, a program might use this interface to generate + a specialized tone-mapping function for performing color space conversions, + then call that from their own fragment shader code. This abstraction has an + optional dependency on `gpu.h`, but can also be used independently from it. + +In addition to this low-level interface, there are several available shader +routines which libplacebo exports: + +- `shaders/colorspace.h`: Shader routines for decoding and transforming + colors, tone mapping, and so forth. +- `shaders/custom.h`: Allows directly ingesting custom GLSL logic into the + `pl_shader` abstraction, either as bare GLSL or in [mpv .hook + format](https://mpv.io/manual/master/#options-glsl-shaders). +- `shaders/deinterlacing.h`: GPU deinterlacing shader based on yadif. +- `shaders/dithering.h`: Shader routine for various GPU dithering methods. +- `shaders/film_grain.h`: Film grain synthesis shaders for AV1 and H.274. +- `shaders/icc.h`: Shader for ICC profile based color management. +- `shaders/lut.h`: Code for applying arbitrary 1D/3D LUTs. +- `shaders/sampling.h`: Shader routines for various algorithms that sample + from images, such as debanding and scaling. + +### Tier 3 (shader dispatch) + +- `dispatch.h`: A higher-level interface to the `pl_shader` system, based on + `gpu.h`. This dispatch mechanism generates+executes complete GLSL shaders, + subject to the constraints and limitations of the underlying GPU. + +This shader dispatch mechanism is designed to be combined with the shader +processing routines exported by `shaders/*.h`, but takes care of the low-level +translation of the resulting `pl_shader_res` objects into legal GLSL. It also +takes care of resource binding, shader input placement, as well as shader +caching and resource pooling; and makes sure all generated shaders have unique +identifiers (so they can be freely merged together). + +### Tier 4 (high level renderer) + +- `options.h`: A high-level options framework which wraps all of the options + comprising `pl_render_params` into a memory-managed, serializable struct that + can also be treated as a key/value dictionary. Also includes an options + parser to load options provided by the API user in string format. +- `renderer.h`: A high-level renderer which combines the shader primitives + and dispatch mechanism into a fully-fledged rendering pipeline that takes + raw texture data and transforms it into the desired output image. +- `utils/frame_queue.h`: A high-level frame queuing abstraction. This API + can be used to interface with a decoder (or other source of frames), and + takes care of translating timestamped frames into a virtual stream of + presentation events suitable for use with `renderer.h`, including any extra + context required for frame interpolation (`pl_frame_mix`). +- `utils/upload.h`: A high-level helper for uploading generic data in some + user-described format to a plane texture suitable for use with `renderer.h`. + These helpers essentially take care of picking/mapping a good image format + supported by the GPU. (Note: Eventually, this function will also support + on-CPU conversions to a different format where necessary, but for now, it + will just fail) +- `utils/dav1d.h`: High level helper for translating between Dav1dPicture + and libplacebo's `pl_frame`. (Single header library) +- `utils/libav.h`: High-level helpers for interoperation between + libplacebo and FFmpeg's libav* abstractions. (Single header library) + +This is the "primary" interface to libplacebo, and the one most users will be +interested in. It takes care of internal details such as degrading to simpler +algorithms depending on the hardware's capabilities, combining the correct +sequence of colorspace transformations and shader passes in order to get the +best overall image quality, and so forth. + +## Authors + +libplacebo was founded and primarily developed by Niklas Haas +([@haasn](https://github.com/haasn)), but it would not be possible without the +contributions of others, especially support for windows. + +[](https://github.com/haasn/libplacebo/graphs/contributors) + +### License + +libplacebo is currently available under the terms of the LGPLv2.1 (or later) +license. However, it's possible to release it under a more permissive license +(e.g. BSD2) if a use case emerges. + +Please open an issue if you have a use case for a BSD2-licensed libplacebo. + +## Installing + +### Obtaining + +When cloning libplacebo, make sure to provide the `--recursive``` flag: + +```bash +$ git clone --recursive https://code.videolan.org/videolan/libplacebo +``` + +Alternatively (on an existing clone): + +```bash +$ git submodule update --init +``` + +Doing either of these pulls in a handful of bundled 3rdparty dependencies. +Alternatively, they can be provided via the system. + +### Building from source + +libplacebo is built using the [meson build system](http://mesonbuild.com/). +You can build the project using the following steps: + +```bash +$ DIR=./build +$ meson $DIR +$ ninja -C$DIR +``` + +To rebuild the project on changes, re-run `ninja -Cbuild`. If you wish to +install the build products to the configured prefix (typically `/usr/local/`), +you can run `ninja -Cbuild install`. Note that this is normally ill-advised +except for developers who know what they're doing. Regular users should rely +on distro packages. + +### Dependencies + +In principle, libplacebo has no mandatory dependencies - only optional ones. +However, to get a useful version of libplacebo. you most likely want to build +with support for either `opengl`, `vulkan` or `d3d11`. libplacebo built without +these can still be used (e.g. to generate GLSL shaders such as the ones used in +VLC), but the usefulness is severely impacted since most components will be +missing, impaired or otherwise not functional. + +A full list of optional dependencies each feature requires: + +- **glslang**: `glslang` + its related libraries (e.g. `libSPIRV.so`) +- **lcms**: `liblcms2` +- **libdovi**: `libdovi` +- **opengl**: `glad2` (*) +- **shaderc**: `libshaderc` +- **vulkan**: `libvulkan`, `python3-jinja2` (*) +- **xxhash**: `libxxhash` + +(*) This dependency is bundled automatically when doing a recursive clone. + +#### Vulkan support + +Because the vulkan backend requires on code generation at compile time, +`python3-Jinja2` is a hard dependency of the build system. In addition to this, +the path to the Vulkan registry (`vk.xml`) must be locatable, ideally by +explicitly providing it via the `-Dvulkan-registry=/path/to/vk.xml` option, +unless it can be found in one of the built-in hard-coded locations. + +### Configuring + +To get a list of configuration options supported by libplacebo, after running +`meson $DIR` you can run `meson configure $DIR`, e.g.: + +```bash +$ meson $DIR +$ meson configure $DIR +``` + +If you want to disable a component, for example Vulkan support, you can +explicitly set it to `false`, i.e.: + +```bash +$ meson configure $DIR -Dvulkan=disabled -Dshaderc=disabled +$ ninja -C$DIR +``` + +### Testing + +To enable building and executing the tests, you need to build with +`tests` enabled, i.e.: + +```bash +$ meson configure $DIR -Dtests=true +$ ninja -C$DIR test +``` + +### Benchmarking + +A naive benchmark suite is provided as an extra test case, disabled by default +(due to the high execution time required). To enable it, use the `bench` +option: + +```bash +$ meson configure $DIR -Dbench=true +$ meson test -C$DIR benchmark --verbose +``` + +## Using + +For a full documentation of the API, refer to the above [API +Overview](#api-overview) as well as the [public header +files](src/include/libplacebo). You can find additional examples of how to use +the various components in the [demo programs](demos) as well as in the [unit +tests](src/tests). |