# arc-camera **Repository Path**: mirrors_chromium_googlesource/arc-camera ## Basic Information - **Project Name**: arc-camera - **Description**: No description available - **Primary Language**: Unknown - **License**: Not specified - **Default Branch**: main - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2021-03-19 - **Last Updated**: 2025-10-20 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README # Chrome OS Platform Camera The repository hosts the core Chrome OS platform camera components, including: - Camera Hardware Abstraction Layers (HALs) of different platforms - Common dependencies and libraries needed by the camera HALs - [Camera HAL adapter](/hal_adapter) to interface with all the camera clients through Mojo IPC - [Camera conformance test suite](/camera3_test) for the camera HALs [TOC] ## System Overview ![Chrome OS camera stack](/docs/images/cros_camera_stack.png) The camera service provider on Chrome OS is a standalone process that can be divided into two part: - **Platform-specific camera HAL** that interfaces with the kernel drivers and provide all the camera functions through the [**Android camera HAL v3 APIs**]( /android/header_files/include/hardware/libhardware/include/hardware/camera3.h). - **Camera HAL v3 adapter** that provides Mojo IPC interface for all the clients on Chrome OS to access the platform-specific camera HAL. Currently we have two major camera clients on Chrome OS: _Chrome browser_ and _Android container_. All the clients connect to the camera HAL adapter through the [**Camera Module Mojo IPC interface**](/mojo/camera_common.mojom) and the [**Camera Device Mojo IPC interface**](/mojo/camera3.mojom) to access camera functions. The Mojo IPC interface is very similar to the Android camera HAL v3 APIs. ### Camera 3A Library Sandboxing Usually the platform-specific camera HAL is accompanied with a proprietary camera 3A (auto focus, auto exposure, and auto white-balance) library that provides the algorithms to control the camera subsystem for capturing high quality images. We isolate the camera 3A library in a separated sandboxed process for security consideration. The camera HAL accesses the camera 3A library through the [**Camera Algorithm Mojo IPC interface**]( /mojo/algorithm/camera_algorithm.mojom). ### Encoding / Decoding JPEG images The camera HAL needs to generate JPEG images when processing still shot requests. On Chrome OS the JPEG codec service, if supported on the platform, is provided by the GPU process in Chrome browser. We provide libraries to handle JPEG encoding and decoding: On platform that supports hardware-accelerated JPEG encoder/decoder, the JPEG libraries connect to the Chrome GPU process through Mojo IPC channels to encode/decode JPEG images; othewise the JPEG encoding/decoding is done through software. ## Adding a New Camera HAL ### Creating a Camera HAL for Chrome OS The Chrome OS camera HAL are essentially the following shared libraries, plus and dependencies required by them: - `camera_hal.so` that provides the [**camera HAL interface**]( /android/header_files/include/hardware/libhardware/include/hardware/camera_common.h). This is very similar to a regular Android camera HAL. _(Required)_ - `libcam_algo.so` that provides the [**camera algorithm interface**]( include/cros-camera/camera_algorithm.h) for the isolated camera 3A library. _(Required if the camera HAL requires 3A library to work)_. We provide the following packages that are required to build the camera HAL: - `media-libs/cros-camera-android-headers` A package that installs all the necessary Android headers files required by the camera HAL. - `media-libs/cros-camera-libcab` Provides functions to access the isolated camera 3A library if the camera HAL requires it to work. - `media-libs/cros-camera-libcbm` A replacement for Android gralloc. The library provides [APIs]( include/cros-camera/camera_buffer_mapper.h) to import and map buffer handles received in capture requests. - `media-libs/cros-camera-libcamera_client` A port of the Android `libcamera_client`. - `media-libs/cros-camera-libcamera_metadata` A port of the Android `libcamera_metadata`. - `media-libs/cros-camera-libcamera_v4l2_device` Provides functions to access camera V4L2 devices. - `media-libs/libsync` A port of the Android `libsync`. In addition to the required packages, we also have some useful packages that can handle some general functions for the camera HAL: - `media-libs/cros-camera-libcamera_exif` Provides utility functions to fill in the EXIF headers of a JPEG image. - `media-libs/cros-camera-libcamera_jpeg` Provides utility functions to encode JPEG image. - `media-libs/cros-camera-libcamera_timezone` Provides utility functions to get the local timezone. ### Uploading the Camera HAL Source Code To add a new camera HAL for a new platform, one needs to upload the source code of the camera HAL to the [camera HAL directory](/hal). Examples: [**Intel camera HAL**](/hal/intel), [**USB camera HAL**](/hal/usb). ### Adding ebuild Files After the camera HAL source code is uploaded, one needs to add corresponding packages to build and install the camera HAL and the required libraries. On Chrome OS, packages are managed by ebuild files. The following ebuild files are required for a new camera HAL: - A ebuild file for the newly added camera HAL. The ebuild file is used to build and install the platform specific camera HAL and the camera algorithm (`libcam_algo.so`) shared libraries into the board sysroot. To integrate the camera HAL into the OS image, a `virtual/cros-camera-hal` ebuild that includes the newly added camera HAL as `RDEPEND` is required in the baseboard or board overlay. - Camera HAL ebuild examples: [**Intel Kabylake camera HAL**], [**USB camera HAL**] - Camera HAL virtual ebuild example: [**Intel Kabylake camera HAL virtual package**] [**Intel Kabylake camera HAL**]: https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master/chipset-kbl/media-libs/cros-camera-hal-intel-ipu3/ [**USB camera HAL**]: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/master/media-libs/cros-camera-hal-usb/ [**Intel Kabylake camera HAL virtual package**]: https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master/baseboard-poppy/virtual/cros-camera-hal/ - For board-specific camera HAL config files, we have the `virtual/cros-camera-hal-configs` ebuild. One can add a new ebuild to install the board-specific camera HAL config files, and list the new ebuild as `RDEPEND` of the virtual ebuild. - Camera HAL config ebuild example: [**Intel Kabylake camera HAL configs**] - Camera HAL config virtual ebuild example: [**Intel Kabylake camera HAL configs virtual package**] [**Intel Kabylake camera HAL configs**]: https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master/baseboard-poppy/media-libs/cros-camera-hal-configs-poppy/ [**Intel Kabylake camera HAL configs virtual package**]: https://chromium.googlesource.com/chromiumos/overlays/board-overlays/+/master/baseboard-poppy/virtual/cros-camera-hal-configs/