@@ -76,3 +76,34 @@ The camera stack comprises four software layers. From bottom to top:
* The applications and upper level frameworks are based on the
libcamera framework or libcamera adaptation, and are outside of
the scope of the libcamera project.
+
+V4L2 Compatibility Layer
+ V4L2 compatibility is achieved through a shared library that traps all
+ accesses to camera devices and routes them to libcamera to emulate high-level
+ V4L2 camera devices. It is injected in a process address space through
+ ``LD_PRELOAD`` and is completely transparent for applications.
+
+ The compatibility layer exposes camera device features on a best-effort basis,
+ and aims for the level of features traditionally available from a UVC camera
+ designed for video conferencing.
+
+Android Camera HAL
+ Camera support for Android is achieved through a generic Android camera HAL
+ implementation on top of libcamera. The HAL implements features required by
+ Android and out of scope from libcamera, such as JPEG encoding support.
+
+ This component is used to provide support for ChromeOS platforms
+
+GStreamer element (gstlibcamerasrc)
+ A `GStreamer element`_ is provided to allow capture from libcamera supported
+ devices through GStreamer pipelines, and connect to other elements for further
+ processing.
+
+ Development of this element is ongoing and is limited to a single stream.
+
+Native libcamera API
+ Applications can make use of the libcamera API directly using the C++
+ API. An example application and walkthrough using the libcamera API can be
+ followed in the :doc:`Application writer's guide </guides/application-developer>`
+
+.. _GStreamer element: https://gstreamer.freedesktop.org/documentation/application-development/basics/elements.html
@@ -26,10 +26,8 @@ desirable results from the camera.
.. _Media Controller: https://www.linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/mediactl/media-controller.html
-In this developers guide, we will explore the `Camera Stack`_ and how it is
-can be visualised at a high level. The current `Platform Support`_ is
-detailed, as well as an overview of the `Licensing`_ requirements of the
-project.
+In this developers guide the current `Platform Support`_ is detailed, as well as
+an overview of the `Licensing`_ requirements of the project.
This introduction is followed by a walkthrough tutorial to newcomers wishing to
support a new platform with the `Pipeline Handler Writers Guide`_ and for those
@@ -41,112 +39,6 @@ provides a tutorial of the key APIs exposed by libcamera.
.. TODO: Correctly link to the other articles of the guide
-Camera Stack
-------------
-
-The libcamera library is implemented in userspace, and makes use of underlying
-kernel drivers that directly interact with hardware.
-
-Applications can make use of libcamera through the native `libcamera API`_'s or
-through an adaptation layer integrating libcamera into a larger framework.
-
-.. _libcamera API: https://www.libcamera.org/api-html/index.html
-
-::
-
- Application Layer
- / +--------------+ +--------------+ +--------------+ +--------------+
- | | Native | | Framework | | Native | | Android |
- | | V4L2 | | Application | | libcamera | | Camera |
- | | Application | | (gstreamer) | | Application | | Framework |
- \ +--------------+ +--------------+ +--------------+ +--------------+
-
- ^ ^ ^ ^
- | | | |
- | | | |
- v v | v
- Adaptation Layer |
- / +--------------+ +--------------+ | +--------------+
- | | V4L2 | | gstreamer | | | Android |
- | | Compatibility| | element | | | Camera |
- | | (preload) | |(libcamerasrc)| | | HAL |
- \ +--------------+ +--------------+ | +--------------+
- |
- ^ ^ | ^
- | | | |
- | | | |
- v v v v
- libcamera Framework
- / +--------------------------------------------------------------------+
- | | |
- | | libcamera |
- | | |
- \ +--------------------------------------------------------------------+
-
- ^ ^ ^
- Userspace | | |
- --------------------- | ---------------- | ---------------- | ---------------
- Kernel | | |
- v v v
-
- +-----------+ +-----------+ +-----------+
- | Media | <--> | Video | <--> | V4L2 |
- | Device | | Device | | Subdev |
- +-----------+ +-----------+ +-----------+
-
-The camera stack comprises of four software layers. From bottom to top:
-
-* The kernel drivers control the camera hardware and expose a low-level
- interface to userspace through the Linux kernel V4L2 family of APIs
- (Media Controller API, V4L2 Video Device API and V4L2 Subdev API).
-
-* The libcamera framework is the core part of the stack. It handles all control
- of the camera devices in its core component, libcamera, and exposes a native
- C++ API to upper layers.
-
-* The libcamera adaptation layer is an umbrella term designating the components
- that interface to libcamera in other frameworks. Notable examples are the V4L2
- compatibility layer, the gstreamer libcamera element, and the Android camera
- HAL implementation based on libcamera which are provided as a part of the
- libcamera project.
-
-* The applications and upper level frameworks are based on the libcamera
- framework or libcamera adaptation, and are outside of the scope of the
- libcamera project, however example native applications (cam, qcam) are
- provided for testing.
-
-
-V4L2 Compatibility Layer
- V4L2 compatibility is achieved through a shared library that traps all
- accesses to camera devices and routes them to libcamera to emulate high-level
- V4L2 camera devices. It is injected in a process address space through
- ``LD_PRELOAD`` and is completely transparent for applications.
-
- The compatibility layer exposes camera device features on a best-effort basis,
- and aims for the level of features traditionally available from a UVC camera
- designed for video conferencing.
-
-Android Camera HAL
- Camera support for Android is achieved through a generic Android camera HAL
- implementation on top of libcamera. The HAL implements features required by
- Android and out of scope from libcamera, such as JPEG encoding support.
-
- This component is used to provide support for ChromeOS platforms
-
-GStreamer element (gstlibcamerasrc)
- A `GStreamer element`_ is provided to allow capture from libcamera supported
- devices through GStreamer pipelines, and connect to other elements for further
- processing.
-
- Development of this element is ongoing and is limited to a single stream.
-
-Native libcamera API
- Applications can make use of the libcamera API directly using the C++
- API. An example application and walkthrough using the libcamera API can be
- followed in the `Application Writers Guide`_
-
-.. _GStreamer element: https://gstreamer.freedesktop.org/documentation/application-development/basics/elements.html
-
Platform Support
----------------
The Camera Stack section of the introduction is largely a duplicate of the section broken out from docs.rst. Remove it from the introduction.rst file and consolidate anything that wasn't duplicated into camera_stack.rst. Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com> --- Documentation/camera_stack.rst | 31 +++++++ Documentation/guides/introduction.rst | 112 +------------------------- 2 files changed, 33 insertions(+), 110 deletions(-)