1 .. SPDX-License-Identifier: GPL-2.0
3 The Virtual Media Controller Driver (vimc)
4 ==========================================
6 The vimc driver emulates complex video hardware using the V4L2 API and the Media
7 API. It has a capture device and three subdevices: sensor, debayer and scaler.
12 The topology is hardcoded, although you could modify it in vimc-core and
13 recompile the driver to achieve your own topology. This is the default topology:
15 .. _vimc_topology_graph:
17 .. kernel-figure:: vimc.dot
18 :alt: Diagram of the default media pipeline topology
21 Media pipeline graph on vimc
23 Configuring the topology
24 ~~~~~~~~~~~~~~~~~~~~~~~~
26 Each subdevice will come with its default configuration (pixelformat, height,
27 width, ...). One needs to configure the topology in order to match the
28 configuration on each linked subdevice to stream frames through the pipeline.
29 If the configuration doesn't match, the stream will fail. The ``v4l-utils``
30 package is a bundle of user-space applications, that comes with ``media-ctl`` and
31 ``v4l2-ctl`` that can be used to configure the vimc configuration. This sequence
32 of commands fits for the default topology:
36 media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
37 media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
38 media-ctl -d platform:vimc -V '"Sensor B":0[fmt:SBGGR8_1X8/640x480]'
39 media-ctl -d platform:vimc -V '"Debayer B":0[fmt:SBGGR8_1X8/640x480]'
40 v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
41 v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
42 v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81
47 Subdevices define the behavior of an entity in the topology. Depending on the
48 subdevice, the entity can have multiple pads of type source or sink.
51 Generates images in several formats using video test pattern generator.
57 Transforms images in bayer format into a non-bayer format.
64 Re-size the image to meet the source pad resolution. E.g.: if the sync
65 pad is configured to 360x480 and the source to 1280x720, the image will
66 be stretched to fit the source resolution. Works for any resolution
67 within the vimc limitations (even shrinking the image if necessary).
74 Exposes node /dev/videoX to allow userspace to capture the stream.
83 Vimc has a module parameter to configure the driver.
85 * ``allocator=<unsigned int>``
87 memory allocator selection, default is 0. It specifies the way buffers