Glossary

Note

The goal of this section is to standardize the terms used within the media userspace API documentation. This is Work In Progress.

Bridge Driver

A Device Driver that implements the main logic to talk with media hardware.

CEC API

Consumer Electronics Control API

An API designed to receive and transmit data via an HDMI CEC interface.

See Part V - Consumer Electronics Control API.

Data Unit

Unit of data transported by a bus. On parallel buses, the data unit consists of one or more related samples while on serial buses the data unit is logical. If the data unit is image data, it may also be called a pixel.

Device Driver

Part of the Linux Kernel that implements support for a hardware component.

Device Node

A character device node in the file system used to control and transfer data in and out of a Kernel driver.

Digital TV API

Previously known as DVB API

An API designed to control a subset of the Media Hardware that implements digital TV (e. g. DVB, ATSC, ISDB, etc).

See Part II - Digital TV API.

DSP

Digital Signal Processor

A specialized Microprocessor, with its architecture optimized for the operational needs of digital signal processing.

FPGA

Field-programmable Gate Array

An IC circuit designed to be configured by a customer or a designer after manufacturing.

See https://en.wikipedia.org/wiki/Field-programmable_gate_array.

Hardware Component

A subset of the Media Hardware. For example an I²C or SPI device, or an IP Block inside an SoC or FPGA.

Hardware Peripheral

A group of hardware components that together make a larger user-facing functional peripheral. For instance, the SoC ISP IP Block and the external camera sensors together make a camera hardware peripheral.

Also known as Peripheral.

I²C

Inter-Integrated Circuit

A multi-master, multi-slave, packet switched, single-ended, serial computer bus used to control some hardware components like sub-device hardware components.

See http://www.nxp.com/docs/en/user-guide/UM10204.pdf.

IC

Integrated circuit

A set of electronic circuits on one small flat piece of semiconductor material, normally silicon.

Also known as chip.

IP Block

Intellectual property core

In electronic design a semiconductor intellectual property core, is a reusable unit of logic, cell, or integrated circuit layout design that is the intellectual property of one party. IP Blocks may be licensed to another party or can be owned and used by a single party alone.

See https://en.wikipedia.org/wiki/Semiconductor_intellectual_property_core).

ISP

Image Signal Processor

A specialized processor that implements a set of algorithms for processing image data. ISPs may implement algorithms for lens shading correction, demosaicing, scaling and pixel format conversion as well as produce statistics for the use of the control algorithms (e.g. automatic exposure, white balance and focus).

Media API

A set of userspace APIs used to control the media hardware. It is composed by:

See Documentation/userspace-api/media/index.rst.

MC API

Media Controller API

An API designed to expose and control the relationships between multimedia devices and sub-devices.

See Part IV - Media Controller API.

MC-centric

V4L2 Hardware device driver that requires MC API.

Such drivers have V4L2_CAP_IO_MC device_caps field set (see ioctl VIDIOC_QUERYCAP).

See Controlling a hardware peripheral via V4L2 for more details.

Media Hardware

Subset of the hardware that is supported by the Linux Media API.

This includes audio and video capture and playback hardware, digital and analog TV, camera sensors, ISPs, remote controllers, codecs, HDMI Consumer Electronics Control, HDMI capture, etc.

Microprocessor

Electronic circuitry that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output (I/O) operations specified by the instructions on a single integrated circuit.

Peripheral

The same as Hardware Peripheral.

RC API

Remote Controller API

An API designed to receive and transmit data from remote controllers.

See Part III - Remote Controller API.

SMBus

A subset of I²C, which defines a stricter usage of the bus.

SPI

Serial Peripheral Interface Bus

Synchronous serial communication interface specification used for short distance communication, primarily in embedded systems.

SoC

System on a Chip

An integrated circuit that integrates all components of a computer or other electronic systems.

Stream

A distinct flow of data (image data or metadata) from an initial source to a final sink. The initial source may be e.g. an image sensor and the final sink e.g. a memory buffer.

V4L2 API

V4L2 userspace API

The userspace API defined in Part I - Video for Linux API, which is used to control a V4L2 hardware.

V4L2 Device Node

A Device Node that is associated to a V4L driver.

The V4L2 device node naming is specified at V4L2 Device Node Naming.

V4L2 Hardware

Part of the media hardware which is supported by the V4L2 API.

V4L2 Sub-device

V4L2 hardware components that aren’t controlled by a Bridge Driver. See Sub-device Interface.

Video-node-centric

V4L2 device driver that doesn’t require a media controller to be used.

Such drivers have the V4L2_CAP_IO_MC device_caps field unset (see ioctl VIDIOC_QUERYCAP).

V4L2 Sub-device API

Part of the V4L2 API which control V4L2 sub-devices, like sensors, HDMI receivers, scalers, deinterlacers.

See Controlling a hardware peripheral via V4L2 for more details.