Introduction to video4linux Embedded Image System

1. Introduction to video4linux

Video4linux (v4l) is the basis of the Linux image streaming system and embedded image system. The most popular research field of Linux in TV and multimedia applications, and the most critical technology is the Linux video4linux.

Video4linux is a set of APIs that support image devices by Linux kernel. It is driven by an appropriate video capture card and video capture card.ProgramVideo4linux allows us to implement image acquisition, AM/FM Wireless broadcast, image codec, channel switching, and other functions.

In the application of embedded Linux, video4linux is often used in scenarios where image collection is required, such as video surveillance systems, webcam, and videophone.

Video4linux architecture: video4linux is a 2-layer architecture, the top layer is the video4linux driver itself, and the bottom layer is the driver of the image device. We generally study the top-level driver of v4l, that is, the APIS provided by v4l to program developers.

Currently, based on different kernel versions, there are two versions: video4linux (v4l) and video4linux2 (v4l2). Here we use v4l as the main version.

Video4linux2 main URL: http://www.thedirks.org/vl2/vl2.htm

01. bt878 chip and bttv driver

The bt878 chip is an image acquisition chip used by many digital video capture cards.

Bttv is a Linux kernel bt848/849/878/879/chip driver. Its main function is frame grabber ). Bttv is the underlying driver in the v4l2 layer. It is the driver that actually drives the video capture card. Currently, v4l2 is supported as bttv2.

Bttv Official Website: http://www.metzlerbros.org/bttv.html

Bttv2 Official Website: http://bttv-v4l2.sourceforge.net

Bttv users please use the new Official Website: http://bytesex.org/bttv

II. Introduction to video4linux applications

01. bttv-related application software-xawtv

Http://bytesex.org/xawtv/index.html

The xawtv architecture can be divided into seven parts:

> Xawtv: main program section.

> Fbtv: a TV application in Linux Console mode. It uses the framebuffer of Linux kernel2.2.x.

> Set-TV: a command line tool used to set video4linux parameters.

> Streamer: a command line tool used to capture dynamic and AVI images.

> Radio: Radio application.

> Webcam: uploads captured images to the Web server using FTP to design a Web image implementation tool.

> Alevtd: the Web server of videotext pages.

02. expresstv

TV is a program designed by Japanese people. It also uses video4linux for image collection. You can use this software to learn some image processing skills. This software is a software that supports special effects.

03. Use jrtplib to join the Network

Iii. Output JPEG and PPM Images

You can directly output data to framebuffer, display data using SDL, or output data to a file.

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