V4L2

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Introduction

Video For Linux Two is the second version of the Video For Linux API, a kernel interface for analog radio and video capture and output drivers.

Early drivers used ad-hoc interfaces. These were replaced in Linux 2.2 by Alan Cox' V4L API, based on the interface of the bttv driver. In 1999 Bill Dirks started the development of V4L2 to fix some shortcomings of V4L and to support a wider range of devices. The API was revised again in 2002 prior to its inclusion in Linux 2.5/2.6, and work continues on improvements and additions while maintaining compatibility with existing drivers and applications. In 2006/2007 efforts began on FreeBSD drivers with a V4L2 interface.

This book documents the V4L2 API. Intended audience are driver and application writers.

If you have questions or ideas regarding the API, please write to the Video4Linux mailing list: https://listman.redhat.com/mailman/listinfo/video4linux-list. For inquiries about the V4L2 specification contact the maintainer mschimek@gmx.at.

The latest version of this document and the DocBook SGML sources are hosted at http://v4l2spec.bytesex.org, and http://linuxtv.org/downloads/video4linux/API/V4L2_API.

V4L2(V4L version 2)는 analog radio와 video의 driver라고 할 수 있다. V4L2를 통해 입력된 순수 데이터는 다른 형태의 포맷으로 바뀌어 스트리밍되거나 파일로 저장될 수 있다. 만약 Linux에서 웹캠 드라이버나 캡쳐보드를 활용한 어플리케이션을 사용하려고 한다면, 이 라이브러리는 필수라고 할 수 있다. Download를 클릭하면 상세한 설명과 API의 man page를 참조할 수 있다.
V4L2를 사용하기 위해서는 mmap, ioctl, fctnl등을 잘 알고 있어야 한다.