Chapter 9:Leveraging the V4L2 API from the User Space
The main purpose of device drivers is controlling and leveraging the underlying hardware while exposing functionalities to users. These users may be applications running in user space or other kernel drivers. While the two previous chapters dealt with V4L2 device drivers, in this chapter, we will learn how to take advantage of V4L2 device functionalities exposed by the kernel. We will start by describing and enumerating user space V4L2 APIs, and then we will learn how to leverage those APIs to grab video data from the sensor, including mangling the sensor properties.
This chapter will cover the following topics:
- V4L2 user space APIs
- Video device property management from user space
- Buffer management from user space
- V4L2 user space tools