v4l2format

The Video4Linux2 (V4L2) API is a framework within the Linux kernel that provides applications with access to video capture devices and other multimedia peripherals. The concept of "format" in V4L2 refers to the way image data is structured and represented by a video device. This includes details such as pixel format, resolution, and frame rate.

When an application interacts with a V4L2 device, it must negotiate a format with the device. This negotiation typically involves the application querying the device for supported formats and then selecting one that meets its requirements. Key aspects of a V4L2 format include the pixel encoding (e.g., YUYV, MJPEG), the width and height of the image in pixels, and the desired frame interval (which determines the frame rate).

The V4L2 API uses structures like 'struct v4l2_format' to exchange format information between the application and the kernel. This structure contains nested structures for pixel format details, crop and scaling parameters, and other related settings. Properly understanding and setting the V4L2 format is crucial for successful video capture and manipulation, ensuring that the data read from the device is interpreted correctly by the application. Different hardware may support different sets of formats, making format negotiation a fundamental step in V4L2 programming.