videobuf

videobuf is a historical component of the Linux kernel multimedia subsystem that provided a framework for managing video buffers in device drivers. It was introduced in the early 2000s to simplify the development of video capture and output drivers by offering a generic buffer queueing mechanism. The API exposed a set of ioctl operations for allocating, mapping, and queuing buffers between user space and kernel space. Driver developers could use videobuf to interface with hardware encoders, decoders, and capture devices without having to implement low‑level DMA operations themselves.

The videobuf framework supported both contiguous and non‑contiguous memory layouts and included support for scatter‑list based I/O. It also integrated with the Video4Linux2 (V4L2) device type system, allowing applications that use V4L2 to seamlessly interact with videobuf‑based drivers. Common operations included videobuf_alloc to reserve memory buffers, videobuf_qbuf to enqueue a buffer for processing, videobuf_dqbuf to dequeue completed buffers, and videobuf_merge_buffers for merging multiple buffers into a single mapping.

Over time, the videobuf API was superseded by a newer, more robust interface known as videobuf2. The newer system provides improved memory handling, better support for multi‑plane formats, and a more flexible buffer caching strategy. Many modern Linux video drivers have migrated to videobuf2, phasing out direct usage of videobuf, although legacy drivers and certain non‑standard hardware may still rely on the original API.