Open Source Summit + Embedded Linux Conference + OSPOCon 2021

Have you ever wondered how the buffers are managed when running a video or using camera or any streaming application? Videobuf framework was introduced in Linux for this sole purpose, to make life of video device driver developer easier with a more robust and resilient video buffer management framework. To handle complex media device use case and zero-copy media pipeline, the videobuf framework was deprecated in favor of videobuf2 (VB2) VB2 provides APIs that a video device driver can use without worrying about buffer management. It allows smooth buffer flow between userspace and kernel space (userptr vs mmap) or between drivers via shared buffer (dma-buf). It also maintains states for each transition for better error handling This talk will cover VB2 framework overview, its core data structures, initialization and callback flow control. In this talk we will explore details of various buffer types, important APIs, queue operations acting as communication/synchronization interface from VB2 to driver. With the help of an M2M driver running on ARM64 system, we will explain stage by stage transitions of a VB2 buffer. At the end of this session, audience will have better understanding of the media buffer management and flow of the same between userspace and kernel space using VB2.