Open Source Summit + Embedded Linux Conference Europe 2020

The media subsystem and the V4L2 API have recently been extended to support hardware-accelerated video decoding for stateless implementations, with drivers such as cedrus and hantro supporting embedded platforms like Allwinner and Rockchip. While the stateless decoding work is being finalized, the next order of business is stateless video encoding. This talk will present the research and first implementation attempts to support H.264 encoding, using the Hantro H1 hardware. It will start with an introduction to H.264 encoding and rate-control approaches, one of the key aspects of encoding. It will follow with details about the hardware and provide an overview of the implementation challenges, choices that were made and their limitations for a common interface that can apply to any kind of stateless H.264 encoder. With that, a general picture of what a generic stateless encoding API for V4L2 would look like will be drawn.