Bootlin Releases Open Source VPU Driver for Allwinner Processors with MPEG2 and H.264 Video Decoding

At the beginning of the year, Bootlin – formerly Free Electrons – launched a crowdfunding campaign to bring open source Allwinner VPU driver to mainline Linux. VPU (Video Processing Unit) drivers are used to encode and decode videos. They were successfully in raising enough money from small donors, as well as several companies manufacturing Allwinner development boards including Olimex, Pine64, Libre Computer, FriendlyELEC, and Xunlong Software (Orange Pi).

The amount raised (€31,612) was enough to assign two engineers to work on the main goals, as well as some stretch goals namely support for newer Allwinner H3, H5, and A64 processors, and H.265 video decoding. The good news is the company has now delivery the first release for their work on the main goals.

allwinner open source vpu driver mpeg2 & h264
Open Source VPU Driver on A33-OLinuXino and ALL-H3-CC Boards – Click to enlarge

The photo above illustrated a demo of Kodi running with bootlin open source Cedrus VPU driver on top of Linux 4.18-rc kernel. Both MPEG2 and H264 are supported, and they’ve gone a little beyond one of their main goal since Allwinner H3 is also supported. Their work was based on libvdpau-sunxi project and other work from linux-sunxi community.

Bootlin announcement goes into more details, but here’s a quick report card of the main goals achievements so far:

  • Support for older Allwinner SoCs: A10, A13, A20, A33, R8 and R16 – Fully met, plus H3 support as a bonus (that was planned for the stretch goals)
  • Production-ready MPEG2 decoding –  Fully met with improvements in both the kernel  and user-space code. MPEG2 codec was already partially supported.
  • H264 video decoding implementationFully met, including  high-profile H264 support. Further debugging likely needed.
  • Modifying the Allwinner display driver (DRM) to directly display the decoded frames instead of converting and copying those frames – Fully met, plus hardware scaling fixed, and patch sets contributed to upstream. Bootlin work on the A20 and A33 display driver, and the community on H3.
  • User-space library to integrate in open-source video players. Partially met via libva-v4l2-request user-space libraries that can be used by all libva capable video players. That’s the theory, and in practise it’s only working with Kodi for now, and more work is needed for VLC and GStreamer.
  • Upstreaming changes to the official Linux kernel. Almost met.  They’ve gone though five iterations of the Sunxi-Cedrus Linux kernel driver, but they have yet to be merged. It should just be a question of time.

So soon enough, you’ll be just able to get mainline kernel and the open source user-space libraries to have MPEG2 and H.264 video work on Allwinner processors. If you want to give a try at the ope nsource driver, Bootlin prepared a LibreELEC rootfs with Sunxi-Cedrus driver that works on Allwinner A20, A33 and H3 boards.

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