CedarX/Reverse Engineering

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Current status

MBOX icon important.png FIRST NOTE: Allwinner's CedarX video de-/encoding engine is successfully reverse engineered in the most common parts (HEVC, H264, MPEG1/2, MPEG4).

The results of this reverse engineering are bundled in a vdpau driver backend since January 2014.

To do hardware accelerated video decoding on sunxi devices nowadays, you don't need any software provided by Allwinner, which is either (partly) closed sourced and/ or violating the GPL. Instead you should use the result of the community's reverse engineering work, called Cedrus.

As this is only proof of concept code, the goal is a mainlined video engine driver in the end. To take full advantage of such a driver, the other bits (display, hdmi, sound ...) also have to be rewritten in ongoing mainline process.

Hardware registers

The closed source blob uses direct access to hardware registers using mmap to userspace. Currently known register usage is documented:

There's ongoing register documentation effort using envytools.

Progress history

15 June 2012
Iain Bullard started reverse engineering the proprietary libraries.
3 May 2013
wingrime and oliver started work on register guide, JPEG, MPEG decoding manuals and binary analysis.
20 May 2013
nove introduced new MMIO tracer based on Valgrind
  • ReCedro has similar tools as those from IanB above, but with a different angle, works really well.
22 June 2013
JPEG decoding proof-of-concept was introduced by Jemk JPEG/MPEG-12 Decoding PoC
30 August 2013
Workable proof-of-concept VDPAU decoder was introduced by Jemk support MPEG-1/2 and MPEG-4 AVC/h.264 decoding libvdpau-sunxi
24 August ~ 12 September 2013
Paullo612 worked in documenting vp8 decoding.
12 January 2014
First MPEG-4 AVC/h.264 encoder proof-of-concept from Jemk
15 January 2014
Jpeg encoding proof-of-concept by nove jepoc
31 January 2014
Jemk added to libvdpau-sunxi the first support for decoding (some) mpeg4 videos
12 July 2016
ubobrov modified Jemk's proof-of-concept h264 encoder sources making them workable on H3 platform

A first proof at the end ...

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