Allwinner framework for their Video Processing Unit (VPU) in their Cortex A8 processors (A10, A13, etc..) is called CedarX. It relies on a binary blob that is working just fine for Android, but not so well for Linux. So several developers started to reverse-engineer CedarX a while back, to fix issues with Linux, and provide an open source driver.
Yesterday, they upload a video to show the development progress, and show Big Buck Bunny 1080p H.264 playback using libvdpau-sunxi open source driver with mplayer, and without any binary blobs. The video resize function are not been implemented yet, which is why we can only see the left corner of video, but nevertheless it shows an open source hardware video decoder is on the way.
That means once the Lima driver for Mali-400 GPU, and libvdpau-sunxi driver for AllWinner VPU are implemented (which may still take a while), AllWinner A10 SoC will be mostly open source, and the only SoC with open source hardware video decoding. I guess the only parts that may not be open source are things such as
2D graphics (See comments), the NAND driver (although people are working on that), and maybe a few other parts I’m missing.
Via Olimex Blog.