The point

So, let's remember that the point of an hardware video decoding/encoding unit is to take an encoded or decoded frame and get a decoded or encoded frame, respectively, as a result.

So basically, encoded frame goes in, decoded frame goes out.

[Encoded frame]→[VPU]→[Decoded frame]

[Decoded frame]→[VPU]→[Encoded frame]

The encoding and decoding being limited by what the hardware understands, of course.

We'll first focus on storing the decoded frame in a buffer that can be displayed directly on the screen, for video players. Then we'll see if it's possible to write a driver that provides simple decoding/encoding facilities for FFMPEG users.

Workings of the driver