NihAV — Processing Graph Notes

I’m giving only a short overview for now, more to come later.

Basically, you have NAGraph that connects different workers (processing units with queues).
Lock-free NAQueue should accept only objects of certain type (side note: introduce libnaarch/naatomics.h).
Also those objects should have a common base (NAGraphObject) that extends NAClass by adding side data and signaling subtype (NAPacket, NARawData or NAFrame for now).
Multiple object types with a common base allow to have the same processing interface (after all, both encoders and decoders simply take some input data and output something else).
Elementary stream from demuxers can be either fed to parser filter that will produce proper packets or it will be directly accepted by decoder or muxer.
Later I should make those parser filters autoinserted too.
Uniform interface should allow easier integration of third-party components even in binary form (if there’s somebody willing to use not yet existing library like this).

Zonal partitioning of the graph (inputs, processing, outputs) maybe should include generic filters (e.g. de/noise) too, and maybe set a flag on NAFrame if it can be modified or should be kept intact.
Errors should be caught right at graph processing stage (do that with callbacks and have fun).
Roughly, this should be the architecture for NihAV till the end of its days since it should be future proof.

Of course, all things described here should be implemented too eventually (sigh).

One Response to “NihAV — Processing Graph Notes”

  1. Luca Barbato says:

    It is a nice outer interface, I’m not completely sold on it yet but probably having the Graph builder doing the validation is as good as having interfaces less flexible to enforce it.

    Internally you still have something that takes Frames and gets you Packets anyway.

    I’m sure Alexis would love this approach though.