Hi Stanimir, I know you were looking for some ways to pass back data post encoding per frame in V4L2 a while ago, but I think I lost track. I *think* you were looking for a way to pass back HDR10+ metadata from the decoder. I'm currently trying design a a way to pass back SVC encoded frame info (layer(s)_id and references). This is somewhat similar, for each frames being encoded I need some information from the encoder, so I can pass it back to the RTP payloader. This issue was fixed in AV1, but VP9 is still pretty important. On my side, I was thinking that a driver could stack the data per encoded buffer internally, and update a control state at DQBUF(capture) time. This should not be racy, as the next update will stay pending till the next DQBUF, but I'm worried of the overhead and maybe complexity. your feedback would be welcome, Nicolas
