On Tue, Nov 19, 2019 at 11:18 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > > On 11/2/19 1:50 PM, Hans Verkuil wrote: > > <snip> > > > Action Items > > ------------ > > > > Hans Verkuil: > > > > - Ask Cisco colleagues which bitrate-related parameters have to be per-frame for > > an encoder > > - make stateful encoder infrastructure + documentation for the missing bits > > - investigate using different sizes for metadata controls in the control framework: > > is this possible? > > The problem is with compound arrays. struct v4l2_ext_control just provides a size field > for the total size and so for an array there is no way to discover the actual element > size. > > That said, to my knowledge there are currently no compound arrays defined in the mainline > kernel. V4L2_CTRL_TYPE_H264_SLICE_PARAMS is a compound array, with one element of the array for each slice in the bitstream buffer. > So one option is to take the last reserved __u32 field and split it in a > __u16 elem_size and a __u16 reserved2 field, or just use the full __u32 for the elem size > and drop the reserved2 field. __u16 would limit the element size to 64k. While I don't see any controls bigger than that on the horizon (and with the current design handling such big controls would add a lot of memcpy overhead anyway), I wonder if that's a good assumption. I'd probably just go with __u32. > > Alternatively, we prohibit compound arrays for now and postpone making any changes to > struct v4l2_ext_control until we actually need this. > > As long as it is not an array, then we can safely extend these compound control structs > later. It requires some work in the control framework, but it isn't too bad. > > I'm in favor of implementing this, and for now prohibiting the use of compound arrays. > > It is really helpful making these codec state controls at least somewhat future-proof. > > Comments? > > Hans > > > > > Michael Tretter: > > > > - Support the new encoder stateful controls in the driver > > > > Tomasz Figa: > > > > - look up AMD encoder support > > > > Boris Brezillon: > > > > - send v3 of hantro g1 fixes > > > > Nicolas Dufresne: > > > > - look into multiview and sublayers support > > > > Paul Kocialkowski: > > > > - check metadata controls against the standards and update the docs if needed > > > > Ezequiel Garcia and Boris Brezillon: > > > > - add VP9 support > > >
