Is that actually the case? GStreamer has a default alignment for any given format, but we can and do change that. That's the point of all that complicated alignment logic we have. Is some component rejecting alignment _below_ the default?
See my comment higher up. Alignment in gstreamer is hard-coded to 4 for NV12, and when d3d-awareness is enabled, we allocate the sample buffer, which ends up being too small for gstreamer to use.
Hmm, what happens when you try?
I was getting wires crossed with some other testing I did a while ago. The issue is NV12 output from Theora, which we don't need to deal with in upstream Wine, and it also only occurs with d3d-aware output, which limits the scope. I tested d3d-aware h264 -> NV12 and there is no issue. It looks like upstream should be left as it is, at least for the moment.