Mpeg2 hardware accelerated decoding broken on Maxwell / Pascal

It seems both vdpau and nvdec are broken for Mpeg2 video. Particularly video that is 1080i, deinterlaced or not. I see blocking artifacts that are not present with VA-API or software decoding. This is reproducible in mpv and mythtv, but essentially anything that uses ffmpeg. I have generated a VDPAU trace but the partner sftp site doesn’t seem to work with blank credentials like this forums claims it does.

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