Since Roku supports mpeg2 decodings, I having playback issue with 1080i content at high bitrate (>17mbps). The playback breaks up, pixalized, etc. forcing the server to transcode it to h264 solves this issue.
i know that it's not an emby issue, since I have the exact same behavior when trying it with the orange brand competitor (On the preview channel, they now support direct play on mpeg2 content).
I'm just wondering if you can pass this issue along to Roku?
In Canada, the broadcasters don't have any sub channel, only the primary channel and they use all the ATSC 1.0 bandwith available in a 6 MHz width channel. So all my local ota channels are between 18 and 19 mbps. All those channels have the playback issue. I also received the major USA broadcasts from Vermont. The biterate of those broadcasts are lower. For example, CBS is around 13mbps. I don't have issue with CBS and the other USA channels.