Got 1080i Live TV Transcoding Working at True 59.94p – Can Emby Support This Natively?

[bzellinger 0]

I've been testing Emby Live TV with an HDHomeRun and 1080i59.94/29.97 MPEG-2 OTA channels.

When these channels have to be transcoded for a browser, Emby currently outputs 1080p29.97. This discards half of the temporal resolution of the original interlaced broadcast and is very noticeable with sports, racing, scrolling text, and camera pans.

I was able to get proper 1080p59.94 output by modifying Emby's generated FFmpeg command.

Emby normally generates CUDA deinterlacing similar to:

yadif_cuda@f1

with:

-r:v:0 29.970029830932617

Changing those to:

yadif_cuda@f1=mode=send_field

and:

-r:v:0 59.940059661865234

produces true field-rate 1080p59.94 output.

I verified this in the FFmpeg transcode log. The output reports 1920x1080 progressive at 59.94 fps, and 3-second HLS segments contain approximately 180 frames. Motion on 1080i sports/racing content is noticeably smoother and looks like properly deinterlaced broadcast television.

I currently accomplish this with a small FFmpeg wrapper that intercepts Emby's generated command and makes those two changes before launching Emby's real FFmpeg. It works reliably with NVIDIA NVDEC/NVENC on an RTX 2080.

It would be great if Emby supported this natively, perhaps with an option such as:

Deinterlacing frame rate

• Same as source frame rate (29.97p/25p)
• Field rate (59.94p/50p)

Or Emby could automatically use field-rate deinterlacing when the client supports the resulting 50/59.94 fps progressive stream.

For NVIDIA/CUDA, yadif_cuda=mode=send_field already appears to provide everything needed. Similar field-rate modes could presumably be used for the other supported hardware/software deinterlacers.

This would make a substantial difference for transcoded 1080i Live TV, particularly sports.