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.

[Luke 43210]

Hi @bzellingercan we please see an ffmpeg log example?

By the way you can also accomplish this with the diagnostics plugin. It has an option to search and replace on the generated ffmpeg command line.