Cannot transcode HFR Video

[caffeineshock 18]

heyho

i tried using Emby to play back some private video recordings, including stuff i shot with an action cam (DJI Action 2). main reason: the bitrate is sometimes too high for smooth streaming. so i thought, why not use Emby since i already have it running anyway?

well… turns out it doesn’t really work out. some videos shot in WQHD at 60fps work fine(almost. more infos later): i can direct stream, i can transcode, all good. but the UHD 120fps recordings… not so much. direct streaming works as expected, but as soon as i try to transcode them to a lower resolution/bitrate, this happens: Emby (or more precisely ffmpeg, i guess) tries to deliver the file but fails with a “no compatible stream found” error in emby (error text is probably a bit different in English, mine’s in German). this only happens in a browser.

with the WQHD 60fps files i can direct stream just fine, BUT as soon as i try to transcode, the video gets rotated 180°. probably because the action cam was upside down when recording, so the rotation info is in the EXIF metadata, which ffmpeg seems to ignore, leaving me with an upside-down video as soon as i trascode.

weird thing: i can transcode the UHD 120fps files if i use my Android phone. the transcode does start in the right resolution and bitrate, but the speed is terrible – like 10fps instead of the usual ~100.

so yeah, looks like ffmpeg really doesn’t like something about these files. maybe the crazy bitrate (130 Mbit/s at UHD@120fps) combined with the rotation data in EXIF?

anyway:  does anyone know a fix for this without having to manually transcode the files beforehand? i’d like to keep the originals.

(logs are trimmed to the important parts + censored for obvious reasons)

emby logs.zip

[Luke 42077]

HI, we're looking into the rotation but are you sure your server can handle the transcoding anyway? In these logs you're not getting fast enough performance for it to be playable.

[caffeineshock 18]

3 hours ago, Luke said:

HI, we're looking into the rotation but are you sure your server can handle the transcoding anyway? In these logs you're not getting fast enough performance for it to be playable.

I might run a benchmark later, but the problem is that playback doesn’t even start. The GPU load spikes for a few seconds (looks like it’s starting to transcode) and then just drops off without any clear reason. After that, I get the same error I mentioned before. 

[caffeineshock 18]

i did perform a quick benchmark and it should work. 30fps is what i got. even if its slower, it should lead to buffering but not stopping the playback (it actually does not even start at all)

 

[Luke 42077]

HI, can you provide a sample video for testing? Thanks.

[caffeineshock 18]

9 hours ago, Luke said:

HI, can you provide a sample video for testing? Thanks.

sure. uhd 120fps recording. 2gb size

https://drive.google.com/file/d/1QImK5Ly-q-NUwomjX-0PGSuqQoaCWE4H/view?usp=drive_link