[Feature request] Slow down 24.000 FPS video to 23.976 FPS

[LinAGKar]

Describe the bug

The Chromecast does not support video output at 24.000 FPS or 60.000 FPS, only 50 FPS and 59.94 FPS. This means that when playing 24 FPS content on it, there is a regular stutter. It would be nice if Jellyfin could slow down the video to 23.976 FPS (or maybe speed it up to 25 FPS when the Chromecast is set to 50 FPS), as is usually done to movies when they are broadcast on TV. Not sure what level of access Jellyfin has to the video, and if this is something possible to do on the client (maybe by setting playbackRate to 1000/1001?), otherwise it might need to be done on the server, which may require transcoding (unless -itsscale or something works, or maybe this method).

System (please complete the following information):

• OS: Docker
• Jellyfin Version: 10.8.0-beta1
• Cast client: Gen 2

[LinAGKar]

I've experimented with the raw bitstream method from there, but that makes the video stuttery AF. So unless the video can be slowed down on the client, it probably requires transcoding on the server, e.g. with ffmpeg -i "$INPUT" -itsscale 1.001 -i "$INPUT" -filter:v "setpts=1001/1000*PTS" -r 23.97602398 -filter:a "atempo=1000/1001" -map 0:v -map 0:a -map 1:s "$OUTPUT" (plus codec settings).