Transcoding on i7 4770k & GTX 770 (docker)

[TheDreadPirate]

The codec check boxes are for DECODING only. If the boxes are check your GPU will decode them but only if the GPU supports that. If they are uncheck your CPU will decode the video. By default Jellyfin transcodes to H264, which your GPU supports. There is an option for HEVC and AV1, but your GPU does not support those codecs.

Your GPU only supports DECODING for H264, VC1, MPEG2, and VP8. HEVC is not supported.

CPU/GPU decoding only happens when you are transcoding. If you are direct playing, Jellyfin simply sends the file to the client unmodified.