Am i Wrong about how transcoding works?

[Mesoraven]

Could someone better aquainted with jellyfin just sanity check my understanding cause im pulling my hair out here.

so i have 2 roku tvs. a 4k one and a 1080p one.
i have jellyfin set up on an old v520 and the roku client installed on each tv.
the server is hardwired to the network and the two tvs are connected to the network wirelessly
the collection has both 4k H.265 10 bit and 1080p videos.

as far as i understand it. the H.265 videos will not play on the 1080p tv as the client doesnt support that codec. so i should be able to go into the dashboard and turn on hardware acceleration. and jellyfin should automatically transcode the video into one that the 1080p roku can play?

am i understanding all this correctly? cos i cant for the life of me get the 4k videos to play on the 1080p Roku
Thanks in advance

[TheDreadPirate]

What hardware is in the server?

[Mesoraven]

Its only an I5-7400 with intergrated 530 graphics. but it manages to transcode on my phone and on a tablet and on my laptop, its litrally just only the roku it wont transcode

[tmsrxzar]

each client reports it's playback capabilities to the jellyfin server, from that information the jellyfin server decides whether it needs to be transcoded

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if there is a setting in the roku client then you can change it there
if not then it is an incomplete feature and you should look for something to limit the bandwidth to force transcoding


settings on the server are only telling jellyfin what the Server is capable of doing in the event that a client does not support something

f.e. if transcoding is disabled on the server and the client does not support HEVC then it will simply fail
if transcoding is enabled on the server and the client reports it can not play HEVC then it will transcode to h264 (or what you have configured)

the jellyfin server logs should show this and likely the roku client is telling the server it is capable even when it's not

[GenericUser72]

I'm actually having the same issue, I think. I have two TCL roku TVs, one 1080p on a different network than the server, one 4K on the same network as the server. I've got an old Dell optiplex that I installed a Quadro P400 in and can get transcoding to work (as shown by nvidia-smi), including on devices outside my network, but I cannot get the 1080p roku to play any of the 4K content, which I think is largely down to being 265 instead of 264. For reference, I'm running jellyfin in a docker container on Ubuntu.

I've gone in the settings on the jellyfin app on the troublesome TV and explicitly turned off hevc playback and tried the same thing for h264, and limited the bitrate to 9Mbps in an attempt to force transcoding to 1080p with no success. 

I'll attach logs from FFMPEG showing a failed transcoding, as well as a snippet of the full jellyfin log from when it tried to transcode. I'm not trying to hijack this thread, it just seemed like it might be the same issue but if I should create a new thread instead, I'll be happy to do so.

[tmsrxzar]

I'll attach logs from FFMPEG showing a failed transcoding, as well as a snippet of the full jellyfin log from when it tried to transcode. I'm not trying to hijack this thread, it just seemed like it might be the same issue but if I should create a new thread instead, I'll be happy to do so.

your logs show roku correctly identified that is was NOT capable and so the jellyfin server went to transcoding
but the roku client stopped playback at 0ms and the transcoding was cancelled

in your instance i would try to eliminate the subtitles tracks, in some instances these can cause issues with clients and yours shows to have more than 40 subtitle tracks

create a test file with an ffmpeg remux, ffmpeg -i <inputfile> -map 0:v -map 0:a -c copy <outtestfile>.mkv
test playback for changes


perhaps one of the more versed members here can provide information on forcing downscaling (->1080p) if that is an option on the jellyfin server, i have not ever used such and im not sure it exists

[tmsrxzar]

looks like scaling was introduced from PR 1299 on Sep 11 https://github.com/jellyfin/jellyfin-roku/pull/1299

if the option is not in your client consider updating, if it has not been made available consider compiling your own version from source if possible

if the option IS in your client but IS NOT functional then follow up with an issue on github and reference that PR

[Mesoraven]

each client reports it's playback capabilities to the jellyfin server, from that information the jellyfin server decides whether it needs to be transcoded

---

if there is a setting in the roku client then you can change it there
if not then it is an incomplete feature and you should look for something to limit the bandwidth to force transcoding


settings on the server are only telling jellyfin what the Server is capable of doing in the event that a client does not support something

f.e. if transcoding is disabled on the server and the client does not support HEVC then it will simply fail
if transcoding is enabled on the server and the client reports it can not play HEVC then it will transcode to h264 (or what you have configured)

the jellyfin server logs should show this and likely the roku client is telling the server it is capable even when it's not

Missing puzzle pieces there for me thanks, i didnt realise the workflow happened in that order.

I'm actually having the same issue, I think. I have two TCL roku TVs, one 1080p on a different network than the server, one 4K on the same network as the server. I've got an old Dell optiplex that I installed a Quadro P400 in and can get transcoding to work (as shown by nvidia-smi), including on devices outside my network, but I cannot get the 1080p roku to play any of the 4K content, which I think is largely down to being 265 instead of 264. For reference, I'm running jellyfin in a docker container on Ubuntu.

I've gone in the settings on the jellyfin app on the troublesome TV and explicitly turned off hevc playback and tried the same thing for h264, and limited the bitrate to 9Mbps in an attempt to force transcoding to 1080p with no success. 

I'll attach logs from FFMPEG showing a failed transcoding, as well as a snippet of the full jellyfin log from when it tried to transcode. I'm not trying to hijack this thread, it just seemed like it might be the same issue but if I should create a new thread instead, I'll be happy to do so.

no worries, if it is the same problem (it is i just checked my logs) then more heads and more data sets help to solve it.

im gunna try removing the subtitle tracks as suggested when i get back from see if that helps

[GenericUser72]

Removing the subtitles with ffmpeg as described above worked for the video from my previous logs.

I double checked and I also had the user for that TV limited to 9Mbps and stereo audio on the admin side of the server when the transcoding worked. I've removed those limits and if that causes transcoding to fail again, I'll update.