I’ve tested to play a media on a chromecast this weekend, but the quality when transcoded was really bad. I was having optic fiber on both ends(where I’ve my server and where I was having the player).
My server is quite a beast(32GB of ram, I7 3.06Ghz) and usually transcode 1080p footage between 7 and 11x, so easy.
But at the end, I was having a really bad quality at some time.
So I’ve made additional tests on the same media.
I’ve asked the plesk server to make an optimized version, in “Original Quality”.
Like this I’m sure that the time availble to transcode is not an issue and that the network is not an issue too.
Regarding my plex server settinggsg, here are all the settings values that I could think are related to the quality of encoding:
Web -> Quality -> Video Quality: Maximum
Server -> Transcoder -> Transcoder quality: Make my CPU hurt
Server -> Transcoder -> Transcoder default throttle buffer: 120
Server -> Transcoder -> Background transcoding x264: Slow EDIT: Just tried Very Slow, doesn’t change anything.
Server -> Transcoder -> Use hardware acceleration when available: Checked
Server -> Transcoder -> Maximum simultaneous video transcode: 3
How big is the quality of your original file?
If you use highly compressed files, they have a very low bitrate. If you tell Plex to stick to this low bitrate by selecting ‘Original Quality’, then it might be not enough. Particularly when transcoding from HEVC.
Please post the Plex XML info of the video which you used for your test.
An average bitrate of 2.6 mbps for a 1080p H.264 movie is very low, particularly when there are action scenes.
You will need at least 6 to 8 mbps on average for a good quality on a bigger screen.
Try the ‘Custom’ profile and select ‘Universal TV’ and ‘8 mbps’
Second test: try disabling any subtitles and play the original version of the file on your Chromecast.
I tried to do Universal TV and 8 mbps. I can see a very slight improvement, but still, nothing I can watch.
When I select the media, it tells me it has been encoded in 3.5mbps(even if I set the 8 mbps limit).
Currently I’m doing the test directly on my computer and it still fails, so I guess we should first fix this, then have it working on google chrome.
An average bitrate of 2.6 mbps for a 1080p H.264 movie is very low, particularly when there are action scenes.
I understand that, but why is the plex transcoder not able to do exactly the same? Just with the subtitles burned in(because at the end I guess it’s what is causing the issue). I mean, I transcode really fast(most of the time between 10 and 11x), so why I cannot set a better quality and transcode half the speed? Because here transcoding is useless.
EDIT
I even tried to convert it to Universal TV 20Mbps, but the results tells me it’s a 3.5Mbps encoding.(And surprinsingly, it tells me that the original is at 3.9, not 2.6)
The video file you have doesn’t have any quality reserve for yet another transcoding.
What ‘speed’ did you set under
Settings - Server - Transcoder - ‘Show Advanced’ - “Background transcoding x264 preset”
?
I recommend ‘Slow’.
I’ve provided this. I’ve tried with slow and very slow, both product very bad results.
First I’m not sure why plex would not be able to match the compression of the original file. I mean, I’m sure that if I start to play with ffmpeg options, I will be able to match them at some point.
Second, if it is not able to match the compression, and that I allow him to create video with a 20mbps bit rate, why would it not use it? The output file is just a 3.5mbps file…
If you do not mind to significantly increase the load on your CPU just disable hardware acceleration in Plex and restart Plex. This should increase the quality significantly.
