What is the cause of loss of video quality?

[mrSadu]

I ripped a blu-ray movie to my pc using MameMKV and streamed it to Plex on AppleTV. Plex is set to use the original movie quality. The bitrate of the movie is 40Mbps. I was shocked to see how washed out the video quality was in comparison to the disk version. Playing the blu-ray disk on my ps4 the movie quality contains lush and deep colors while the 1-on-1 rip lacks any of these things. Isnt MakeMKV not apply any compressions? So what is the culprit of the quality disparity?

[Woodstock]

Not much to work from, but that bitrate indicates you're dealing with a UHD title, not "just" a Bluray. In which case, you are probably dealing with at least HDR, possibly DolbyVision. With Plex in the picture, the full dynamic range probably isn't available without some configuration.

[mrSadu]

I double checked and this is what I found. My bluray player said the following:
source: 1080/p24 SDR BT.709 YCBbr 4:2:0/8bit
output: 1080/p24 SDR BT.709 YCBbr 4:4:4/12bit
movie variable bitrate: 20 - 32 Mbps

My bluray player has the ability to upscale the content and other features that improve image quality. I disabled those. You mentioned UHD, but according to the the player it's SDR. Also notice that the output of the player is 12bit. Might be this be a cause in the quality disparity?

What other info do you need to make a more informative reply?

[dcoke22]

Plex might be transcoding the movie before it sends it to the Apple TV. In an ideal scenario, Plex will do Direct Play (https://support.plex.tv/articles/200250 ... ct-stream/) which means Plex doesn't transcode the movie in any way because the client can play it directly. If the Plex client has some limitations the Plex server will transcode the file to a format the client can play.

I'm pretty sure the Apple TV Plex client will tell you if the movie it is playing is Direct Play, Direct Stream, or being transcoded.