Server Version#: 1.43.2.10687
Player Version#: 2026.10.1 (971050205)
My Plex server isn’t a powerhouse. So, I have chosen to optimize my videos for mobile so that they don’t need to transcode on the fly. However, no matter what settings I have used to optimize it, every download has to be transcoded before downloading.
I have tried optimizing on the server using default “Optimized for Mobile”, Custom “Universal Mobile” at 0.7 Mbps and 1.5 Mbps.
I have configured my mobile app to 480p (1.5Mbps) for Download Quality, 480p for Local Quality, 480p for Wi-Fi Quality, and 480p for Cellular Quality.
How should I configure my optimization on the server and my mobile app so that I can avoid the on the fly transcoding of my videos?
I’m curious what hardware you are running that cannot handle on the fly transcoding?
Any Intel CPU within the past 10 years with integrated graphics can handle a lot of transcodes at the same time. Newer ones can even do multiple 4K transcodes
Might be worth getting a new CPU instead of min-maxing quality settings
@RealJerk There are multiple factors involved. My server runs many containers on it. It isn’t just dedicated to Plex at this time. It is very capable of transcoding the MKVs made from DVDs. It does pretty well with Blu-rays, but 4Ks are so large that it can take an hour to transcode it before downloading.
Am I misunderstanding the purpose of the “optimize” functionality? Isn’t it supposed to improve performance by having videos prepared for play and download?
@BigWheel Am I looking at this incorrectly? I am not seeing any benefit to optimizations for mobile devices, because it will always transcode before downloading.
Personally I do not allow transcoding of 4K files (even though my CPU can handle it)
If people cannot play 4K, they don’t get access to the 4K libraries
I’ve never used the optimize option before, I prefer to just let people transcode as needed
Under Settings>Transcoder I have set Transcoder default throttle buffer to 15000 - this will quickly transcode the entire file when someone requests it, freeing the CPU for other tasks ASAP
I did a bunch of testing regarding this last year, and the issue I found is that even if you optimize for 1.5 Mbps (as an example), that’s only the video and doesn’t take into account audio. So you could end up with a file that’s exactly 1.5 Mbps (video), but a bit higher in total because of the audio.
I reported it and it was supposed to be logged but I doubt it got fixed yet.
Yes that’s correct. The client issue was partly fixed back on 2026.7.0 but only if the file is under the threshold. An optimized 1.5 Mbps file would need the limiting threshold set a higher than the file to be used without further transcoding. The second issue which would be more server side related needs more thought.
Yeah I think I tested and confirmed that. As long as you have your client settings set to a higher value than the bitrate of the optimized version, it will select the optimized version correctly.
@Atomatth This was helpful. So, I found that when I optimize using the default “Optimized for Mobile” and I set my phone to 720p 4Mbps, it downloads without having to transcode first.
However, when I optimize using “Custom” “Universal Mobile” “1.5Mbps, 480p” and set my phone to 720p 4Mbps, it will not download it.
So, only the Optimized for Mobile appears to work.
What I am really hoping for is a setting on the server that I can use to lower the quality below 480p. I usually try to do “Custom” “Universal Mobile” “0.7Mbps”. I have found that I don’t need better quality than that on my phones and takes up less than half as much space. Currently, my optimized at 0.7Mbps takes up about a terabyte of data. I would expect it to take up more than 2 terabytes of data otherwise.
Is this possible for the mobile app to be able to use the 0.7Mbps? Or should I use the 1.5Mbps?
Sorry for the late response, kept getting distracted. It looks like any download will likely need to kick off another transcoding jump regardless of any pre-optimized versions. This looks to be an extension of the issue that @Lazarus_Long identified. Filing an issue for downloads falling into a similar pattern. Thanks for reporting and your patience.
@Atomatth The latest version of the Android app is working way better. Many of my pre-transcoded videos (0.7Mbps) now download without additional transcoding.
However, there are several that I have pre-optimized using the 0.7Mbps or the default Mobile profiles that still require transcoding before they will download.
I have attached an archive with the Get Info source XML for 4 videos.
Little Mermaid and Martian do not require transcoding.
Lord of the Rings and Living Daylights do require transcoding.
Is there a way that I can use the built in pre-optimization tool so that it will not require transcoding at download on the mobile? Or is this another bug that will need to be fixed?
What quality profile are you selecting to download the titles you listed above? After downloading the titles that did not require transcoding, can you confirm what profile was actually downloaded?
I don’t think that that is correct. My understanding is that the optimized version profile and download profile need to match. For the case of 0.7Mbps optimizations, no download profile matches so it won’t get downloaded.
Unfortunately there isn’t a way to see the current quality metadata of downloaded content in app. Which would be helpful here. I’m assuming that of the titles that did not need transcoding while downloading was actually downloading the Optimized for TV profiles instead of the 0.7Mbps.
In order to check what got downloaded, you’d need to connect your phone to a PC and search for downloaded content and inspect it there. This is where I found a downloaded file.
This PC\Pixel 10a\Internal shared storage\Android\data\com.plexapp.android\files\downloads\35450e803b570a65\3fe63c1c15188b000757c772d11747ef3c733ad0\341818
I just checked one of my videos that did download correctly. The original file was 1.48GB. The pre-optimized was 162.15MB. The file on the phone per the Android File Transfer is 162.2MB. It seems to me that it downloaded the pre-optimized. I double checked it with The Martian. It’s original size is 20GB. The pre-optimized is 802.47MB and on the device it shows it as 802.5MB.
BTW, I would be happy if there was an option that I could select to tell the mobile device to download a specific pre-optimized video or a specific optimization profile. I manually downloaded the 0.7Mbps file of a video that was requiring transcoding onto my phone and tried playing it with the built in video playing capabilities and it played fine.
