How is this client feature working nowadays? I know it’s super buggy in the past but are the bugs on this fixed already?
@anon18523487 do you recommend enabling this feature now or not yet? I know you told me before that this is best kept disabled.
This feature works fine. The only issue I’m actively aware of is on Android with that setting and enabling subtitles. I’m not aware of any other issue.
There’s a lot of issues with it. It’s all over the net:
I for one experienced it just today. I’ve noticed that one of my users, using an iPhone, was transcoding 4K content down to 384Kbps (SD SDR) which is insane. My PMS has 800Mbps upload and is not limited. As soon as I had her disable automatic adjust quality, the transcode was from 4K HEVC to 4K something which is a very significant change.
Question though. If you have this feature disabled, what happens if there’s not enough bandwidth or there are codec differences between the client and server? In my user’s case, it still transcoded the media so that it makes it compatible with the client. If that’s the case, what does the automatic adjust quality really do?
That feature changes the quality on the fly based on measurements the clients take on how fast the data is being received from the server. This can be affected by the user’s download speeds and the internet activity on their end too.
Plex Media Server can only change the bitrate on the fly when the stream is being transcoded so enabling that setting will force a transcode. It will start at the remote quality setting on the client end and then move up or down depending on the speed it calculates.
I would need to see logs from the client to check what’s going on, but this could be the expected behavior depending on their quality settings.
Right, yes. I understand about the Internet activity. That’s the whole purpose of that setting, so it can adjust on the fly. So it just adjusts the bitrate of the media?
What is the difference between transcoding when that feature is turned off and on?
Oh and yes, my users are using subs. What is the issue with that feature when using subs?
Yes.
What is the difference between transcoding when that feature is turned off and on?
With this setting off, transcode happens only if needed, and then only at the quality setting set in the client. The bitrate won’t change even if more or less bandwidth is available.
What is the issue with that feature when using subs?
On Android, videos won’t play. Turn off the setting, or don’t use subs.
I see. So if that’s off and the client doesn’t have enough bandwidth to stream at that quality, it just stalls? When you say “quality”, that is the bitrate and resolution of the media, correct?
For the Android issue, is that in the pipeline already? Do you know what’s causing it? And why isn’t it a problem with other clients (iOS, webOS, etc.)?
Yes and yes.
For Android, the issue is filed, but the devs haven’t had time to look at why it fails.
If there are multiple quality versions of the movie, say 1080p and 4K, how does Plex know how to use the 1080p file when transcoding?
The app requests a bitrate. PMS will pick the source that is closest to that requested bitrate.
So let’s say there are two versions of the file:
1080p 10Mbps
4K 20Mbps
If the app requests 15Mbps, which of the two will it choose? Transcode 4K or direct play 1080p?
If the app requests 17Mbps, will it choose the 4K copy and transcode?
If the app requests 14Mbps, will it choose to direct play the 1080p copy?
If the app requests 6Mbps, will it choose to transcode the 1080p copy?
For 1-3 it should choose to direct play the 1080p version. However, if it can’t direct play, it will transcode the 4K version since we don’t upscale. 20 → 15, 17, 14
For 4, it will transcode the 1080p version. 10 → 6.
Edit - I’m checking if there is a margin where if the version’s bitrate is too different from the request it won’t try to direct play that version. i.e. requesting 17 Mbps may be too far from 10 Mbps so it will just transcode from 20 Mbps without trying to direct play.
I see. Yeah, thr 17Mbps one is the one that confuses most. Since it’s nearer to the 4K 20Mbps version, I would think it would try to transcode 4K.
For a 14Mbps request, which instances will it require to transcode if a lower bitrate is available?
@anon18523487 do you have any updates to this?
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