Bug, when changing quality.

[yocker 1248]

Might have stumbled on a bug where changing quality can make it seem like Emby has failed with a black screen but in fact it is trying to download the whole video in background before resuming playback.
This can be observed by fx. using Windows Egde -> F12 -> Network and then looking at amount transferred, continue to change quality until bug happens.
Shouldn't be hard to replicate.

Only way to temporary fix it is to stop video and start it again, this sadly often makes the video start from the beginning.

Have this happen with Emby Apps as well as i can observe the traffic on my network.

This can really consume bandwidth on slower connections.

[visproduction 315]

Yock,

I think you are hoping for a multi- resolution copy of media.  This would allow a synced connection between different resolutions.  I am not sure how that is done, I think it may be inside a single file.  I've never bothered to look it up.  Unless you have media that can auto switch with resolution, you are going to be stuck with the file needing to be reencoded when you change resolution.  The only exception would be if there were two files which both could play back directly to a user's setup.  You can try that out.  Just make two lower bitrate h.264 .mp4 with AAC audio.  Such files can play back directly for anyone.  You should be able to switch between resolutions easily.

The original media in whatever codec, h.265 is a compressed version which requires proper decoding over several seconds of media to get any image between I frames.  It has to be decoded.  If it also needs to be transcoded for the user to see, than the whole transcoding process has to start over.  If you try to do it in the middle, you will get many seconds of artifacts and probably have an audio sync issue.  You are not pulling video from a lossless master file that gives you full res sequential images 24 frames / second or whatever.  There is no way to easily immediately switch resolution when you have these compressed copies of media that also need transcoding to play.

Maybe there is some trick, that I don't know of.  Does anyone have another idea?

Hope that makes some sense.

Edited February 23, 2025 by visproduction

[yocker 1248]

While playing a video and changing quality with the button to do so usually works, sometimes it just tries to download the video instead of streaming it.
All using the normal Emby functions. That's all i mean.
 

[visproduction 315]

Yock,

Aha!  That would be a bug.  Changing res should not start a download.  Which Emby version and what browser version of Edge are you using? Are you using a TV App?  When I use Emby web the latest beta, I have to stop playback to change resolutions and it works fine.  I don't have an option to change resolution in the player.  What is the exact combination of app, TV / browser when this happens?

[yocker 1248]

My version of Emby is 4.8.10.
It doesn't seem to matter what client or app that's used to play a video, the bug will be there and can and will happen so i figure it must be server sided.

Tried with everything from, Chrome, Windows Edge, Firefox, Emby for Android, Emby for WebOS, Chromecasting and Iphone.

Sorry didn't think of that, some clients might only give the option to change birate but sticking with Windows Edge (for simplicity) i know that when playing a 4K video there you get the option to downscale to 1080p or other resolutions when selecting quality.

Just in case to make 100% sure there is no misunderstanding.
I'm talking about the changing quality using the cogwheel in the video player, not in playback settings of Emby.

[speechles 2055]

  

43 minutes ago, yocker said:

I'm talking about the changing quality using the cogwheel in the video player, not in playback settings of Emby.

web app

roku

When you change it from inside the video player with the gear/cog the apps will only give you options for the resolution you are playing. For example playing a 480P item I only get options related to 480P and lower. You cannot gain quality from within the video player. The setting inside the main playback settings of each app gives you the full quality menu.

9 hours ago, yocker said:

continue to change quality until bug happens.
Shouldn't be hard to replicate.

Why? What is the purpose for changing quality like that? Are we simulate someone on a really horrible connection and they keep dropping down and down until it plays without buffering? Or just trying to break it by fiddling with it constantly?

Are there any ffmpeg logs created? Those might shed light since changing quality lower and lower should eventually cause transcoding.

Edited February 23, 2025 by speechles

[yocker 1248]

1 hour ago, speechles said:

 Why? What is the purpose for changing quality like that? Are we simulate someone on a really horrible connection and they keep dropping down and down until it plays without buffering? Or just trying to break it by fiddling with it constantly?

Are there any ffmpeg logs created? Those might shed light since changing quality lower and lower should eventually cause transcoding.

Continuously changing quality like that is just to replicate it easier. It can happen with just changing quality once.

Tbh. i didn't think of making one as it is so easy to replicate but once my server is empty so i don't stress it while people are on it i will make one.

[speechles 2055]

21 minutes ago, yocker said:

Continuously changing quality like that is just to replicate it easier. It can happen with just changing quality once.

Tbh. i didn't think of making one as it is so easy to replicate but once my server is empty so i don't stress it while people are on it i will make one.

It depends on the container and codecs inside and how high the bitrate is on the original media. If you stay above that direct play should occur. If you choose a quality below the original media bitrate then it will transcode. But if you raise the quality over the original media bitrate after it has started transcoding it will direct play again. If you change quality only once, without hammering repeatedly it should never lock up. It should never lock up even with hammering the button repeatedly but it might get confused if you bang on it. But you are saying it also does it right off the bat for you with changing quality only once. That in itself is concerning as that should never happen. If you can provide ffmpeg and server logs we could probably see what is happening and why. But without those it is hard since I cannot reproduce. It has to be related to container/codec possibly and something I haven't tried.

It will only direct play if the device supports the container and codecs inside fully. If the container or video codec isn't supported it transcodes regardless of quality setting.

Edited February 23, 2025 by speechles

[yocker 1248]

Sadly i have the broken car and the mechanic syndrome right now, can't get it do it now after i have finally reported it.
Doing it on Emby for Android on a mobile was where it had the biggest chance of just locking up and staying to download the whole file after one try of changing quality.

I have just rebooted the server so don't know if that has anything to do with it, will keep trying and if nothing else keep in mind to send log when it happens again, as i'm pretty sure it will people using my server have told me about it for a while now).

[visproduction 315]

Aha.  I see the quality setting now.

Say you have these media copies:

1. 1080P direct at 2.5 Mbps (.mp4)
2. 720P direct at 1.8 Mbps (.mp4)

Quality setting starts at Auto:

Either one will play back directly, depending on which you pick to start.

If you then change to any other Quality choice,  the server will take whichever one you are playing (1080P or 720P) and transcode it to the new speed.

1. 1080P quality 4 Mbps will get transcoded, in this case, upward to a higher bit rate, which makes no sense. New .ts files will be created.
2. 720P quality 1.5 Mbps will also transcode from 1.8 down to 1.5 and new .ts files will be created.

Your playback for that user will be remembered, even when the same user comes back later.  You have to switch back to Auto to stop the transcoding.
===
If your media is h.265 HEVC and many users cannot play that directly, then transcoding is always happening for that user.  Changing the quality would start a new transcoding speed.  

I think it would make sense to check the actual bitrate of the original media and just not offer higher bitrates in quality. I suppose a 3 Mbps .mkv h.265 that needs to be converted to h.264, .mp4 would look better at a higher bit rate, because h.264 needs it, when it's converted quickly in real time.  But, what is the point of taking a 1.5 Mbps h.264 .mp4 and converting it to 2 Mbps .mp4 and lose a generation?

I think this behind the scene activity of what happens is sort of hidden.  Is it explained anywhere in the FAQ?

Hope that makes sense.

Edited February 24, 2025 by visproduction