Playback error with HLS Subtitles and remuxed container

[starisme 5]

I'm migrating my Emby instance to a new server and I don't seem to be able to play any MKVs with SRT subs turned on. I was able to narrow it down to needing to remux the MKV when going through my reverse proxy. On LAN, the container is direct play but through a reverse proxy it remuxes to HLS but states its recovering from a playback error and will freeze at 0:00:00. The video will play if I disable HLS subtitles in diagnostics but no subtitles show then. Any help would be appreciated. Thanks!

embyserver.txt ffmpeg-directstream-38085468-7bb3-4fa7-9b3d-a06242b308b5_1.txt hardware_detection-63902702315.txt

[Neminem 1516]

Hmm can you try stripping out the subs you don't need.

There are 47 embedded subs in that file.

You can do this with MKVToolNix.

MKVToolNix Downloads – Matroska tools for Linux/Unix and Windows

Make a backup of the movie before you do this, then you don't loss the original.

[starisme 5]

Thanks for the suggestion, I made pared down remuxed MKV with only three embedded subs and still the same issue. The video will not play if I select an embedded sub but will without. I've tested on other videos since then and is not unique to this file, I get the same issue with any matroska that has to be remuxed with HLS subs to the iOS app. I think its inherent to that.

[sa2000 673]

could you establish if the issue also arises with a 3 minute sample of that file - you can use mkvtoolnix to split and then add the first 3 minute split video to a test library and see if that exhibits the problem. Let me know if it does and I will send you a link to upload that sample and you can also include server embyserver and ffmpeg logs awith debug logging enabled before the start. I will see if I can reproduce the problem. 

As another experiment, you can try reducing to 1 subtitle stream and see if that makes a difference

 

[pwhodges 2012]

On 30/12/2025 at 19:50, starisme said:

I was able to narrow it down to needing to remux the MKV when going through my reverse proxy. 

That seems very unlikely to me - how did you determine that the reverse proxy is the cause?  Can you give details of the reverse proxy and its setup?

I routinely play MKS files with multiple embedded subtitles on an iOS device, both locally and through a reverse proxy, and do not see the behaviour you describe.

Paul

[starisme 5]

Thanks for looking into it. The reason I suspect its related to remuxing is because on dashboard it prints MKV > HLS Recovering from Playback Error Under Stream when accessing through my reverse proxy and its direct play if its on my LAN. My reverse proxy is through NPM and configured according to the linked NGINX config post on the forum. Its just a wild guess on my part, happy to be shown if I've misconfigured something since I am migrating the server to new hardware and am new to Intel Arc.

On 1/1/2026 at 6:33 AM, sa2000 said:

could you establish if the issue also arises with a 3 minute sample of that file - you can use mkvtoolnix to split and then add the first 3 minute split video to a test library and see if that exhibits the problem. Let me know if it does and I will send you a link to upload that sample and you can also include server embyserver and ffmpeg logs awith debug logging enabled before the start. I will see if I can reproduce the problem. 

As another experiment, you can try reducing to 1 subtitle stream and see if that makes a difference

 

I made two new test files, one with just a 1 subtitle stream and another with 1 subtitle stream with only 3 mins.

• The full file with 1 subtitle stream still exhibits the same issue, i.e. it does not play if I turn I select the subtitle but will if I turn it off
• The 3 min clip will play after a loading for a few minutes but no subtitles are shown despite having it selected.

I've attached the logs for both cases with emby server log as well the emby server log when I'm on local. Let me know if there is anything else you need. Really appreciate the help!

ffmpeg-directstream-816cf47f-30df-4a1c-b67a-c8e9e72eca42_1.txt embyserver.txt embyserver-local.txt ffmpeg-directstream-6f345713-f85d-47f6-951f-834597c59c00_1.txt

[Luke 42077]

Hi, have you compared your reverse proxy configuration to this?

 

[starisme 5]

22 hours ago, Luke said:

Hi, have you compared your reverse proxy configuration to this?

 

Yep, I literally followed that config post.

[sa2000 673]

On 02/01/2026 at 18:57, starisme said:

The 3 min clip will play after a loading for a few minutes but no subtitles are shown despite having it selected.

Thanks for sending me the first 3 minute test file of the mkv. I have forced transcoding by reducing quality and i am losing some subtitles when playing on Emby for iOS - first displayed subtitle was at offset 00:59 when there were few earlier ones strating at offset 00:38 that did not show.  I will follow this up. Could you repeat your test to see if you really do not get subtitles but just missing out some as I found.

Do you have any android devices you could repeat your test on ?

On 02/01/2026 at 18:57, starisme said:

The full file with 1 subtitle stream still exhibits the same issue, i.e. it does not play if I turn I select the subtitle but will if I turn it off

Are you able to reproduce this symptom with a smaller portion of the file - if you are, you could let me have it. You say the file does not play  - is that for all playbacks with transcoding = including Play from beginning ? or just resuming ?

 

[starisme 5]

On 1/5/2026 at 7:51 AM, sa2000 said:

Thanks for sending me the first 3 minute test file of the mkv. I have forced transcoding by reducing quality and i am losing some subtitles when playing on Emby for iOS - first displayed subtitle was at offset 00:59 when there were few earlier ones strating at offset 00:38 that did not show.  I will follow this up. Could you repeat your test to see if you really do not get subtitles but just missing out some as I found.

Do you have any android devices you could repeat your test on ?

Are you able to reproduce this symptom with a smaller portion of the file - if you are, you could let me have it. You say the file does not play  - is that for all playbacks with transcoding = including Play from beginning ? or just resuming ?

 

Thanks for looking at it! 

• I tried forcing transcoding by reducing the quality to 720p, the 3min test still took a significant amount of time to just start playing. I watched the entire 3 min clip and no subtitles showed up at all.
• Would a firetv count?
• For the behavior with the full file, I can replicate that with the 3 min file as well. If i turn off subtitles the video begins playback after a slight delay and with subtitles turned on it takes several minutes of loading for it to begin playback.

[sa2000 673]

16 minutes ago, starisme said:

I tried forcing transcoding by reducing the quality to 720p, the 3min test still took a significant amount of time to just start playing. I watched the entire 3 min clip and no subtitles showed up at all.

it could be different timing on the server. I have referred the issue i encountered with the first few subtitles to the development team. It looked like the server was not waiting for the subtitle file to be available from the ffmpeg process

My ffmpeg logs were all with names starting "ffmpeg-transcode-"  I noticed the original logs you provided for the 2nd January were all named "ffmpeg-directstream-" - so our tests were not identical

My tests were with an Ipad on iPadOS 18.6.2 running Emby for iOS 2.2.46 with Emby Server beta 4.9.4.1

In your logs I see your iOS device being iPhone with iOS 18.7 and Emby for iOS 2.2.46 with Emby Server 4.9.1.90

I don;t believe there was any change relating to this between the two Emby Server versions. The Emby for iOS version is the same. 

26 minutes ago, starisme said:

Would a firetv count?

I am not a fan and FireTV could bring in its own problems - but I do have a fireTV as well - so we could compare your results with mine.

29 minutes ago, starisme said:

For the behavior with the full file, I can replicate that with the 3 min file as well. If i turn off subtitles the video begins playback after a slight delay and with subtitles turned on it takes several minutes of loading for it to begin playback

I thought for the full file it was not playing if subtitle was selected

On 02/01/2026 at 18:57, starisme said:

The full file with 1 subtitle stream still exhibits the same issue, i.e. it does not play if I turn I select the subtitle but will if I turn it off

You could try with a 20 minute clip and compare. I can send a new upload link if it expired

[Luke 42077]

On 1/4/2026 at 2:55 PM, starisme said:

Yep, I literally followed that config post.

How does your configuration compare to it?

[starisme 5]

Yep sorry, I was speaking about the 3 min file. I cannot get the full file to playback with subtitles on. I will make a 20 min test file and see. I'll post the ffmpeg transcodes later today.

As for the nginx configuration, it matches the setup in the thread.

[starisme 5]

I created a 20 min test file and forced transcoding by reducing the quality in the player. The video took about 5-10 mins before it would play, I just let my phone continue to load. Unfortunately subtitles did not show, even delayed on the entire 20 min segment but I was able to see a glimpse of subtitles moving back to fullscreen from PIP almost like the overlay is under the video. I watched the entire clip just to be sure and that's the only time I could see any subtitles. Attached are the server log and transcode log. Really appreciate the continued help with this!

embyserver.txt ffmpeg-transcode-08079309-8837-4321-b4f4-553463f986fa_1.txt

[sa2000 673]

3 hours ago, starisme said:

The video took about 5-10 mins before it would play, I just let my phone continue to loa

Thanks. The logs show no delays from the emby server or transcoder ffmpeg process. In fact the transcoder finished transcoding the whole 20 minute clip within under 2 minutes

So it is either the network or the iOS app

The logs show the first two 3 second segments requests being seen and dealt with by the emby server and then over 2 minute gap before the request for the next two 3 second segments arrived at the server end and was responded to immediately and another 2 minute gap before the full set of segments requested starting with the first again

i will see if the issue happens in my tests. Thanks for uploading the 20 minute video

In the mean time, you could try as a test a simple network setup without any proxy setup and see if the issue arises

 

 

Edited January 13 by sa2000

[sa2000 673]

I forgot to say I did not have any PIP in my earlier tests. All my tests were default on screen

[sa2000 673]

4 hours ago, starisme said:

I created a 20 min test file and forced transcoding by reducing the quality in the player. The video took about 5-10 mins before it would play, I just let my phone continue to load. Unfortunately subtitles did not show, even delayed on the entire 20 min segment but I was able to see a glimpse of subtitles moving back to fullscreen from PIP almost like the overlay is under the video. I watched the entire clip just to be sure and that's the only time I could see any subtitles. Attached are the server log and transcode log. Really appreciate the continued help with this!

Just tested your 20 minute file - on iPhone through cellular connection running Emby for iOS 2.2.46 and reducing quality as you did to 1080p 4Mb

I selected the English subtitles and played from beginning after selecting the subtitles. 

Tested both on screen and PIP and subtitles appeared ok for me and there was no delay in starting playback. Tested with 2 servers - 4.9.3.1 (with https) and beta 4.9.4.1 (with http) and both worked fine. I only played the first 1 minute of the 20 minute video as there were no issues with the start of playback or subtitles

Attached screenshots shows subtitles showing

I did not have hardware acceleration enabled but I do not expect that to be a factor. You could try with it disabled and see 

Could you try through a cellular connection and reduced quality without going through the reverse proxy to see how that behaves?

Is there any traffic monitoring you can add for the reverse proxy to help identify if any packets being dropped or delays ?

 

[sa2000 673]

5 hours ago, starisme said:

watched the entire clip just to be sure and that's the only time I could see any subtitles

Sorry - did not mention that the logs you attached do not show any vtt segment (subtitles) requests from the Emby for iOS app reaching the server during the playback test during  10:10 am to 10:15 am

[starisme 5]

Hi I tried again on just my cellular and here are the attached logs. I tried twice, once with English turned off then on in the video and once with it turned on at the outset. I was able to get the subtitles to work although it was showing double for one of the sessions but that went away after I closed the app and restarted. Not sure why it just started working now but it seems to be working now.

 

Forgot to attach the logs if they are useful.

embyserver.txt ffmpeg-transcode-b8933963-e7d6-47f0-a516-7f870361ca57_1.txt ffmpeg-transcode-45bb9619-d035-4cf8-b102-47b530f9365f_1.txt

Edited January 16 by starisme

[sa2000 673]

On 16/01/2026 at 20:31, starisme said:

Hi I tried again on just my cellular and here are the attached logs. I tried twice, once with English turned off then on in the video and once with it turned on at the outset. I was able to get the subtitles to work although it was showing double for one of the sessions but that went away after I closed the app and restarted

Thank you for the tests

On 16/01/2026 at 20:31, starisme said:

Not sure why it just started working now but it seems to be working now.

So the problem that you had before is no longer showing up?