MOV_TEXT subtitle support partially broken in 4.7.0.X..?

[BagronkeN 1]

Hi,

MOV_TEXT subtitle support seems to have been partially broken in the latest version. This is the subtitle format used in YouTube videos, and probably other streaming platforms.

1. MOV_TEXT subtitles can no longer be directly played. Playing a video file with subtitles will force video transcoding, citing that the subtitles are not supported for direct play. This applies to both Emby Theater and the iOS app.

2. If video transcoding is disabled, the video will never start but try to load forever until you forcibly quit the application (eg Alt+F4). This applies to Emby Theater, the iOS app will stop trying after a few seconds, but does not show any error message.

3. If video transcoding is enabled, the correct subtitle formatting will not be used, and instead the subtitles seem to be displayed in Times New Roman. However, if you disable and re-enable the subtitles while playing the video (ie CC-button -> Off, CC-button -> MOV_TEXT subtitles), the subtitles will now be displayed with the correct formatting.

4. Also, if you start the video without subtitles enabled, the video will start direct playing, and if you then enable subtitles while still playing the video, Emby is able to display the MOV_TEXT subtitles while still direct playing, and shows them with the correct formatting straight away.

I have uploaded the video I used as an example, so you can try to recreate the same issue on your end. The issue applies to all my videos with MOV_TEXT subtitles, and started happening after the latest update. It has been working flawlessly before that, and since there has been several other subtitle-related topics after the update, maybe something has been changed in how Emby initially loads internal subtitles..?

Or is this problem just totally unrelated to any update..? Maybe some setting got reset in the update that changed how Emby handles these files? I've not changed any settings recently, nor installed any new plug-ins, nor changed any hardware or software, except for regular Windows Updates and updated NVIDIA drivers.

Emby Server: Windows v4.7.0.60. No custom CSS.
Emby Theatre: Windows Desktop v3.0.15
Emby for iOS: v2.1.6
Server and ffmpeg logs attached. These logs are from when the server forcibly transcodes the video, and when Emby Theatre displays the subtitles with the wrong formatting, ie scenario 1 above.

Let me know if you need anything else, or if I can try anything more on my end.

Thanks!

EDIT: Just to clarify, other subtitle formats work just fine with direct play, both internal and external SRT/Subrip, as well as DVBSUB and PGS. No forced transcoding or wrong formatting with those subtitle formats, it's just MOV_TEXT that seems to have started having issues recently.

embyserver.txt ffmpeg-transcode-d2b4c37c-3005-4953-acd4-64686c0eeb20_1.txt

Edited May 20, 2022 by BagronkeN
Added information about other subtitle formats still working as intended.

[BagronkeN 1]

According to this topic, dated before the recent updates, MOV_TEXT doesn't seem to be supported without transcoding: 

I've actually not checked if my MOV_TEXT videos have always been transcoded in the past (since I normally allow transcoding), but I've never experienced any delay in the video starting to play until very recently, and the incorrect formatting has never happened before.

Also, it does seem like Emby is still capable of direct playing these videos, as long as you enable the MOV_TEXT after you start the video, so I still think something has changed from how it handled these files before.

[Luke 42085]

Hi, check your server transcoding settings. You may have disabled on the fly subtitle extraction. When playing in the browser, the browser doesn't support embedded subtitles so we extract them on the fly. But if you disabled that, then transcoding becomes the next option.

Theater can handle mov_text but it looks like it has never reported this to the server, so that's why it's transcoding, but that can corrected in the next update to the Theater app.

And it looks like iOS is in the same boat as Theater, so that will be in the next Emby iOS update.

[BagronkeN 1]

@Luke, thanks for a quick reply, as always!

Yes, you are correct, on the fly subtitle extraction was disabled. I've not changed that setting (knowingly) and I don't know what it has been set to before, but with that enabled, Theater is able to directly play MOV_TEXT. Thank you!

However, now that it is extracting the subtitles, Theater is now using a font face that the MOV_TEXT has specified, which seems to be "Serif".

Disabling and re-enabling the subtitles while the video is playing does not help, like it did with scenario 3 in my original post.

In the iOS app the subtitles are now displayed with the correct formatting (and the normal Emby subtitle font), and it works with direct play without any issues.

Is there a way to get Theater to work like it did before, or get it to handle these subtitles just like when you enable subtitles after stating to play the video (scenario 3 above)..?

I want it to display the subtitles without the custom font setting from the subtitle, and without transcoding the video, just like it has done before. (And just like the iOS app does right now with subtitle extraction enabled.)

[Luke 42085]

Right now, there's no way to control that. It's just different behavior from the video players on different platforms.

[BagronkeN 1]

Well, it's great shame that you changed this then. I understand that it's a niche use point, but watching YouTube clips this way was the main advantage with Emby over Plex for me, and sadly these Serif fonts make me want to stab my eyes out. And to turn off subtitles, only to turn them on after I've hit play, just to force Emby to then magically manage to direct play and handle the subtitles correctly at the same time is too big of a hassle each time.

Hopefully you'll add better subtitle support down the road, or change this back to how it worked before, whatever was changed (which I still don't understand), it still seems like a bug to me ¯\_(ツ)_/¯

[pwhodges 2014]

Presumably if the subtitles actually specify "serif" that is what is intended.  I certainly get annoyed when software doesn't do what's specified in ASS subtitles, for instance. 

But given that YouTube doesn't display serif subtitles, it's strange that the file contains that specification.  For my part, I'd be trying to find out why.  When I capture subtitles from YouTube, I get either SRT or VTT format files, with no font specification in either...

Paul

[BagronkeN 1]

@pwhodges, yes, the MOV_TEXT from YouTube does specify Serif, I extracted the subtitles from the mp4 and checked the file before my second post. And I know that Emby has never implemented proper external subtitle support to override the font. Why they haven't is totally beyond me, but I guess it hasn't been a requested enough feature, and I also know that this is a very niche use case.

I'm not looking to switch my YouTube downloader, it's a very popular one that handles subscriptions automatically, and I really can't be bothered to switch that just because Emby has broken their subtitle support. But yes, your recommendation is totally valid for other users if they aren't bothered by switching to a YouTube downloader that doesn't use MOV_TEXT or doesn't specify the font face.

I'm just looking for Emby to either have better subtitle support for external subtitles, or for it to switch back to how it handled the internal subtitles before the recent change. And since Emby obviously is (still) able to direct play and handle internal MOV_TEXT subtitles properly, as long as you don't activate the subtitles when you start the video, I can't see a reason why I should change anything on my end.

I'm seeing it as bug, and I'm hoping they fix it because I generally like Emby better than Plex. But I'm also fine with going back to Plex in the meantime, their subtitle support has always been better, and their PC client isn't as much of a janky mess that the Electron platform is. But it might also seem that Emby is finally (almost) ready to release the new Windows App that has been promised for so very long, which hopefully will resolve a lot of longtime issues with Theatre, but who knows.

(Not that Plex is without their own issues of course, none of them are perfect by any means, but I digress.)