subtitle problems

Anything and everything to do with DCP-o-matic.
Ross Meyer
Posts: 11
Joined: Fri Jun 04, 2021 12:48 am

subtitle problems

Post by Ross Meyer »

I created a 2K flat SMPTE DCP with burned in subtitles from an .mkv file a handful of days ago and the subtitles displayed for only a very few frames and disappeared. They also bled off the sides of the image and off the bottom of the screen. I tried again today with a different subtitled .mkv file and had the same problem. I uninstalled DOM and reinstalled. Now I can't get the subtitles to display at all but it looks like they'd be hanging off the bottom of the screen in any case. Perhaps this is a simple setting that I'm not familiar with.

Is anyone else having subtitle problems right now?

I've attached a screen grab of what I'm seeing in the DOM preview window as well as a screen grab of the same file in VLC player.
DCP o Matic screen grab.jpg
DCP o Matic screen grab.jpg (939.19 KiB) Viewed 3554 times
vlc screen grab.jpg
vlc screen grab.jpg (1.18 MiB) Viewed 3554 times
Carsten
Posts: 2044
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: subtitle problems

Post by Carsten »

Hmm. Very unusual. Are you sure you used the same subtitle track of that MKV? It looks as if these subtitles are actually text subtitles (mostly, subtitles are PNG raster images).

- Carsten
IoannisSyrogiannis
Posts: 86
Joined: Mon Nov 13, 2017 8:40 pm

Re: subtitle problems

Post by IoannisSyrogiannis »

If this was a BD ripped into an MKV file, it would most probably be PNG subtitles.
Yet, it may as well be an MKV file created otherwise.
I would try to find the correct ffmpeg command to extract the subtitles and open them with a text editor. I would then investigate there and save as UTF-8 before importing to DCP-o-matic.
Apart from that, I would check VLC's setting on Subtitles / OSD > Default Encoding and see if it's UTF-8 or what else and whether another Encoding would show the subtitles' characters as boxes or properly.

My best bet is on the encoding of the text not agreeing with the default for DCPs.
I can't find a setting on DCP-o-matic for the input file or essence, so the conforming would need to be done before adding to DCP-o-matic.
Ross Meyer
Posts: 11
Joined: Fri Jun 04, 2021 12:48 am

Re: subtitle problems

Post by Ross Meyer »

This particular .mkv file has ASS [Eng] and ASS [Ita] subtitles. The English titles are the ones I'd like to be working with. I don't know the origin of the file as it was sent to me online. The file that I had similar problems with earlier in the past week was an .mkv that I ripped from a Warner Archive MOD DVD-R with MakeMKV. I don't know what the subtitle format was as I've already deleted the file but I could rip it again and see what I end up with.
carl
Site Admin
Posts: 1638
Joined: Thu Nov 14, 2013 2:53 pm

Re: subtitle problems

Post by carl »

This file should work better in 2.15.171 if you would like to try that.
Herbert
Posts: 16
Joined: Sun Mar 14, 2021 4:14 pm

Re: subtitle problems

Post by Herbert »

Same Problem, with UTF-8 .srt and .ass files.
Same effect on all languages.
Choosing a Font from the system (Mac) did not help.
Before DOM 2.15.178 the English and French subs were displayed correctly
The screenshot shows the .srt file.
The .ass variants do also store the size and placement of the subs in the image.
Using .ass (not shown in the screenshot) the subs are way off, too small and
too close to the bottom compared to Subtitle Edit and VLC.
Probably because of the "flat" Container/Aspect Ratio
Best, Herbert
Attachments
ShotSubs.jpg
ShotSubs.jpg (881.96 KiB) Viewed 2413 times
carl
Site Admin
Posts: 1638
Joined: Thu Nov 14, 2013 2:53 pm

Re: subtitle problems

Post by carl »

Can you send me the .srt or .ass file you are using? carl@dcpomatic.com
Herbert
Posts: 16
Joined: Sun Mar 14, 2021 4:14 pm

Re: subtitle problems

Post by Herbert »

Dear Carl,
I did mail you some subs yesterday.
In the meantime I tried a workaround:
I took the ProRes Quicktime master and remuxed
it with the .ass subtitle files using MKVToolnix.
Opened the resulting MKV in DOM.
Now the subs are displayed, but too large and too close to the center.
To my understanding, text size and placement are stored within the .ass.
If so, this data seems to be lost or changed due to the 1998x1080 "flat" container.
Also checking the subs took painfully long.
Just to change the appearance resulted in a 90 Min.
evaluation process beforehand (the film is 139Min.) in DCP-o-matic 2.14.56.
DCP-o-matic 2.15.178 crashed on this task.
Best, Herbert
carl
Site Admin
Posts: 1638
Joined: Thu Nov 14, 2013 2:53 pm

Re: subtitle problems

Post by carl »

It sounds like there are a few problems here:
  • missing characters (replaced by numbers in boxes) - I think this is only for Chinese Simplified, right? I see it too, if that's the case; I added a bug. Or do you see that for the English and Spanish subtitles too?
  • ASS subtitles being the wrong size - as far as I can see, ASS sizing is done in points, and this has a pretty arbitrary relationship to the size of text on a cinema screen; the idea was that you fix this using DoM's controls. Though I agree it would be good if DoM agreed with things like VLC on how the sizing should work.
  • long check times for subs - it's always a bit tricky to check multiplexed subs, since it requires reading the whole of the (potentially large) multiplexed file from disk. But I don't understand why it rescanned when you changed some properties... can you give us a bit more detail on that?
Thanks!
Carl
Herbert
Posts: 16
Joined: Sun Mar 14, 2021 4:14 pm

Re: subtitle problems

Post by Herbert »

Dear Carl,
thanks a lot for your reply and your efforts.
No, the missing characters replaced by numbers in boxes
seems to happen with all subtitles, Spanish and English as well.
See the screenshot in my post, Spanish is highlighted.
But maybe it is just a very long lag - Spanish was highlighted, but Chinese displayed
and after some time (hours?) the sub in the image would have changed to spanish...?

But AFAIK isn`t the display of Chinese characters up to the computer´s system?
They are displayed well in VLC, Mac and PC.

Long scanning times: Using a multiplexed file was just a shot at
trying a workaround.
If one does not transfer Blu-Ray to DCP, but a film`s master in ProRes or DnHd,
it would be more sensible and faster to add the subtitles
as .srt or .ass.
This is what I did first when I encountered the problem and even started with
the finished DCP, adding the subs as extra tracks.
Happy new year, Herbert
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