Including subtitles in MKV files created by DVBViewer

[kaledii]

Under the DVBViewer Server configuration > Recorder > Task After recording it can be set to create an MKV file. This works except the subtitles aren't muxed into the MKV. Is there a setting that can force this?

[Griga]

vor 7 Stunden schrieb kaledii:

Is there a setting that can force this?

 

No, there isn't. Nevertheless it may be possible to achieve what you want. But that raises some difficult questions. Which kind of subtitles do you want to mux into the MKV? Teletext? DVB subtitles? 

 

Let's assume DVB subtitles. Do the MKV container specifications allow to include DVB subtitles, so they just can be copied to it? If yes, is FFmpeg able to do it? If yes, which command line parameters are required? And is the player of your choice able to detect and display DVB subtitles embedded in an MKV container?

 

If one of the answers is no, the subtitles must be converted to another format, and then it becomes even more difficult. I know that FFmpeg is able to create burned-in subtitles out of DVB subtitles (which means, they become part of the video and can't be switched off anymore), but that requires to decode and re-encode video, which takes much more processing time than just copying it from one container to another one, and inevitably lowers the video quality a bit.

 

So there is no quick answer... anyway, when I find time for it I will try to find out more about this topic.

 

[Griga]

I've found a working solution that you may want to try. It lets FFmpeg convert DVB subtitles to DVD subtitles that can be embedded in MKV files. Just copy the attached tasks.xml file to the C:\Program Files (x86)\DVBViewer\Default\config directory. It provides an additional "Generate MKV with subtitles" task. After that, stop and restart the Media Server.

 

However, there are pitfalls that have to be considered:

• If your recordings only contain DVB subtitles, but no teletext, everything should be fine.
• if a recording (additionally) contains teletext and you are using the FFmepg version 4.2.1 that has been downloaded by the Media Server installer, creating an MKV with subtitles will fail altogether, due to a missing teletext decoder.
• if a recording (additionally) contains teletext and you are using an up-to-date ffmpeg.exe (stored in the DVBViewer program directory) from VideoHelp, creating the MKV will succeed, but the (additional) subtitle track originating from teletext will probably be unusable.
• Since the DVD subtitles colour palette is more limited than the DVB subtitles palette, some of the original colours will get lost. It could be avoided by letting FFmepg copy the DVB subtitles to the MKV, instead of converting them, but this yielded bad results here (missing horizontal lines in the subtitles). If you want to try, open tasks.xml with a text editor and replace -c:s dvdsub by -c:s copy.

Conclusion: The recorder should be set up in the Media Server Options to include subtitles, but no teletext. Please note that you can also create MKVs from former recordings: Web Interface -> Recordings Page -> Click the pencil icon on the right that appears on mouse over -> select the task at the bottom of the popup window -> click "Apply Task". Before you do that, make sure that no MKV file with the same (recording) filename and path already exists, because FFmpeg will refuse to overwrite it.

 

tasks.xml