Cannot switch audio tracks and subtitles in m4v containers

[emingy 2]

I recently converted a couple of DVDs for Emby, using DVDDecrypter and HandBrake. Some contain audio tracks in different languages and also subtitles. While I can perfectly choose both during playback in VLC Media Player, Emby will stick to one audio track and seems to also have issues with the embedded subtitles (meaning: not showing them). Is this a known issue?

One more hint: both videos where I realized this behaviour had been in my library before. More precisely: a different copy of the film, containing a different set of audio tracks/subtitles. I'm wondering if something is left over in the database, because also the information of having played a video partly will remain when replacing the file. I use .nfo files for metadata and also tried deleting them. However, some data seems to be stored somewhere else, so I wonder if a cleanup is possible and might be of help here.

Here are two screenshots of the file details.

Thanks in advance!

[Luke 42083]

Hi there, let's look at an example of playing one of these:

Thanks.

[emingy 2]

I guess you're asking for the logs. Here you are. As I didn't see anything of interest on first try, I enabled debug logging.

The last attempt is between lines 29048 and 29150.

embyserver.txt

[Luke 42083]

HI, this is your problem:

[emingy 2]

Thanks Luke!

Uh, I had to disable those because our Synology NAS couldn't cope with it. Is there an alternative container format that would make this possible? Or do we need a hardware upgrade?

[Luke 42083]

The browsers have no support for selecting secondary audio tracks, so we can only accomplish that with a conversion. But usually it's just going to be a container swap rather than a full transcode.

[emingy 2]

Indeed. Taking a closer look, I realized that it's the subtitles that trigger the transcoding, not the different audio tracks. Sorry.

However, choosing an embedded subtitle leads to "Reason for transcoding: Subtitle format not supported". Therefore I'm wondering which subtitle format would be supported. Does this depend on the browser I'm using? Is there a setting in Handbrake that could avoid this?

 

[Luke 42083]

8 minutes ago, emingy said:

Therefore I'm wondering which subtitle format would be supported.

 

In the browser it would be plain text formats, e.g. srt, vtt, subrip, etc.

[emingy 2]

I see. So to stick with our current setup, I'd need to extract srt files from the m4v containers and subsequently delete subtitles from the containers (so that users are not confused by error messages). I found a couple of tutorials regarding srt extraction (including ffmpeg), but none of them worked for me. Is anyone experienced with these steps?

If extracting is no option, I might simply use ffmpeg to delete the subtitles from the container and use Emby to search for subtitles. But it seems a waste as they're already there.

[pwhodges 2012]

2 minutes ago, emingy said:

I'd need to extract srt files from the m4v containers and subsequently delete subtitles from the containers

If the subs were SRT in the container, you'd have no need to remove them.  If not, then you need to remove them and use an OCR program to convert them to text - this is often a tedious and error-prone process, because many graphical subtitles are not as clean images as you might expect, so finding existing SRT subs might well be easier (and often you can see the OCR errors in them as well, but at least you've saved yourself some effort).

Paul

[emingy 2]

I see! Thanks for your hints - I'm happy to understand this issue more and more in-depth.

As far as I understand now, DVDs tend to include bitmap subtitles (VOBSUB). This seems far more common than I expected. I understand that it isn't promising to do OCR on this. So I'll start deleting VOBSUB subtitles from the containers and start adding srt files instead.

Thanks!

[pwhodges 2012]

DVDs and BDs only ever have graphical subtitles.  Allowing transcoding with burn-in would be the expected way to handle this in Emby when the clients can't handle them - but I understand you have a problem with that.

Paul