Archive: enhance mkv tracks metadata

[hekmon]

Hello,

Just wondering why subtitles have their title set to human readable locale but not the their metadata language field ? (which is even more important for players to automatically select the right one for their user)

You do set the language field for video and audio. Why not subtitles ?

It seems to me that your actual locales would be valid values for mkv (from what I see in mkvtoolnix-gui).

Anyway, thank you for your work this software has been working flawlessly so far !

[hekmon]

I guess we could extend this bug report to the language metadata values set for audio/video track (here and here).

You set it to the human readable form but ffmpeg expects for matroska a particular encoding (ISO 639-2/B).

So I guess the correct line could look like something like this if you want to keep the human readable form:

// video
metadata = append(metadata, fmt.Sprintf("-metadata:s:v:%d", i), fmt.Sprintf("language=%s", locale)
metadata = append(metadata, fmt.Sprintf("-metadata:s:v:%d", i), fmt.Sprintf("title=%s", utils.LocaleLanguage(locale))
// audio
metadata = append(metadata, fmt.Sprintf("-metadata:s:a:%d", i), fmt.Sprintf("language=%s", locale)
metadata = append(metadata, fmt.Sprintf("-metadata:s:a:%d", i), fmt.Sprintf("title=%s", utils.LocaleLanguage(locale))
// subtitle
metadata = append(metadata, fmt.Sprintf("-metadata:s:s:%d", i), fmt.Sprintf("language=%s", locale)
metadata = append(metadata, fmt.Sprintf("-metadata:s:s:%d", i), fmt.Sprintf("title=%s", utils.LocaleLanguage(locale))

If ffmpeg accepts the current form of locale values (or another helper could produce valid values based on the current ones).

[hekmon]

Commit 06a5414 seems to work fine, cheers !

The last thing a bit annoying with subtitle is that without any particular options, the first track will be marked as default which will not necessarily be the one the user reads. I saw you try to detect the user local, it could be a nice addition to set the track language corresponding to the user local as default ?

In case local is not detected or if detected but no corresponding subtitle track can be found, you can still add the -default_mode infer_no_subs flag to ffmpeg in order to not mark any default subtitle track.

Thanks again for your work.

Edit: just reread the doc; you could actually always leave the flag -default_mode infer_no_subs on as it will not interfere if you manually set a default subtitle track based on local and act as a fail safe if no default is explicitly defined.

[bytedream]

Fixed in newest commit 0c92fc0, but I had to use -disposition:s:0 0 instead of -default_mode infer_no_subs since this didn't work for some reason (and -disposition is supported by older ffmpeg versions).

[hekmon]

I can confirm 0c92fc0 works fine on my side, thanks !

[bytedream]

I saw you try to detect the user local, it could be a nice addition to set the track language corresponding to the user local as default ?

This is already implemented since v2.0.1, I totally forgot about that lol xd. Just set the environment variable SORT_SUBTITLES=1 before executing and the subtitles should be sorted.