Fix MKV metadata loading

[malaterre]

The correct Mastroska tag used by ffmpeg is 'DATE', not 'date_released'.

Description

I'd like to be able to retrieve both 'title' and 'date' as stored in different containers (eg. avi, mp4 and mkv) in a portable manner.

Motivation and Context

The makes the mkv scrapping consistant with other containers (eg. avi or mp4).

How Has This Been Tested?

Setup kodi to load Video/tag. Settings/Media>'Advanced'>Videos>'Extract thumbnails and video information'

Prepare a folder with:

$ mkdir /tmp/demo
$ cd /tmp/demo
$ wget http://techslides.com/demos/sample-videos/small.mp4
$ ffmpeg -i small.mp4 -map_metadata -1 -metadata title="the mummy" -metadata date="1932" movie.mp4
$ ffmpeg -i small.mp4 -map_metadata -1 -metadata title="the mummy" -metadata date="1932" movie.avi
$ ffmpeg -i small.mp4 -map_metadata -1 -metadata title="the mummy" -metadata date="1932" movie.mkv
$ ffmpeg -i movie.avi movie.avi.mkv
$ ffmpeg -i movie.mp4 movie.mp4.mkv
$ rm small.mp4

All 5 files should load the exact same movie:

• https://www.themoviedb.org/movie/15849-the-mummy

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[malaterre]

For reference:

• Scan video title #13519

[malaterre]

@notspiff let me know if you'd prefer to keep some kind of backward compatible code path (instead of a breaking change). Thanks.

[notspiff]

back then it definitely used date_released, as per https://www.matroska.org/technical/tagging-video-example.html

if ffmpeg has changed this, there is no reason for backwards compatibility, so it's all good.

[malaterre]

@notspiff You may have actually found a regression in ffmpeg. The specification seems to be quite clear about temporal information in MKV container:

• https://www.matroska.org/technical/tagging.html#temporal-information

Let's see what the ffmpeg developers have to say:

• http://ffmpeg.org/pipermail/ffmpeg-user/2020-December/050970.html

[malaterre]

Reported as bug against ffmpeg instead:

• https://trac.ffmpeg.org/ticket/9021

[luzpaz]

No activity upstream unfortunately.

[luzpaz]

This PR should be tagged 'waiting upstream' or something similar