Tagging of webm files is incomplete

[nexus07]

Summary of the bug:
After conversion of an avi file published in the internet under CC-BY-NC-ND license into webm format (file: tr3d.webm), I tried to add the original avi tags from the video to the converted one. (This is necessary due to BY and ND restrictions of the license, the video is not edited anywhere, only converted to make it displayable as HTML5 video).

But it seems not to work. The result file tr3d_tagged.webm does not show the media information. When I select tr3d_tagged.mkv as output file, it works. I used VP80 codec, which is allowed in webm container as subset of mkv codecs.

How to reproduce:

% ffmpeg -i D:\tr3d.webm -c copy -metadata title="A roundtrip with the Transrapid TR09 maglev" -metadata license="CC-BY-NC-ND" -metadata description="Eine Fahrt im TR09" -metadata copyright="Michael Dittmer" -metadata genre="Documentation" -metadata date_released="2014" -metadata url="http://www.pro-transrapid.org" -metadata artist="GFM-eV" -metadata publisher="Pro-Transrapid" -metadata:s:v:0 stereo_mode="left_right" D:\tr3d_tagged.webm
ffmpeg version N-74131-g9ec17e4
built with gcc 4.9.2 (GCC)

[nexus07]

ffmpeg and ffprobe outputs for tr3d_tagged.mkv and tr3d_tagged.webm and VLC media information

[nexus07]

ffprobe of webm video displays only title tag and VLC media player displays title and url in the media information. In both cases, publisher, license, description, copyright, genre, date_relesed and artist information are missing.

[Carl Eugen Hoyos]

Do you have a webm file that shows information about publisher, license, description, copyright, genre, date_relesed and artist information?

[nexus07]

I have uploaded such a webm file here (as part of an archive):

​http://www.datafilehost.com/d/75656526

When the file is opened by VLC media player, the information is visible in the "Current Media Information" window. The file is also playable when embedded in a HTML5 Tag by Mozilla Firefox.

It is an "artificial" webm file because I found no program which writes these information directly into the webm container. After creation it contains no

TAGS container (ID=0x1254C367) before the Cluster container (ID=0x1F43B675)

Maybe this also is an issue for the webm project. Maybe the TAGS container was forgotten in the official specification, but inserting the TAGS into the webm container seems not to make problems.

Maybe this "bug" is a feature request, which is IMHO in the interest of many video producers:

ffmpeg -i <input>.webm -c copy -metadata ... <output>.webm

should insert a TAGS container with the metadata information into the output webm file.

[compn]

could you manually on the command line just stuff all of the info into the webm title tag?
so the title would be "author blah license cc by sa blah" etc.
that would then work in all other software, but it may go against webm spec.

this is just my bad idea.......

[Carl Eugen Hoyos]

Replying to nexus07:

It is an "artificial" webm file because I found no program which writes these information directly into the webm container.

Is it possible that the reason there is no program that writes this information is that it is not allowed by the webm specification?

[nexus07]

Meanwile, I found in the internet more information about the webm container.

I don't believe that the information about publisher, license, description, copyright, genre, date_released and artist is not allowed by the webm specification. See Page

​http://www.webmproject.org/docs/container/

"Work in progress"

The tags I used are listed here and in discussion ("TBD"):

​http://wiki.webmproject.org/webm-metadata/global-metadata#TOC-Official-Tags

But it seems that doing this may not have had the highest priority in the past.

At least there are programs (e.g. VLC Media Player, Media PLayer Classic, Selene) that can read this helpful information.

[nexus07]

I also have submitted an issue to the webm project to enhance the specification and to make a reference implementation:

​https://code.google.com/p/webm/issues/detail?id=1077

[mkver]

Fixed in 27b7800ba907ff4fbb8ecacc50e19a1386f1c643.