[FFmpeg-devel] Why the tag “DURATION” is a necessity in Matroska files?

[wm4]

On Fri, 16 Jun 2017 13:51:20 +0200
21naown at gmail.com wrote:

> Le 16/06/2017 à 12:55, wm4 a écrit :
> > On Fri, 16 Jun 2017 02:32:10 +0200
> > 21naown at gmail.com wrote:
> >  
> >> Hello,
> >>
> >>
> >> I would like to know why the tag “DURATION” in Matroska files (.mkv) is
> >> a necessity? Even mkvmerge lets the choice to use it or not with
> >> “--enable-durations”, in addition it is written “Write durations for all
> >> blocks. This will increase file size and does not offer any additional
> >> value for players at the moment.” (source
> >> https://mkvtoolnix.download/doc/mkvmerge.html#d4e535).
> >>
> >> Possibly linked to
> >> http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=31852540d4fba0c4e8a16d0b3ddff08fc98e48fd  
> > As far as I'm aware, the linked commit does not do the same thing as
> > the mkvmerge option you pointed out.  
> 
> Yes that is why I wrote “possibly”, also because this commit is the one 
> which adds the tag “DURATION” as a necessity, but a necessity that no 
> software seems to use and it is not even a standard in the Matroska’s 
> documentation if I am not mistaken. So the fact that it is a necessity 
> and not a choice is the main problem.

Who says it's a necessity or standard? It's just what mkvmerge does.
Since the patch is by google, I assume google has some use for it
(there might also be a discussion about it on the ML).