[Matroska-devel] Tagging MKV files

Steve Lhomme slhomme at matroska.org
Sat Sep 15 16:48:43 CEST 2012


I know, I'm just saying it's an edge case that is not even documented.
If you want you can add an entry here about it:
http://www.matroska.org/technical/specs/notes.html
I also think that the first SeekHead should have more than just a link
to the secondary one. A player/parser that only care about SegmentInfo
should need to go all the way back to find where it is. At the very
least this one as it's the only Level 1 element that is mandatory.
Also you mentioned somewhere to read recursively, I think there should
only be 2 maximum, more can always be reduced to 2. Otherwise you
could easily do an infinite loop within a file (although you can even
with just one, tests are easier if there is a max of 2 possible).

As for mkvalidator, it's more for developers than end users. mkclean
is the tool for end users and that's what people are presented with on
Sourceforge downloads. But the double SeekHead check could be improved
in mkvalidator, like check if the secondary one would actually fit
where the primary one is.

On Sat, Sep 15, 2012 at 4:35 PM, Moritz Bunkus <moritz at bunkus.org> wrote:
> Hey,
>
> On Sat, Sep 15, 2012 at 4:26 PM, Steve Lhomme <slhomme at matroska.org> wrote:
>
>> Now I never liked the idea of a secondary SeekHead in the first place.
>
> It's absolutely necessary in order to be able to edit files in place,
> especially when adding information like the title, tags, chapters or
> attachments. If it weren't allowed you'd always have to remux the
> whole file. This would make Matroska way, way more useless in my
> opinion -- we're talking about a format for daily use vs. a format
> primarily for archiving (create once, don't touch again).
>
> I feel very strongly about this whole point. If you'd say that linked
> seek heads would violate specs then I would quit Matroska development
> immediately. Don't take this as a threat; you didn't say that. I'm
> trying to make a point. If it weren't allowed then you could
> completely forget about things like mmg's header editor, its chapter
> editor, 3rd party tag editors etc. They all would have to re-mux the
> whole friggin' file and users would simply abandon the format.
>
> Kind regards,
> mosu
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-- 
Steve Lhomme
Matroska association Chairman


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