[Matroska-devel] Voids in Matroska

Hendrik Leppkes via Matroska-devel matroska-devel at lists.matroska.org
Sun Feb 14 11:20:40 CET 2016

On Sun, Feb 14, 2016 at 10:44 AM, Sebastian G. <bastik> via
Matroska-devel <matroska-devel at lists.matroska.org> wrote:
> Hello,
> Is there a recommendation how muxers should use Voids in Matroska?

Voids are placed to reserve space, so eg. tags can be written into the
header, or mkvmerge's header editor can append extra properties
without the need to remux the entire file.
Strictly speaking they are "wasted" space, but they are extremely
useful. Being able to modify elements in the track headers without a
full remux is very useful.

> mkvalidator complains about void data, that mkvmerge intentionally
> places [1].

I think the link explains why this warning is not really a "bad" one.
Surely its wasted space, but for a good reason.

> Having a validator complain about Voids would make me change my muxer
> (if I would and could ever write one) so it wouldn't get the warning
> anymore. However there seems to be a valid reason, from my
> understanding, that there could be Voids.
> They are in the specification, but I don't see a recommendation on how
> to use them.
> If they are indeed valuable and do not violate the specs, could
> mkvalidator not just print it as INFO line and/or warn only if a certain
> threshold of void data is found within a file?

Its not up for me to decide that, but making it less severity than
other "problems" in a file is probably not a bad idea.

- Hendrik

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