[Matroska-devel] Voids in Matroska

Sebastian G. <bastik> via Matroska-devel matroska-devel at lists.matroska.org
Sun Feb 14 19:45:39 CET 2016

14.02.2016, 17:36 Steve Lhomme:
> 2016-02-14 17:35 GMT+01:00 Steve Lhomme <slhomme at matroska.org>:
>> 2016-02-14 10:44 GMT+01:00 Sebastian G. <bastik> via Matroska-devel
>> <matroska-devel at lists.matroska.org>:
>>> Hello,
>>> Is there a recommendation how muxers should use Voids in Matroska?
>>> mkvalidator complains about void data, that mkvmerge intentionally
>>> places [1].
>> Another case of warning misunderstanding. It doesn't mean the file is
>> invalid, like an error. It just means the file could be optimized
>> further.

Indeed, that is a misunderstanding of what a warning is supposed to
evoke. E.g here it is only meaningful if I want to save a tiny bit of space.

>>> 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?
>> Yes, maybe warning sounds too severe when in fact it's not.
> I see it more like a compiler warning. Your compiler often report
> warnings on things you know are fine. That doesn't mean your code is
> wrong, it does the compilation just fine. It just tells you there
> things you may have to look at, just in case.

I see that mkvmerge follows that logic. It has warnings and errors.
Warnings can be harmless.

>> mkvalidator returns an error when the file is invalid and 0 (IIRC) if
>> the file is valid. When your file only has warnings, it's actually
>> valid and doesn't return an error.
>>> Regards,
>>> Sebastian
>>> [1] https://github.com/mbunkus/mkvtoolnix/wiki/mkvalidator-WRN0D0-void-data


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