Re: Question about mandatory entries

Dan Hinsley via Matroska-users <[email protected]> Mon, 14 Mar 2016 10:30:50 -0700
Newsgroups gmane.comp.multimedia.matroska.user
Message-ID <[email protected]>
Makes sense, thanks

Dan

-----Original Message-----
From: Matroska-users [mailto:[email protected]] On Behalf Of Moritz Bunkus via Matroska-users
Sent: Monday, March 14, 2016 1:11 AM
To: [email protected]
Subject: Re: [Matroska-users] Question about mandatory entries

Hey,

> Mortiz and/or Steve can probably give more insight or could explain it
> more detailed. (And correct me if I said anything wrong)

You were 100% correct. The reason for having default values in general
was twofold:

1. It makes files smaller. For header elements this doesn't matter much
   as there at most a handful of occurrences, but for elements that
   occur frequently (e.g. BlockDuration, ReferencePriority) this does
   matter.

2. It allows extension of the container format in later revisions
   without breaking backwards compatibility. When you introduce a new
   element that's really important you can make it mandatory and give it
   a default value of 0 (for integers, "" for strings etc) with a
   semantic that equals the handling before the element was introduced.

Kind regards,
mosu

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