Re: [codec] Fwd: New Version Notification for draft-terriberry-oggopus-00.txt

"Timothy B. Terriberry" <tterribe@xiph.org> Wed, 11 July 2012 01:32 UTC

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Subject: Re: [codec] Fwd: New Version Notification for draft-terriberry-oggopus-00.txt
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Jean-Marc Valin wrote:
> One thing we should explicitly mention in the draft is that a decoder
> MUST NOT reject a file because the header is longer than expected.

Yeah, I hadn't touched on this because I wasn't sure what I thought yet.

> This makes it possible to have a minor revision to the format that
> adds a field to the header. As an exception, if the decoder knows the
> exact length of header for the minor revision that the file uses, then
> it MAY reject it. Any thoughts?

The test would actually have to be: exact version is known (0 or 1) AND 
(mapping family is 0 AND length is not 19, OR mapping family is > 0 and 
length is not 21+c). I don't see a reason to disallow rejection this 
case beyond the complexity required to explain how to allow rejection. 
What's the upside to allowing rejection?