Re: [Cellar] Conversation about a NON-IANA request in Matroska

Steve Lhomme <> Wed, 25 August 2021 07:03 UTC

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To: Michael Richardson <>, "Murray S. Kucherawy" <>, Spencer Dawkins at IETF <>, Codec Encoding for LossLess Archiving and Realtime transmission <>, Francesca Palombini <>
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From: Steve Lhomme <>
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Date: Wed, 25 Aug 2021 09:03:42 +0200
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Subject: Re: [Cellar] Conversation about a NON-IANA request in Matroska
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On 2021-08-24 23:01, Michael Richardson wrote:
> Steve Lhomme <> wrote:
>      > Given one of the goal on this Matroska specification is long time
>      > preservation, that would seem odd to design something that renders
>      > older systems incompatible with the current/new specifications. If any
>      > of the MIME types we have in attachments were to become invalid all of
>      > a sudden we wouldn't like it.
> That's not what I suggested.

Sorry for misinterpreting your words.

> I suggested that every reader would always accept both values.
> But that, at some date in the future, writers would start using the new
> values.  I suggested that the date be decided now in order to:
>    a) establish a deadline for readers to get updated.
>    b) allow writing software to gracefully transition without having to be updated.
>    (of course, such software could also have an option)
> We assume that the files are forever, but that the software that reads them
> will get updated now and then.
> In reality, the mime type doesn't really go anywhere specific unless the file
> is being transfered over email or http.  On MAC, with HFS, the MIME type
> might lookup a resource type which gets associated with the file.
> But I suspect that one can associate two things with one resource, and I also
> suspect (having really never coded for MacOS) that it doesn't take mime types
> as input anyway.

I agree with that. But I have the same concern as Murray that a 
hardcoded deadline may not really work.

It also doesn't seem like how our RFCs are designed, where we have some 
legacy values that should not be used throughout the Matroska format. 
Then we would also need to set some deadline for these values not be 
allowed to be written.

In the end when we say it SHOULD NOT be used, it applies right away, not 
some date in the future. That's the same approach I took with the 
transition of MIME types. Just like updating muxers may take some time, 
updating web servers and UPNP servers to update they MIME database will 
take some time.

> --
> ]               Never tell me the odds!                 | ipv6 mesh networks [
> ]   Michael Richardson, Sandelman Software Works        |    IoT architect   [
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