Re: comments on draft-barth-mime-sniffing

At 18:55  +0000 12/06/09, Ian Hickson wrote:
>On Mon, 1 Jun 2009, Robert O'Callahan wrote:
>>  On Mon, Jun 1, 2009 at 8:18 PM, Ian Hickson <> wrote:
>>  > The current HTML5 spec's position on this issue is that the
>>  > Content-Type header is completely ignored in the processing of
>>  > <video>, I believe.
>>  Hmm, really? In our media element implementation, we honor Content-Type
>>  completely and do no sniffing whatever.
>I've updated HTML5 to require that Content-Types of types that are not
>supported cause the resource to be ignored (even if it would otherwise be

We're concerned about this, though we support the hope that we can 
get away from doing content-type sniffing in this area.

1) if you use a multimedia framework that you don't control, and it 
does content-type sniffing, then you get it whether you want it or 
not.  QuickTime does, so Safari does, right now.

2) End-users posting AV content rarely have access to the MIME type 
config. of their server (often, their ISP's server).  Getting the 
MIME type table updated can take ages.

3) Once one browser gets a competitive 'edge' by sniffing, the rest 
usually follow.  It's hard to see why this would not happen in this 

Our data suggests that the amount of AV content on the net, today, 
that is served under 'wrong' MIME types is perhaps 10-15%, which 
doesn't seem ignorable.  One of the 'wrong' types is 
application/octet-stream, which seems to invite sniffing;  and of 
course a lot of the rest is text/plain, which is (I believe) Apache's 

So, we're with the motivation, but not sure we're with the spec. as 
written. Hm.
David Singer
Multimedia Standards, Apple Inc.

Received on Tuesday, 16 June 2009 20:46:54 UTC