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Re: Range syntax

From: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
Date: Wed, 09 Sep 2009 13:56:54 +0200
Message-ID: <4AA79806.4090408@cwi.nl>
To: Yves Lafon <ylafon@w3.org>
CC: public-media-fragment@w3.org
Hi Yves,

> I has two ideas for solving this one.
> The first one is very straighforward and reuse the units we already 
> defined:
> Range: npt=12:23.2s-13
> Range: smpte-30-drop=1:22:33-2:33:44
> 
> ie: Range: <timeformat> '=' <start time> - <end time>
> 
> And the same logic for Content-Range:
> 
> Content-Range: npt 12:22.5-13.01/25.1
> Content-Range: smpte-30-drop 1:22:33-2:33:44.1/4:00:00
> 
> ie: Content-Range: <timeformat> ' ' <real start time> '-' <real end time>
>                    '/' <total duration>
> 
> Note that the use of '=' and ' ' is aligned with the Byte range definition.

I like very much this option. As you said, this is aligned with a 
current Byte range request.

> The other option would be to say that it's a time unit, and precise the 
> unit later:
> 
> Range: time=npt:12:22.7-npt:13
> =>
> Content-Range: time=npt:12:22.5-npt:13.01/npt:25.1
> 
> This one has the advantage of being more flexible, but less robust to 
> the introduction of new units (as they can't be advertised using 
> Accept-Ranges).

With this option, one could then express a Range request, for example, 
for a time interval where the start time would be expressed in npt and 
the end time in smpte-30. Is this what you call 'flexibility'? I'm 
afraid that it also adds extra-complexity which is not really required. 
As you say, this solution has also the drawback of we cannot use 
Accept-Ranges.

Question: is it possible to have multiple values for the Accept-Ranges 
header? I can see that:
  Accept-Ranges: none
  Accept-Ranges: bytes
are valid!
Is:
  Accept-Ranges: npt smpte-30 smpte-25
valid too?
Should it be white space separated?

   RaphaŽl

-- 
RaphaŽl Troncy
EURECOM, Multimedia Communications Department
2229, route des CrÍtes, 06560 Sophia Antipolis, France.
e-mail: raphael.troncy@eurecom.fr & raphael.troncy@gmail.com
Tel: +33 (0)4 - 9300 8242
Fax: +33 (0)4 - 9000 8200
Web: http://www.cwi.nl/~troncy/
Received on Wednesday, 9 September 2009 11:57:44 GMT

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