Hypertext Coordination Group Teleconference
01 Jul 2011

See also: IRC log


Debbie_Dahl, glazou, +, shepazu, Janina, Steven, +, raphael, Yves
paul_cotton, kazuyuki


<trackbot> Date: 01 July 2011

<raphael> why the pass code 4824 is not valid ?

<glazou> worked for me immediately but I was 1st on the call

<Steven> It didn't work for me the first time; had to repeat it; in the second time

<scribe> Scribenick: Steven_

<scribe> scribe: Steven

rrsagenat, make minutes

Media fragements

Raphael: Media fragments has gone to last call twice, one set of comments not yet resolved
... a number of things say that the fragment should be rendered
... informative in the spec, not required for the implementor
... Do you think that way we have defined media fragments clashes with the SVG definition?

<shepazu> (http://www.example.com/multiresimage#xywh=10,20,30,40 )

Raphael: and do you think that CSS should be able to define the interpretation of a fragment URL?

Glazou: The CSS parser has to validate the URL
... and whether to throw a CSS error
... and drop the rule
... and I don't see another way of doing it

Doug: It's up to the parsing engine on the UA to interpret URLs
... since that's what the RFC says

Glazou: It is also common practice

Raphael: Is the syntax the same?

Glazou: Exactly as defined by the RFC

(RFC 3986)

<raphael> http://dev.w3.org/csswg/css3-images/#url

Raphael: OK, so in the above section you reference the fragment identifiers
... from a syntax point of view that is OK, but how do you interpret the fragment?

Steven: So you don't interpret the fragment?

Glazou: Right.

Raphael: But your spec defers to the mimetype for the meaning of the fragment?
... for many specs there is no definition of what a fragment means
... But you do provide interpretation of fragments
... for instance clipping out a part of an image
... fine for me, but that should really be defined by the resource type, not by CSS
... Media Fragments wants to give guidance when registering a mimetype

Bert: I agree with Glazou's position, I think we should make it nonnormative

Glazou: The examples on images, it is not the job of CSS to clip it. It is the user agent that does it

<Bert> section 4.1 of editor's draft of css3-images

Glazou: CSS is *requesting* something there.

Raphael: So we agree that there should be no clash between the different specs

Glazou: So, the presence of an equals sign allows the discrimination between a reg. ID and an XPath
... to know what kind of thing they are, you have to stop parsing

Raphael: The Media Fragments spec defines something that is a subset of the syntax for fragments
... a set of name value pairs
... so we have to parse to see if it is a media fragment URI
... so I agree you have to parse

Daniel: This is not an issue for CSS/Media fragments, but for the rendering layer

Raphael: I tend to agree
... except for the case where an image container contains more than one image
... of different types

Glazou: Up to the image format

Raphael: Well the CSS people want to know how to do it

Glazou: Not our role to do that; external to CSS.

Raphael: Good; we shall note the case and say it is undefined

Doug: The syntax for media fragments seems fine
... audio/video commands
... clipping of audio/video
... but what if that video file is just one of three on the HTML page?

Glazou: xywh is not an id, it is a command

Doug: I meant, what if I link to a youtube video?

Raphael: This is a frequent case. Already planned to propagate the hash to the actually sourced video

Glazou: Example please?

<shepazu> http://www.example.com/example.ogv#t=10,20


<raphael> #t=30,120 for example

<shepazu> http://www.example.com/example.html#t=10,20

<glazou> then <video id="t"> and #t vs. #t=10,20

Doug: In the second example the big content providers will rpoagate the #t= to the actual video

Raphael: Almost, The spec says nothing normative
... in the example the HTML will try to find an ID called t=10,20
... but youtube will do something special

Glazou: Why a hash instead of a "?" ?

Raphael: There's a big section in the spec on the different behaviours
... you can use a ? as well
... with a ? you get a new resource, which is not cached etc
... with a # you can cache, and you have the whole root resource as well
... we have tried to define it so that nothing breaks. We have found no counter-example yet.

<Bert> (Error in minutes? A "?" doesn't influence caching. Caching is controled by HTTP headers, not by the shape of the URL.)

Glazou: So you are targetting media, but a web page is not media

<raphael> indeed, I just say it just creates a completely new resource which has nothing to do from the "parent" resource

Raphael: The spec doesn't recommend what happens with HTML pages, it is just what some sites do

Doug: I will email my problems; I think we are setting ourselves for trouble

Glazou: what if "rewind" is a command for videos and there is a "rewind" ID in the document ?

Steven: #rewind isn't a MF URL, no problem

<raphael> Raphael: this has nothing to do with media fragments

Doug: The question is whether there are existing clashes with other fragment syntaxes

<shepazu> http://www.w3.org/TR/2009/WD-SVGParam-20090616/

Doug: I have a question about SVG
... SVG parameters, not there yet, but specced out
... minting URLs that act on the existing resource and passes name/value pairs

<glazou> s/rapahel/raphael

Doug: I hope we can avoid clashes

<shepazu> http://dev.w3.org/SVG/modules/param/master/SVGParam.html

<janina> +1 to Doug. I see the problem here is how, not whether to specify something/somewhere within a doc/object.

Yves: SVG is an XML media type so should obey rfc 3023
... then you have to use xpointer
... which is different from formats that are not XML-based

Doug: Don't assume that SVG will be XML-only
... maybe you and I could discuss the SVG param stuff sometime

Glazou: Original question, conflics with CSS< there is no problem

Debbie: I think we have a resolution here

Raphael: No problem with CSS and SVG, need to watch out with SVG2

Glazou: The CSS WG needs to look at this, next Wednesday

Doug: SVG is a timed media that uses # for other purposes, but I need to check

Glazou: So we will go back to our WGs and come back to the HCG

Debbie: 15th July?

Bert: Bad day for me (French holiday)

Glazou: In any case we will send an email to the HCG

Raphael: Thank you for this discussion. Looking forward to your responses

Doug: Already implementations, and tests?

Raphael: Ongoing
... Firefox and Opera in so far
... and big servers


Summary of Action Items

[End of minutes]

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$Date: 2011/07/01 15:03:01 $

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Default Present: Debbie_Dahl, glazou, +, shepazu, Janina, Steven, +, raphael, Yves
Present: Debbie_Dahl glazou + shepazu Janina Steven + raphael Yves
Regrets: paul_cotton kazuyuki
Found Date: 01 Jul 2011
Guessing minutes URL: http://www.w3.org/2011/07/01-hcg-minutes.html
People with action items: 

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