[vlc-devel] mrl & uri

[Rafaël Carré]

On Fri, 26 Jun 2009 16:11:34 +0200
Rémi Denis-Courmont <remi at remlab.net> wrote:

> 
> On Fri, 26 Jun 2009 15:44:29 +0200, Rafaël Carré
> <rafael.carre at gmail.com> wrote:
> > IMO we should just stop using "mrls" but URIs (explanation at the
> > end)
> 
> There are no URI schemes for discs, DVB, radios, RTP, etc, that I
> know. So err... we are kind of bound to use a superset of URIs. I
> definitely agree that we should accept URLs, and use them when
> possible, but I am afraid we are bound to MRLs as a *superset* of
> URLs.

A superset with a valid syntax.

If a bit of work is required to adhere to the syntax described in
RFC3986 I am willing to do it.

> > Use cases of MRLs :
> > 
> > - access/demux://blabla
> > 
> >     The demux should be specified otherwise since schemes (the part
> >     before ":") can not contain "/".
> >     With input_item_AddOption() for example.
> 
> Unfortunately, it seems that --demux is inherited, in case the input
> item gets children items, which is typically inappropriate. IMHO, the
> fact that the slash violates the URI grammar is a non-issue, so long
> as it does not create any ambiguity. If I'm not mistaken, the scheme
> always ends with a colon, so there should be no parsing ambiguity. I
> must say, I fail to see what problem you are trying to solve by
> forbidding the VLC demux specifier.

No problem within VLC, but what when VLC communicates with the external
world ? (xspf playlists, DBus interface, ..)

This is why I wanted to stick with the syntax, because if we use
unregistered schemes, other applications than vlc would not choke on
the validity but just ignore them.

+ . and - are valid in schemes, so we could for example use
  file+avformat:// to keep the demux specifier.

> > - access://blabla@options (for example cdda:///dev/cdrom@53 , or
> > vcd)
> > 
> > We should use something more correct, but it's not very important
> > since cdda: is not a registered scheme
> > (http://en.wikipedia.org/wiki/URI_scheme for the list)
> > 
> > Here is an example from rfc3986:
> > 
> >          foo://example.com:8042/over/there?name=ferret#nose
> >          \_/   \______________/\_________/ \_________/ \__/
> >           |           |            |            |        |
> >        scheme     authority       path        query   fragment
> > 
> > cdda:///dev/cdrom#53 looks fine to me.
> 
> This might be a good idea.
> 
> > If you know of other cases for "MRLs" please state so.
> 
> SSM with UDP and RTP remain problematic; we have two address & port
> tuples to fit in the location.

Thanks, I'll look into these.

-- 
Rafaël Carré
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