- From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Date: Sat, 24 Mar 2007 07:27:21 +1100
On 3/23/07, Nicholas Shanks <contact at nickshanks.com> wrote:
> Can't we have all of:
> 1) A way for authors to match up timecodes with fragment identifiers
> in the fallback content
> 2) A way for UAs to skip to that time code if a fragment identifier
> is requested and it's contained within fallback the UA isn't displaying
> 3) And a way for users to link to timecodes that aren't marked up at
> all.
I completely agree.
Since we have to stick with the way that URIs are defined and the way
that HTTP works, we can realise these in the following ways:
1. Either the fallback content has a means in which fragment
identifiers are encoded into the video (as e.g. CMML/Annodex provides
for Ogg Theora, or chapter markers in QuickTime), or the UA can
request this information from the server, where it may be stored in a
DB or in a XML file (such as CMML) and can be returned to the UA.
2. Again, there are two alternatives that are possible - either using
the fragment ("#") for identifiers or using queries ("?") to provide
the offset (or named anchor, or time section) in the URI. When using
fragments, the UA first has to download the full file and then
undertake the offset for playback itself. When using queries, a server
module can do the offset and thus avoid potentially large amounts of
binary data to be downloaded to the UA which the users may never want
to look at. The use of queries will be absolutely necessary for mobile
phones for example, where you pay through the nose for bandwidth use.
3. covered in my reply to 2.
I know of only one format that provides for all this functionality at
the moment and that is Ogg Theora with the Annodex and CMML
extensions.
In particular the part where a server component is required to provide
a valid file from a time offset (and - don't get me wrong - a anchor
is nothing else but a named time offset) is unique. Annodex has a
apache module called mod_annodex to provide this functionality. And it
has python, php and perl bindings to provide this functionality
through typical Web scripting languages.
Cheers,
Silvia.
Received on Friday, 23 March 2007 13:27:21 UTC