On Thu, 20 Jan 2011 04:20:09 +0100, Matthew Gregan <kine...@flim.org>
wrote:
Hi,
The media seek algorithm (4.8.10.9) states that the current playback
position should be set to the new playback position during the
asynchronous
part of the algorithm, just before the seeking event is fired. This
implies
the following behaviour:
0. Initial load state (currentTime reports 0)
1. currentTime set to 20 by script
2. currentTime continues to report 0
3. Script returns to main loop
4. "seeking" event raised
5. currentTime reports 20 in "seeking" event handler
This is the behaviour in Firefox 4. In every other browser I tested
(Chrome
10, Opera 11, Safari 5, and Internet Explorer 9), the following
behaviour is
observed:
2. currentTime immediately reports 20
This doesn't seem to be required by the current wording of the spec (in
fact, it seems to be incorrect behaviour), but I think this behaviour is
more intuitive, as it seems unusual that currentTime returns to the old
value immediately after being set and remains that way until the
"seeking"
event fires.
Does it make sense to update the seeking algorithm to reflect how
non-Firefox browsers are implementing this? My proposal is,
effectively, to
take steps 5 through 8 and insert them before step 4.
I've uploaded a testcase to http://flim.org/~kinetik/seek-627139.html if
anyone's curious.
Thanks,
-mjg
There have been two non-trivial changes to the seeking algorithm in the
last year:
Discussed at
http://lists.w3.org/Archives/Public/public-html/2010Feb/0003.html lead to
http://html5.org/r/4868
Discussed at
http://lists.w3.org/Archives/Public/public-html/2010Jul/0217.html lead to
http://html5.org/r/5219
At least we (Opera) just haven't gotten around to updating our
implementation yet.
With that said, it seems like there's nothing that guarantees that the
asynchronous section doesn't start running while the script is still
running. It's also odd that currentTime is updated before the seek has
actually been completed, but the reason for this is that the UI should
show the new position.
--
Philip Jägenstedt
Core Developer
Opera Software
