Re: some tech questions

Emmanuel BEUQUE (ebeuque@pratique.fr)
Tue, 10 Jun 1997 09:45:08 +0200

=C0 (At) 16:01 +0200 9/06/97, Klaus Hofrichter =E9crivait (wrote) :
>Folks,
>
>here are two more technical questions on MHEG-5. This time, I do not
>call directly for a Amendment Process... :-) Last time, it was too fast.
>But I am thinking about an extension of the techFAQ from Tom Schwengler
>with the recent (and upcoming) issues. Tom, are you still out there??
>
>
>Q1: Timer: When I run a timer with absolute value (i.e relative to the
>scene), and the indicated time has already passed, shall an engine fire
>the event off?
>
> my suggestion: yes
> this is a clarification only, hence something for the techFAQ

IMHO, I don't agree with you, Klaus. Here is why.
In general, a timer is fired only when the time pass over the timer
temporal position, so as it is said in MHEG-5 IS at section 11.1.3, timers
represent "the temporal positions where the Scene shall receive TimerFired
events".
=46ollowing this, I would say that TimerFired events could never be sent
elsewhere (and I'm sure that most interpreters would act like that because
it seems simpler). If we used MHEG-1, it would be clear with triggers that
include both a previous condition (i.e. current time < timer position) and
a current condition (i.e. current time >=3D timer position). I think we
should follow this mechanism.

Moreover, following what you suggest, I think it would be hard to explain
why the following sentence at section 11.4.SetTimer.2 (paragraph 3) : "If
the timerValue parameter is zero and AbsoluteTime is False, the Timer shall
be fired immediately." would specify "and AbsoluteTime is False".

Just my own opinion anyway.

>Q2: The action SetData requires the ContentHook of the target to be
>encoded. Isn't that too strong?
>
> my suggestion: yes, too strong.
> This would be a change in the semantics. Hence, people have to be
> aware of this, and this issue might be something to consider during
> maintainance of the standard
>

The contentHook is specified in the Ingredient class but cannot be changed
by the setData action. Is it that point that you are grumbling about ?
Would you prefer that the setData action would have to specify the
contentHook ? I don't really see why. Do you have to use some medias coded
in different formats in the same place of your application ? And can't you
managed to have them all in the same format ? I'm not opposed to your
suggestion but I think it could be useful only in very rare case.
(PS : if you have to batch - convert many bitmaps files, just use
Equilibrium Debabelizer (http://www.equilibrium.com)

Best regards to all,

__________________________________________________________________
Emmanuel BEUQUE mailto:ebeuque@pratique.fr
MediaServ tel: +33 (0) 2 99 64 35 64
Multimedia consultant & developer fax: +33 (0) 2 99 64 36 65