[Ambulant-users] Timing bug in Ambulant?

Jack Jansen Jack.Jansen at cwi.nl
Sun Aug 24 22:14:46 CEST 2008


On  23-Aug-2008, at 14:51 , Chris Abrams wrote:

> I'm a relative newcomer to SMIL but I'm confused as to the behaviour  
> of the
> Ambulant Player when given the following SMIL:

You're not the only one: even though I've been involved with SMIL  
since the early days I am always confused about the behaviour of  
"indefinite". So, I've cc'd Sjoerd Mullender on this conversation, he  
co-wrote the Timing and Synchronisation chapter, so I hope he'll be  
able to tell us what should happen (and how you should get the  
behaviour you want).

The main thing to note is that "indefinite" is not "infinite", though.
>
>
> <?xml version="1.0" encoding="UTF-8"?>
>
> <!DOCTYPE smil PUBLIC "-//W3C//DTD SMIL 2.0//EN"
>                      "http://www.w3.org/2001/SMIL20/SMIL20.dtd">
>
> <smil xmlns="http://www.w3.org/2001/SMIL20/Language">
>    <head>
>        <layout type="text/smil-basic-layout">
>            <root-layout width="400" height="300"  
> backgroundColor="#FFFFFF" />
>            <region regionName="img" left="25" width="350" top="25"  
> height="250"
> backgroundColor="transparent" showBackground="whenActive" />
>        </layout>
>    </head>
>    <body>
>        <seq repeatCount="indefinite">
>            <img src="a.gif" dur="1.5s" region="img" fill="remove" />
>            <img src="b.gif" dur="1.5s" region="img" fill="remove" />
>            <img src="c.gif" dur="1.5s" region="img" fill="remove" />
>        </seq>
>    </body>
> </smil>
>
> I would have expected the sequence of images a, b and c to be repeated
> indefinitetly. However, when run on either Ambulant 1.8 on Windows  
> or the
> latest Ambulant Player built from source and running under Linux,  
> the sequence
> of images is shown just once before play stops.

I could understand it if it was played zero times, or infinitely many  
times, but once indeed sounds funny. I tried it in the RealPlayer, and  
it plays it infinitely many times.

Sjoerd, what is the correct behaviour here?


> The problem is fixed by
> modifying the opening seq element as follows:
>
> <seq dur="4.5s" repeatCount="indefinite">

Here I would have expected the total duration to be 4.5s, in other  
words, I would have expected the sequence to be played once.  
RealPlayer has a very surprising behaviour: it plays the whole  
sequence once, and then continually repeats the first item.
>


--
Jack Jansen, <Jack.Jansen at cwi.nl>, http://www.cwi.nl/~jack
If I can't dance I don't want to be part of your revolution -- Emma  
Goldman


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