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Re: Same SMIL source on different Players G2 and Soja

From: Lloyd Rutledge <Lloyd.Rutledge@cwi.nl>
Date: Tue, 16 Mar 1999 16:22:37 +0100
Message-Id: <UTC199903161522.QAA05303.lloyd@klipper.cwi.nl>
To: www-smil@w3.org

On Thu, 17 Dec 1998 jose wrote:
>         I have a example of the same SMIL source code and media that plays
> exactly the same on 
> RealNetworks G2 and Helio's Soja

I have also run this SMIL presentation on GRiNS to add some conclusions to
yours.  GRiNS ran the presentation correctly, with the right displaying
and right synchronization.

> http://www.empirenet.com/~joseram/universal/universal.html
> 
>         I did have some problems trying this. I have included all the source
> code (links fixed),
> maybe someone else can see if my conclusions on incompatibilities are
> correct.

The main potential for incompatabilities lies not in the processing of
SMIL but in the media types.  GRiNS does not process RealText, so I
switched the text file names to the ASCII text files you provided.
The text that GRiNS displays is larger in size than SOJA, so wider
regions had to be used to make the text not wrap around.  The assumed
size of text in SMIL presenations is not standardized, so it is up to
each player to determine text size.  Once these adjustments were made,
GRiNS played the presentation correctly.

So while all players handle what SMIL does specify (synchronization,
screen placement, etc.) the same, they don't accept the same media
types.  Furthermore, while they all accept plain text as a media type,
they handle its display differently.  In order to ensure the same
behavior of a SMIL presentation across different systems, media
formats must be used that all systems recognize and that all play in
the same manner.  These would be public formats whose playback has no
ambiguities.  Visual public formats such as JPEG and MPEG have no
display ambiguities.  Plain text, however, does.  Perhaps HTML with
detail font specificiation, or HTML with CSS with detail font
specificiation would display non-ambiguously across platforms.

-Lloyd

--
Lloyd Rutledge                              vox: +31 20 592 41 27
CWI (Centrum voor Wiskunde en Informatica)  fax: +31 20 592 41 99
PO Box 94079                                net: Lloyd.Rutledge@cwi.nl
NL-1090 GB Amsterdam, The Netherlands       Web: http://www.cwi.nl/~lloyd
Received on Tuesday, 16 March 1999 10:22:42 GMT

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