[vorbis-dev] granulepos start/end revisited

[Conrad Parker]

On Sun, May 23, 2004 at 02:38:34PM +0800, illiminable wrote:
> 
> In my opinion, subtitles should be text. For three main reasons.
> 1) It is a more efficient way to transmit them.
> 2) It allows search engines to use text searches.
> 3) It allows more fleixibility to the player to use different fonts or
> colours if the user so desires.
> 
> I think a better approach is for setup headers to contain "font/display"
> information, this way the "image" data is only defined once per physical
> stream. This means a mechanism for associating for associating a track or
> phrase to a display characteristic is needed. Also, if no display
> characteristics are offered, the player can use a default one.
> 
> Furthermore, for end users, if they decide they don't like the fancy script
> font the author thought was so cool, he can just tell his player to display
> the text using his prefered display characteristics. Similarly for text
> size, someone with not so good vision may not like the cool micro font the
> author decided to use, they may want to use a bigger font that is easier to
> read.
> 
> This mechanism provides many advantages, it lets authors create artistic
> subtitling as the default display characteristics for a stream, but it also
> allows the user to override that choice and choose display characteristics
> suitable to them.

absolutely (eg. CSS for CMML)

> Also, another alternative to which would completely solve the missing
> subtitle problem (though it does introduce it's own issues) is for subtitles
> to have a pointer back to their predecessor. As muxing is a forward
> operation this is not overly complex for a muxer to imlpement as all data is
> known at the specified time point. Though it does introduce some special
> requriements in seeking. But assuming we are resigned to the periodic
> refresh strategy, then this should not be overly taxing. And it also
> introduces new issues to splitting and remuxing streams.

good idea, again this is part of the subtitle data stream (ie. not
paging info). If it's a temporal reference, not a byte reference, it will
survive remuxing.

Conrad.
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