[vorbis-dev] granulepos start/end revisited
dholth at fastmail.fm
Sun May 23 18:28:03 PDT 2004
André Pang wrote:
> The case where it helps you is in implementation. As I said before,
> I'll take a bet that if you implement subtitles with a duration field,
> you'll find it a lot more painful than implementing it if they were
> state changes. I've done both, and while I'm rather far from winning
> the world's most kickass programmer title, I found it much harder and
> more complex to do the former -- I suspect (and hope) that people who
> have implemented similar code would agree. IMHO, I think it's
> significantly harder that implementing it as state change rather than
> duration is worth the effort (although I don't think there's much
> effort involved -- it's a spec change).
If I was implementing duration subtitles I would be sure to decode my
stream into priority queue of upcoming events and break the 'duration'
subtitle into a 'turn on now' and 'turn me off at this time' event.
It's pretty embarassing when MIDI people lose a 'note off' event, and
are stuck with an infinite last note. An alternative developed by a
project that implemented real-time remote duets using midi pianos, was
to assume 'note off' if a repeating 'note continue' was not recieved
within a certain short period of time.
Say you are implementing a Theora TV system, and are putting the
subtitles in real time with a speech recognizer that routinely misspels
the names of terrorists. A separate 'subtitle off' event might reduce
latency, though what I expect an optional 'continue subtitle' or 'early
subtitle disappear, poof!' command would be more useful, or a small
scrolling window that will disappear after a certain amount of
I'm sure if a physicist starts recording Theora home movies of his
particle accellerator experiments he will find a suitable way to
represent the results that is not OggWrit. Who would write the player,
anyway? Icecast support? No thanks.
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