[whatwg] Cue points in media elements

Dave Singer singer at apple.com
Wed May 2 11:01:30 PDT 2007

At 17:04  -0400 1/05/07, Brian Campbell wrote:
>On May 1, 2007, at 1:05 PM, Kevin Calhoun wrote:
>>I believe that a cue point is "reached" if its time is traversed 
>>during playback.
>What does "traversed" mean in terms of (a) seeking across the cue 
>point (b) playing in reverse (rewinding) and (c) the media stalling 
>an restarting at a later point in the stream?

I would say that playing (at any rate and in any direction) is a 
continuous function, and therefore cue points are triggered, when 
playing, whenever two samples of the time straddle the cue point 
(where straddel includes one of the samples being at the cue point).

Seeking is discontinuous, and therefore cue points are triggered only 
if a seek results in landing on the cue point, if not playing.  If 
playing, then the usual rules apply.

Frame dropping, stalling, and so on, are aspects of the playback 
behavior and nothing to do with the logical model of cues laid on a 
time axis.
David Singer
Apple Computer/QuickTime

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