[whatwg] Cue points in media elements

[Kevin Calhoun]

On May 2, 2007, at 11:01 AM, Dave Singer wrote:

> 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.

A discontinuous jump will result in a timeupdate notification, which  
among other things is supposed to enable scripts to issue  
notifications of interesting times that are traversed not during  
playback but while seeking.