On Aug 31, 2010, at 3:15 PM, Dan Wood wrote:

> In our Mac-based website building app, Sandvox, I am trying to come up with a 
> way to get at some properties of a movie which I am loading with a <video> 
> tag.
> 
> What I have been doing so far is populating <video> with the source of the 
> movie to show in the webview, and then *concurrently* creating a QTMovie 
> object that I start loading so I can, for instance, generate a poster image 
> for it (by getting the poster frame, or if it not set, some frame a little 
> way into the movie).  
> 
> Though this approach is OK, it's not ideal ... when I specify a source video 
> from a remote URL, this means that (as far as I can tell) the movie data is 
> being loaded twice, in parallel .... slowing down the process.  A <video> tag 
> has its own QTMovie  reference behind the scenes (from what I can tell 
> looking at WebKit source), and there is my QTMovie as well -- both sucking up 
> network bandwidth.  (Well, unless I prevent preloading of the <video> tag.)
> 
  Are you opening your movie with QTMovieOpenForPlaybackAttribute>

> What if there were some way to get at the underlying QTMovie object used by 
> the <video> tag, so that I could perform my QTMovie operations, and not have 
> to have the movie be loaded separately?
> 
> If I could do this, then theoretically I could also do something nice like 
> get the current frame, so I could have an interface to set my poster frame to 
> the currently displayed frame in the <video>.  (I know that I can get to the 
> current time in the movie using the currentTime attribute, but actually 
> getting the frame image data would require going into the underlying 
> QuickTime movie.  Or, I'd have to get the code from my "other" QTMovie 
> object, which might still be loading...)
> 
> Can anybody help me figure out a trick to get at the underlying QTMovie data 
> of a <video> tag so that I can accomplish this stuff?  This is only from a 
> Mac client, so I can safely assume it's a QTMovie in the background....
> 
  The framework used to back a <video> element is an implementation detail, and 
you definitely don't want assume anything about it.

  If all you want is a frame from the <video>, why don't you seek to the frame 
you want and draw it to a canvas?

eric

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