As for the quicktime plugin it provides two concepts. 

(a) we get quicktime to write bits to a squeak surfaceplugin guy which means for for a 480x640 pixel move we don't move 36MB of memory around
every second. That can result in *better* fps and for the minor amount of code involved it's win win. 

(b) we get quicktime to tell us when a frame is ready to be rendered to the display based on when quicktime has finished rendering the frame. That prevents tearing...  Plus if the compression algorithm is really smart it can so, oh don't need to alter the frame because this frame is the same as the last frame... 

As for the semaphore, notes say... 

"If you recall we added that a few years back when we had race conditions on the movie, is it open, is it closed?
Who's closing it, when's it opened..."

The situation is you open and preroll the movie, that is running as a tweak process, you tap stop, that is running as a tweak process. Lots of multi-threading going on. 
So is the movie open or closed? Got a race condition? Oh yes...  Because of that complexity over the years we *managed, just managed* to convince the logic not to crash if the user tapped close at any random point in time during critical phases like when you assume you have an open viable movie, not a zombie... 



On 2011-01-01, at 11:36 AM, Sean P. DeNigris wrote:

> 
> 
> John M McIntosh wrote:
>> 
>> Ok, well it is great that someone is attempting to drag that movie player
>> out of sophie. 
>> Since we must have re-written it 7 times over four years. 
>> 
> 
> John, there are a bunch of semaphore critical blocks in the movie code.  Is
> this because Tweak scripts run in separate processes, or does it have
> something to do with the QuickTime API?  If all code was running in one
> process, could they be removed?
> 
> Thanks.
> Sean
> -- 
> View this message in context: http://forum.world.st/Playing-Flash-movies-in-image-tp3167383p3170351.html
> Sent from the Squeak - Dev mailing list archive at Nabble.com.
> 

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John M. McIntosh <johnmci at smalltalkconsulting.com>   Twitter:  squeaker68882
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