Re: QTMovie grabing while playback

FROM : Bob Smith
DATE : Wed Apr 23 20:39:16 2008

On Wed, 23 Apr 2008 20:15:39 +0200
  Jean-Daniel Dupas <<email_removed>> wrote:
>
> Le 23 avr. 08 à 19:58, Randall Meadows a écrit :
>

>> On Apr 23, 2008, at 11:30 AM, Bob Smith wrote:

>>> On Apr 23, 2008, at 10:05 AM, douglas a. welton wrote:
>>>

>>>> QTMovieView has a delegate method
>>>>
>>>>     - (CIImage*) view: (QTMovieView *)Target_View
>>>>willDisplayImage: 
>>>> (CIImage *)New_Image
>>>>
>>>> This method gives you a CIImage to play with before it
>>>>is 
>>>> displayed in the Target_View.  Check the header file for
>>>>
>>>> QTMovieView.h (near the bottom).  I think the the
>>>>MyMovieFilter 
>>>> sample code uses this method.

>>>
>>> I cannot find this method in the documentation, where is
>>>it 
>>> described?  Is it in the public interface?  This is the
>>>perfect 
>>> solution to a similar problem I'm having with a Cocoa
>>>app using 
>>> QuickTime, but I don't want to use undocumented private
>>>APIs.

>>
>> I think he means QTCaptureView.  It's not undocumented;
>>you'll find 
>> it in the QTCaptureView class reference material
>>(available in QT 
>> 7.2.1 and later).
>>
>> Whether it's relevant for you or not depends on how
>>you're 
>> displaying the movie.  I *think* (but am not 100% sure)
>>that this 
>> delegate method is only valid for this particular type
>>of view 
>> (which displays a video preview of a capture session).

>
> This delegate method was also added to QTMovieView. It's
>really  helpfull for example if you want to apply some
>effect or if you want  to insert text in your movie.


Exactly what I'm trying to do, add text overlay to any
movie being played.  I have been using the Core Video
display link which is fine most of the time, except for
unknown reasons it doesn't work with a streaming video
source.  QTMovieView plays streams just fine, so if I can
hook in to it's Core Image processing chain to add my
overlays, problem solved.

One question, is it correct to assume the delegate method
might be called on a secondary thread?

Thanks!

Bob