Re: QTMovie grabing while playback

FROM : douglas a. welton
DATE : Wed Apr 23 22:08:38 2008

Bob & Randall,

If all you want to do is slap some arbitrary text over a movie, I 
would suggest that you take a look at using  QTMovieLayer and 
CATextLayer as the mechanism for doing this.  I don't have any code 
that I can share with you on this, but a previous client project used 
these two Core Animation objects with excellent results.

regards,

douglas

On Apr 23, 2008, at 2:39 PM, Bob Smith wrote:

> 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
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