How are you accessing your frame from the movie? frameImageAtTime: ? if you
request an NSImage, its very slow from my (limited) experience. Requesting a
CVPixelBuffer or CIImage may be faster via frameImageAtTime: withAttributes,
and you could even go with a QTVisualContext and stop the movie, and go to the
next frame manually and extract the frame from your visual context via
QTVisualContextCopyFrameForTime, which is very fast from my experience. The
method commonly used for realtime rendering is using an QTOpenGLTextureContext,
requesting CVOpenGLTextureRefs, and passing them to a QCRenderer that is
initted with the same OpenGL context, or a shared context from the one you
initted your Visual Context with. This guarantees texture sharing, but may be
overkill. I suspect it will be pretty fast, even for stepping through and
rendering "offline" compared to other methods.
As far as sanctioned or not, well, looping like that will not let you process
events in your main thread so you would not be able to pass in mouse events/etc
to QC, but it sounds like you want offline rendering anyway, right? Theres more
than one way to handle drawing to GL, NSOpenGLView, or a making your own
NSOpenGLCOntext and CVDisplayLink, or an NSTimer, etc.
On May 30, 2010, at 3:00 AM, Rick Mann wrote:
> It's either a sanctioned way to draw, or it's not. The fact that they even
> draw in a loop is more telling, because you can't do that in drawRect, either.
>
> I'm processing videos by passing a single frame "through" a composition, then
> taking that result and writing it to a new QTMovie. The view is just to give
> some feedback to the user while this is going on.
>
> (It's terribly slow, getting a single frame out of the input movie at a time,
> but I've gotten no response on the QT list as to why.)
>
> --
> Rick
>
> On May 29, 2010, at 23:56:21, vade wrote:
>
>> Thats note is really more, bare bones, get something on the screen. Most dev
>> examples either subclass drawRect, or use a timer/CVdisplay link to draw
>> multiple frames at a video like framerate. If you only need to draw one
>> frame, that method could work, but re-sizing your view you require a redraw,
>> etc. What is your goal with this app?
>>
>> On May 30, 2010, at 2:53 AM, Rick Mann wrote:
>>
>>> Yet the docs clearly show the QCRenderer being initialized and then
>>> immediately drawing to the view, which you wouldn't do in a drawRect
>>> method, so what gives?
>>>
>>> On May 29, 2010, at 23:52:50, vade wrote:
>>>
>>>> "As with other views, you use your OpenGL view’s drawRect: method to draw
>>>> the content of your view. When your drawRect: method is invoked, the
>>>> environment is automatically configured for drawing using the OpenGL
>>>> graphics context associated with your view."
>>>>
>>>> "To use an OpenGL view in your program, you create a subclass of
>>>> NSOpenGLView and add that view to your window, either programmatically or
>>>> using Interface Builder."
>>>>
>>>> file:///Developer/Documentation/DocSets/com.apple.adc.documentation.AppleSnowLeopard.CoreReference.docset/Contents/Resources/Documents/documentation/Cocoa/Conceptual/CocoaDrawingGuide/QuartzOpenGL/QuartzOpenGL.html#//apple_ref/doc/uid/TP40003290-CH211-BAAECJDJ
>>>>
>>>> On May 30, 2010, at 1:46 AM, Rick Mann wrote:
>>>>
>>>>>
>>>>> On May 29, 2010, at 17:17:26, vade wrote:
>>>>>
>>>>>> Is that code in your NSopenGLView, and are you rendering in drawRect?
>>>>>> when is that actually happening? In init? In awake from nib? You
>>>>>> probably want to move the rendering to drawRect in your NSOpenGLView,
>>>>>> but without more details its hard to know.
>>>>>
>>>>> No, I do this call once, when I create the renderer (which is after the
>>>>> user chooses a couple of files for processing).
>>>>>
>>>>> This is straight from the QCRenderer reference doc overview. Nothing
>>>>> tells me I have to subclass the view and do this in the drawRect method,
>>>>> and I don't think that is necessarily the right way to do this (is it?).
>>>>>
>>>>>>
>>>>>> On May 29, 2010, at 8:07 PM, Rick Mann wrote:
>>>>>>
>>>>>>> I tried my first stab at rendering a simple composition with QCRenderer:
>>>>>>>
>>>>>>> NSOpenGLContext* glCTX = self.outputFrameView.openGLContext;
>>>>>>> if (mQCRenderer == nil)
>>>>>>> {
>>>>>>> NSOpenGLPixelFormat* pixelFormat =
>>>>>>> self.outputFrameView.pixelFormat;
>>>>>>> mQCRenderer = [[QCRenderer alloc]
>>>>>>> initWithOpenGLContext: glCTX
>>>>>>> pixelFormat: pixelFormat
>>>>>>> file: mCompositionPath];
>>>>>>> }
>>>>>>>
>>>>>>> bool success = [mQCRenderer renderAtTime: 0.0 arguments: nil];
>>>>>>> [glCTX flushBuffer];
>>>>>>>
>>>>>>> But nothing appeared in my GL view. success was true.
>>>>>>>
>>>>>>> Any suggestions? Thanks!
>>>>>>>
>>>>>>> --
>>>>>>> Rick
>>>>>>>
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>>>>>>
>>>>>
>>>>
>>>
>>
>
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