I'm having quite a strange problem with
QTVisualContextCopyImageForTime. When I play most movies, it only
plays the first couple of frames. Repeated calls to this function do
not return the current frame that is actually playing. Because I can
hear the audio from the movie, I'm quite sure the whole movie is
playing.
To make this even weirder, I do have a couple of movies that play
fine. But most (320x240 Photo JPEG codec) do not. Both movies that
play fine were DV movies exported to the 320x240 Photo JPEG format.
It is interesting to note that if I comment out the call to
QTVisualContextTask described below -- then all movies play OK. But
the memory usage indicator in "Activity Monitor" just grows and
grows. Obviously not calling QTVisualContextTask causes a memory leak.
I've struggled to find out why this isn't working, but to no avail.
I've outlined the steps I'm using to play the movie below. If anyone
has any ideas, I'd be very eager to hear them.
Also, if someone at Apple thinks this is worth a bug report, I've
created a small application that recreates the problem that they can
examine.
Many Thanks in Advance,
Mark
----
Steps to recreate the problem in my Carbon/MachO application
Carbon/MachO application
0) call NSApplicationLoad to make nice with Cocoa
1) Create a Window for the Movie and Show it (so it is visible)
2) Create a QTVisualContextRef with an CGLContext context in
preparation for opening the movie with NewMovieFromProperties. The
pixel format properties are
3) Create the movie using NewMovieFromProperties and the
aforementioned QTVisualContextRef
4) Create an AGL OpenGL context for the window (I'm trying to
integrate this into legacy code that uses AGL -- hopefully this
doesn't matter to QT in the end.)
5) Create a CIContext for the AGL context, using the
contextWithCGLContext class method. I'm using aglGetCGLContext and
aglGetCGLPixelFormat to get the CGL form of the AGL context and pixel
format before making this call.
6) Then, in an idle procedure, call
6a) MoviesTask
6a) QTVisualContextTask
6c) QTVisualContextIsNewImageAvailable, and if an image is available call
6d) QTVisualContextCopyImageForTime to get a new CVImageBufferRef
6e) Use initWithCVImageBuffer to create a CIImage from the CVImageBufferRef
6f) Then use the following code to prepare the AGL world
Result: only two or three frames ever play, even though the audio
playing in the movie tells me that it is actually playing the whole
thing.
--
=====================================================================
Mark Coniglio, Artistic Co-Director | email@hidden
Troika Ranch Dance Theater | http://www.troikaranch.org
=====================================================================
_______________________________________________
Do not post admin requests to the list. They will be ignored.
QuickTime-API mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quicktime-api/email@hidden
