Re: [Pyobjc-dev] Problem with signature for QTKit Delegate (CVImageBufferRef)

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Hi Ronald,

thanks for your immediate action/help !!!

i updated pyobjc-svn today and i can access the CVImageBufferRef now  
(still struggling how to use it) but my initial problem is fixed now.

when i have a working example, i'll post it to the list for the records.

thanks and have a nice day!

Ulrich

Am 21.04.2009 um 17:05 schrieb Ronald Oussoren:

> Ulrich,
>
> The CoreVideo bindings in subversion were incorrect until a moment  
> ago. I've just checked in an updated version of the Quartz bindings  
> (r2166), those fix most of the problems with CoreVideo.
>
> That said, I haven't used the CoreVideo bindings in real code yet  
> and there aren't any Python examples using CoreVideo either and this  
> means there may be issues left.  Other than creating CVPixel buffers  
> in Python code (CVPixelBufferCreate and friends) the bindings should  
> be complete though.
>
> To answer your question:
>
> First of all: use "import Quartz" in your module to ensure that the  
> CoreVideo bindings are loaded, otherwise
>   PyObjC won't load the right framework bindings.
>
> PyObjC should then automaticly deduce the correct signature for the  
> delegate method, not doing so would be a bug in the QTKit bindings.
>
> BTW. Which version of PyObjC are you using?
>
> Ronald
>
> On 20 Apr, 2009, at 3:23, Ulrich Eck wrote:
>
>> hi,
>>
>> i spend a couple of days to find out how to do video capturing  
>> using the current pyobc QTKit framework wrappers and run into a  
>> problem...
>>
>> i couldn't find out, how to write the signature for the selector of  
>> my delegate for QTCaptureDecompressedVideoOutput
>> with the following definition:
>>
>> - (void)captureOutput:(QTCaptureOutput *)captureOutput  
>> didOutputVideoFrame:(CVImageBufferRef)videoFrame
>>       withSampleBuffer:(QTSampleBuffer *)sampleBuffer  
>> fromConnection:(QTCaptureConnection *)connection
>>
>> i tried several signature definitions like:
>>
>> @objc.signature('v@:@{__CVBuffer=*}@@')
>> @objc.signature('v@:@{__CVBuffer=@}@@')
>> @objc.signature('v@:@^{__CVBuffer=}@@')
>> @objc.signature('v@:@@@@')
>>
>> but they all end up in either a PyObcPointer created warning or a  
>> NSCFType for videoStream, which seems not be usable
>> at all (can i cast to an CVImageBufferRef somehow ?).
>>
>> output example without signature:
>> PyObjCPointer created: at 0x29f4590 of type {__CVBuffer=}@@
>> got frame: <QTCaptureDecompressedVideoOutput: 0x2981ac0>  
>> <PyObjCPointer object at 0x25c8b78> <QTSampleBuffer: 0x29f3600>  
>> <QTCaptureConnection: 0x2982510 vide 2vuy>
>>
>> output example for the "@objc.signature('v@:@@@@')" signature:
>> got frame: <QTCaptureDecompressedVideoOutput: 0x2982010> <NSCFType:  
>> 0x29f7310> <QTSampleBuffer: 0x29f5bf0> <QTCaptureConnection:  
>> 0x2982a60 vide 2vuy>
>>
>> using "@objc.signature('v@:@{__CVBuffer=}@@')" results in an error  
>> message:
>> <type 'exceptions.RuntimeError'>: Cannot create FFI CIF: 1
>>
>>
>> now i'm lost ... has anyone here on the list an idea how to convice  
>> the pyobjc wrapper to pass me a valid object/reference to the
>> CVImageBufferRef or what to do with the NSCFType to get to the  
>> buffer -- as shown in the example below .. i want to extract the  
>> image-data
>> from the captured video (possibly as string-buffer reference for  
>> further use with numpy+ctypes).
>>
>> any help is greatly appreciated !!
>>
>> thanks for your help
>>
>> cheers Ulrich
>>
>>
>> here is a minimal example of my code (created a simple pyobjc app  
>> in xcode and this is the main app-delegate):
>> i can also provide the whole example for tests if needed.
>>
>>
>> ############################
>> from Foundation import *
>> from AppKit import *
>> from QTKit import *
>>
>> k24RGBPixelFormat             = 0x00000018    # 24 bit rgb
>> k32ARGBPixelFormat            = 0x00000020    # 32 bit argb    (Mac)
>>
>> class qtkit_captureAppDelegate(NSObject):
>>    def applicationDidFinishLaunching_(self, sender):
>>        NSLog("Application did finish launching.")
>>
>>
>>        session = QTCaptureSession.alloc().init()
>>
>>        device =  
>> QTCaptureDevice.defaultInputDeviceWithMediaType_(QTMediaTypeVideo)
>>        if device is None:
>>            print "failed to open device."
>>            return
>>
>>        device.open_(None)
>>
>>        input = QTCaptureDeviceInput.alloc().initWithDevice_(device)
>>        session.addInput_error_(input, None)
>>
>>        output = QTCaptureDecompressedVideoOutput.alloc().init()
>>
>>        settings = dict(kCVPixelBufferWidthKey=640.0,
>>                        kCVPixelBufferHeightKey=480.0,
>>                         
>> kCVPixelBufferPixelFormatTypeKey=k32ARGBPixelFormat,
>>                        )
>>
>>        output.setPixelBufferAttributes_(settings)
>>        session.addOutput_error_(output, None)
>>
>>        class logger(NSObject):
>>
>>            current_buffer = None
>>
>>            # Declaration:
>>            #- (void)captureOutput:(QTCaptureOutput *)captureOutput  
>> didOutputVideoFrame:(CVImageBufferRef)videoFrame
>>            #       withSampleBuffer:(QTSampleBuffer *)sampleBuffer  
>> fromConnection:(QTCaptureConnection *)connection
>>
>>            #@objc.signature('v@:@{__CVBuffer=*}@@')
>>            #@objc.signature('v@:@{__CVBuffer=@}@@')
>>            #@objc.signature('v@:@^{__CVBuffer=}@@')
>>            @objc.signature('v@:@@@@')
>>            def  
>> captureOutput_didOutputVideoFrame_withSampleBuffer_fromConnection_ 
>> (self, captureOutput, videoFrame, sampleBuffer, connection):
>>                NSLog("got frame: %s %s %s %s" % (captureOutput,  
>> videoFrame, sampleBuffer, connection))
>>
>>                # always have only one frame retained
>>                #CVBufferRetain(videoFrame)
>>                #buffer_to_release = self.current_buffer
>>                #self.current_buffer = videoFrame
>>                #if buffer_to_release is not None:
>>                #    CVBufferRelease(buffer_to_release)
>>
>>                # convert the CVImageBuffer into an NSImage
>>                #cimg = CIImage.initWithCVImageBuffer_(test)
>>                #rep = NSCIImageRep.initWithCIImage_(cimg)
>>                #nimg = NSImage.alloc().initWithSize_(rep.size())
>>                #nimg.addRepresentation_(rep)
>>
>>
>>        cb = logger.alloc().init()
>>        output.setDelegate_(cb)
>>        session.startRunning()
>>
>>        self._data = (session, device, input, output, cb)
>>
>> ############################
>>
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