How can I capture iSight frames with Python in Snow Leopard?

Question

I have the following PyObjC script: ``` from Foundation import NSObject import QTKit error = None capture_session = QTKit.QTCaptureSession.alloc().init() print 'capture_session', capture_session device = QTKit.QTCaptureDevice.defaultInputDeviceWithMediaType_(QTKit.QTMediaTypeVideo) print 'device', device, type(device) success = device.open_(error) print 'device open success', success, error if not success: raise Exception(error) capture_device_input = QTKit.QTCaptureDeviceInput.alloc().initWithDevice_(device) print 'capture_device_input', capture_device_input, capture_device_input.device() success = capture_session.addInput_error_(capture_device_input, error) print 'session add input success', success, error if not success: raise Exception(error) capture_decompressed_video_output = QTKit.QTCaptureDecompressedVideoOutput.alloc().init() print 'capture_decompressed_video_output', capture_decompressed_video_output class Delegate(NSObject): def captureOutput_didOutputVideoFrame_withSampleB…

Accepted Answer

Your problem here is that you don't have an event loop. If you want to do this as a standalone script, you'll have to figure out how to create one. The PyObjC XCode templates automatically set that up for you with:

```
from PyObjCTools import AppHelper
AppHelper.runEventLoop()
```

Trying to insert that at the top of your script, however, shows that something inside `AppHelper` (probably `NSApplicationMain`) expects a plist file to extract the main class from. You can get that by creating a `setup.py` file and using `py2app`, something like this example from a PyObjc talk:

```
from distutils.core import setup
import py2app
plist = dict(
    NSPrincipalClass='SillyBalls',
)
setup(
    plugin=['SillyBalls.py'],
    data_files=['English.lproj'],
    options=dict(py2app=dict(
        extension='.saver',
        plist=plist,
    )),
)
```

How can I capture iSight frames with Python in Snow Leopard?

Solution

Problem