added instructions to build a wheel

Author: MichaelBarz

README.md

@@ -3,12 +3,7 @@ This is a simple and lightweight Python extension that allows developers to enum
 
 ```python
 from windows_capture_devices import get_capture_devices
-import av
-
-if __name__ == "__main__":
-    device_list = get_capture_devices()
-
-    # TODO: pyav example 
+device_list = get_capture_devices()
 ```
 
 We use this extension in the `WebcamSource` of our [**multisensor-pipeline**](https://github.com/DFKI-Interactive-Machine-Learning/multisensor-pipeline).
@@ -23,6 +18,19 @@ We use this extension in the `WebcamSource` of our [**multisensor-pipeline**](ht
   ```commandline
   python setup.py build install
   ```
+* Build a wheel
+  ```commandline
+  pip install wheel
+  python setup.py bdist_wheel 
+  ```
+
+## PyAV Example
+We include an example for grabbing an image frame using PyAV in `demo.py`. The demo has additional dependencies:
+
+```commandline
+conda install av -c conda-forge
+pip install Pillow
+```
 
 ## Credits
 This repository is forked from https://github.com/yushulx/python-capture-device-list.

demo.py

@@ -0,0 +1,24 @@
+from windows_capture_devices import get_capture_devices
+import av
+from PIL import Image
+
+
+if __name__ == "__main__":
+    # get list of device names
+    device_list = get_capture_devices()
+
+    # initialize a webcam handle using PyAV and the DirectShow backend
+    cam_device = av.open(format="dshow", file=f"video={device_list[0]}")
+    video_stream = cam_device.streams.video[0]
+
+    # grab one frame from the video stream and save it
+    for frame in cam_device.decode(video_stream):
+        img = frame.to_image()
+        break
+
+    assert isinstance(img, Image.Image)
+    img.save(f"test_{device_list[0]}.jpg")
+    print(f"Success! An image from the {device_list[0]} webcam was stored.")
+
+    # clean up
+    cam_device.close()

setup.py

@@ -1,3 +1,4 @@
+import setuptools
 from distutils.core import setup, Extension
 
 setup(