VideoCapture - A Win32 Python Extension for Accessing Video Devices (e.g. a USB WebCam, a TV-Card, ...)

A Win32 Python Extension for Accessing Video Devices (e.g. a USB WebCam, a TV-Card, ...)

by Markus Gritsch (

)
I would like to put together a list of Python-powered WebCam URLs, so please send me an email with the URL of the plain image or the URL of the HTML page if you use VideoCapture.

Download
PIL version 1.1.2 and below shows a memory leak when using .gif fonts. Remove the files 'helvB08.gif' and 'helvetica-10.gif' in the Lib folder of your Python installation if you have used a version of VideoCapture prior to 0.7!!
[ VideoCapture-0.9-5.zip ]
binaries, sourcecode, examples, and batteries included - no warranty, no liability, provided 'as is'

A stand-alone binary of the included GUI tool 'webcam-watcher' is available here.

What it is
VideoCapture is a Python extension for Win32 which makes it possible to access video-capture devices (e.g. a USB webcam). It consists of a low-level native module (vidcap.pyd) and a high-level module written in Python (VideoCapture.py) which should be used solely.

Also included are some tools which can be used to periodically upload a WebCam-image to a WebServer, monitor and save a picture at a given URL to the local disk, and so on. Please refer to the README.txt file in the 'Tools' folder for further details.

In action
Here is a list of VideoCapture-powered WebCams:

What you need
Beside Python and the VideoCapture module itself, you will need the following additional components:

The low-level module uses DirectShow which is already included in DirectX 8.0 and higher. If you don't have DirectShow, download DirectX from Microsoft and install it. Windows XP has DirectX included.
The high-level module needs PIL to produce actual images from the pixel-data. PIL can be downloaded from PythonWare.
(optionally) If you want to use 'scp' as the transfer method in webcam-uploader.py, you need either scp2.exe, which is included in the installer available from SSH, or pscp.exe, which is available bundled or separately at the PuTTY homepage.

How you install it
To make use of VideoCapture just copy the files from the 'PythonXX' folder to the corresponding folders of your 'PythonXX' installation, where XX must match with the version of Python you have installed on your system.

Trying it out
Taking a snapshot is as easy as

            from VideoCapture import Device

            cam = Device()
            cam.saveSnapshot('image.jpg')

The 'Examples' folder contains simple examples which show how easy it is to obtain images from a video device by using VideoCapture. Refer to 'exa2_show-possibilities.py' for further details on additional options available.
Look at the module documentation for in-depth information.

Shortcomings (ToDo)

setResolution() probably does not work on Devices where the resolution is set in the CaptureFilterProperties.
Some TV-cards forget the tuner (channel) settings after TV-application termination, so VideoCapture should provide a method to display the tuner's property page.

Related stuff
If you want to acquire pictures from a scanner or a digital camera which supports the TWAIN protocol you can use Kevin Gill's excellent twainmodule.

Version history

Version 0.9-5

Added a new function to vidcapmodule.cpp to obtain the Windows "friendly name" (e.g. "Microsoft Lifecam VX-4000") for an instantiated device. Contributed by Jeremy Mortis.

Version 0.9-4

Included a precompiled binary of the low level module linked against Python 2.7 64-bit contributed by Jurriaan Schreuder.

Version 0.9-3

Included a precompiled binary of the low level module linked against Python 2.7 contributed by Chris Spencer.

Version 0.9-2

Included a precompiled binary of the low level module linked against Python 2.6 contributed by Jim Gasbarro.

Version 0.9-1

Included a precompiled binary of the low level module linked against Python 2.5.

Version 0.9

Jonathan Viney fixed a bug which had the potential of leading to a crash when using the module without a camera connected.
Included a precompiled binary of the low level module linked against Python 2.4.

Version 0.8

Added module documentation.
Moved project to SourceForge.net.
Included a precompiled binary of the low level module linked against Python 2.3.
Incorporated stand-alone webservers from Don Garrett and Don Kimber (Tools\3rdParty). The pushserver from Don Kimber is quite interesting. Now I can watch TV in a Mozilla window with 25 fps :-)
Added setResolution() method contributed by Don Kimber. (Probably works only on devices which have the resolution specified in the CapturePinProperties.)
Don Kimber fixed a small but serious inconsistency in displayCapturePinProperties() with sometimes resulted in a seg-fault.

Version 0.7

Replaced the .gif fonts by .png fonts, since PIL version 1.1.2 and below shows a memory leak when using .gif fonts. Remove the files 'helvB08.gif' and 'helvetica-10.gif' in the Lib folder of your Python installation if you have used a version of VideoCapture prior to 0.7!!
Replaced displayPropertyPage() by displayCaptureFilterProperties() and displayCapturePinProperties(). This finally allows selecting things like the video size used during capturing for every kind of device-drivers (now also for WDM drivers, previously only for VfW drivers).
Since there were some memory-leak issues with some device drivers when the filter graph was started and stopped for each capture, the graph is now continuously running. Beside solving the memory issue this has the big advantage, that taking snapshots is *really* fast now. Taking 10 and more snapshots per second is no problem :-)
scp can now also be performed with the pscp.exe program found in the PuTTY distribution.
Fixed a minor memory leak by freeing MediaType.pbFormat.
Added the DirectShow AMCAP utility which can be used to check whether the capture device is compatible with VideoCapture.

Version 0.6

Included a precompiled binary of the low level module linked against Python 2.2.
Put a stand-alone executable of the GUI program 'webcam-watcher' on the webpage.
Added scp as an additional upload method for webcam-uploader (additionally to ftp).
Other minor enhancements to all the programs in the 'Tools' folder.
The displayPropertyPage() dialog is displayed on top of all other windows.
The filtergraph is rebuild after calling displayPropertyPage().

Version 0.5

Changed the filtergraph initialization to use the capture-pin instead of the preview-pin of the video device filter. This should resolve a strange timeout problem and it even allows me to capture snapshots from my TV-card :-)
Added a method displayPropertyPage() to the Device class which displays a dialog-box containing the property pages of the capture device. This should allow selecting things like the video size used during capturing.

Version 0.4

Added a PyQt based program which periodically retrieves a picture from the web and displays it in a GUI window.
Several enhancements to webcam-uploader. Now also a HTML file which displays the uploaded image and periodically reloads itself is placed together with the image on the WebServer.

Version 0.3

Included a precompiled binary of the low level module linked against Python 2.1 (in addition to the one which was already there for Python 2.0).
Added a tool to periodically upload a WebCam-image to a WebServer via FTP.
Added a tool to monitor (and save in case of a change) a Picture located at a given URL.
More than one Device instance can be held open at the same time.
The location of the timestamp in the image is selectable.

Version 0.2

Added extensive error checking after every system call. In case something goes wrong an exception is raised.
Some enhancements to the high level interface like selectable fontstyle, various shadow modes for better font legibility.
The video-device that should be used can be specified.

Version 0.1

Initial release.

Have fun!