This is the core class of the Capture Class Library. The following
sections introduce the Capture class and how to use this library.
Basic Usage
The Capture class only requires a video device and/or audio device
to begin capturing. The class provides
lists of the installed video and audio devices.
// Remember to add a reference to DirectX.Capture.dll
using DirectX.Capture
...
Capture capture = new Capture( Filters.VideoInputDevices[0],
Filters.AudioInputDevices[0] );
capture.Start();
...
capture.Stop();
Setting Common Properties
The example below shows how to change video and audio settings.
Properties such as and
allow you to programmatically adjust
the capture. Use and
to determine valid values for these
properties.
Capture capture = new Capture( Filters.VideoInputDevices[0],
Filters.AudioInputDevices[1] );
capture.VideoCompressor = Filters.VideoCompressors[0];
capture.AudioCompressor = Filters.AudioCompressors[0];
capture.FrameRate = 29.997;
capture.FrameSize = new Size( 640, 480 );
capture.AudioSamplingRate = 44100;
capture.AudioSampleSize = 16;
capture.Filename = "C:\MyVideo.avi";
capture.Start();
...
capture.Stop();
Listing Devices
Use the collection to list
video capture devices installed on the system.
foreach ( Filter f in Filters.VideoInputDevices )
{
Debug.WriteLine( f.Name );
}
Preview
Video preview is controled with the
property. Setting this property to a visible control will immediately
begin preview. Set to null to stop the preview.
// Enable preview
capture.PreviewWindow = myPanel;
// Disable preview
capture.PreviewWindow = null;
Property Pages
Property pages exposed by the devices and compressors are
available through the
collection.
// Display the first property page
capture.PropertyPages[0].Show();
Saving and Restoring Settings
To save the user's choice of devices and compressors,
save and user it later
to recreate the Filter object.
To save a user's choices from a property page use
. However, only the audio
and video compressor property pages support this.
The last items to save are the video and audio settings such
as FrameSize and AudioSamplingRate. When restoring, remember
to restore these properties after setting the video and audio
compressors.
// Disable preview
capture.PreviewWindow = null;
// Save settings
string videoDevice = capture.VideoDevice.MonikerString;
string audioDevice = capture.AudioDevice.MonikerString;
string videoCompressor = capture.VideoCompressor.MonikerString;
string audioCompressor = capture.AudioCompressor.MonikerString;
double frameRate = capture.FrameRate;
Size frameSize = capture.FrameSize;
short audioChannels = capture.AudioChannels;
short audioSampleSize = capture.AudioSampleSize;
int audioSamplingRate = capture.AudioSamplingRate;
ArrayList pages = new ArrayList();
foreach ( PropertyPage p in capture.PropertyPages )
{
if ( p.SupportsPersisting )
pages.Add( p.State );
}
// Restore settings
Capture capture = new Capture( new Filter( videoDevice),
new Filter( audioDevice) );
capture.VideoCompressor = new Filter( videoCompressor );
capture.AudioCompressor = new Filter( audioCompressor );
capture.FrameRate = frameRate;
capture.FrameSize = frameSize;
capture.AudioChannels = audioChannels;
capture.AudioSampleSize = audioSampleSize;
capture.AudioSamplingRate = audioSamplingRate;
foreach ( PropertyPage p in capture.PropertyPages )
{
if ( p.SupportsPersisting )
{
p.State = (byte[]) pages[0]
pages.RemoveAt( 0 );
}
}
// Enable preview
capture.PreviewWindow = myPanel;
TV Tuner
To access the TV Tuner, use the property.
If the device does not have a TV tuner, this property will be null.
See ,
and
for more information.
// Change to channel 5
capture.Tuner.Channel = 5;
Troubleshooting
This class library uses COM Interop to access the full
capabilities of DirectShow, so if there is another
application that can successfully use a hardware device
then it should be possible to modify this class library
to use the device.
Try the AMCap sample from the DirectX SDK
(DX9\Samples\C++\DirectShow\Bin\AMCap.exe) or
Virtual VCR from http://www.DigTV.ws
Credits
This class library would not be possible without the
DShowNET project by NETMaster:
http://www.codeproject.com/useritems/directshownet.asp
Documentation is generated by nDoc available at
http://ndoc.sourceforge.net
Feedback
Feel free to send comments and questions to me at
mportobello@hotmail.com. If the the topic may be of interest
to others, post your question on the www.codeproject.com
page for DirectX.Capture.