// Retrieve capabilities of a video device
internal VideoCapabilities(IAMStreamConfig videoStreamConfig, int index)
{
AMMediaType mediaType = null;
VideoStreamConfigCaps caps = new VideoStreamConfigCaps();
try
{
// retrieve capabilities struct at the specified index
int hr = videoStreamConfig.GetStreamCaps(index, out mediaType, caps);
if (hr != 0)
Marshal.ThrowExceptionForHR(hr);
// extract info
FrameSize = caps.InputSize;
FrameRate = (int)(10000000 / caps.MinFrameInterval);
}
finally
{
if (mediaType != null)
mediaType.Dispose();
}
}
// Set frame's size and rate for the specified stream configuration
private void SetFrameSizeAndRate(IAMStreamConfig streamConfig, Size size, int frameRate)
{
bool sizeSet = false;
AMMediaType mediaType;
// get current format
streamConfig.GetFormat(out mediaType);
// change frame size if required
if ((size.Width != 0) && (size.Height != 0))
{
// iterate through device's capabilities to find mediaType for desired resolution
int capabilitiesCount = 0, capabilitySize = 0;
AMMediaType newMediaType = null;
VideoStreamConfigCaps caps = new VideoStreamConfigCaps();
streamConfig.GetNumberOfCapabilities(out capabilitiesCount, out capabilitySize);
for (int i = 0; i < capabilitiesCount; i++)
{
if (streamConfig.GetStreamCaps(i, out newMediaType, caps) == 0)
{
if (caps.InputSize == size)
{
mediaType.Dispose();
mediaType = newMediaType;
sizeSet = true;
break;
}
else
{
newMediaType.Dispose();
}
}
}
}
VideoInfoHeader infoHeader = (VideoInfoHeader)Marshal.PtrToStructure(mediaType.FormatPtr, typeof(VideoInfoHeader));
// try changing size manually if failed finding mediaType before
if ((size.Width != 0) && (size.Height != 0) && (!sizeSet))
{
infoHeader.BmiHeader.Width = size.Width;
infoHeader.BmiHeader.Height = size.Height;
}
// change frame rate if required
if (frameRate != 0)
{
infoHeader.AverageTimePerFrame = 10000000 / frameRate;
}
// copy the media structure back
Marshal.StructureToPtr(infoHeader, mediaType.FormatPtr, false);
// set the new format
streamConfig.SetFormat(mediaType);
mediaType.Dispose();
}
