CommandCam

CommandCam is a simple and easy to use command line webcam image grabber for Windows. It captures a single image from a webcam and stores it in a bitmap file. CommandCam is ideal for use in batch files and other situations where you want a very simple way to automate image capture. CommandCam uses Microsoft’s DirectShow API to access webcams, so it should work with most USB cameras.

CommandCam (the source code and the executable version) are published under the GNU General Public License (version 3).

Download CommandCam

CommandCam can be downloaded from my page on Github:

https://github.com/tedburke/CommandCam

The executable file, CommandCam.exe, can be downloaded directly using the following link:

CommandCam.exe (65KB, date: 21-Oct-2021)

The full CommandCam source code, which is contained in a single C++ file, is also available:

CommandCam.cpp (17KB, date: 21-4-2012)

Running CommandCam

To run CommandCam:

1. Firstly, open a console window. From the Windows start menu, select Start -> Accessories -> Command Prompt.
2. Make sure your webcam is plugged in.
3. Move to the directory where you downloaded CommandCam.exe. For example, cd "My Documents\Downloads".
4. Type CommandCam and press return.
5. The captured image will be saved to the file image.bmp.

Here’s how that appears in the console window.

The above example captured the following image of my cup of tea to a file called "image.bmp" (the image was converted to PNG format prior to uploading).

CommandCam Options

Several useful options can be specified using command line arguments.

To specify a time delay between the camera being turned on and the image being grabbed, use the "/delay" option to specify a time delay in milliseconds. For example, to add a 5 second delay,

CommandCam /delay 5000

The default output filename for the grabbed image is "image.bmp". To specify a different filename, use the "/filename" option. If the filename contains any spaces, enclose it in inverted commas. For example, to save the image as "face.bmp":

CommandCam /filename face.bmp

By default, the first available video capture device will be used. To specify a particular device (if you have more than one), use the "/devnum" option. For example, to open the second video capture device:

CommandCam /devnum 2

Alternatively, to specify a capture device by name, use the "/devname" option. If the device name contains any spaces, it should be enclosed in inverted commas. For example, to select a device called “USB Video Device”:

CommandCam /devname "USB Video Device"

To specify a capture device by serial number (for example if you wish to select between two cameras of the same model), use the "/devserial" option. For example, to select a device with the serial number “314159265”:

CommandCam /devserial 314159265

By default, CommandCam does not display any video on the screen before capturing the image. However, you can enable a video preview window using the "/preview" option.

CommandCam /preview

To list the available capture devices, for example to check which device number corresponds to which device, use the "/devlist" option.

CommandCam /devlist

To list the available capture devices with extra detail (currently just the DevicePath for each camera), use the "/devlistdetail" option.

CommandCam /devlistdetail

More than one command line option can be specified at once. For example, to capture an image from the second video capture device to a file called "output.bmp" after a 10 second delay, the following command would be used:

CommandCam /filename output.bmp /delay 10000 /devnum 2

To suppress the text normally printed to the console by CommandCam (welcome message and other information), use the "/quiet" option.

CommandCam /quiet

CommandCam error codes

If CommandCam exits due to an error, it returns one of the following error code values:

1. “Error: no filename specified”
2. “Error: invalid delay specified”
3. “Error: invalid device number”
4. “Error: invalid device name”
5. “Error: invalid device serial number”
6. “Unrecognised command line argument”
7. “Could not initialise COM”
8. “Could not create filter graph”
9. “Could not create capture graph builder”
10. “Could not attach capture graph builder to graph”
11. “Could not create system device enumerator”
12. “No video devices found”
13. “No devices found”
14. “Video capture device not found”
15. “Error getting device name and DevicePath”
16. “Could not create capture filter”
17. “Could not add capture filter to graph”
18. “Could not create Sample Grabber filter”
19. “Could not get ISampleGrabber interface to sample grabber filter”
20. “Could not enable sample buffering in the sample grabber”
21. “Could not set media type in sample grabber”
22. “Could not add Sample Grabber to filter graph”
23. “Could not create Null Renderer filter”
24. “Could not add Null Renderer to filter graph”
25. “Could not render capture video stream”
26. “Could not render preview video stream”
27. “Could not get media control interface”
28. “Could not run filter graph”
29. “Could not get buffer size”
30. “Could not allocate data buffer for image”
31. “Could not get buffer data from sample grabber”
32. “Could not get media type”
33. “Error opening output file”
34. “Wrong media type”

Compiling CommandCam

To compile CommandCam, you will probably require the Microsoft C++ compiler, called "cl.exe", which is included with Visual C++.  Personally, I compile the program from the command line (rather than through the Visual C++ IDE) using the following command:

cl CommandCam.cpp ole32.lib strmiids.lib oleaut32.lib

It should also be straightforward to compile it through the Visual C++ GUI, but it will probably be necessary to specify the following libraries in your project’s linker options:

ole32.lib, strmiids.lib, oleaut32.lib

Source code

The complete source code for CommandCam resides in a single file. Here it is in its entirety:

//
// CommandCam - A command line image grabber
// Copyright (C) 2012-2013 Ted Burke
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program (see the file "COPYING").
// If not, see <http://www.gnu.org/licenses/>.
//
// Website: https://batchloaf.wordpress.com
//
// To compile using the MSVC++ compiler:
//
//		cl CommandCam.cpp ole32.lib strmiids.lib oleaut32.lib
//
// Last modified 24-1-2013
//

// DirectShow header file
#include <dshow.h>

// This is a workaround for the missing header
// file qedit.h which seems to be absent from the
// Windows SDK versions 7.0 and 7.1.
// To use the items defined in this dll, the
// DexterLib namespace must be specified.
// The items in question are:
//
//		DexterLib::_AMMediaType
//		DexterLib::ISampleGrabber
//		DexterLib::IID_ISampleGrabber
//
#import "qedit.dll" raw_interfaces_only named_guids

// For some reason, these are not included in the
// DirectShow headers. However, they are exported
// by strmiids.lib, so I'm just declaring them
// here as extern.
EXTERN_C const CLSID CLSID_NullRenderer;
EXTERN_C const CLSID CLSID_SampleGrabber;

// DirectShow objects
HRESULT hr;
ICreateDevEnum *pDevEnum = NULL;
IEnumMoniker *pEnum = NULL;
IMoniker *pMoniker = NULL;
IPropertyBag *pPropBag = NULL;
IGraphBuilder *pGraph = NULL;
ICaptureGraphBuilder2 *pBuilder = NULL;
IBaseFilter *pCap = NULL;
IBaseFilter *pSampleGrabberFilter = NULL;
DexterLib::ISampleGrabber *pSampleGrabber = NULL;
IBaseFilter *pNullRenderer = NULL;
IMediaControl *pMediaControl = NULL;
char *pBuffer = NULL;

void exit_message(const char* error_message, int error)
{
	// Print an error message
	fprintf(stderr, error_message);
	fprintf(stderr, "\n");

	// Clean up DirectShow / COM stuff
	if (pBuffer != NULL) delete[] pBuffer;
	if (pMediaControl != NULL) pMediaControl->Release();
	if (pNullRenderer != NULL) pNullRenderer->Release();
	if (pSampleGrabber != NULL) pSampleGrabber->Release();
	if (pSampleGrabberFilter != NULL)
			pSampleGrabberFilter->Release();
	if (pCap != NULL) pCap->Release();
	if (pBuilder != NULL) pBuilder->Release();
	if (pGraph != NULL) pGraph->Release();
	if (pPropBag != NULL) pPropBag->Release();
	if (pMoniker != NULL) pMoniker->Release();
	if (pEnum != NULL) pEnum->Release();
	if (pDevEnum != NULL) pDevEnum->Release();
	CoUninitialize();

	// Exit the program
	exit(error);
}

int main(int argc, char **argv)
{
	// Capture settings
	int quiet = 0;
	int snapshot_delay = 2000;
	int show_preview_window = 0;
	int list_devices = 0;
	int list_devices_with_detail = 0;
	int device_number = 1;
	char device_name[255];
	char device_serial[255];
	char filename[255];

	// Other variables
	char char_buffer[100];

	// Default device name and output filename
	strcpy(device_name, "");
	strcpy(filename, "image.bmp");

	// First check if output messages should be suppressed
	int n;
	for (n=1 ; n < argc ; n++)
	{
		// Check next command line argument
		if (strcmp(argv[n], "/quiet") == 0)
		{
			// Enable preview window
			quiet = 1;
		}
	}

	// Information message
	if (!quiet)
	{
		fprintf(stdout, "\n");
		fprintf(stdout, "CommandCam  Copyright (C) 2012-2013 Ted Burke\n");
		fprintf(stdout, "This program comes with ABSOLUTELY NO WARRANTY;\n");
		fprintf(stdout, "This is free software, and you are welcome to\n");
		fprintf(stdout, "redistribute it under certain conditions;\n");
		fprintf(stdout, "See the GNU General Public License v3,\n");
		fprintf(stdout, "<http://www.gnu.org/licenses/gpl.txt>\n");
		fprintf(stdout, "\n");
		fprintf(stdout, "https://batchloaf.wordpress.com/CommandCam\n");
		fprintf(stdout, "This version 24-1-2013\n");
		fprintf(stdout, "\n");
	}

	// Parse command line arguments. Available options:
	//
	//		/delay DELAY_IN_MILLISECONDS
	//		/filename OUTPUT_FILENAME
	//		/devnum DEVICE_NUMBER
	//		/devname DEVICE_NAME
	//		/devserial DEVICE_SERIAL_NUMBER
	//		/preview
	//		/devlist
	//
	n = 1;
	while (n < argc)
	{
		// Process next command line argument
		if (strcmp(argv[n], "/quiet") == 0)
		{
			// This command line argument has already been
			// processed above, so just ignore it now.
		}
		else if (strcmp(argv[n], "/preview") == 0)
		{
			// Enable preview window
			show_preview_window = 1;
		}
		else if (strcmp(argv[n], "/devlist") == 0)
		{
			// Set flag to list devices rather than capture image
			list_devices = 1;
		}
		else if (strcmp(argv[n], "/devlistdetail") == 0)
		{
			// Set flag to list devices rather than capture image
			list_devices = 1;
			list_devices_with_detail = 1;
		}
		else if (strcmp(argv[n], "/filename") == 0)
		{
			// Set output filename to specified string
			if (++n < argc)
			{
				// Copy provided string into char buffer
				strcpy(char_buffer, argv[n]);

				// Trim inverted commas if present and copy
				// provided string into filename char array
				if (char_buffer[0] == '"')
				{
					strncat(filename, char_buffer, strlen(char_buffer)-2);
				}
				else
				{
					strcpy(filename, char_buffer);
				}
			}
			else exit_message("Error: no filename specified", 1);
		}
		else if (strcmp(argv[n], "/delay") == 0)
		{
			// Set snapshot delay to specified value
			if (++n < argc) snapshot_delay = atoi(argv[n]);
			else exit_message("Error: invalid delay specified", 2);

			if (snapshot_delay <= 0)
				exit_message("Error: invalid delay specified", 2);
		}
		else if (strcmp(argv[n], "/devnum") == 0)
		{
			// Set device number to specified value
			if (++n < argc) device_number = atoi(argv[n]);
			else exit_message("Error: invalid device number", 3);

			if (device_number <= 0)
				exit_message("Error: invalid device number", 3);
		}
		else if (strcmp(argv[n], "/devname") == 0)
		{
			// Set device number to specified value
			if (++n < argc)
			{
				// Copy device name into char buffer
				strcpy(char_buffer, argv[n]);

				// Trim inverted commas if present and copy
				// provided string into device_name
				if (char_buffer[0] == '"')
				{
					strncat(device_name, char_buffer, strlen(char_buffer)-2);
				}
				else
				{
					strcpy(device_name, char_buffer);
				}

				// Remember to choose by name rather than number
				device_number = 0;
			}
			else exit_message("Error: invalid device name", 4);
		}
		else if (strcmp(argv[n], "/devserial") == 0)
		{
			// Set device serial number to specified string
			if (++n < argc)
			{
				// Copy device name into char buffer
				strcpy(char_buffer, argv[n]);

				// Trim inverted commas if present and copy
				// provided string into device_serial
				if (char_buffer[0] == '"')
				{
					strncat(device_serial, char_buffer, strlen(char_buffer)-2);
				}
				else
				{
					strcpy(device_serial, char_buffer);
				}

				// Remember to choose by serial number rather than number
				device_number = 0;
			}
			else exit_message("Error: invalid device serial number", 5);
		}
		else
		{
			// Unknown command line argument
			fprintf(stderr, "Unrecognised option: %s\n", argv[n]);
			exit_message("", 6);
		}

		// Increment command line argument counter
		n++;
	}

	// Intialise COM
	hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
	if (hr != S_OK)
		exit_message("Could not initialise COM", 7);

	// Create filter graph
	hr = CoCreateInstance(CLSID_FilterGraph, NULL,
			CLSCTX_INPROC_SERVER, IID_IGraphBuilder,
			(void**)&pGraph);
	if (hr != S_OK)
		exit_message("Could not create filter graph", 8);

	// Create capture graph builder.
	hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL,
			CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2,
			(void **)&pBuilder);
	if (hr != S_OK)
		exit_message("Could not create capture graph builder", 9);

	// Attach capture graph builder to graph
	hr = pBuilder->SetFiltergraph(pGraph);
	if (hr != S_OK)
		exit_message("Could not attach capture graph builder to graph", 10);

	// Create system device enumerator
	hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL,
			CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pDevEnum));
	if (hr != S_OK)
		exit_message("Could not create system device enumerator", 11);

	// Video input device enumerator
	hr = pDevEnum->CreateClassEnumerator(
					CLSID_VideoInputDeviceCategory, &pEnum, 0);
	if (hr != S_OK)
		exit_message("No video devices found", 12);

	// If the user has included the "/list" command line
	// argument, just list available devices, then exit.
	if (list_devices != 0)
	{
		if (!quiet) fprintf(stdout, "Available capture devices:\n");
		n = 0;
		while(1)
		{
			// Find next device
			hr = pEnum->Next(1, &pMoniker, NULL);
			if (hr == S_OK)
			{
				// Increment device counter
				n++;

				// Get device name
				hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
				VARIANT var;
				// Retrieve and print device name
				if (list_devices_with_detail)
					if (!quiet) fprintf(stdout, "Capture device %d:\n", n);
				VariantInit(&var);
				hr = pPropBag->Read(L"FriendlyName", &var, 0);
				if (!quiet) fprintf(stdout, "  Device name: %ls\n", var.bstrVal);
				VariantClear(&var);
				// Retrieve and print device path
				if (list_devices_with_detail)
				{
					VariantInit(&var);
					hr = pPropBag->Read(L"DevicePath", &var, 0);
					if (!quiet) fprintf(stdout, "  Device path: %ls\n\n", var.bstrVal);
					VariantClear(&var);
				}
			}
			else
			{
				// Finished listing device, so exit program
				if (n == 0) exit_message("No devices found", 13);
				else exit_message("", 0);
			}
		}
	}

	// Get moniker for specified video input device,
	// or for the first device if no device number
	// was specified.
	VARIANT var;
	n = 0;
	while(1)
	{
		// Access next device
		hr = pEnum->Next(1, &pMoniker, NULL);
		if (hr == S_OK)
		{
			n++; // increment device count
		}
		else
		{
			if (device_number == 0)
			{
				fprintf(stderr,
					"Video capture device %s not found\n",
					device_name);
			}
			else
			{
				fprintf(stderr,
					"Video capture device %d not found\n",
					device_number);
			}
			exit_message("", 14);
		}

		// If device was specified by name or serial number...
		if (device_number == 0)
		{
			// Get video input device name
			hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
			if (hr == S_OK)
			{
				// Get current device name
				VariantInit(&var);
				hr = pPropBag->Read(L"FriendlyName", &var, 0);

				// Convert to a normal C string, i.e. char*
				sprintf(char_buffer, "%ls", var.bstrVal);
				VariantClear(&var);

				// Exit loop if current device name matched devname
				if (strcmp(device_name, char_buffer) == 0) break;

				// Get current device path
				VariantInit(&var);
				hr = pPropBag->Read(L"DevicePath", &var, 0);

				// Convert to a normal C string, i.e. char*
				sprintf(char_buffer, "%ls", var.bstrVal);
				VariantClear(&var);

				pPropBag->Release();
				pPropBag = NULL;

				// Exit loop if specified serial number appears in DevicePath
				if (strlen(device_serial) && strstr(char_buffer, device_serial)) break;
			}
			else
			{
				exit_message("Error getting device name and DevicePath", 15);
			}
		}
		else if (n >= device_number) break;
	}

	// Get video input device name
	hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
	VariantInit(&var);
	hr = pPropBag->Read(L"FriendlyName", &var, 0);
	if (!quiet) fprintf(stdout, "Capture device: %ls\n", var.bstrVal);
	VariantClear(&var);

	// Create capture filter and add to graph
	hr = pMoniker->BindToObject(0, 0,
					IID_IBaseFilter, (void**)&pCap);
	if (hr != S_OK) exit_message("Could not create capture filter", 16);

	// Add capture filter to graph
	hr = pGraph->AddFilter(pCap, L"Capture Filter");
	if (hr != S_OK) exit_message("Could not add capture filter to graph", 17);

	// Create sample grabber filter
	hr = CoCreateInstance(CLSID_SampleGrabber, NULL,
		CLSCTX_INPROC_SERVER, IID_IBaseFilter,
		(void**)&pSampleGrabberFilter);
	if (hr != S_OK)
		exit_message("Could not create Sample Grabber filter", 18);

	// Query the ISampleGrabber interface of the sample grabber filter
	hr = pSampleGrabberFilter->QueryInterface(
			DexterLib::IID_ISampleGrabber, (void**)&pSampleGrabber);
	if (hr != S_OK)
		exit_message("Could not get ISampleGrabber interface to sample grabber filter", 19);

	// Enable sample buffering in the sample grabber filter
	hr = pSampleGrabber->SetBufferSamples(TRUE);
	if (hr != S_OK)
		exit_message("Could not enable sample buffering in the sample grabber", 20);

	// Set media type in sample grabber filter
	AM_MEDIA_TYPE mt;
	ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
	mt.majortype = MEDIATYPE_Video;
	mt.subtype = MEDIASUBTYPE_RGB24;
	hr = pSampleGrabber->SetMediaType((DexterLib::_AMMediaType *)&mt);
	if (hr != S_OK)
		exit_message("Could not set media type in sample grabber", 21);

	// Add sample grabber filter to filter graph
	hr = pGraph->AddFilter(pSampleGrabberFilter, L"SampleGrab");
	if (hr != S_OK)
		exit_message("Could not add Sample Grabber to filter graph", 22);

	// Create Null Renderer filter
	hr = CoCreateInstance(CLSID_NullRenderer, NULL,
		CLSCTX_INPROC_SERVER, IID_IBaseFilter,
		(void**)&pNullRenderer);
	if (hr != S_OK)
		exit_message("Could not create Null Renderer filter", 23);

	// Add Null Renderer filter to filter graph
	hr = pGraph->AddFilter(pNullRenderer, L"NullRender");
	if (hr != S_OK)
		exit_message("Could not add Null Renderer to filter graph", 24);

	// Connect up the filter graph's capture stream
	hr = pBuilder->RenderStream(
		&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,
		pCap,  pSampleGrabberFilter, pNullRenderer);
	if (hr != S_OK)
		exit_message("Could not render capture video stream", 25);

	// Connect up the filter graph's preview stream
	if (show_preview_window > 0)
	{
		hr = pBuilder->RenderStream(
				&PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
				pCap, NULL, NULL);
		if (hr != S_OK && hr != VFW_S_NOPREVIEWPIN)
			exit_message("Could not render preview video stream", 26);
	}

	// Get media control interfaces to graph builder object
	hr = pGraph->QueryInterface(IID_IMediaControl,
					(void**)&pMediaControl);
	if (hr != S_OK) exit_message("Could not get media control interface", 27);

	// Run graph
	while(1)
	{
		hr = pMediaControl->Run();

		// Hopefully, the return value was S_OK or S_FALSE
		if (hr == S_OK) break; // graph is now running
		if (hr == S_FALSE) continue; // graph still preparing to run

		// If the Run function returned something else,
		// there must be a problem
		fprintf(stderr, "Error: %u\n", hr);
		exit_message("Could not run filter graph", 28);
	}

	// Wait for specified time delay (if any)
	Sleep(snapshot_delay);

	// Grab a sample
	// First, find the required buffer size
	long buffer_size = 0;
	while(1)
	{
		// Passing in a NULL pointer signals that we're just checking
		// the required buffer size; not looking for actual data yet.
		hr = pSampleGrabber->GetCurrentBuffer(&buffer_size, NULL);

		// Keep trying until buffer_size is set to non-zero value.
		if (hr == S_OK && buffer_size != 0) break;

		// If the return value isn't S_OK or VFW_E_WRONG_STATE
		// then something has gone wrong. VFW_E_WRONG_STATE just
		// means that the filter graph is still starting up and
		// no data has arrived yet in the sample grabber filter.
		if (hr != S_OK && hr != VFW_E_WRONG_STATE)
			exit_message("Could not get buffer size", 29);
	}

	// Stop the graph
	pMediaControl->Stop();

	// Allocate buffer for image
	pBuffer = new char[buffer_size];
	if (!pBuffer)
		exit_message("Could not allocate data buffer for image", 30);

	// Retrieve image data from sample grabber buffer
	hr = pSampleGrabber->GetCurrentBuffer(
			&buffer_size, (long*)pBuffer);
	if (hr != S_OK)
		exit_message("Could not get buffer data from sample grabber", 31);

	// Get the media type from the sample grabber filter
	hr = pSampleGrabber->GetConnectedMediaType(
			(DexterLib::_AMMediaType *)&mt);
	if (hr != S_OK) exit_message("Could not get media type", 32);

	// Retrieve format information
	VIDEOINFOHEADER *pVih = NULL;
	if ((mt.formattype == FORMAT_VideoInfo) &&
		(mt.cbFormat >= sizeof(VIDEOINFOHEADER)) &&
		(mt.pbFormat != NULL))
	{
		// Get video info header structure from media type
		pVih = (VIDEOINFOHEADER*)mt.pbFormat;

		// Print the resolution of the captured image
		if (!quiet) fprintf(stdout, "Capture resolution: %dx%d\n",
			pVih->bmiHeader.biWidth,
			pVih->bmiHeader.biHeight);

		// Create bitmap structure
		long cbBitmapInfoSize = mt.cbFormat - SIZE_PREHEADER;
		BITMAPFILEHEADER bfh;
		ZeroMemory(&bfh, sizeof(bfh));
		bfh.bfType = 'MB'; // Little-endian for "BM".
		bfh.bfSize = sizeof(bfh) + buffer_size + cbBitmapInfoSize;
		bfh.bfOffBits = sizeof(BITMAPFILEHEADER) + cbBitmapInfoSize;

		// Open output file
		HANDLE hf = CreateFile(filename, GENERIC_WRITE,
					FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, 0, NULL);
		if (hf == INVALID_HANDLE_VALUE)
			exit_message("Error opening output file", 33);

		// Write the file header.
		DWORD dwWritten = 0;
		WriteFile(hf, &bfh, sizeof(bfh), &dwWritten, NULL);
		WriteFile(hf, HEADER(pVih),
					cbBitmapInfoSize, &dwWritten, NULL);

		// Write pixel data to file
		WriteFile(hf, pBuffer, buffer_size, &dwWritten, NULL);
		CloseHandle(hf);
	}
	else
	{
		exit_message("Wrong media type", 34);
	}

	// Free the format block
	if (mt.cbFormat != 0)
	{
		CoTaskMemFree((PVOID)mt.pbFormat);
		mt.cbFormat = 0;
		mt.pbFormat = NULL;
	}
	if (mt.pUnk != NULL)
	{
		// pUnk should not be used.
		mt.pUnk->Release();
		mt.pUnk = NULL;
	}

	// Clean up and exit
	if (!quiet) fprintf(stdout, "Captured image to %s", filename);
	exit_message("", 0);
}

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