Pete,
A few things. First, I don't know why you are using unsafe code,
because everything that you are using is safe. Rather, you could declare
the array in unsafe code, fix the pointer to it, and then pass it to the
GetCurrentImage method.
Doing some research, it seems that GetCurrentImage method on the
IBasicVideo2 interface is not supported, so I don't think it is a good idea
to go about using it.
Rather, what you should do is use the DirectShow.NET library to
construct your filter graph (you can render it from a file, which is what I
think you want). You can find the managed direct show library at:
http://directshownet.sourceforge.net/
On top of that, there is a blog entry that I have found which describes
how to get the bitmap bits in C# (it uses an interop library to DirectX, but
I think the sourceforge project is better, and you can easily convert the
code to use that):
http://www.a2ii.com/DasBlog/CommentV...c44c7883c.aspx
I do think that the IMediaDet interface is a little out of date though
(as is the ActiveMovie stuff, btw, it's all DirectShow now). You should be
using the ISampleGrabber interface instead.
There is an example out there that shows how to do this. You can see it
at:
http://www.a2ii.com/tech/directx/tutorialDS6.htm
The link for the code for that tutorial is hard to find, so here it is:
http://www.a2ii.com/tech/directx/tutorialDS6.zip
Note, in that project you will have to remove the reference to
DirectShowLib and replace it with a reference to DirectShowLib that you
downloaded (it's not included in the project).
In the ISampleGrabber.BufferCB method, you can create an instance of a
Bitmap class, using the overload that takes the scan0 parameter. You can
pass the pBuffer parameter into that, and use the video header info (which
has the bitmap header info) information to get the dimensions of the video.
If you are going to save the image, or draw on it, you ^might^ have to
rotate it. If you are going to draw on the image before you save it, then
you should apply a Matrix to the Transform property of the Graphics instance
for the bitmap. Once done drawing, you can call the RotateFlip method to
flip the image (if needed).
Of course, you can always just flip the image before you get the
graphics instance and draw on that. I believe the height property in the
bitmap info header is negative if you need to flip the image.
Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
-
mv*@spam.guard.caspershouse.com
"Pete Davis" <pdavis68@[nospam]hotmail.com> wrote in message
news:aK********************@giganews.com...
I've got an app that plays video using the ActiveMovie COM stuff.
I'm using the FilgraphManagerClass to play the movie and I'm trying to get
an image from the currently displayed scene.
The call to do it is FilgraphManagerClass.GetCurrentImage(ref int
bufferSize, out int dibImage)
Now, I'm aware that my code, as-is, might not free what it's allocating.
That's okay for the moment. I just want to get it working first, then I'll
get it working cleanly.
unsafe private byte[] GetImageData()
{
byte[] buffer = null;
try
{
int buffSize = 0;
int zero = 0;
fmc.GetCurrentImage(ref buffSize, out zero);
IntPtr tempBuffer = Marshal.AllocHGlobal(buffSize);
int tempBufferInt = tempBuffer.ToInt32();
fmc.GetCurrentImage(ref buffSize, out tempBufferInt);
buffer = new byte[buffSize];
Marshal.Copy((IntPtr) tempBufferInt, buffer, 0, buffSize);
Marshal.FreeHGlobal((IntPtr) tempBufferInt);
}
catch(System.Exception ex)
{
Debug.WriteLine(ex.Message);
}
return buffer;
}
Calling GetCurrentImage with zero for the dibImage, should set the
buffSize. This does not happen, however.
If I skip that first call to GetCurrentImage and instead set buffSize to
say, 10*height*width (which should be more than enough room to store the
image), then on the call to GetCurrentImage causes my application to exit.
No exceptions, no messages in the debug output, the app just ends.
Any ideas?
Pete
