Output much GREEN with custom DShow Transform filter

[maderlock]

Here's an odd thing. I am using the DirectX 9 SDK to develop a DirectShow app using live input from a firewire camera.

Using just a capture input and default renderer, I build the filter graph and set it to run. No problem. Lovely live output onto the screen.

However, when I use my custom transform filter inbetween these filters, I just get green on the screen. Debugging shows that even the input to the Transform(IMediaSample *pSource, IMediaSample *pDest) function is entirely green.

Even better, when I set my filter to just make pDest = pSource, the output is still green so I have tried setting the first 100 pixels to 0 and the output is... yes indeed... green.

Going a little mad here. Any suggestions? Would a dump of some of my code help (there is much)

 

[PjotrvA]

Hi,

Does this behaviour also occur when playing files in GraphEdit?

Pjotr

 

[maderlock]

My filter is compiled directly into my app, so I'm not sure I can use GraphEdit without registering the filter first. So, I don't know. If no-one has come across this problem before, then I'll spend the time needed to make the filter into a dll and COM object.

 

[maderlock]

Right. A friend on IRC solved this for me. Basically, I was not copying memory correctly so my output was uninitialised memory. Because my camera outputs UYVY and therefore my filter outputs UYVY, when this is uninitialised (in windows, this has a value), the RGB output is converted to green. Sorry, no way for anyone to have guessed that. The correct was wasto use CopyMemory e.g. CopyMemory((PVOID) pBufferOut,(PVOID) pBufferIn, lSourceSize); (this is in fact used in the contrast filter example in the SDK).

So I guess, in this case RTFMandExamplesInTheSDK.

Thanks