[RESOLVED] bitblt problem

[NotepadGuru]

Hai all,

Why bitblt does not work on videos and on some windows that i hope created using alphablend functions ?

my project bitblt from display dc to memory dc.

thanks.

[dglienna]

What do you mean, "It doesn't work..."

That tells us nothing. Post some code, and error msg(s) and line #'s, etc

' Use Code Tags also

[NotepadGuru]

No dg.
in simple words, why you can capture a screen shot of the WMP video using bitblt?

[GremlinSA]

BitBlt Copies Pixel data from Shared Video Memory,(Normally sits between 640k & 1024k) however there is a second level of video memory, that bitBlt does not reach.. this is memory that only the Video processor can work with.

When using hardware accelerated functions, bitBlt will not be able to capture the results.

Also Hardware decoded video streams can not be captured by BitBlt..

Gremmy

[NotepadGuru]

BitBlt Copies Pixel data from Shared Video Memory,(Normally sits between 640k & 1024k) however there is a second level of video memory, that bitBlt does not reach.. this is memory that only the Video processor can work with.

When using hardware accelerated functions, bitBlt will not be able to capture the results.

Also Hardware decoded video streams can not be captured by BitBlt..

Gremmy

Nice explanation Gremlinsa,
so how to capture them which bitblt cannot reach?
say, a frame in the WMP.

[NotepadGuru]

I think reducing the hardware acceleration might work. so how to reduce this using code?

[dglienna]

You know that would slow down everything, if it was even possible. Can you say BOTTLENECK?

[GremlinSA]

Nice explanation Gremlinsa,
so how to capture them which bitblt cannot reach?
say, a frame in the WMP.

Hmmm .. that will require you to write your own Media Player, and use software decoders.. And the problem is, many of the software decoders still use some of the hardware acceleration functions, so you will need to shut down all hardware acceleration functions, and then, like David says, Bottleneck the system...

unfortunately there's not much you can do about all of this, as Windows itself requires allot of these functions to simply operate.

The other option is to study the built in Functions on the video card, by using some of the built in commands you may be able to get a data stream from the video card direct, problem is these commands are different for each card (why windows requires a driver) and not all cards have a full two way data streaming system..

Gremmy

[Tom Moran]

There are many commercial video capture cards out there. Capturing video is not trivial like bitblt.

Depending on what you're trying to accomplish, you could certainly pause a video display at any frame and then capture the region of the displayed frame. If all you need is an occasional frame or two that should work okay. If, however, you're trying to capture a series of frames for re-display, etc. you should look in to obtaining video capture card.

[NotepadGuru]

Thank boys (David, gremmy, tom) for the comments.
i had two problem,
1. could not capture a video frame
2. Could not capture Layered Windows ( the Name i forgotten to mentioned in my first post. So i put it as "some windows " and you could not figured it out coz of that )

I manage to solve the second problem by addining a flag CAPTUREBLT with vbsrccopy and sorted out.

After seeing your comments, i think, for now, video capture is not that important to my project. But now i got some idea about that from your posts. All i had to solve is the layerd window issue.