I'm programming a directshow application with streaming card. First I installed the drivers and tried their streaming software, everything works perfect and its pixel perfect.
Then make C# code for capturing still images through directshow, pretty much exact copy of DxWebCam example, to be found here in official net library:
https://sourceforge.net/projects/directshownet/files/DirectShowSamples/2010-February/
I also tried more modern approach of using pins and smartee, however I was not able to make it work.
The issue is, the images captured with directshow are just a bit off, like it is using some sort of compression. To demonstrate my issue, here is the original pixel perfect image:
and here is the directshow captured image, with some sort of horizontal pixel mashup: (need to zoom in to see the wrong pixels)
I've tried setting massive bitrate as well as playing with video formats etc.
However I'm just not able to stream pixel perfect in directshow, yet on the same computer with native manufacturer application it works perfectly.
I'm lost as in how to continue or how to try to debug this. Any help appreciated
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I'm being annoyed by an odd behavior of Interop.quartztypelib in making media player with c#. With the help this link
http://www.codeproject.com/Articles/2632/DirectShow-MediaPlayer-in-C?msg=4853463#xx4853463xx
I created my own video player with Interop.quartztypelib. There's an important function for me to implement is that my application shall be able to capture the video image, just like you click "ALT" + "Printscreen" to make a screenshot of an active window in windows. But surprisingly I found that in the image captured by my application (I use
Graphics.CopyFromScreen
in my code), there's no video image on the video screen! I got the image of my form (the video player) but not the image of the video being played! And clicking "ALT" + "Printscreen" just gives me the same result!
I'm wondering if this Interop.quartztypelib doesn't support image capture. Anybody knows if there's a way to do settings to enable this? Thanks.
Printscreen doesn't do that
You need to implement some way of switching out of overlay, or some other way of getting a still. There is some trick with hardware acceleration, buts its not really applicable to you as the application dev. You're probably have to get antiquated with rendering api's.
For OpenGL api I think it would be glReadPixels.
For directX here's a SO question. I'm going to guess its directX in your case.
I am developing a game for Windows in C# using Visual Studio 2010 and XNA 4.0. I would like to be able to set and change the play position of an HD video and also play the video in reverse, depending on user input.
I am having trouble finding where to start. XNA's videoPlayer class does not provide these type of functions. I've read that XNA DirectShow is now out of date and slow when using HD video.
I don't quite understand how I would be able to use or implement tools such as ffmpeg with my project. It seems some people have had similar questions and posted solutions but without much detail. These are below.
interop out to talk to the core DX functionality.
write a managed c++ wrapper to interop ffmpeg.
write an mpeg decoder.
I am not sure what would be best and where to begin.
Thanks!
The VideoPlayer class has a "PlayPosition" property, which you should be able to play with.
Otherwise (and I don't know how big your video file is nor how long) try an image sequence and animate the current image sequence and control that with user input. Of course working with image sequences would make audio reversal (if there is audio) etc very complicated.
Last but not least, you can see if you can figure anything out from this mpeg decoder here:
https://www.box.com/shared/ojzfv0qzfx
Something else that might help with mpeg decoding:
http://chrisa.wordpress.com/2007/11/21/decoding-mpeg2-information/
I have a small video clip that I've run through my video to image software and noticed that the images come out different. Both set of images are identical in which they are cut at 1 second segments. Where they vary is one of the images seem to be brighter then the other set. I'm trying to think what can cause this subtle difference, but I'm at a loss.
I thought that maybe because the hardware is different that would cause this, but I'm not doing anything on the GPU. I also thought that it could be the codec being used, but if the video is encoded the same way using the same codec and information then would decoding really effect it in this way?
Below is a list of what the program is:
Takes a video and saves it out as 1 second images
Uses DirectX in C# to load in a video and saves out the texture.
Video is encoded using MPEG-4 similar compression
I understand that this may not be much information to go off of, but I am at a loss of where I can look.
Any advice is greatly appreciated.
I'd say that images are not actually different. It is unlikely that MPEG-4 decoding uses any GPU resources. Well, it's possible to hardware decode MPEG-4 Part 10, but it's subject to certain conditions too. Far more likely, the effect is due to on of the reasons below (or both):
if you show the picture up within video streaming context, or as you mentioned textures in use - the images might be appearing from YUV surfaces which video hardware is managing differently from regular stuff like desktop, and video hardware might be having a different set of brightness/contrast/gamma controls for those, which result in different presentation
you have different codecs/decoders installed and they decode video with certain differences, such as with post-processing; with all the same encoded video, decoded presentation might be a bit different
Does anyone know how to apply effects to the entire screen, in c# or any programming language.
I'm mostly interested in making the screen monochrome (specifically green-white instead of black white).
I know a cross-graphic card solution is possible because I found a program that can do it:
http://www.freedomscientific.com/products/lv/magic-bl-product-page.asp
Anyone knows how to accomplish something this or where to look?
Thanks !!
There is no easy Windows API to modify the entire screen contents. But this could be done at the device driver level.
Otherwise you have to resort to some Windows API tricks: place a "fake" window over the entire desktop, in a loop: grab the entire screen contents without grabbing fake window contents, do your processing to get the monochrome effect, then display that on the fake window. Yes, it's hacky and slow, but possible. Even more hacky, when you get mouse clicks to "go through" the fake window (lots of SetWindowsRgn calls).
So cross-platform here means using GDI, though some older DirectDraw APIs might work, in that case, you have a much easier time with hardware overlays (and better performance). Though I'm not sure how many cards actually support hardware overlays, and if newer versions of windows support the older DirectDraw APIs.
One more possibility is if the video card has a C# or C++ or C API, then you can do whatever you want with the card without writing device driver code.
Then there's CUDA, but I haven't yet tried that out. I know it's for stream processing on nVidia boards, but I wonder if it could get you an easy backdoor into the video display stuff.
To help people in the future who are interested in this:
This is possible with the Magnification API's color effect method. This allows one to use a matrix that can be applied to the whole screen.
NegativeScreen is an open source project that implements the feature you are describing in C#.
Unfortunately, this only works with affine transformations, as the API takes only an augmented matrices rather than a delegate or something.
So I've been looking into the world of media playback for windows and I've started making a C# Media Player using DirectShow. I started off using the VRM-7 windowed video renderer and it was brilliant except it had a couple of small problems (multi monitors, fullscreen). But after some research I found that it's deprecated and I should be using VRM9.
So I changed it to use VRM9 windowless then found out that was an old post rofl >_< so finally I'm using Vista/Win7 (or XP .net 3) Enhanced Video Renderer (EVR) which is apparently the most up to date Microsoft video renderer and has all the flashy performance/quality things added to it. (tbh I haven't noticed any difference but maybe I need a blue-ray or HQ video to notice it).
With using EVR everything is working fine except resizing the video. Its really laggy/choppy/teary and probably something to do with its frame queueing mechanism.
To demonstrate my problem
open up windows media player classic.
View -> Options -> Playback -> output
Chose the "EVR" DirectShow Video renderer
Now restart wmp class and play a video, while it's playing click and drag a corner to resize it. You'll notice its horribly laggy. This is the exact same problem i am having.
But if you chose "EVR Custom Pres. **" or EVR Sync **" resizing works beautifully! So i tried googling around for anything about EVR resizing issues and how to fix it but i couldn't believe how little i could find. I'm guessing "Custom Pres." stands for "Custom Presenter" which sounds like they made their own.
Also you'll notice on the right hand size when you swap between EVR and the other EVR's the Resizer drop down on the right greys out.
So basically I wan't to know how I can fix this retarded resizing problem and is there any decent documentation out there? There is a fair bit for VMR7/9 but not much for EVR. I downloaded the DirectX SDK which apparently has samples but it was a waste of 500mb of bandwidth as it had nothing relevant.
Perhaps there is some way to force it not queueing up frames if that is the problem?
If you want code say the word and I'll paste some in. But it's really quite simple and nothing much happens, i'm convinced it's a problem with the EVR renderer.
EDIT: Oh and one other thing, what does VLC use? If you go into vlc options and change the renderer to anything but default, they all suck. So is it using VMR7? Or its own?
I need to write my own Custom Presenter, which from the looks of http://msdn.microsoft.com/en-us/library/bb530107(VS.85).aspx is a relatively big task.
Guess i'll look at the sample and try to go from there