I would like to know how can a single specific program/window can be video recorded in Windows. There are some ways in which you can video record the entire screen, or a specific region (using GDI, DirectX, etc) but what I specifically want is to record a single program/window, even though if that program/window is or isn't on focus or it is moved. The only program that I've seen capable of doing this is Microsoft Lync, and I am really interested in who it's done. Is there any SDK, framework, etc that I can use for achieving this ? (it doesn't matter the programming language, either it's C#, C++, etc).
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For a some-what small (at least hopefully) project, I am hoping to gain access to the current audio being played through the "main line" (i.e. what is heard through the speakers.) Specifically, I'd like to create a visual equalizer of the audio currently being played. I do not wish to capture or "tamper" with the audio in any way, just run a little analysis on it. That being said, I'd imagine access to such information is not handed out nicely in a high-level API.
I noticed a similar question which is concerned with looking at system sound. The accepted answer points to looking into Soundflower's source code. I am not completely adverse to doing this but I'd like to ensure there isn't a simpler way before I got into it (especially because I have no real audio programming experience, especially at the system level.)
Any input is very much appreciated,
--Sam
There is no simple way to do this on OS X. You really have to do this from a kext, unfortunately.
I already know that iTunes has an interface that I can control, but the API is a bit opaque and I can't find it documented anywhere. Does anyone know of any good open-source or at least well-working media players that can be programmatically controlled?
In particular, I would like to be able to search a media library for a song by title or artist, and play, pause, resume, stop the song.
Ruby would be nice, because I'm working in it, but C would work too. I could write a wrapper.
Edit: My solution has to work on Windows, as that is the environment I am developing in.
XMMS works on a server / client basis. This means that it is relatively easy to control the playback, and the song queue. I'm not sure how easy is to handle file metadata (song info), but maybe that part can be handled independently.
Check this guide to get an overview of functions you can use.
Back in the day, I used MPD.
I want my program to be able to launch any Windows game, and while the user is playing it, intermittently display some text or pictures in some part of the game window. The game may be in windowed or full-screen mode. From what I have been able to figure out from online resources, this could be done using a graphics library that supports overlays and using Windows Hooks to keep track of the target application's window. In this context I have some questions.
Will the overlays affect the game's performance?
How will hooking the application affect performance?
Is there any other way one could achieve this? For example, how do you think PIX, the DirectX debugging and analysis tool, work?
Fraps is the archetypal example of doing this sort of thing to a fullscreen DirectX application from a third-party app. It works by hooking some system calls and inserting itself into the call-chain between an app and DirectX. There is some performance hit, but in general its minimal.
This page seems to have some details and sample code on how to hook the app in this way.
If I recall correctly, from other forum discussions (can't find the link at the moment. search for things like "how does fraps work", it's a popular question), Fraps hooks a few things to force the app to load its DLL, then hooks Present() calls and executes a device->Clear() call before calling the real Present(), with a list of small rectangles to set to a different color, which can spell out the FPS number that it displays. This has a minimal performance impact and is widely compatible with whatever rendering the app is doing. Overlaying a bitmap would be more complicated since it wouldn't be as easy to do at Present-time. Perhaps if you could hook EndScene, then you could do more, but you would have to be careful to not change the device state.
PIX has privileged access to the DirectX driver, so I wouldn't expect to be able to use that as a model to emulate.
If an the target app is running in windowed mode, hooking DirectX still work, but you could also just use GDI instead.
Edit: I think this is the link I was originally thinking of.
I'm ready to outsource the screen capture functionality of our application, because it's not our core business and I've spent too much time trying to get our code to do all the things I need. Time for a specialist, I think. My requirements, in decreasing order of importance, are below. Does anyone have experience with any commercial or free libraries that meet most or all of these requirements?
Has to work in Windows XP and higher. (But not Win95/98/Me.)
Visual C++ 2005 compatible, where screenshot can be triggered from my code. Preferably a static library, but a DLL or COM object is OK. I'd prefer not to shell out to a standalone EXE because there are some users that will try to tamper with our application and I think having an obvious separate screenshot EXE makes that too easy.
Must be able to take full screenshots of multiple monitor systems. (Preferably the way the "Print Screen" key does in Windows, by making a bitmap of the displays stitched together, but if I have to take the pictures separately and combine them myself that's acceptable.)
Must be able to capture screen correctly when Remote Desktop Client (or any RDP client or VM) is in full screen mode. (Of course, it should also work when RDP is in windowed mode, but that shouldn't be a problem as long as it doesn't operate by simulating a key press that might get transmitted to the remote OS instead of being handled locally.)
Must be able to capture screen correctly when Windows Media Player (or any other media player) is in full screen mode.
Must be able to capture screen correctly when game (e.g. World of Warcraft) is in full screen mode.
Would be nice to be able to capture a few seconds of user activity as a video.
I don't know of a library that would do what you want.
If I had to code your requirements, I would probably use the source code of the TightVNC server as my starting point. I think it has the technology to do everything on your list EXCEPT....
I'm not sure that technically there's ANYTHING that can do a screen capture of somebody's Remote Desktop session. Think about it: There can be multiple remote desktop sessions (the csrss.exe process) occuring using the same physical remote desktop server. If you were sitting in front of the machine looking at the video monitor, you wouldn't see anything happening at all. So what woould you expect to capture. VNC is only going to capture what's happening with the "real" video (the non-remote csrss.exe).
I dont know if this really helps, but the best imaging libraries available are available from
www.accusoft.com and
www.leadtools.com
Both support creatting screenshots, though i don't know, if hey will properly capture movie player output that displays through graphics acceleration or the recording of movies from screen.
If I were you I would investigate WindowsClippings, a pretty mature and extensible application written in C++ that does precisely what you need. It has an API you can extend to your requirements and is pretty cheap at 18$
Some people in our office are using Magick++ (an ImageMagick library) to make screenshots. I don't know all the specs, but you could take a look at it and see if it matches your requirements.
I want to write a app which change the microphone input voice and make it like robot or some funny man's voice.It must support send changed voice to all application like IM Software or Game Client. Which technology should I pick up? Windows WaveForm Api? DirectX?
audio driver?
Thank you very much!
There's an MSDN Coding4Fun article that explains how to create a voice changer that operates over Skype, in C# (.NET). The full source code is also hosted as a project on CodePlex. In addition, it should be fairly easy do something else with the audio (as opposed to streaming it via Skype), since the project is based around the NAudio framework, which contains a good level of abstraction. Anyway, it is a reasonably complete (and stable) example - definitely worth checking out in my opinion.
If you want/need to use C++ or some other language for development, then this project should at least give you some ideas about how to go about it. Still, if you can use .NET, then you're in luck I think.
Robot voice is often done with a ring modulator effect, mixing the voice with a sine wave - this is easier. Or use a vocoder effect, modulating the voice onto some other waveform, like rectangle - might be a bit more tricky. Go read up how the effects work, get a program with which you can check out how they sound (Audacity works for the ring modulator, finding and using a vocoder may be a bit harder). Then read how it's done or get a library which will do the processing for you.
You are looking to support VSTi or DXi plugins.
There are tons that also act as vocoders, even for free.
You just need to write the host application.
Take a look here :)
Now that's a neat idea, especially for a mobile app.
I'd probably start off-line by using a .wav file as input to get the effects working the way I wanted. You can use any high level language for this, but you probably want something that will map reasonably well into C/C++.
In terms of a production version, I'd go native and do this in C or C++. You want something fast for real time audio processing & I like to avoid dependencies on things like .net for distribution. (Not that I have anything against .net, it's great for servers and distribution within a company but I'm not so keen on having it as a dependency for shrink wrap software.)
Windows DirectShow would be a tempting option - you could do some interesting effects with multi-media as well if you had the voice morpher implemented as a direct show filter.
What you're looking for is a vocoder. I don't know if any of the technologies listed above has a vocoder effect, but the best chance would be with DirectX.
Try this sample app .I think its useful to you.Link