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hi,
may be my question is too open but i just need a general view of how to do it.
the problem is:
How to make a webcam work using a C program and then stream the video on network?
Another problem is that the streaming server should be capable of handling multiple requests at the same time so that more than one users are able to view the video.
Any suggestions or views?
Try having a look at DirectShow. You could also look at the Video For Windows help pages.
Darwen.
i realize that this is an old post, but here's hoping!
i am trying to do exactly teh same thing! and i was wiondering if you decided to use directshow or vfw.. which one did you choose and why? this would really help me out!
VFW is really old. I'd recommend getting to know the Windows Media Encoder which will act as a basic streaming server.
Darwen.
hi Darwen,
Thanks for replying. i'm a little bit stumped tho!
i tried to install the directx sdk. all the info i found on teh web seems very hyped on something called a graph editor. i found that you have to go to start, programs, microsoft directx version wahtever, graph editor to launch it. but after having installed it, i cannot find this! seems there was a problem in installing it. just to make sure i have the right file, i went to http://msdn.microsoft.com/library/de...st/directx.asp and downloaded:
"DirectX 9.0c Redistributable for Software Developers - Multilingual with Updated DirextX for Managed Code - (December 2004)
This download provides the end-user redistributable that developers may include with their product. The redistributable license agreement covers the terms under which developers may use the Redistributable. This update includes the DirectX for Managed Code Update from the DirectX 9.0 SDK Update (December 2004).
Date: December 10, 2004
"
is this the correct file? and is there some special way to install it or something? i just unzipped teh file and ran the setup like i would for anythign else... what could be wrong?
i would really appreciate any info you guys could give me.. i'm really stumped! :(
thanks a lot!
drew.
looks like i might have had the wrong file:(
stupid ms said it was the right one!
for future reference for anyone who needs directx sdk, go to: http://www.activewin.com/awin/commen...=14757&Group=1
there are a bunch of links.. make sure the file you're downloading is atleast 200mb!
will get back to you and let you know if its actually the right file i got this time!
The Graph Editor is part of the SDK, not part of the redistributable code. Once you've got it, you'll quickly understand why it's regarded as an essential part of DirectX development!
Firstly, thanks for filling in the holes.
In fact, the graph editor can be used to view the filter graph in your application.
You need to use the Running Object Table COM object (which is a way of doing interprocess communication - it registers COM objects which are running).
Have a look at these code snippets from the DirectX documentation (just search for IRunningObjectTable and you'll get to them)
and to remove :Code:HRESULT AddToRot(IUnknown *pUnkGraph, DWORD *pdwRegister)
{
IMoniker * pMoniker;
IRunningObjectTable *pROT;
if (FAILED(GetRunningObjectTable(0, &pROT))) {
return E_FAIL;
}
WCHAR wsz[256];
wsprintfW(wsz, L"FilterGraph %08x pid %08x", (DWORD_PTR)pUnkGraph, GetCurrentProcessId());
HRESULT hr = CreateItemMoniker(L"!", wsz, &pMoniker);
if (SUCCEEDED(hr)) {
hr = pROT->Register(ROTFLAGS_REGISTRATIONKEEPSALIVE, pUnkGraph,
pMoniker, pdwRegister);
pMoniker->Release();
}
pROT->Release();
return hr;
}
If you keep the format string to what is defined, then GraphEdit will pick it up and you can see exactly what's going on in your filter graph.Code:void RemoveFromRot(DWORD pdwRegister)
{
IRunningObjectTable *pROT;
if (SUCCEEDED(GetRunningObjectTable(0, &pROT))) {
pROT->Revoke(pdwRegister);
pROT->Release();
}
}
I find this invaluable !
I should write a book on this subject you know....
Darwen.
And don't forget to rate !
Darwen.
Q: You know what I say to any one who is just starting to learn DirectShow?Quote:
Originally Posted by drewdaman
A: GOOD LUCK, and Heart felt sympathies.... :-)
Let me give you a news you may be interested in - starting from the october 2004 update, MS decided to REMOVE DIRECTSHOW from the DirectX SDK.... It has now been moved to the Platform SDK......
Thanks for the downloading tip.
DirectShow is complicated, and needs a great deal of COM knowledge.
It's not easy. In fact it's extremely difficult in C++ - bearing in mind the COM knowledge that is required.
However, I'm working on a C# interop dll for DirectShow as we speak, and then it'll get a whole lot easier.
I don't know when it'll be released but the .NET capability of wrapping COM objects should make interfacing with DirectShow a lot easier....
Makes my article about interfacing with COM IUnknown interfaces come into focus eh ?
Darwen.
Oh and to rate, you need to go to the 'rate this post' link at the top right of the particular submission, not the entire article.
Please rate again.
Darwen.
hi guys. thanks for all the replies. don't worry about the rating.. it it (or will be in a minute) taken care of!
i have no com knowledge at at :( so.. from what you guys are telling me, it directshow would be really hard for me to learn.
so, what i would like to ask you guys now is if there is a simpler way to do waht i need. when i researched teh web and looked up other codeguru artilces, everythign seemed to point towards directshow.
to recap, what i would like to do is to be able to get hold of a stream from a webcam, send it out over the internet and be able to view it at another machine. so basically, i want to be able to connect my webcam at home, go on vacation and be able to see my house from my laptop. can anyone suggest a simplier way to accomplish this than directshow? i was looking into vfw, but it seems that vfw was intended mainly for capturing stuff to your hard drive. please correct me if i am wrong.
thanks again for all the interest and information! ratings are coming!
Again download the windows media encoder and see if it'll do what you ask.
You won't have to touch direct show then.
Darwen.
I'm not sure I'm too clear on this. Do you want to write code to forward the video traffic from your web cam, or write a video viewing application, or both?
Maybe no code is needed at all, it seems to me this is just a network traffic issue.
All you need to do is map the port from you web cam through your firewall/router so that it is visible externally. You'll need to have a static IP address so you can be sure what address to browse to whilst you are on holiday (some ISPs allocate them dynamically and you can never be sure of getting the same address twice).
With any luck, the viewing software on your laptop should allow you to specify the IP address and port number.
If you set this up all should be fine. You'll need to leave your PC running the whole time you are away though unless it's dedicated, free standing IP camera.
Hope this is relevant and helps!
Mark
PS Another alternative would be to periodically capture images from your web camera and upload them onto a web server so you could browse them externally through an ordinary browser. Good luck.
ok.. i have to clarify this. i'm sorry it wasn't clear earlier.
first of all, i have to write code. not writing code is not an option.. i'm an intern!
secondly, i can use sdks if i want... or any libraries, but i have to actually write the code because there are several other requirements that make this project unique. they will not be too hard to implement once i can get the streaming stuff going, but i have to be able to do that.
both. i'm building a client server model (actually there are two types of clients: 1. computers with webcams attached- there can be several of these. 2. actual client who wants to view the webcam from a remote location). the camera client sends the stream to the server, the server to the actual client. the actual client must be able to view the stream- and therefore, i have to create a video viewing application as well. eventually, i have to support wireless webcams as well- but that is later once i get teh wired (USB) ones going.Quote:
I'm not sure I'm too clear on this. Do you want to write code to forward the video traffic from your web cam, or write a video viewing application, or both?
that sounds ok to me.. but i'm not sure if any data is sent to teh webcam from teh driver or computer or anything.. if i were to do this, would i be responsible to respond to teh webcam? i dont' even know for sure that any data is sent to the webcam. but if it is, this might be an issue? just a thought.. but not sure. also, i don't really know how to go about doing this. do you know of any links or something where i can read up on it? would really help me out!Quote:
All you need to do is map the port from you web cam through your firewall/router so that it is visible externally.
Edit: actually, for the above quote, if i am doing something like that, i would rather grab the info and send it through a socket.. do you think that is workable too? and if so, hwo do i go about grabbing the info?
i hope that clarifies things. if you have any further questions, please let me know. all suggestions still welcome!
thanks for all the help so far guys! keep those suggestions coming! i really appreciate them!
Hi drewdaman,
As I can speak as someone who hasn't been using dshow for too long, take heart! You do not need to know all of COM in order to program dshow. A definite subset of concepts is necessary, but the nuts and bolts aren't particularly needed. First of all, you won't need to use any idl. If you are comfortable instantiating objects and querying interfaces, that will get you a good bit of the way. Please note that I haven't actually send video over the network, so I'm hypothesizing a bit.
I'll take this slowly and build it up a bit. Please don't think I'm patronizing.
All of directshow uses graphs to string together and connect various components called filters. A typical filter will consist of a source filter, several intermediate filters to get the video into a stream of bitmaps, and finally a renderer. The renderer is what you see in the window that plays the video. The graph is kind of the overseer of all of the components. Through methods called on the graph, you can stop, pause, play, get notifications, etc. This compartmentalization is very useful, as MSoft provides many filters that are very useful. Graphedit is a harness that simulates a graph you would build programatically. It is a very useful tool, but unfortunately not a means to an end. The bottom line is that if you cannot get it to work in graphedit, it won't work at all!
So, now I have good news and bad news for you. Windows media appartently has filters that work over the internet through directshow. The bad new is that I have no knowledge of them, so I can't help you! The application to view the video is almost trivial to write, so don't worry as much about that. Getting data over the network will be the hard part. I have to get going, but I'll update this with some more thought when I have time. Good luck.
~Steve
i m working on a project which needs to stream video from a webcam or file to a remote location.. 1 way broadcast is needed. i hv gone through the options like Windows Media Encoder and DirectShow. However, I couldn't find a way to implement direct video streaming to a server n then clients will b able to receive the streams immediately.
how m i go about developing it?
fyi, i m a college student. i did some research n i still couldn't find an appropriate to do it. Dealing with COM is pretty complicated coz I need to develop it under C#
thanks...
Hi,
Sorry, AFAIK there is no way to use directshow in C#. There is no indication that a managed interface is coming either. There is some info on how to use VB, but that's it. You might want to check out the code of videolan, I'm not sure how that works.
~Steve
Actually you CAN use direct show from C#. I know, I've just written an assembly which'll give you full access to the underlying interfaces etc.
I've had to do some pretty heavy interop to do it though, so it's not for the faint hearted.
I could potentially write something so you could write filters in C# but that's WAY too much like hard work. The C++ base classes in the DirectShow examples are ok at doing much of the hard graft for you, so I've not bothered.
Unfortunately no I can't release the source code for it because it's part of a commercial project. But just to let you know it IS possible.
As an aside, if you pipe the output from the encoder into Media Server then you can multicast the output. In fact from what I've read it's not difficult : the whole UI is set up to help you do just this.
No coding involved though... if you're looking at writing all of this yourself then you're looking at having expert knowledge of
(1) COM (to use DirectShow to do the capture. You could always use the old way of course using VFW - video for windows - but I don't know much about that).
(2) COM again to write an addin for Internet Explorer to connect to your media server (which you'll have to write of course) and buffer/stream the video/audio.
(3) Networking. You'll have to work out an efficient way of transferring the images.
To write all of the above yourself is an INCREDIBLY challenging problem and one which you'll have to be working on until 2am for the whole year to get anywhere close.
It's unlikely you'll be able to do it purely in C#. My DirectShow interface has grown out of years of knowledge and experience with DirectShow and COM.
If you're going to get anywhere close to acheiving your goal you will have to learn C++/MFC.
Darwen.
Maybe avphone is fit for you:
http://www.banasoft.net/AVPhone.htm