Develop Reference

Obtain the current audio playback stream

So, I need to obtain the current audio playback that is happening on my pc programatically in real time. This includes all the audio(you can check this in the playback devices tab of the Sound settings). I need it because I'm doing an analysis over the stream which I then put into use in another software. Until now, I've used the 'StereoMix' option, which actually relay's the current audio as an input(something like an internal microphone). However, I can't use this method when I connect external speakers to my pc(through HDMI, PC/AUX works though).
Is there some way to obtain the audio stream no matter if external speakers are connected or not.
The programming language does not matter in the current case, everything is fine with me. However, I prefer if there is a C# / Processing solution.
EDIT:
Here's the technique(and method) I currently use to obtain the audio in http://code.compartmental.net/minim/minim_method_getlinein.html. The library/code is related to Processing: https://processing.org/.

Basically, NAudio would be a good place to look for a prospective solution. Its not quite clear what you intend to do with the audio such as if you're recording/dumping data, or simply analyzing live-data so I'm thinking NAudio is going to have something such as you're looking for, as far as getting your hands on live-data.
NAudio has an FFT, but not quite robust in the area of analysis as the JS-libs you may be accustomed to ;)
http://naudio.codeplex.com/
https://github.com/naudio/NAudio
There are plenty of examples provided to get you started, and many in the wild.
Though its pretty outdated and the API may or not look slightly different (in regard to...), the following video may provide a nice relaxing quick-start to help familiarize you with this lib.
C# Audio Tutorial 6 - Audio Loopback using NAudio

Using ffmpeg codec inside Xamarin?

I've been struggling with this topic for the past few weeks and I am yet to find a way to use ffmpeg inside my Xamarin project. There are couple of C# wrappers that work great but they don't work for API 15 and below versions of Android.
I'm trying to use ffmpeg in my project but I really don't know how to. I have tried to bind a Java project I found but .jar binding didn't work and apparently the only way is to use JNI for the binding which isn't very easy to do, at least for me.
I'm hoping someone can provide me some sources I can read on and understand how it works and what ways I can use ffmpeg in my project.
I will really appreciate any kind of help I can get.

c# - How to use SAPI to do speech to text?

I want to learn the SAPI api for c# to do speech to text recognition.
I can't find any tutorials. Can anyone show me where an example is or can show it here?
It needs to have aupport to get the speech from a webcam mic.
Thanks.

API documentation: http://msdn.microsoft.com/en-us/library/ms723627(v=vs.85).aspx
Using SAPI in C#: http://windowscoding.com/blogs/blake/archive/2006/11/01/How-to-use-Microsofts-Speech-API-in-a-managed-application.aspx
You're right, there aren't many/any tutorials. But there's the basics - and there are plenty of C/C++ resources. Give it a go and if you have a specific question, that's a far better thing to ask on StackOverflow.

I know it's a little late for this question, but hopefully it can help people later. I want to do the same thing recently, using micphone as voice input, then sapi do the recognition part. I actually found the example code in sapi's own documents, which is written by C#. As default install location, it should be in the folder C:\Program Files\Microsoft SDKs\Speech\v11.0\Docs. It works pretty well.

Using Mapnik in .net environment

Has anybody used Mapnik for rendering Maps from .net c# environment? I would like to use it to render maps in a desktop application developed under .net4. I found it the best open source map renderer tool, much more better, than the well known sharpmap, dotspatial (...). The 'only' problem is that it was written in C++ and Python and does not have a trivial way to use it from C#.
Do you know any .net Mapnik wrappers? Do you know any sample code?

I've just published my attempts in C# bindings.
They are available at: http://sourceforge.net/projects/mapniknet/

Some good new about Mapnik-.Net integration:
"Another thing that will help Windows developers is a way to use Mapnik from .Net languages. Although a full .Net wrapper is too much work besides all the other issues, hopefully I can make a meaningful start and open the door for .Net developers to leverage Mapnik in their applications."
Source: Mapnik homepage http://mapnik.org/news/2011/jun/09/gsoc_2011_windows_build_system_introduction/

NET-Mapnik
You might want to give this a try. Its pretty recent and has a simple example with options to create vector tiles.
https://github.com/kernelsanders/NET-Mapnik

So, finally I hacked it. Not a nice solution, but it works at least. In nutshell it operates in the following way:
developed a python script, which takes parameters as command line arguments. (using python api of mapnik)
call this python script by shell fom c# code (Process)
after map image has been generated, I show it in SharpMap as a background layer
In case of any map refresh (zoom, pan) I regenerate 'mapnik map layer'. I have also some kind of cache, in which I can store generated maps, so I can make tricks by using earlier generated map images or pre-generate them (e.g. generate maps for the next zoom level when user uses zoom tool). I also use some asynchron calls to do this, so I can create 1-3 map images paralelly.
The weak part of this solution is the communication between python and c# modules. I could not find better than command line arguments + shell.
My solution works, mapnik is fast, can genarate my maps less than a sec.
If you have any advice on .net - python communication (NO ironpython, it is not suitable for manik api), pls write it here. Thx.

Do you know about TAO Project?
It is a .Net project that takes unmanaged opengle library to .Net Managed Form by calling DllIMport() in C#.
You must do it for Mapnik, simaliar to TAOFramework.net

Working way to make video from images in C#

Does anybody have a known reliable way to create a video from a series of image files? Before you mod me down for not searching for the answer before posting the question, and before you fire off a simple message like "use FFMPEG," read the rest of this message.
I'm trying to create a video, it doesn't matter too much what format as long as it's widely supported, from a series of images (.jpg, .bmp, etc.). My platform is Windows Server 2008, 64-bit. If I can make the video from within my C# program, that's great, but I'm not averse to writing a series of image files to a directory and then firing off an external program to make a video from those images.
The only constraints are: it must work on my Windows Server 2008 system, and be scriptable. That is, no GUI programs that require operator intervention.
I found a number of similar questions on StackOverflow, and have tried several of the solutions, all with varying degrees of frustration and none with anything like success.
FFMPEG looks like a great program. Maybe it is, on Linux. The two Windows builds I downloaded are broken. Given this command line:
ffmpeg -r 1 -f image2 -i jpeg\*.jpg video.avi
One of the builds reads the images and then crashes due to data execution prevention. The other reads the first file and then spits out an error message that says "cannot find suitable codec for file jpeg/image2.jpg". Helpful, that. In any case, FFMPEG looks like a non-starter under Windows.
One answer to a previous posting recommended Splicer . It looks like pretty good code. I compiled the samples and tried to run, but got some cryptic error message about a file not found. It looks like a COM class isn't registered. I suppose I need to install something (DirectShow, maybe, although I thought that was already installed?). Depending on what's required, I might have a difficult time justifying its installation on a server. ("What? Why do you need that on a server?")
Another answer suggested the AviFile library from Code Project. That looks simple enough: a wrapper around the Windows AviFile subsystem. Except that the AVI files the package creates appear to have all of the frames, but only the first frame shows when I play the AVI in Windows Media Player. Well, that and if you try to create a compressed video, the program throws an exception.
So, I'm left wondering if there is a good, reliable way to do what I want: on a Windows system, create an AVI or other common video file format from a series of images, either through a .NET API or using an external program. Any help?

After working with it a while and taking a look at x264 and VideoLan, I went back to Splicer. It turns out that the cryptic error message was due to an error in my code.
It looks like Splicer will do what I want: programmatically create videos from a series of images.
Thanks to all who responded.

You can use VideoLan and I'd recommend it.
I've had direct experience in a C# application with VideoLan doing these two things:
Embedding a VLC viewer in my C# application (there are 3-4 C# "wrappers" for the VLC veiwer).
Using vlc.exe in a separate Process by sending it command-line arguments.
The fact that VideoLan has a command-line interface is a great thing. And VLC supports a command-line option that disables any visual element; so the VLC GUI doesn't pop up and neither does a command-line window. Thus, in a C# application you can farm out the video-related work to the VLC client. C# has the Process class which can manage your vlc.exe instances for you. It ends up being a pretty neat solution.

The handling of video on Windows (encoding and playback) is a real quagmire. And .NET isn't going to help you at all - you're always going to be either PInvoking/COM-interoping native APIs or using a .NET wrapper that someone else has built to do the same.
Anyway, I can't say I've used it, but a good bet seems to be the x264 library that is part of the videolan project. That gives you a self-contained C library that you can PInvoke and you don't have to worry about installing and DirectShow garbage on your server. It'll generate H.264 format video which is playable in Flash as I understand it.

I've used mplayer's mencoder to create AVI (with codecs msmpeg4/mp3, readable by default with Windows Media Player) from TGA files on linux like this:
mencoder mf://*.tga -mf fps=25:type=tga \
-audiofile /tmp/test.mp3 -oac copy \
-of lavf -ovc lavc \
-lavcopts vcodec=msmpeg4v2:mbd=2:mv0:trell:cbp:last_pred=3:vbitrate=3000 \
-o /tmp/test.avi
I know mplayer does have a Windows version.

Instead of just going through all the hassle, you could coppy all the images that you want to be included in your video to the clipboard and have it imported into Windows Live Movie Maker (dynamically, of course!) and have it compile for you!
All of this CAN be done through code, but this way, you don't have to create it yourself. As you said that the platform was Windows, and ALL Windows comps have Windows Live Movie Maker installed, so it shouldn't be a problem for anyone using your application unless
a) They uninstalled Windows Live Movie Maker
b) They are using a computer running on a Windows Version more than 8 or 9 years old...