.NET news » Multimedia

There are several ways to grab and process webcamera images: WIA, DirectShow, VFW... There are lots of C# VFW examples on the internet and most of them use .NET clipboard to transfer each frame's data from buffer to Bitmap-recognizable object. Unfortunately, this makes multithreading unavailable and reduces FPS (frames per second). The native Win32 clipboard and multithreading solve the speed problem, but I thought that it wasn't the most elegant solution and there should be another way to get frames from Avicap. I have referred to MSDN (see VFW link above) and discovered that function callback was available. This article explains, step-by-step, how to capture frames using avicap32.dll (VFW) in a multi-thread environment..

A little program to exercise children math skills.

In this article, we'll look at how sound waves work and interact with each other, as well as how to represent waveforms in PCM WAVE format (.wav). Then we'll build on that understanding to create a class that generates musical tones, which will allow us to create whole songs from scratch. Example code is included in the source download.

One of my favorite new features in Windows Vista is Windows Speech Recognition, which allows you to operate your computer using only your voice, including dictating text into e-mail messages or other documents. Windows Speech Recognition uses the Text Services Framework (TSF) to insert, select, and correct dictated text. TSF is a scalable framework for the delivery of advanced text input technologies. It provides a standardized method for text services—such as voice recognition, handwriting recognition, spell checkers, and Japanese Input Method Editors—to communicate with applications and text controls. In particular, TSF allows bidirectional communication between applications and text services. This means that text services can read and write to an application’s document and an application can ask a text service to perform actions such as correcting text.

One of the coolest features to be introduced with Windows Vista is the new built in speech recognition facility. To be fair, it has been there in previous versions of Windows, but not in the useful form in which it is now available. Best of all, Microsoft provides a managed API with which developers can start digging into this rich technology. For a fuller explanation of the underlying technology, I highly recommend the Microsoft whitepaper. This tutorial will walk the user through building a common text pad application, which we will then trick out with a speech synthesizer and a speech recognizer using the .Net managed API wrapper for SAPI 5.3. By the end of this tutorial, you will have a working application that reads your text back to you, obeys your voice commands, and takes dictation.

Managed wrapper for accessing the Vista Core Audio API

This article describes how to use DirectShow.NET. DirectShow.NET is a dll to use DirectShow as managed code. I found it hard to find examples for using DirectShow. I still didn't find out how that all works. That is why I translated a C# example of DirectShow.NET to VB.NET code..

The included Sophia project is intended to be both instructive and fun. It is, at the most basic level, a chatterbox application with speech synthesis and speech recognition tacked on to it.

This article provides an overview of the various features of the GrammarBuilder class, including how to build increasingly sophisticated recognition rules. I will go over some tricks for making the bot personality appear more lifelike. I will also try to unravel some of the issues involving deploying an SR application to Windows XP rather than deploying to Vista. This article will also highlight some of the other gotchas you might encounter while working with the Vista managed Speech API. Finally, it will demonstrate an extensible design that allows multiple speech recognition applications to run together at the same time.

Creating PDF Tables using C# (.NET 2.0) and iTextSharp

There are several ways to create PDFs. The hardest of them all is perhaps to create it on your own using C#. However, if you want to learn how to do so, you have to climb a steep learning curve. You can either read the 1300+ page specification document available free from Adobe's PDF Technology Center or use an open source library called iTextSharp. iTextSharp eases the learning curve a fair amount. But learning to use iTextSharp is itself non-trivial...