Mp4 Explorer

Brief Introdution
This software is a very helpful tool to inspect and see in details a mp4 file and it is open source. In my case, I was trying to write a program to convert certain video to be compatible with iPhone, but I had no idea about it. Then, I found this useful utility and used it to inspect the video structure of some compatible mp4 files.

You can download the program and its source code in the following web site:

Official Website - Mp4 Explorer
http://mp4explorer.codeplex.com/

How To: Get the Content of Certain Environment Variable, ie: %ProgramFiles%

Code Snippet

#include <windows.h>
#include <string>

using namespace std;

wstring GetContentFromEnvironmentVariable(const wstring& wstrVariable)
{
  // Get the content of %ProgramFiles%

  wstring wstrRtn;
  DWORD dwSize = ::GetEnvironmentVariableW(wstrVariable.c_str(), NULL, NULL);
  if(dwSize > 0)
  {
    wchar_t* wszContent = new wchar_t [dwSize];
    dwSize = ::GetEnvironmentVariableW(wstrVariable.c_str(), wszContent, dwSize);

    wstrRtn = wszContent;

    delete [] wszContent;
    wszContent = NULL;
 }

 return wstrRtn;
}

Reference on MSDN
GetEnvironmentVariable Function

How To: Get the Installation Directory of Windows Media Player

Code Snippet

bool GetWMPInstallDirectory(wstring& wstrDirectory)
{
  bool bOK = false;
  HKEY hkResult = NULL;

  LONG lRet = ::RegOpenKeyExW(HKEY_LOCAL_MACHINE,
    L"SOFTWARE\\Microsoft\\MediaPlayer", NULL, NULL, &hkResult);

  if(lRet == ERROR_SUCCESS)
  {
    wchar_t wszRet[_MAX_PATH] = {0};
    DWORD type = REG_SZ;
    DWORD cbData = sizeof(wszRet);

    lRet = ::RegQueryValueExW(hkResult, L"Installation Directory",
      NULL, &type, (LPBYTE)wszRet, &cbData);

    if(lRet == ERROR_SUCCESS)
    {
      // We've got the installation directory of WMP
      wstrDirectory = wszRet;
      bOK = true;
    }

    ::RegCloseKey(hkResult);
    hkResult = NULL;
  }

  return bOK;
}

How To: Disable General Protection Fault Dialog for Your Program

Abstraction

Are you using any 3rd-party componet or ActiveX, which is not stable enough, in your program? You will get a GPF dialog if the componet in your program goes abnormal. That is not your problem totally, but actually your program crashed. There's a Windows API to prevent showing GPF dialog, you may adapt this solution if the crash can be ignored.

Code Snippet

UINT uPrevErrMode = SetErrorMode(SEM_NOGPFAULTERRORBOX);

Do you not know what GPF is?

General Protection Fault

Reference on MSDN

SetErrorMode Function

Read/Write Windows Registry on Windows 64-Bits Platforms (C# Version)

Abstraction

How does a 32-bits(x64) program running on Windows 64-bits(x64) access the 64-bits registry? In C#, you can use P/Invoke to call RegOpenKeyEx function with KEY_WOW64_KEY to access the 64-bits registry.

Code Snippet

//
// This is a C# example to get the version of Windows Media Center on Windows 7 64-bits.
//
class RegQueryValueDemo
{
  [DllImport("advapi32.dll", CharSet = CharSet.Unicode, EntryPoint = "RegOpenKeyExW", SetLastError = true)]
  public static extern int RegOpenKeyEx(UIntPtr hKey, string subKey, uint options, int sam, out UIntPtr phkResult);
  public static UIntPtr HKEY_CURRENT_USER = (UIntPtr)0x80000001;
  public static UIntPtr HKEY_LOCAL_MACHINE = (UIntPtr)0x80000002;
  public static int KEY_QUERY_VALUE = 0x0001;
  public static int KEY_SET_VALUE = 0x0002;
  public static int KEY_CREATE_SUB_KEY = 0x0004;
  public static int KEY_ENUMERATE_SUB_KEYS = 0x0008;
  public static int KEY_WOW64_64KEY = 0x0100;
  public static int KEY_WOW64_32KEY = 0x0200;

  [DllImport("advapi32.dll", CharSet = CharSet.Unicode, EntryPoint = "RegQueryValueExW", SetLastError = true)]
  public static extern int RegQueryValueEx(UIntPtr hKey, string lpValueName, int lpReserved, out uint lpType,
    StringBuilder lpData, ref int lpcbData);

  public string GetMCEIdent()
  {
    UIntPtr regKeyHandle;
    if (RegOpenKeyEx(
    HKEY_LOCAL_MACHINE,
    "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Media Center",
    0, KEY_QUERY_VALUE | KEY_WOW64_64KEY, out regKeyHandle) == 0)
    {
      uint type;

      StringBuilder stringBuilder = new StringBuilder(2048);
      int cbData = stringBuilder.Capacity;
      if (RegQueryValueEx(regKeyHandle, "Ident", 0, out type, stringBuilder, ref cbData) == 0)
      {
        return stringBuilder.ToString();
      }
    }

    return string.Empty;
  }
}

Find a C++ version?
Read/Write Windows Registry on Windows 64-Bits Platforms

Reference on MSDN:
RegOpenKeyEx Function
32-bit and 64-bit Application Data in the Registry

How To: A Web Page Interacts with a Embedded Web Browser Control

If your application contains a web browser control to show certain web page, can the web page interact with your application by script language? Yes, it can.

There's a sample on MSDN, it's very short but clear, please refer to the following link:

Reference on MSDN

WebBrowser.ObjectForScripting Property

Windows Media ASF Viewer

Windows Media® ASF Viewer 9 Series is a tool for inspecting the contents of files (such as .asf. .wma, and .wmv file) to make sure they meet the requirements of the Advanced Systems Format (ASF) specification. -- Microsoft

Brief Introduction

This tool is very helpful for analyzing the contents of ASF files, it helps us to know the media structure and content easily. I was trying to encode WMV using Windows Media Format SDK, and this tool really helped me to verify the output content.

Download from Microsoft

Windows Media ASF Viewer 9 Series