Scripting the Task Scheduler to Create System Restore Points

I ran into an interesting situation the other day: I had a hard drive that was going bad, and thankfully I had most of my data backed up on a schedule. However, before I removed the old hard drive, I wanted to log into the system to double-check a few settings. Unfortunately, several of the operating system files had become corrupted and the system wouldn’t boot.

I didn’t think that was a big deal, because I could try a system restore. However, I had forgotten that Windows 10 creates far less restore points than previously, so I had fewer to work with. In the end, I wasn’t able to boot the system that final time.

Now that I have my newly rebuilt computer up and going, I set out to create a scheduled task that will create system restore points on a schedule. However, I wasn’t content to create the task; I wanted to create the task using a batch file script so I could easily run the script to create the same task on any new systems that I might build.

It took me a while to get the script parameters the way that I wanted them, but the following one-line script achieves everything that I wanted to do. Note that you need run this script in an elevated command prompt, otherwise it might fail with an access denied error.

schtasks.exe /create /tn "Create Restore Point (MONTHLY)" /sc MONTHLY /d SUN /mo FIRST /st 05:00 /rl HIGHEST /ru "NT AUTHORITY\SYSTEM" /tr "PowerShell.exe -ExecutionPolicy Bypass -Command \"Checkpoint-Computer\" -Description \"AUTOMATIC-$(Get-Date -Format \"yyyyMMddHHmmss\")\" -RestorePointType \"MODIFY_SETTINGS\""

Here are the different parts of that script in detail, so you can modify them for your situation:

schtasks.exe This is Windows’ command line application for managing scheduled tasks.
/create Specifies that we will be creating a scheduled task.
/tn "Create Restore Point (MONTHLY)" Specifies the name for the scheduled task.
/sc MONTHLY Specifies the schedule type, which could be MONTHLY, WEEKLY, DAILY, HOURLY, etc.
/d SUN These two parameters work together to specify how often the task runs, and the options for these values will depend on the schedule type. In this example, it is specifying the FIRST SUNDAY of each month.
/mo FIRST
/st 05:00 Specifies the starting time in 24-hour format.
/rl HIGHEST Specifies the "run level," which in this example is the highest level.
/ru "NT AUTHORITY\SYSTEM" Specifies the user account to run the task as, which in this case is "NT AUTHORITY\SYSTEM".
/tr "<<SEE BELOW>>" Specifies the command to run inside the task. The actual command in this example is somewhat complex, so I’ve broken it down in the following table. Note that this command needs to be within a pair of quotation marks; if you need to include quotation marks for the values inside this script, you will need to escape those characters as I have done in this example.

And here are the parameters for the task that is going to run as part of the task:

PowerShell.exe The application that we're running in this application is PowerShell.exe, because PowerShell has a cmdlet to create a restore point.
-ExecutionPolicy Bypass Specifies the execution policy, which in this example specifies that nothing will be blocked and there are no warnings or prompts.
-Command "Checkpoint-Computer" Specifies the PowerShell cmdlet that creates a system restore point, which takes the following two parameters.
-Description "AUTOMATIC-$(Get-Date -Format \"yyyyMMddHHmmss\")"

Specifies the description of the system restore point, which in this example invokes another PowerShell cmdlet to specify a date/time stamp that will show when the restore point was created. The restore points created by this task will look like “AUTOMATIC-20211201015150.”

-RestorePointType "MODIFY_SETTINGS" Specifies the type of restore point, which could be APPLICATION_INSTALL, APPLICATION_UNINSTALL, DEVICE_DRIVER_INSTALL, MODIFY_SETTINGS, or CANCELLED_OPERATION.

That's about all there is to it. In a sense, this task is a bit of a script hack by invoking PowerShell cmdlets via the command line, but it works. And at the end of the day, that's all that matters.

Here are a few additional resources that provide more detail on the commands that I was using to create this script:

I hope this helps!

Adjusting Pitch for MP3 Files with FFmpeg

I recently ran into a situation where I needed to adjust the pitch of an MP3 file for a song that I needed to learn. The problem was that song was recorded in a specific key, and I needed to play the song a half-step different. Of course, rehearsing in the original key and transposing on-the-fly is pretty trivial, but sometimes I prefer to learn a song in the key which I will be playing.

In the past I have always used a tool like Cakewalk Sonar to load the MP3 file, adjust the pitch, and then save out the adjusted audio. But I thought that was far too prosaic of an approach; I wanted a way to script the pitch change. This got me thinking about one of my favorite tools: FFmpeg.

I have mentioned FFmpeg in previous blogs, and it's one of my favorite tools; I use it almost every day for one purpose or other, and I have a large collection of batch files to automate various tasks. But unfortunately, I didn't have anything for adjusting audio pitch. That being said, I have done a lot with various FFmpeg audio and video filters, and after a little while of sifting through some of the various settings I came up with a way to easily change the pitch for an MP3 file. (And if I ever need to automate a whole directory of MP3 files, it would be simple to update this script with a loop.)

Here's the secret to the way this works - there are two audio filters that I am using:

  • asetrate - this filter adjusts the sample rate; altering the sample rate will stretch or shrink the audio, thereby changing the pitch and length of the audio.
  • atempo - this filter adjusts the tempo of the audio; altering the tempo will change the length of the audio, without changing the pitch.

So the trick is to use these two filters inversely; in other words:

  • If you increase the sample rate by 2, then you need to decrease the tempo by 2.
  • If you decrease the sample rate by 1.5, then you need to increase the tempo by 1.5.

With that in mind, I pulled out one of my favorite math constants: 2^(1/12), which is roughly 1.0594630943592952645618252949463. You might recall from some of my other blogs that this is the value by which every pitch in Equal Temperament is derived; in other words, that value is used to create every note in the chromatic scale which is used throughout the planet.

Taking that into account, I looked at the filter settings that were possible for use with FFmpeg:

  • If I assume that MP3 files are using a sample rate of 44.1khz, then I need to use values for the asetrate filter which raise or lower the sample rate by r*2^(n/12), where:
    • r is the sample rate.
    • n is the number of half steps to raise or lower.
  • The atempo can be values between 0.5 and 2.0, where:
    • 0.5 is half-tempo
    • 1.0 is the original tempo
    • 2.0 is double-tempo
    With that in mind, I used a similar formula to increase or decrease the tempo by 2^(n/12), where n is the number of half steps to raise or lower.

The math is a little weird, I'll admit - but it's pretty straight-forward. And here's the great part for you: I've already done the math, and I've written a batch file which defines a set of constants that can be used in batch files to script the raising or lowering the pitch of an MP3 file.

Here's the code for the batch file:

@echo off

set TMPFILE1=InputFile.mp3
set TMPFILE2=OutputFile.mp3

set RAISE_PITCH_01=asetrate=r=46722.3224612449211671764955071340,atempo=0.94387431268169349664191315666753
set RAISE_PITCH_02=asetrate=r=49500.5763304433484812188074908520,atempo=0.89089871814033930474022620559051
set RAISE_PITCH_03=asetrate=r=52444.0337716199990422417487017170,atempo=0.84089641525371454303112547623321
set RAISE_PITCH_04=asetrate=r=55562.5183003639065662339877809700,atempo=0.79370052598409973737585281963615
set RAISE_PITCH_05=asetrate=r=58866.4375688985154890396859602340,atempo=0.74915353843834074939964036601490
set RAISE_PITCH_06=asetrate=r=62366.8181006534916521544727376480,atempo=0.70710678118654752440084436210485
set RAISE_PITCH_07=asetrate=r=66075.3420902616540970482802825140,atempo=0.66741992708501718241541594059223
set RAISE_PITCH_08=asetrate=r=70004.3863917975968365502186919090,atempo=0.62996052494743658238360530363911
set RAISE_PITCH_09=asetrate=r=74167.0638253776226953452670037700,atempo=0.59460355750136053335874998528024
set RAISE_PITCH_10=asetrate=r=78577.2669399779266780879513330830,atempo=0.56123102415468649071676652483959
set RAISE_PITCH_11=asetrate=r=83249.7143785253664038167404180770,atempo=0.52973154717964763228091264747317
set RAISE_PITCH_12=asetrate=r=88200.0000000000000000000000000000,atempo=0.50000000000000000000000000000000

set LOWER_PITCH_01=asetrate=r=41624.8571892626832019083702090380,atempo=1.05946309435929526456182529494630
set LOWER_PITCH_02=asetrate=r=39288.6334699889633390439756665420,atempo=1.12246204830937298143353304967920
set LOWER_PITCH_03=asetrate=r=37083.5319126888113476726335018850,atempo=1.18920711500272106671749997056050
set LOWER_PITCH_04=asetrate=r=35002.1931958987984182751093459540,atempo=1.25992104989487316476721060727820
set LOWER_PITCH_05=asetrate=r=33037.6710451308270485241401412570,atempo=1.33483985417003436483083188118450
set LOWER_PITCH_06=asetrate=r=31183.4090503267458260772363688240,atempo=1.41421356237309504880168872420970
set LOWER_PITCH_07=asetrate=r=29433.2187844492577445198429801170,atempo=1.49830707687668149879928073202980
set LOWER_PITCH_08=asetrate=r=27781.2591501819532831169938904850,atempo=1.58740105196819947475170563927230
set LOWER_PITCH_09=asetrate=r=26222.0168858099995211208743508580,atempo=1.68179283050742908606225095246640
set LOWER_PITCH_10=asetrate=r=24750.2881652216742406094037454260,atempo=1.78179743628067860948045241118100
set LOWER_PITCH_11=asetrate=r=23361.1612306224605835882477535670,atempo=1.88774862536338699328382631333510
set LOWER_PITCH_12=asetrate=r=22050.0000000000000000000000000000,atempo=2.00000000000000000000000000000000

ffmpeg -y -i "%TMPFILE1%" -af "%RAISE_PITCH_01%" "%TMPFILE2%"

The only parts that you need to configure are:

  • TMPFILE1 - set this variable to the name of your original input MP3 file.
  • TMPFILE2 - set this variable to the name of your adjusted pitch output MP3 file.
  • Specify whether to raise or lower the pitch in the FFmpeg command by choosing one of the constants defined in the batch file; for example:
    • RAISE_PITCH_02 would raise the pitch of the original audio file by two half-steps (or one whole step).
    • LOWER_PITCH_05 would lower the pitch of the original audio file by five half-steps (or 2½ whole steps).

There are, of course, hundreds of other parameters which you can pass to FFmpeg in order to customize how FFmpeg processes the audio, but those are way out of scope for this blog.

With that in mind, that's it for now; have fun!

Fixing Underwater Videos with FFMPEG

I ran into an interesting predicament: I couldn't get the right color adjustment settings to work in my video editor to correct some underwater videos from a scuba diving trip. After much trial and error, I came up with an alternative method: I have been able to successfully edit underwater photos to restore their color, so I used FFMPEG to export all of the frames from the source video as individual images, then I used a script to automate my photo editor to batch process all of the images, then I used FFMPEG to reassemble the finished results into a new MP4 file.

The following video of a Goliath Triggerfish in Bora Bora shows a before and after of what that looks like. Overall, I think the results are promising, albeit via a weird and somewhat time-consuming hack.

Exporting Videos as Images with FFMPEG

Here is the basic syntax for automating FFMPEG to export the individual frames:

ffmpeg.exe -i "input.mp4" -r 60 -s hd1080 "C:\path\%6d.png"

Where the following items are defined:

-i "input.mp4" specifies the source MP4 file
-r 60 specifies the frame rate for the video at 60fps
-s hd1080 specifies 1920x1080 resolution (there are others)
"C:\path\%6d.png" specifies the directory for storing the images, and specifies PNG images with file names which are numerically sequenced with a width of 6 digits (e.g. 000000.png to 999999.png)

Combining Images as a Video with FFMPEG

Here is the basic syntax for automating FFMPEG to combine the individual frames back into an MP4 file:

ffmpeg.exe -framerate 60 -i "C:\path\%6d.png" -c:v libx264 -f mp4 -pix_fmt yuv420p "output.mp4"

Where the following items are defined:

-framerate 60 specifies the frame rate for the output video at 60fps (note that specifying a different framerate than you used for exporting could be used to alter the playback speed of the final video)
-i "C:\path\%6d.png" specifies the directory where the images are stored, and specifies PNG images with file names which are numerically sequenced with a width of 6 digits (e.g. 000000.png to 999999.png)
-c:v libx264 specifies the H.264 codec
-f mp4 specifies an MP4 file
-pix_fmt yuv420p specifies the pixel format, which could also specify "rgb24" instead of "yuv420p"
"output.mp4" specifies the final MP4 file

Creating an HTML Application to Convert Text Files to Audio Files

I'd like to take a brief departure from my normal collage of web-related and server-management examples and share a rather eclectic code sample.

Here's the scenario: I am presently working on another college degree, and I was recently taking a class which required a great deal of reading.  These assignments were all in digital form: I was using PDF or Kindle-based versions of the textbooks, and the remaining reading consisted of online articles. However, I am also an avid bicyclist, and the voluminous amount of reading was preventing me from going on some of my normal weekly rides. This gave me an idea: if I could convert the digital text to audio, I could bring my assignments with me on my longer rides and have my MP3 player read my assignments to me as I pedaled my way around the Arizona deserts.

I had experimented with Microsoft's built-in text-to-speech features some years ago, so I thought that this would be the perfect opportunity to revisit some of those APIs and write a full application to do the conversions for me. That being said, I could have written this application by using C# (which is my preferred language), but I decided to create an HTML Application for two reasons: 1) it is easier for me to share HTMLA applications in a blog, and 2) I keep this application in my OneDrive, so it's easier for me to modify the source code on systems where I don't have Visual Studio installed.

With that in mind, here is the resulting script which will convert a Text File to a Wave (*.WAV) File.

Using the HTML Application

As with most of my HTML Applications, the user interface is pretty simple to use; when you double click the HTA file, it will present you with the following user interface:

Clicking the Browse button will obviously allow you to browse to a text file, clicking the Close button will close the application, and clicking the Write File button will create a Wave file that is in the same path as the source text file. For example, if you have a text file at "C:\Text\Test.txt", the script will create a Wave file at "C:\Text\Test.txt.wav".

That being said, there are a few options which you can set:

  • Depending on your version of Windows and which languages you have installed, you will be presented with a list of available voices in the first drop-down menu; the following example is from a Windows 8 computer:
  • The second drop-down menu allows you to vary the playback speed; sometimes I prefer the playback speed to be slighter faster than normal:
  • The third drop-down menu allows you to alter the volume of the resulting Wave file:

Note: You can modify the script to alter the values that are used in the playback speed and volume drop-down menus, but the list of voices is obtained dynamically from your operating system.

Creating the HTML Application

To create this HTML Application, save the following HTMLA code as "Text to Wave File.hta" to your computer, and then double-click its icon to run the application. (Note that in a few places I added code comments which contain the MSDN URL for the APIs that I am using for this sample.)

<html>
<head>
<title>Text-to-Speech Writer</title>
<HTA:APPLICATION
  APPLICATIONNAME="Text-to-Speech Writer"
  ID="TextToSpeech"
  VERSION="1.0"
  BORDER="dialog"
  BORDERSTYLE="static"
  INNERBORDER="no"
  CAPTION="yes"
  SYSMENU="no"
  MAXIMIZEBUTTON="no"
  MINIMIZEBUTTON="no"
  SCROLL="no"
  SCROLLFLAT="yes"
  SINGLEINSTANCE="yes"
  CONTEXTMENU="no"
  SELECTION="no"/>
</head>

<script language="VBScript">

Option Explicit

Dim blnCancelBubble

' ----------------------------------------
' 
' OnLoad event handler for the application.
' 
' ----------------------------------------

Sub Window_OnLoad
  blnCancelBubble = False
  ' Set up the UI dimensions.
  Const intDialogWidth = 550
  Const intDialogHeight = 125
  ' Specify the window position and size.
  Self.resizeTo intDialogWidth,intDialogHeight
  Self.moveTo (Screen.AvailWidth - intDialogWidth) / 2,_
    (Screen.AvailHeight - intDialogHeight) / 2
  ' Load the list of text-to-speech voices into the drop-down menu.
  ' See the notes in WriteFile() for more information.
  Dim objSAPI, objVoice, objSelect, objOption
  Set objSAPI = CreateObject("SAPI.SpVoice")
  For Each objVoice In objSAPI.GetVoices("","")
    Set objSelect = Document.getElementById("optVoices")
    Set objOption = Document.createElement("option")
    objOption.text = objVoice.GetDescription() 
    objSelect.Add objOption
  Next
End Sub

' ----------------------------------------
' 
' Click handler for the Write button.
' 
' ----------------------------------------

Sub btnWrite_OnClick()
  ' Test for a file name.
  If Len(txtFile.Value) > 0 Then
    ' Test if we need to cancel bubbling of events.
    If blnCancelBubble = False Then
        ' Write the input file.
        Call WriteFile(txtFile.Value)
      End If
    End If
    ' Specify whether to bubble events.
    blnCancelBubble = IIf(blnCancelBubble=True,False,True)
End Sub

' ----------------------------------------
' 
' Change handler for the input box.
' 
' ----------------------------------------

Sub txtFile_OnChange()
  ' Enable the Write button.
  btnWrite.Disabled = False
  ' Enable event bubbling.
  blnCancelBubble = False
End Sub

' ----------------------------------------
' 
' Click handler for the Close button.
' 
' ----------------------------------------

Sub btnClose_OnClick()
  ' Test if we need to cancel bubbling of events.
  If blnCancelBubble = False Then
    ' Prompt the user to exit.
    If MsgBox("Are you sure you wish to exit?", _
      vbYesNo+vbDefaultButton2+vbQuestion+vbSystemModal, _
      TextToSpeech.applicationName)=vbYes Then
      ' Enable event bubbling.
      blnCancelBubble = True
      ' Close the application.
      Window.close
    End If
  End If
  ' Specify whether to bubble events.
     blnCancelBubble = IIf(blnCancelBubble=True,False,True)
End Sub

' ----------------------------------------
' 
' This is an ultra-lame workaround for the lack
' of a DoEvents() feature in HTA applications.
' 
' ----------------------------------------

Sub DoEvents()
  On Error Resume Next
  ' Create a shell object.
  Dim objShell : Set objShell = CreateObject("Wscript.Shell")
  ' Call out to the shell and essentially do nothing.
  objShell.Run "ver", 0, True
End Sub

' ----------------------------------------
' 
' This is an ultra-lame workaround for the lack
' of an IIf() function in vbscript applications.
' 
' ----------------------------------------

Function IIf(tx,ty,tz)
  If (tx) Then IIf = ty Else IIf = tz
End Function

' ----------------------------------------
' 
' Main text-to-speech function
' 
' ----------------------------------------

Sub WriteFile(strInputFileName)
  On Error Resume Next
  Dim objFSO
  Dim objFile
  Dim objSAPI
  Dim objFileStream
  Dim strOldTitle
  Dim strOutputFilename
  Const strProcessing = "Creating WAV file... "
  
  ' Define the audio format as 44.1kHz / 16-bit audio.
  ' See http://msdn.microsoft.com/en-us/library/ms720595.aspx
  Const SAFT44kHz16BitStereo = 35
  ' Allow text to be read as well as written.
  ' See http://msdn.microsoft.com/en-us/library/ms720858.aspx
  Const SSFMCreateForWrite = 3
  
  ' Define the output WAV filename.
  strOutputFilename = strInputFileName & ".wav"

  ' Create a file system object and open the input file.
  Set objFSO = CreateObject("Scripting.FileSystemObject")
  Set objFile = objFSO.OpenTextFile(strInputFileName, 1)
  
  ' Disable the form fields.
  optVoices.Disabled = True
  optRate.Disabled = True
  optVolume.Disabled = True
  txtFile.Disabled = True
  btnWrite.Disabled = True
  btnClose.Value = "Cancel"

  ' Test for an error.
  If Err.Number <> 0 Then
      MsgBox "Error: " & Err.Number & vbCrLf & Err.Description
  Else
    ' Store the original dialog title.
    strOldTitle = Document.title
    ' Display a status message.
    Document.title = strProcessing & Time()
    ' Pause briefly to let the screen refresh and capture events.
    Call DoEvents()
    ' Create a text-to-speech object.
    ' See http://msdn.microsoft.com/en-us/library/ms720149.aspx
    Set objSAPI = CreateObject("SAPI.SpVoice")
    ' Create a SAPI file stream object.
    ' See http://msdn.microsoft.com/en-us/library/ms722561.aspx
    Set objFileStream = CreateObject("SAPI.SpFileStream")
    ' Specify the stream format.
    ' See http://msdn.microsoft.com/en-us/library/ms720998.aspx
    objFileStream.Format.Type = SAFT44kHz16BitStereo
    ' Open the output file stream.
    objFileStream.Open strOutputFilename, SSFMCreateForWrite
    ' Specify the output file stream.
    ' See http://msdn.microsoft.com/en-us/library/ms723597.aspx
    Set objSAPI.AudioOutputStream = objFileStream
    
    ' Specify the speaking rate.
    ' See http://msdn.microsoft.com/en-us/library/ms723606.aspx
    objSAPI.Rate = optRate.Options(optRate.SelectedIndex).Value
    ' Specify the speaking volume.
    ' See http://msdn.microsoft.com/en-us/library/ms723615.aspx
    objSAPI.Volume = optVolume.Options(optVolume.SelectedIndex).Value
    ' Specify the voice to use.
    ' See http://msdn.microsoft.com/en-us/library/ms723601.aspx
    ' See http://msdn.microsoft.com/en-us/library/ms723614.aspx
    Set objSAPI.Voice = objSAPI.GetVoices("","").Item(optVoices.SelectedIndex)
    
    ' Loop through the lines in the input file.
    Do While Not objFile.AtEndOfStream
      ' Test if we need to cancel bubbling of events.
      If blnCancelBubble = True Then
        Exit Do
      Else
        ' Display a status message.
        Document.title = strProcessing & Time()
        ' Pause briefly to let the screen refresh and capture events.
        Call DoEvents()
        ' Speak one line from the input file.
        ' See http://msdn.microsoft.com/en-us/library/ms723609.aspx
        objSAPI.Speak objFile.ReadLine
      End If
    Loop
    ' Close the output file stream.
    objFileStream.Close
  End If

  ' Close the input file.
  objFile.Close

  ' Destroy all objects.
  Set objFileStream = Nothing
  Set objSAPI = Nothing
  Set objFile = Nothing
  Set objFSO = Nothing
  
  ' Reset the original dialog title.
  Document.title = strOldTitle

  ' Notify the user that the file has been written.
  MsgBox "Finished!", vbInformation, strOldTitle
  
  ' Re-enable the form fields.
  btnClose.Value = "Close"
  optVoices.Disabled = False
  optRate.Disabled = False
  optVolume.Disabled = False
  txtFile.Disabled = False
  btnWrite.Disabled = False

End Sub

</script>

<body bgcolor="white" id="HtmlBody">
<div id="FormControls">
  <table>
    <tr>
      <td align="left">
        <input type="file"
        style="width:250px;height:22px"
        name="txtFile"
        id="txtFile"
        onchange="txtFile_OnChange">
      </td>
      <td align="left">
        <input type="button"
        style="width:125px;height:22px"
        name="btnWrite"
        id="btnWrite"
        value="Write File"
        disabled
        onclick="btnWrite_OnClick">
      </td>
      <td align="right">
        <input type="button"
        style="width:125px;height:22px"
        name="btnClose"
        id="btnClose"
        value="Close"
        onclick="btnClose_OnClick">
      </td>
    </tr>
    <tr>
      <td align="left">
        <select name="optVoices"
          style="width:250px;height:22px">
        </select>
      </td>
      <td align="left">
        <select name="optRate"
          style="width:125px;height:22px">
          <option value="-2">Slowest</option>
          <option value="-1">Slower</option>
          <option value="0" selected>Normal Speed</option>
          <option value="1">Faster</option>
          <option value="2">Fastest</option>
        </select>
      </td>
      <td align="right">
        <select name="optVolume"
          style="width:125px;height:22px">
          <option value="25">25% Volume</option>
          <option value="50">50% Volume</option>
          <option value="75">75% Volume</option>
          <option value="100" selected>Full Volume</option>
        </select>
      </td>
    </tr>
  </table>
</div>
</body>
</html>

Note that I intentionally chose to have this HTML Application convert the text to audio one line at a time; this slows the down the conversion process, but it allows the conversion to be cancelled if necessary. (My original version of this script would convert an entire text file at one time; since there was no way to cancel the operation, the script appeared to hang when converting larger text files.)

Additional Notes

Once you have created a Wave (*.WAV) file, you can optionally convert it to an MP3 file for use in an MP3 player or mobile phone. (Most devices should playback Wave files, but MP3 files are considerably smaller and more portable.) There are a variety of Wave-to-MP3 converters out there, but I prefer to use the LAME encoder, which is an open-source code project that is available on SourceForge. Once you have the LAME encoder project compiled, (or you have located and downloaded a pre-compiled version), you can use LAME.EXE from a command prompt to convert your Wave files into MP3 files.

That being said, I prefer to automate as much as possible, so I have written a batch file which converts all of the Wave files in a directory to MP3 files and renames the source Wave files with a "*.old" filename extension:

@echo off

for /f "usebackq delims=|" %%a in (`dir /b *.wav`) do (
  for %%b in (^"%%a^") do (
    if not exist "%%~db%%~pb%%~nb.mp3" (
      lame.exe -b 128 -m j "%%a" "%%~nb.mp3"
    )
    if exist "%%~db%%~pb%%~nb.mp3" (
      move "%%a" "%%a.old"
    )
  )
)

Note that the above batch file was written for text-to-speech use, and as such it defines a bit rate of 128kbps, which would be pretty low for music files. If you want to repurpose this batch file for higher bitrates, modify the value of the "-b" parameter for the LAME.EXE command.

That wraps it up for today's post.

Note: This blog was originally posted at http://blogs.msdn.com/robert_mcmurray/

Simple Utility to Calculate File Hashes

I have to download various files from time-to-time, and it's nice when websites provide checksum hashes so I can validate that the file I just downloaded matches the version on the server. (ON a related note, I wrote a blog several years ago which showed how to create a provider for the IIS FTP service which automatically creates checksum files when files are uploaded to a server; see my Automatically Creating Checksum Files for FTP Uploads blog post for the details.)

In order to calculate hashes for files that I have downloaded, several years ago I wrote a simple command-line application for Windows which uses several of the built-in algorithms in .NET's System.Security.Cryptography. And while I realize that there are probably other tools that provide this same functionality, I have used this little utility for years, and I've had several people ask me for copies. With that in mind, I thought that it might make a nice blog topic if I shared the code with everyone. (Note: It's a really simple sample; the .NET framework does all the real work for this application.)

Without further fanfare, here's the source code. In order to use this code sample, you need to create a new C# project in Visual Studio and choose the Console Application template. When the new project opens, replace the template's code with the following:

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Security.Cryptography;

class Hash
{
    static void Main(string[] args)
    {
        // Verify the correct number of command-line arguments.
        if (args.Length != 2)
        {
            // Show the help message if an incorrect number of arguments was specified.
            ShowHelp();
            return;
        }
        else
        {
            byte[] hashValue = null;
            // Verify that the specified file exists.
            if (!File.Exists(args[1]))
            {
                // Show the help message if a non-existent filename was specified.
                ShowHelp();
                return;
            }
            else
            {
                try
                {
                    // Create a fileStream for the file.
                    FileStream fileStream = File.OpenRead(args[1]);
                    // Be sure it's positioned to the beginning of the stream.
                    fileStream.Position = 0;
                    // Use the specified hash algorithm.
                    switch (args[0].ToUpper())
                    {
                        case "MD5":
                            // Compute the MD5 hash of the fileStream.
                            hashValue = MD5.Create().ComputeHash(fileStream);
                            break;
                        case "SHA1":
                            // Compute the SHA1 hash of the fileStream.
                            hashValue = SHA1.Create().ComputeHash(fileStream);
                            break;
                        case "SHA256":
                            // Compute the SHA256 hash of the fileStream.
                            hashValue = SHA256.Create().ComputeHash(fileStream);
                            break;
                        case "SHA384":
                            // Compute the SHA384 hash of the fileStream.
                            hashValue = SHA384.Create().ComputeHash(fileStream);
                            break;
                        case "SHA512":
                            // Compute the SHA512 hash of the fileStream.
                            hashValue = SHA512.Create().ComputeHash(fileStream);
                            break;
                        case "BASE64":
                            // Compute the BASE64 hash of the fileStream.
                            byte[] binaryData = new Byte[fileStream.Length];
                            long bytesRead = fileStream.Read(binaryData, 0, (int)fileStream.Length);
                            if (bytesRead != fileStream.Length)
                            {
                                throw new Exception(String.Format("Number of bytes read ({0}) does not match file size ({1}).", bytesRead, fileStream.Length));
                            }
                            string base64String = System.Convert.ToBase64String(binaryData, 0, binaryData.Length);
                            Console.WriteLine("File: {0}\r\nBASE64 Hash: {1}", fileStream.Name, base64String);
                            hashValue = null;
                            break;
                        default:
                            // Display the help message if an unrecognized hash algorithm was specified.
                            ShowHelp();
                            return;
                    }
                    if (hashValue != null)
                    {
                        // Write the hash value to the Console.
                        PrintHashData(args[0].ToUpper(), fileStream.Name, hashValue);
                    }
                    // Close the file.
                    fileStream.Close();
                }
                catch (Exception ex)
                {
                    Console.WriteLine("Error: {0}", ex.Message);
                }
            }
        }
    }

    // Display the help message.
    private static void ShowHelp()
    {/>        Console.WriteLine("HASH.exe <hash algorithm> <file name>\n\n" +
            "\tWhere <hash algorithm> is one of the following:\n" +
            "\t\tBASE64\n\t\tMD5\n\t\tSHA1\n\t\tSHA256\n\t\tSHA384\n\t\tSHA512\n");
    }

    // Print the hash data in a readable format.
    private static void PrintHashData(string algorithm, string fileName, byte[] array)
    {
        Console.Write("File: {0}\r\n{1} Hash: ", fileName,algorithm);
        for (int i = 0; i < array.Length; i++)
        {
            Console.Write(String.Format("{0:X2}", array[i]));
        }
        Console.WriteLine();
    }/>}

When you compile and run the application, you will see following help message when you specify no command-line parameters:


HASH.exe <hash algorithm> <file name> Where <hash algorithm> is one of the following: BASE64 MD5 SHA1 SHA256 SHA384 SHA512

When you specify one of the supported hashing algorithms and a filename, the application will display something like the following example:


C:\>hash.exe SHA1 foobar.zip File: C:\foobar.zip SHA1 Hash: 57686F6120447564652C20426F6220526F636B73

That's all there is to it. As I mentioned earlier, it's a pretty simple sample. ;-]

Note: This blog was originally posted at http://blogs.msdn.com/robert_mcmurray/

Cleaning Up Your Windows System When QuickTime Has Screwed Up Your Media Settings

So here's the deal: I don't use anything from Apple. I have no iPod, no iPhone, no Mac, etc. I buy all of my MP3s through Xbox Music and Amazon. :-] Because of this, I have had no real need to install iTunes or QuickTime in years.

But unfortunately it seemed that I had to install either iTunes or QuickTime at one time or other, mainly because some of my digital cameras recorded video in QuickTime *.MOV format. But over the years I learned to detest both iTunes and QuickTime because of the undesirable ways in which they modified my system; both iTunes and QuickTime would remap all of media settings to open in their @#$% player, which I didn't really want in the first place.

Now that Windows supports the *.MOV format natively, and I can easily convert *.MOV files into something infinitely more useful and universal like *.MP4 format, I really never see the need for installing either iTunes or QuickTime.

However, just the other day I installed a new video editor (which shall remain nameless) and it quietly installed QuickTime on my system. I presume that this was to make it easier to import files in *.MOV format into the video editor, but I was pretty upset when I discovered that QuickTime had been installed. What's more, I was angry when I discovered that QuickTime had once again messed up all of my media settings.

In all of this misery is one saving grace: QuickTime has the decency to preserve your original settings. I am assuming that the backups are for when you uninstall QuickTime and attempt to reclaim your system from being hijacked by Apple, but just the same - that little nicety allowed me to fix my system with a little bit of scripting.

So without further introduction - first the script, and then the explanation:

Const HKEY_CLASSES_ROOT = &H80000000
Const strQuickTimeBAK = "QuickTime.bak"

Set objRegistry = GetObject("winmgmts:" & _
  "{impersonationLevel=impersonate}" & _
  "!\\.\root\default:StdRegProv")
 
objRegistry.EnumKey HKEY_CLASSES_ROOT, "", arrSubKeys

For Each objSubkey in arrSubKeys
  If Len(objSubkey)>2 Then
    If Left(objSubkey,1)="." Then
      objRegistry.EnumValues HKEY_CLASSES_ROOT, _
        objSubkey, arrEntryNames, arrValueTypes
      If IsArray(arrEntryNames) Then
        For i = 0 To UBound(arrEntryNames)
          If StrComp(arrEntryNames(i), strQuickTimeBAK, vbTextCompare)=0 Then
            intReturnValue = objRegistry.GetStringValue( _
              HKEY_CLASSES_ROOT, objSubkey, strQuickTimeBAK, strEntryValue)
            If intReturnValue = 0 Then
              intReturnValue = objRegistry.SetStringValue( _
                HKEY_CLASSES_ROOT, objSubkey, "", strEntryValue)
            End If
          End If
        Next
      End If
    End If
  End If
Next

Here's what this script does: first the script enumerates all of the keys under HKEY_CLASSES_ROOT and looks for file extension mappings, then it looks for mappings which have been modified and backed up by QuickTime. When it locates file extensions which have been modified, it copies the value which was backed up into the default location where it belongs.

All-in-all, it's a pretty straight-forward script, but it sucks that I had to write it.

FTP ETW Tracing and IIS 8 - Part 2

Shortly after I published my FTP ETW Tracing and IIS 8 blog post, I was using the batch file from that blog to troubleshoot an issue that I was having with a custom FTP provider. One of the columns which I display in my results is Clock-Time, which is obviously a sequential timestamp that is used to indicate the time and order in which the events occurred.

(Click the following image to view it full-size.)

At first glance the Clock-Time values might appear to be a range of useless numbers, but I use Clock-Time values quite often when I import the data from my ETW traces into something like Excel and I need to sort the data by the various columns.

That being said, apart from keeping the trace events in order, Clock-Time isn't a very user-friendly value. However, LogParser has some great built-in functions for crunching date/time values, so I decided to update the script to take advantage of some LogParser coolness and reformat the Clock-Time value into a human-readable Date/Time value.

My first order of business was to figure out how to decode the Clock-Time value; since Clock-Time increases for each event, it is obviously an offset from some constant, and after a bit of searching I found that the Clock-Time value is the offset in 100-nanosecond intervals since midnight on January 1, 1601. (Windows uses that value in a lot of places, not just ETW.) Once I had that information, it was pretty easy to come up with a LogParser formula to convert the Clock-Time value into the local time for my system, which is much easier to read.

With that in mind, here is the modified batch file:

@echo off

rem ======================================================================

rem Clean up old log files
for %%a in (ETL CSV) do if exist "%~n0.%%a" del "%~n0.%%a"

echo Starting the ETW session for full FTP tracing...
LogMan.exe start "%~n0" -p "IIS: Ftp Server" 255 5 -ets
echo.
echo Now reproduce your problem.
echo.
echo After you have reproduced your issue, hit any key to close the FTP
echo tracing session. Your trace events will be displayed automatically.
echo.
pause>nul

rem ======================================================================

echo.
echo Closing the ETW session for full FTP tracing...
LogMan.exe stop "%~n0" -ets

rem ======================================================================

echo.
echo Parsing the results - this may take a long time depending on the size of the trace...
if exist "%~n0.etl" (
   TraceRpt.exe "%~n0.etl" -o "%~n0.csv" -of CSV
   LogParser.exe "SELECT [Clock-Time], TO_LOCALTIME(ADD(TO_TIMESTAMP('1601-01-01 00:00:00', 'yyyy-MM-dd hh:mm:ss'), TO_TIMESTAMP(DIV([Clock-Time],10000000)))) AS [Date/Time], [Event Name], Type, [User Data] FROM '%~n0.csv'" -i:csv -e 2 -o:DATAGRID -rtp 20
)

When you run this new batch file, it will display an additional "Date/Time" column with a more-informative value in local time for the sever where you captured the trace.

(Click the following image to view it full-size.)

The new Date/Time column is considerably more practical, so I'll probably keep it in the batch file that I use when I am troubleshooting. You will also notice that I kept the original Clock-Time column; I chose to do so because I will undoubtedly continue to use that column for sorting when I import the data into something else, but you can safely remove that column if you would prefer to use only the new Date/Time value.

That wraps it up for today's post. :-)

Note: This blog was originally posted at http://blogs.msdn.com/robert_mcmurray/

FTP ETW Tracing and IIS 8

In the past I have written a couple of blogs about using the FTP service's Event Tracing for Windows (ETW) features to troubleshoot issues; see FTP and ETW Tracing and Troubleshooting Custom FTP Providers with ETW for details. Those blog posts contain batch files which use the built-in Windows LogMan utility to capture an ETW trace, and they use downloadable LogParser utility to parse the results into human-readable form. I use the batch files from those blogs quite often, and I tend to use them a lot when I am developing custom FTP providers which add new functionality to my FTP servers.

Unfortunately, sometime around the release of Windows 8 and Windows Server 2012 I discovered that the ETW format had changed, and the current version of LogParser (version 2.2) cannot read the new ETW files. When you try to use the batch files from my blog with IIS 8, you see the following errors:

Verifying that LogParser.exe is in the path...
Done.

Starting the ETW session for full FTP tracing...
The command completed successfully.

Now reproduce your problem.

After you have reproduced your issue, hit any key to close the FTP tracing session. Your trace events will be displayed automatically.

Closing the ETW session for full FTP tracing...
The command completed successfully.

Parsing the results - this may take a long time depending on the size of the trace...
Task aborted.
Cannot open <from-entity>: Trace file "C:\temp\ftp.etl" has been created on a OS version (6.3) that is not compatible with the current OS version


Statistics:
-----------
Elements processed: 0
Elements output: 0
Execution time: 0.06 seconds

I meant to research a workaround at the time, but one thing led to another and I simply forgot about doing so. But I needed to use ETW the other day when I was developing something, so that seemed like a good time to quit slacking and come up with an answer. :-)

With that in mind, I came up with a very easy workaround, which I will present here. Once again, this batch file has a requirement on LogParser being installed on your system, but for the sake of brevity I have removed the lines from this version of the batch file which check for LogParser. (You can copy those lines from my previous blog posts if you want that functionality restored.)

Here's the way that this workaround is implemented: instead of creating an ETW log and then parsing it directly with LogParser, this new batch file invokes the built-in Windows TraceRpt command to parse the ETW file and save the results as a CSV file, which is then read by LogParser to view the results in a datagrid like the batch files in my previous blogs:

@echo off

rem ======================================================================

rem Clean up old log files
for %%a in (ETL CSV) do if exist "%~n0.%%a" del "%~n0.%%a"

echo Starting the ETW session for full FTP tracing...
LogMan.exe start "%~n0" -p "IIS: Ftp Server" 255 5 -ets
echo.
echo Now reproduce your problem.
echo.
echo After you have reproduced your issue, hit any key to close the FTP
echo tracing session. Your trace events will be displayed automatically.
echo.
pause>nul

rem ======================================================================

echo.
echo Closing the ETW session for full FTP tracing...
LogMan.exe stop "%~n0" -ets

rem ======================================================================

echo.
echo Parsing the results - this may take a long time depending on the size of the trace...
if exist "%~n0.etl" (
   TraceRpt.exe "%~n0.etl" -o "%~n0.csv" -of CSV
   LogParser.exe "SELECT [Clock-Time], [Event Name], Type, [User Data] FROM '%~n0.csv'" -i:csv -e 2 -o:DATAGRID -rtp 20
)

Here's another great thing about this new batch file - it will also work down-level on Windows 7 and Windows Server 2008; so if you have been using my previous batch files with IIS 7 - you can simply replace your old batch file with this new version. You will see a few differences between the results from my old batch files and this new version, namely that I included a couple of extra columns that I like to use for troubleshooting.

(Click the following image to view it full-size.)

There is one last thing which I would like to mention in closing: I realize that it would be much easier on everyone if Microsoft simply released a new version of LogParser which works with the new ETW format, but unfortunately there are no plans at the moment to release a new version of LogParser. And trust me - I'm just as depressed about that fact as anyone else. :-(

Note: This blog was originally posted at http://blogs.msdn.com/robert_mcmurray/

Using ASX Files with Windows Media Center

Like a lot of Windows geeks and fanboys, I use Windows Media Center on a Windows 7 system as my Digital Video Recorder (DVR) and media library. My system consists of a Dell GX270 computer with a ZOTAC NVIDIA GeForce GT610 video card, and it uses an InfiniTV 6 ETH tuner to receive cable signals. This setup has served us faithfully for years, and it is the center piece of our home entertainment system. If you're not familiar with Windows Media Center, that's because it's a rather hideously under-advertised feature of Windows. Just the same, here is an official Microsoft teaser for it:

But I've done a few extra things with my Windows Media Center that are a little beyond the norm, and one of the biggest items that I spent a considerable amount of time and effort digitizing my entire collection of DVD and Blu-ray discs as MP4 files, and I store them on a Thecus NAS that's on my home network which I use for media libraries on my Windows Media Center. This allows me to have all of my movies available at all times, and I can categorize them into folders which show up under the "Videos" link on the Windows Media Center menu.

That being said, there's a cool trick that I've been using to help customize some of my movies. Some of the movies that I have encoded have some material that I'd like to cut out, (like excessive opening credits and lengthy intermissions), but I don't want to edit and re-encode each MP4 file. Fortunately, Windows Media Center supports Advanced Stream Redirector (ASX) files, which allows me to customize what parts of a video are seen without having to edit the actual video.

Here's a perfect example: I recently purchased the 50th Anniversary Collector's Edition of Lawrence of Arabia on Blu-ray. The film is one of my favorites, and this reissue on Blu-ray is phenomenal. That being said, the movie begins with a little over four minutes of a blank screen while the musical overture plays. In addition, there is an additional eight minutes of a blank screen while the music for intermission is played. This is obviously less than desirable, so I created an ASX file which skips the opening overture and intermission.

By way of explanation, ASX files are XML files which define a playlist for media types, which can be any supported audio or video media. The individual entries can define various metadata about each media file, and thankfully can be used to specify which parts of a media file will be played.

With that in mind, here's what the ASX file that I created for Lawrence of Arabia looks like:

<ASX VERSION="3.0">
  <!-- Define the title for the movie. -->
  <TITLE>Lawrence Of Arabia</TITLE>
  <!-- Specify the movie's author. -->
  <AUTHOR>Columbia Pictures</AUTHOR>
  <!-- List the copyright for the movie. -->
  <COPYRIGHT>1962 Horizon Pictures (GB)</COPYRIGHT>
  <ENTRY>
    <!-- Define the video file for this entry. -->
    <REF HREF="Lawrence Of Arabia.mp4" />
    <!-- Define the start time for this entry. -->
    <STARTTIME VALUE="00:04:17.0"/>
    <!-- Define the duration for this entry. -->
    <DURATION VALUE="02:15:07.0"/>
  </ENTRY>
  <ENTRY>
    <!-- Define the video file for this entry. -->
    <REF HREF="Lawrence Of Arabia.mp4" />
    <!-- Define the start time for this entry. -->
    <STARTTIME VALUE="02:23:38.0"/>
  </ENTRY>
</ASX>

The XML comments explain what each of the lines in the file is configuring, and it should be straight-forward. But I would like to describe a few additional details:

  • Individual media entries are obviously defined in a collection of <ENTRY> elements, and in this example I have defined two entries:
    • The first entry defines a <STARTTIME> and <DURATION> which skip over the overture and play up to the intermission.
    • The second entry defines a <STARTTIME> which starts after the intermission and plays through the end of the movie.
  • The other metadata in the file - like the <AUTHOR> and <COPYRIGHT> - is just for me. That information is optional, but I like to include it.

There are several other pieces of metadata which can be configured, and a list of those are defined in the Windows Media Metafile Elements Reference and ASX Elements Reference.

Rapid PHP Deployment for IIS using a Batch File

Whenever I am delivering a presentation where I need to use PHP, I typically use a batch file that I wrote in order to rapidly deploy PHP on the system that I am using for my demos. The batch file usually takes less than a second to run, which always seems to amaze people in the audience. As a result, I usually have several people ask me for my batch file after each presentation, so I thought that it would make a good subject for today's blog.

I should mention that I have used this batch file in order to demonstrate PHP with IIS in a variety of scenarios, and one of my favorite demos is when I would borrow someone's laptop and plug in a flash drive where I had IIS Express pre-installed, and then I would run the batch file in this blog to deploy PHP. Next I would launch IIS Express, open a web browser on their system, and then browse to http://localhost/ in order to show that IIS Express was working correctly. Lastly I would write a simple PHP "Hello World" page to show that PHP was up-and-running on their system in a matter of seconds.

That being said, I have to point out that there is a very important prerequisite that you must have in order to follow the steps in the blog: you need to start with a known-good installation of PHP from one of your systems, and I'll explain what I mean by that.

My batch file expects to find a folder containing ready-to-run files for PHP in order to deploy PHP on a new system. I originally obtained my PHP files by using the Web Platform Installer (WebPI) to install PHP, and then I copied the files to my flash drive or some other repository. (Note that WebPI usually installs PHP in the "%ProgramFiles(x86)%\PHP" folder.) If you don't want to use WebPI, you can also download PHP from http://windows.php.net/, but you're on your own for configuration.

Once I have the files from a known-good installation of PHP, I create the following folder structure in the location where I will be storing the files that I use to deploy PHP on other systems:

  • <root folder>
    • SETUP_PHP.cmd (the batch file from this blog)
    • PHP (the folder containing the PHP files)
      • PHP.INI
      • PHP-CGI.EXE
      • etc. (all of the remaining PHP files and folders)

One thing to note is that the PHP.INI file you use may contain paths which refer to specific directories on the system from which you are copying your PHP files, so you need to make sure that those paths will exist on the system where you deploy PHP.

Here is an example: when I used WebPI to install PHP 5.5 on a system with IIS, it installed PHP into my "%ProgramFiles(x86)%\PHP\v5.5" folder. During the installation process, WebPI updated the PHP file to reflect any paths that need to be defined. At the time that I put together my notes for this blog, those updates mainly applied to the path where PHP expects to find it's extensions:

extension_dir="C:\Program Files (x86)\PHP\v5.5\ext\"

What this means is - if you want to deploy PHP to some other path on subsequent systems, you will need to update at least that line in the PHP.INI file that you are using to deploy PHP. In my particular case, I prefer to deploy PHP to the "%SystemDrive%\PHP" path, but it can be anywhere as long as you update everything accordingly.

The following batch file will deploy the PHP files in the "%SystemDrive%\PHP" folder on your system, and then it will update IIS with the necessary settings for this PHP deployment to work:

@echo off

REM Change to the installation folder
pushd "%~dp0"

REM Cheap test to see if IIS is installed
if exist "%SystemRoot%\System32\inetsrv" (
  REM Check for the PHP installation files in a subfolder
  if exist "%~dp0PHP" (
    REM Check for an existing installation of PHP
    if not exist "%SystemDrive%\PHP" (
      REM Create the folder for PHP
      md "%SystemDrive%\PHP"
      REM Deploy the PHP files
      xcopy /erhky "%~dp0PHP\*" "%SystemDrive%\PHP"
    )
    pushd "%SystemRoot%\System32\inetsrv"
    REM Configure the IIS settings for PHP
    appcmd.exe set config -section:system.webServer/fastCgi /+"[fullPath='%SystemDrive%\PHP\php-cgi.exe',monitorChangesTo='php.ini',activityTimeout='600',requestTimeout='600',instanceMaxRequests='10000']" /commit:apphost
    appcmd.exe set config -section:system.webServer/fastCgi /+"[fullPath='%SystemDrive%\PHP\php-cgi.exe',monitorChangesTo='php.ini',activityTimeout='600',requestTimeout='600',instanceMaxRequests='10000'].environmentVariables.[name='PHP_FCGI_MAX_REQUESTS',value='10000']" /commit:apphost
    appcmd.exe set config -section:system.webServer/fastCgi /+"[fullPath='%SystemDrive%\PHP\php-cgi.exe',monitorChangesTo='php.ini',activityTimeout='600',requestTimeout='600',instanceMaxRequests='10000'].environmentVariables.[name='PHPRC',value='%SystemDrive%\PHP']" /commit:apphost
    appcmd.exe set config -section:system.webServer/handlers /+"[name='PHP_via_FastCGI',path='*.php',verb='GET,HEAD,POST',modules='FastCgiModule',scriptProcessor='%SystemDrive%\PHP\php-cgi.exe',resourceType='Either']" /commit:apphost
    popd
  )
)
popd

Once you have all of that in place, it usually takes less than a second to deploy PHP, which is why so many people seem interested during my presentations.

Note that you can deploy PHP for IIS Express just as easily by updating the "%SystemRoot%\System32\inetsrv" paths in the batch file to "%ProgramFiles%\IIS Express" or "%ProgramFiles(x86)%\IIS Express" paths. You can also use this batch file as part of a deployment process for PHP within a web farm; in which case, you will need to pay attention to the paths inside your PHP.INI file which I mentioned earlier.

Note: This blog was originally posted at http://blogs.msdn.com/robert_mcmurray/