[RESOLVED] [2008] Get playing time of a media file without using WMP

[obi1kenobi]

I'm using mciSendString to play a media file inside my form, however I'd like to be able to hide the form after the media has finished playing as well as showing the playing time of the video. Is there a way I can get the playing time of the media file and get an event raised when it finishes playing? I don't want to add another dependency in the form of the WMP component.

I found some code via google, but I can't make heads or tails of it. I don't have much experience with APIs but from what I tried it only returned zero. Here it is:

Function MCIWndGetLength (hwnd As HWND) As Long 
MCIWndGetLength = SendMessage(hwnd, MCIWNDM_GETLENGTH, 0, 0)
End Function

'Found on http://translate.google.co.uk/translate?hl=en&sl=ja&u=http://www.activebasic.com/forum/viewtopic.php%3Fp%3D9024&sa=X&oi=translate&resnum=10&ct=result&prev=/search%3Fq%3DMCIWndGetLength%2B.Net%26start%3D10%26hl%3Den%26lr%3Dlang_en%26sa%3DN%26as_qdr%3Dall

[Half]

What file type?

[obi1kenobi]

Doesn't an all-in-one solution exist? I'd prefer to make it work with all video file types, but if that is too difficult then I guess avi/wmv will have to do.

[jmcilhinney]

You should go to MSDN and start reading about Windows Multimedia Control Interface (MCI) and, in particular, the mciSendString function.

[Half]

Nevermind, it crashes randomly with different types of media.

[user name]

You can use mciSendString to get the file playing length and also the position it is at. You could use a timer to keep checking the position against the length.

[obi1kenobi]

You should go to MSDN and start reading about Windows Multimedia Control Interface (MCI) and, in particular, the mciSendString function.

Boy, I knew you'd say that. In fact I did search MSDN first, unfortunately I am not at all apt with using APIs. I found these two articles which should be related to my problem, however I am at a loss on how to use them:

MCIWndGetLength

MCIWNDM_GETLENGTH

The first one is a macro and the second one is a message. So I haven't got a clue how to use the first one. As for the second one I assume that SendMessage is used, however, having never used it before, I failed.

You can use mciSendString to get the file playing length and also the position it is at.

Would you mind providing an example?

[jmcilhinney]

I suggested that you read up on MCI because there's a lot more to it than we can tell you here. As for the mciSendString function, it's pretty simple stuff... in principle.

If you don't know how calling API functions works then that's the first thing you should address. Again, pretty simple stuff. You simply declare an external function with using VB syntax with a signature that's compatible with the exported C/C++ function. You can do that with the API Viewer or at PInvoke.net. This:

Declare Ansi Function mciSendString Lib "winmm.dll" Alias "mciSendStringA" (ByVal command As String, ByRef buffer As StringBuilder, ByVal bufferSize As Integer, ByVal hWndCallback As IntPtr) As Integer

is from the latter.

Once the managed method signature has been created you can call it like any other method.

The next thing to do is go to MSDN and read the Win32 documentation to find out what the function does and what each parameter means. Once you know all that, then you can think about calling the function.

The trick with mciSendString is to know exactly what string to send to accomplish your desired task. Google can help you there.

[obi1kenobi]

I know how declaring and calling API functions works. I said inapt, not illiterate I just don't know what to pass and how to consume the result. You could say I know the theory but have no practical experience and you wouldn't be far off.

Can an API function be declared in multiple ways (like overloads)? Since I'm using this Declare statement:

    Private Declare Function mciSendString Lib "winmm.dll" Alias "mciSendStringA" (ByVal lpstrCommand As String, ByVal lpstrReturnString As String, ByVal uReturnLength As Integer, ByVal hwndCallback As Integer) As Integer

I'm playing a video on the form and it works fine with that declaration.

I found a list (a rather length one, I might add) containing the Multimedia Command Strings. I'm doing my best to solve the issue myself, but as the list is huge I'd be very grateful if those who know the exact string to use speak up.

[obi1kenobi]

I found the most likely command, it's the status command. It has a length flag which should get the length of the file according to the MSDN documentation.

This is the code I wrote to use it, however it didn't work:

        mciSendString("set VideoFile time format ms", Nothing, 0, 0)  'VideoFile is the file I'm playing
        Dim str As New System.Text.StringBuilder
        Dim i As Integer = mciSendString("status MediaFile length", str, 0, 0)

Both i and str are empty. What am I doing wrong?

[user name]

You need to supply a buffered string for the returned string

Try this.

Dim str As String = New String(CChar(" "), 128)

mciSendString("status MediaFile length", str, 128, 0)

Dim i as Integer = Integer.Parse(str)

[obi1kenobi]

Thank you, it works like a charm. I don't think I could have figured it out by myself. Much appreciated.

Thanks to everyone who participated in this thread.