avicap32.dll issues (Is Ken Tucker Around?)

[Jeremy]

Hello

I am using a web cam service that saves images every five minutes based
off the example given by Ken Tucker. (hopefully I can catch him!) It
works great for the most part.

I need to handle a situation if the camera, or connection to the camera
become interupted. I am connecting through a device called a "dazzle"
which for some reason or another causes a few connection problems here
and there.

If the camera goes offline the image does not update, and the preview
window becomes frozen with the last frame before the connection was
interupted.

I noticed in the CAPSTATUS structure a few properties I could test for
to see if the image is "live". The problem is that "fLiveWindow" always
returns 1...even on a preview window with a still image. There is
another property "fCapturingNow" but it always returns 0. I could even
use "dwCurrentVideoFrame" and see if the count stopped but that too
always returns 0. What am I missing? How can I test if the preview
window has a live or moving image?

Public Structure CAPSTATUS
Dim uiImageWidth As Integer
Dim uiImageHeight As Integer
Dim fLiveWindow As Integer
Dim fOverlayWindow As Integer
Dim fScale As Integer
Dim ptScroll As POINTAPI
Dim fUsingDefaultPalette As Integer
Dim fAudioHardware As Integer
Dim fCapFileExists As Integer
Dim dwCurrentVideoFrame As Integer
Dim dwCurrentVideoFramesDropped As Integer
Dim dwCurrentWaveSamples As Integer
Dim dwCurrentTimeElapsedMS As Integer
Dim hPalCurrent As Integer
Dim fCapturingNow As Integer
Dim dwReturn As Integer
Dim wNumVideoAllocated As Integer
Dim wNumAudioAllocated As Integer
End Structure

I use the following to access the structure...

Dim s As CAPSTATUS

bReturn = SendMessage(hHwnd, WM_CAP_GET_STATUS, Marshal.SizeOf(s), s)

Thanks a million for any assistance!

Thanks,
Jeremy

 

[Supra]

Function capGetStatus(ByVal lwnd As Integer, ByVal s As Integer, ByVal
wSize As Short) As Boolean
capGetStatus = SendMessage(lwnd, WM_CAP_GET_STATUS, wSize, s)
End Function

i haven't tried fLiveWindow yet. because i'm using winXp but doesn't
have capture card yet :-(
regards,

ken tucker is working on website project
regards

 

[Jeremy]

Thanks for your reply Supra,

I read an earlier discussion between you and Henry Wu:

http://groups-beta.google.com/group..._CAP_GET_STATUS&rnum=9&hl=en#960f363163cce7d1

Ken gave the following solution (which is what I am using to update
CAPSTATUS):

Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As
Integer, _
ByRef lParam As CAPSTATUS) As Boolean

Dim bReturn As Boolean
Dim wSize As Integer
Dim s As CAPSTATUS
bReturn = SendMessage(hHwnd, WM_CAP_GET_STATUS,
Marshal.SizeOf(s), s)
Debug.WriteLine(String.Format(­"Video Size {0} x {1}",
s.uiImageWidth, s.uiImageHeight))

Of course not the Debug.WriteLine statement. Since fLiveWindow always
returns true ("1") even with the camera disconnected I am either using
it incorrectly, or it simply has limitations. I am guessing I am using
it incorrectly because many (not all) of the other CAPSTATUS structure
values return 0 no matter what the preview window state.

Is there an event I can use that will fire if the connection status to
the camera changes?

Thanks,
Jeremy