Canon SDK Live View

28 Jun, 2009 justin VB.NET

Okay, recently we needed to make a Canon EOS40D capture a Live Stream (keep in mind this is a Still Camera not a video camera) and pull the Live Stream back to a Windows Forms application and perform interactions with another system via Serial Commands. The biggest struggle throughout the project was the Live Stream. Taking pictures and the rest of the project was a snap (bad pun)….

There was absolutely NO documentation provided in a managed code such as .NET (which is what we were writing it in), Canon does not support the SDK, and documentation on the internet is nearly nothing.

Below is a sample of the LiveView loop and how to call it in a separate thread to make it run.

Imports System.Threading

Public LiveViewRunning As Boolean = False
Private LVThread As Thread

Public Sub PreviewOn()

LVThread = New Thread(AddressOf LiveView)

LiveViewRunning = True

LVThread.Start()

End Sub

Friend Sub LiveView()

While LiveViewRunning
            ' download a live view
            Dim pStream As IntPtr, pImageEvf As IntPtr, pCamera As IntPtr
            Dim result As UInteger
            result = EDSDK.EdsCreateMemoryStream(0, pStream)
            If EDS_ERR_OK <> result Then
                'Program.log(LogCategory.[Error], "Unable to create a memory stream:{0:X}", result)
                'MessageBox.Show("Unable to create a memory stream")
                Exit Sub
            End If

result = EDSDK.EdsCreateEvfImageRef(pStream, pImageEvf)
            If result <> EDS_ERR_OK Then
                'Program.log(LogCategory.[Error], "Unable to create EvfImageRef:{0:X}", result)
                'MessageBox.Show("Unable to create EvfImageRef")
                'cmd.result = False
                EDSDK.EdsRelease(pStream)

Exit Sub
            End If

pCamera = model.getCameraObject()

result = EDSDK.EdsDownloadEvfImage(pCamera, pImageEvf)
            If result <> EDS_ERR_OK Then
                'Program.log(LogCategory.[Error], "Unable to download Evf image:{0:X}", result)

'MessageBox.Show("Unable to download Evf image - " & Hex(result))

EDSDK.EdsRelease(pStream)
                EDSDK.EdsRelease(pImageEvf)

Exit Sub
            End If

'Program.log(LogCategory.Debug, "Downloaded Evf image data.")

' extract image data into

Dim ipData As IntPtr
            result = EDSDK.EdsGetPointer(pStream, ipData)
            If result <> EDS_ERR_OK Then
                'Program.log(LogCategory.[Error], "EdsGetPointer failed: {0:X}", result)

MessageBox.Show("EdsGetPointer failed")

EDSDK.EdsRelease(pStream)
                EDSDK.EdsRelease(pImageEvf)

Exit Sub
            End If

Dim len As UInteger
            result = EDSDK.EdsGetLength(pStream, len)
            If result <> EDS_ERR_OK Then
                'Program.log(LogCategory.[Error], "EdsGetLength failed:{0:X}", result)

MessageBox.Show("EdsGetLength failed")

EDSDK.EdsRelease(pStream)
                EDSDK.EdsRelease(pImageEvf)
                EDSDK.EdsRelease(ipData)

Exit Sub
            End If

Dim buffer() As Byte = New Byte(CInt(len)) {}

Marshal.Copy(ipData, buffer, 0, CInt(len))
            Dim memStream As New System.IO.MemoryStream(buffer)

' get the bitmap

Dim bitmap As Bitmap

bitmap = bitmap.FromStream(memStream)

PictureBox1.Image = bitmap

' cleanup
            memStream.Dispose()
            EDSDK.EdsRelease(pStream)
            EDSDK.EdsRelease(pImageEvf)

EDSDK.EdsRelease(ipData)

End While

End Sub

Canon SDK Live View

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