Video capturing delay (lag) by Itamar Shoham

Hi.
i'm using Microsoft.Expression.Encoder.Live.LiveJob with ConstantBitrate to capture from HD webcam (Logitec C910), and i'm having serious video delay issues.

i'm doing this inside Task with CancellationToken :
() =>
{
liveJob.Job.OutputFormat.VideoProfile.FrameRate = 15;

// Start capturing with live preview
liveJob.StartEncoding();

// loop until i get CancellationToken
..

// Stop capturing
liveJob.StopEncoding();
}

// Move resulted file...
// Close window
// re-open window, and re capture

for some reason, sometime the video actually get cut, and i dont get the last few seconds (before clicking the "stop" button and sending the cancellation token).
and sometimes, it have serious video delay. on Preview as well as the resulted video.

thank you in advance.

p.s.
Sometimes i get this error:
1. {"Error creating window handle."} - ErrorCode -2147467259, NativeErrorCode 87
2. Exception from HRESULT: 0x813A00B
3. Exception from HRESULT: 0x80040217
4. Error HRESULT E_FAIL has been returned from a call to a COM component
at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo)
at System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(Int32 errorCode)
at ThrowHRESULT(Int32 hr)
at MS.Internal.Expression.Encoder.Live.LiveDeviceSource.PickBestFormat(ValueType size, Int64 rtAvgTimePerFrame)
at Microsoft.Expression.Encoder.Live.LiveDeviceSource.PickBestVideoFormat(Size targetSize, Int64 frameDuration)
[then, by using Marshal.GetHRForLastWin32Error() i got: -2147024896    int (80070000 HEX)]