Change DirectShow filter properties using code

[khodam]

Hello

I developed an application in C# using DirectShow.NET which can capture video from a source and create video.
I used several DirectShow filters such as ffdshow Deinterlace, Smart Tee, MPEG-2 Video Encoder, AVI Mux, File Writer and etc.
I want to change properties of MPEG-2 Video Encoder. I found this code:

IVideoEncoder videoEncoder = videoCompressorFilter as IVideoEncoder; 
object min, max, step; 
videoEncoder.GetParameterRange(PropSetID.ENCAPIPARAM_BitRate, out min, out max, out step); 
 
videoEncoder.SetValue(PropSetID.ENCAPIPARAM_BitRate, min);

but this code doesn't work.

After googling more I found this code which opens a filter's property window:

private void DisplayPropertyPage(IBaseFilter dev) 
{ 
    //Get the ISpecifyPropertyPages for the filter 
    ISpecifyPropertyPages pProp = dev as ISpecifyPropertyPages; 
    int hr = 0; 
 
    if (pProp == null) 
    { 
        //If the filter doesn't implement ISpecifyPropertyPages, try displaying IAMVfwCompressDialogs instead! 
        IAMVfwCompressDialogs compressDialog = dev as IAMVfwCompressDialogs; 
        if (compressDialog != null) 
        { 
 
            hr = compressDialog.ShowDialog(VfwCompressDialogs.Config, IntPtr.Zero); 
            DsError.ThrowExceptionForHR(hr); 
        } 
        else 
        { 
            MessageBox.Show("Item has no property page", "No Property Page", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); 
        } 
        return; 
    } 
 
    //Get the name of the filter from the FilterInfo struct 
    FilterInfo filterInfo; 
    hr = dev.QueryFilterInfo(out filterInfo); 
    DsError.ThrowExceptionForHR(hr); 
 
    // Get the propertypages from the property bag 
    DsCAUUID caGUID; 
    hr = pProp.GetPages(out caGUID); 
    DsError.ThrowExceptionForHR(hr); 
 
    //Create and display the OlePropertyFrame 
    object oDevice = (object)dev; 
    hr = OleCreatePropertyFrame(this.Handle, 0, 0, filterInfo.achName, 1, ref oDevice, caGUID.cElems, caGUID.pElems, 0, 0, IntPtr.Zero); 
    DsError.ThrowExceptionForHR(hr); 
 
    Marshal.ReleaseComObject(oDevice); 
 
    if (filterInfo.pGraph != null) 
    { 
        Marshal.ReleaseComObject(filterInfo.pGraph); 
    } 
 
    // Release COM objects 
    Marshal.FreeCoTaskMem(caGUID.pElems); 
}

It works but it's settings/properties doesn't save! Every time I should change it's properties. It weird because everytime GraphEdit opens it's property window, properties are correct (they are what I set).
What's wrong?
How can I change a filter's properties correcly?

Thanks
Regards